Staff Publications

Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

    Full text documents are added when available. The database is updated daily and currently holds about 240,000 items, of which 72,000 in open access.

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    Very long-chain n-3 polyunsaturated fatty acids: a head start to win some years between the ears?
    Dullemeijer, C. - \ 2009
    Wageningen University. Promotor(en): Frans Kok; R.J. Brummer, co-promotor(en): I.A. Brouwer. - [S.l.] : S.n. - ISBN 9789085853770 - 136
    vetzuren met een lange keten - hersenen - cognitieve ontwikkeling - mentale vaardigheid - visoliën - ouderen - vaatziekten - omega-3 vetzuren - kenvermogen - long chain fatty acids - brain - cognitive development - mental ability - fish oils - elderly - vascular diseases - omega-3 fatty acids - cognition
    Very long-chain n-3 (or omega-3) polyunsaturated fatty acids have attracted considerable public interest during the past few years for their potential beneficial role in cognitive performance. The proposed benefits stretch from advantages in developing brains of infants and children to preventing cognitive decline at old age.
    In this thesis, we first examined the role of very long-chain n-3 PUFA at the beginning of the lifespan. We investigated the effects of dietary very long-chain n-3 PUFA on the fatty acid composition of the several brain lobes in juvenile pigs, and showed that a diet enriched with fish oil resulted in higher proportions of DHA in the frontal, parietal and occipital brain lobes compared with the temporal brain lobe. These findings suggest a region-specific incorporation of DHA in the developing brain, which may guide future research into the mechanism by which very long-chain n-3 PUFA may in involved in brain development and function.
    Subsequently, we investigated the role of very long-chain n-3 PUFA near the end of the lifespan. In a population of older adults, we investigated the association between very long-chain n-3 PUFA and cognitive decline over three years in multiple cognitive domains. We demonstrated that higher plasma proportions of very long-chain n-3 PUFA were associated with less decline in the cognitive domains sensorimotor speed and complex speed, but not in memory, information-processing speed and word fluency, compared with lower plasma proportions of very long-chain n-3 PUFA. These results suggest a beneficial role of very long-chain n-3 PUFA in the speed-related cognitive domains, which justifies future research in this area with sensitive cognitive outcome measurements that provide domain-specific information.
    Finally, we touched upon the role of very long-chain n-3 PUFA in the macrovascular and the microvascular blood supply in the head region. We showed that plasma very long-chain n-3 PUFA were not associated with changes in carotid intima-media thickness and common carotid distension in a healthy older adult population. This may suggest that the role of very long-chain n-3 PUFA in a healthy population extends in particular to the smaller blood vessels. The role of very long-chain n-3 PUFA in the microcirculation of the brain could therefore be an interesting future direction of research. Although we did not directly investigate the role of very long-chain n-3 PUFA in the brain microcirculation, we did investigate whether plasma very long-chain n-3 PUFA were associated with age-related hearing loss over a period of three years in older adults. Since microvascular disease may decrease the blood supply to the highly vascularised cochlea, this may result in age-related hearing loss. We showed that higher plasma proportions of very long-chain n-3 PUFA were indeed associated with less age-related hearing loss compared with lower plasma proportions of very long-chain n-3 PUFA which implies that the hypothesis of improved microcirculation, if proven correct, may have far-reaching consequences.
    In summary, this thesis showed that very long-chain n-3 PUFA have region-specific effects on the developing brain and that higher plasma proportions of very long-chain n-3 PUFA were associated with less decline in the speed-related cognitive domains and less age-related hearing loss. Further research is required to establish the role of very long-chain n-3 PUFA in the developing as well as the aging brain and to investigate the underlying mechanisms.

    “Very long-chain n-3 polyunsaturated fatty acids: a head start to win some years between the ears?” PhD-thesis by Carla Dullemeijer, Top Institute Food and Nutrition and Division of Human Nutrition, Wageningen University, Wageningen, the Netherlands, May 15, 2009
    Nutrition counselling in general practice: the stages of change model
    Verheijden, M.W. - \ 2004
    Wageningen University. Promotor(en): Wija van Staveren. - [S.I.] : S.n. - ISBN 9789085040507
    medische voorzieningen - artsen - gezondheidszorg - voedingsinformatie - volksgezondheid - modellen - vaatziekten - hart- en vaatstoornissen - medical services - physicians - health care - nutrition information - public health - models - vascular diseases - cardiovascular disorders
    Healthy lifestyles in the prevention of cardiovascular diseases are of utmost importance for people with non insulin-dependent diabetes mellitus, hypertension, and/or dyslipidemia. Because of their continuous contact with almost all segments of the population, general practitioners can play an important role in initiating and encouraging dietary change. Unfortunately, dietary change programs that may be successful on the short term, often do not lead to long-term success. Using the Stages of Change Model to tailor nutrition counselling activities to patients' different levels of awareness and motivation has been shown to increase program effectiveness. Data from our studies, showed that decreases in (saturated) fat intake were larger in patients who received tailored counselling than in patients who received usual care (total fat intake: -5.6 percent of energy versus -2.4 percent of energy). The extent to which patients reduced their (saturated) fat intake after a nutrition counselling program, however, did not depend on how much their levels of awareness and motivation had changed. In research, short questionnaires are used to measure patients' stage of change. In general practice, however, this does not usually happen and general practitioners likely estimate their patients' interest in lifestyle change. Our study showed that general practitioners do not accurately estimate their patients' readiness to reduce their dietary fat intake (Kappa=0.25). To make dietary counselling in general practice more effective, it was therefore suggested that general practitioners should repeatedly ask their patients about their interest in lifestyle change. In our studies, social support was an independent predictor of intention to reduce dietary fat intake. As our systematic review also supported the key role of social support in the long-termmaintenanceof dietary change, increasing levels of perceived social support should be incorporated in dietary change interventions. The role general practitioners can play in increasing social support, however, may be limited because of the non-reciprocal relationship they have with their patients. Internet has also been suggested as a potential tool to help achieve long-term dietary change. Our final study was therefore designed to study the effectiveness of web-based tailored nutrition counselling and social support for patients at elevated risk for cardiovascular diseases. Patients who reported to use the Internet regularly were either given access to an online counselling tool (intervention) or were given usual care (control). The 33% of the patients in the intervention group who used the online tool had larger reductions in systolic blood pressure (-5.3 mmHg versus -0.16) than patients who did not use the tool. No changes in social support were observed. Nutrition counselling based on the Stages of Change Model is a feasible approach in general practice. As patients' levels of awareness and motivation change continuously, general practitioners' repeated attention for lifestyle is necessary. Collaboration with dieticians can help overcome some of the barriers limiting nutrition counselling practices by general practitioners. In the future, Internet can also play an important role.
    Regular physical activity in old age : effect on coronary heart disease risk factors and well-being
    Schuit, A.J. - \ 1997
    Agricultural University. Promotor(en): F.J. Kok; E.G. Schouten. - S.l. : Schuit - ISBN 9789054857112 - 163
    gezondheidszorg - medische voorzieningen - sociale voorzieningen - therapie - sport - voedselhygiëne - voedingstoestand - consumptiepatronen - vaatziekten - bloedstoornissen - hart- en vaatziekten - hart- en vaatstoornissen - ouderen - ouderdom - nederland - health care - medical services - social services - therapy - sport - food hygiene - nutritional state - consumption patterns - vascular diseases - blood disorders - cardiovascular diseases - cardiovascular disorders - elderly - old age - netherlands

    Background. Regular physical activity is considered an important aspect of a healthy lifestyle. It may improve fitness, physical competence and may lower the risk of coronary heart disease (CHD). However, until now, data on the effects of regular exercise on CHD risk factors in elderly are limited, and there is a particular lack of data about the training effects on recently indicated risk factors, such as fibrinolytic and coagulation factors, and factors involved in the autonomic regulation of the heart.

    Methods . We have conducted a randomised, controlled intervention study, which addressed the effect of a 6 months training programme on 'classical' and 'new' CHD risk factors and well-being in 229 (intervention: 143 and control:86) apparently healthy, free- living elderly men and women (60-80 years).

    Results . Physical fitness (maximal exercise capacity) improved significantly in subjects of the intervention group (mean increase 14.1 Watt , 95%Cl: 10.1-18.1, +9%), compared to the controls. Among the classical CHD risk factors, only the reduction in serum triglyceride concentration in women was significant (-0.11 mmol/L, 95%Cl: -0.22-0.0, -7%). Blood pressure, high- and low density lipoprotein and total serum cholesterol concentration changed in a favourable direction, but not significantly from the control group. No effect of training on body weight and fasting insulin concentration was found. Among the new risk factors, the concentration of tissue type plasminogen activator (t-PA), a fibrinolytic factor, was significantly increased (+0.07 IU/mL, 95%Cl: 0.0-0.14,+11%) in subjects of the intervention group, while plasminogen activator inhibitor (PAI-1, inhibitor of fibrinolysis) was reduced, but not significantly different from the controls. These changes reflect an increase in fibrinolytic activity. However, fibrinogen concentration increased (+0.18 g/L 95%Cl 0.04-0.32,+6%). In addition, heart rate variability was increased and heart-rate- adjusted-QT interval was reduced in subjects of the intervention group (P<0.05). Both changes probably represent increase in parasympathetic activity and a more favourable autonomic regulation of the heart. Finally, physical self-efficacy was significantly improved in the subjects of the intervention group. Symptoms of depression were reduced, but not significantly different from the controls.

    Conclusion . Regular physical activity beneficially affected CHD risk factors, physical fitness and self-efficacy, which are important determinants of the quality of life and longevity in elderly. The magnitude of the benefits on CHD incidence remain unclear, since there is little information on the predictive value of the new risk factors in elderly. However, since elderly, in general, have advanced atherosclerosis and autonomic dysbalance, the improvements of these factors may be of particular importance in this age- group. In conclusion, our observations underline the importance of a public health policy aiming at stimulating regular physical activity in elderly people

    Movement and circulation : population studies on physical activity and cardiovascular disease risk
    Mensink, G.B.M. - \ 1997
    Agricultural University. Promotor(en): F.J. Kok; H. Hoffmeister; B.M. Bellach. - S.l. : Mensink - ISBN 9789054857426 - 149
    lichamelijke activiteit - vaatziekten - bloedstoornissen - hart- en vaatziekten - hart- en vaatstoornissen - sport - spel - lichamelijke opvoeding - physical activity - vascular diseases - blood disorders - cardiovascular diseases - cardiovascular disorders - sport - play - physical education

    The relationship of leisure-time physical activity with cardiovascular risk factors and mortality was determined using data from the German Cardiovascular Prevention Study, conducted from 1984-1991. Three nationally representative crosssectional samples, with a total of 7 689 men and 7 747 women, ages 25-69, were part of this study, originally designed to estimate the impact of community intervention on cardiovascular health. Additionally we analyzed regional cross-sectional and follow-up samples.

    Physically active individuals were more often urbanized, more likely to have high socioeconomic status, less often smokers and had healthier eating patterns and lower body mass index. Compared with sedentary individuals, the most active quartile of men (>18 kcal/kg/week spent on conditioning activities) had significantly favorable levels of serum total cholesterol (-2.5%), HDL/total cholesterol ratio (+4.2%) and resting heart rate (-4.3%). The most active women (>12 kcal/kg/week) had significantly better HDL cholesterol (+3.7%), HDL/total cholesterol ratio (+3.9%), triglycerides (-5.1%), diastolic (-1.3%) and systolic (-1.6%) blood pressure, body mass index (-2.8%) and resting heart rate (-2.5%). With duration and intensity constant, significantly better risk factor levels were observed with increased frequency of physical activity. For active men, we observed a relative risk of 0.33 (95% CI 0.11-0.94) for cardiovascular disease mortality and of 0.67 (95% CI 0.36-1.25) for all-cause mortality (5-8 year follow-up) compared with the least actives, independent of baseline risk factor levels. The elderly (ages 50-69) showed substantial benefits from participation in light to moderate activities, such as walking and cycling, most apparent when conducted frequently (≥5 times/week). Using data from the Spandau Health Test (1827 men and 2 929 women, ages 40-80, followed from 1982-1994) we estimated an all-cause mortality relative risk of 1.7 (95% CI 1.4-2.2) for men and 1.4 (95% CI 1.1-1.8) for women for each 20 beats/min higher resting heart rate.

    More than 40% of German adults are sedentary. We recommend them regularly, preferably daily, to conduct moderately intense activities, such as brisk walking, running, swimming or cycling, for at least 30 minutes. Elderly may prefer light activities, such as walking or gardening. An active lifestyle may substantially improve the cardiovascular risk profile of the German population. For example, if only 50% of sedentary German men, ages 40-69, would become modestly active more than 6 500 cardiovascular deaths could be prevented each year.

    Coagulation factor 7 in elderly people : genetic disposition and diet
    Mennen, L.I. - \ 1997
    Agricultural University. Promotor(en): F.J. Kok; D.E. Grobbee; E.G. Schouten. - S.l. : S.n. - ISBN 9789054857433 - 112
    vaatziekten - bloedstoornissen - hart- en vaatziekten - hart- en vaatstoornissen - voedselhygiëne - voedingstoestand - consumptiepatronen - genetische stoornissen - erfelijke ziekten - ouderen - ouderdom - vascular diseases - blood disorders - cardiovascular diseases - cardiovascular disorders - food hygiene - nutritional state - consumption patterns - genetic disorders - hereditary diseases - elderly - old age
    In elderly people an increase in thrombotic tendency may lead to a increase in the risk of a coronary event. Coagulation factor VII affects this thrombotic tendency and has been recognised as a risk indicator for coronary heart disease. It is not known whether the level of factor VII can be influenced at older age. From studies in young subjects it is clear that dietary fat and the R/Q353 polymorphism (alleles R and Q) are the main determinants of factor VII. We studied the relation of factor VII with diet in elderly men and women, taking the R/Q353 polymorphism into account.

    In a cross-sectional study among 1158 elderly men and women (>55 y) factor VII coagulant activity (FVII:C) and total factor VII (FVIIt) were investigated in relation to serum-triglycerides, the R/Q353 polymorphism and the habitual diet. FVII:C was inversely associated with dietary fibre and protein and positively with saturated fat intake and serum-triglycerides. These associations were much stronger in subjects with the RR genotype compared to those carrying the Q allele; if the mean intake of dietary fibre would increase with 10 g a day, FVII:C would be expected to decrease with 7.6 % in elderly people homozygous for the R allele versus only 1.9 % decrease in those carrying the Q allele. FVIIt was inversely related to intake of dietary fibre and positively to serumtriglycerides, again the associations being stronger in subjects with the RR genotype. In a cross-over study among elderly women (>60 y, 35 RQ/QQ, 56RR) the postprandial response of activated factor VII (FVIIa) to several fat-rich (50 g) breakfasts was evaluated. The response of (FVIIa) was very similar for meals rich in palmitic acid, rich in stearic acid or rich in linoleic/linolenic acid with a ratio of 3:1 or 15:1. The increase in FVIIa ranged from 14.9 (95% CI: 10.6,19.2) IUmL after the stearic rich breakfast to 21.1 (16.6,25.6) IU/mL after the linoleic/linolenic 15:1 rich breakfasts. After the fat-free control breakfast FVIIa decreased with 8.7 (6.3,11.1) IU/mL. The mean absolute total response to the fatrich breakfasts combined was 37 IU/mL in subjects with the RR genotype and 16.1 IU/mL in subjects carrying the Q allele. Also the response relative to the fasting (FVIIa) level differed significantly between the genotype groups (RR: 42%, RQ/QQ: 32%). Serumtriglycerides concentration was not associated with FVIIa.

    In elderly people, factor VII is influenced by dietary fibre, total dietary fat and serumtriglycerides and not by fat type. The R/Q353 polymorphism strongly modifies these effects. This indicates that an increase in dietary fibre and a decrease in dietary fat intake may reduce the risk of a coronary event by reducing the level of factor VII particularly in elderly people with the RR genotype.

    Dietary non-nutrients and haemostasis in humans : effects of salicylates, flavonoids and ginger
    Janssen, P.L.T.M.K. - \ 1997
    Agricultural University. Promotor(en): M.B. Katan; W.A. van Staveren; R.P. Mensink. - S.l. : S.n. - ISBN 9789054857037 - 70
    vaatziekten - bloedstoornissen - hart- en vaatziekten - hart- en vaatstoornissen - bloedsomloopstoornissen - bloedstolling - aspirine - salicylzuur - flavonen - flavonolen - flavonoïden - specerijen - kruiderijen - vascular diseases - blood disorders - cardiovascular diseases - cardiovascular disorders - circulatory disorders - blood coagulation - aspirin - salicylic acid - flavones - flavonols - flavonoids - spices - condiments

    In this thesis we studied the content of acetylsalicylate and total salicylates in foods, and we studied the effects of the dietary non-nutrients salicylates and flavonoids and of certain foods on haemostatic parameters in humans.

    Acetylsalicylic acid -aspirin- irreversibly inhibits platelet cyclo-oxygenase, leading to decreased platelet thromboxane A 2 production and decreased aggregation. Therefore it is effective as an anti-thrombotic drug in doses as low as 30 mg/d. Qualitative analyses by Swain et al suggested the presence of acetylsalicylate in foods. It was estimated that a normal mixed Western diet provides 10-200 mg/d of total salicylate and 3 mg/d of acetylsalicylate. We showed in 10 healthy subjects that 3 mg/d of acetylsalicylic acid decreased mean platelet thromboxane production by 39±8% (±sd). Thus, quantitative data on dietary acetylsalicylate deserved closer investigation. We determined acetylsalicylate and total salicylates in 30 foods using HPLC with fluorescence detection. Acetylsalicylate was lower than the detection limit (0.02 mg/kg for fresh and 0.2 mg/kg for dried products) in all foods. Total salicylates were 0-1 mg/kg in vegetables and fruits, and 3-28 mg/kg in herbs and spices. We showed that urinary excretion was a valid indicator for intake of pure (acetyl)salicylic acid (recovery 77-80%). We then studied urinary salicylate excretion in 17 subjects eating a variety of diets to estimate the content of bio-available salicylates of diets. Median excretion was 1.4 mg/24 h (range 0.8-1.6). Our data suggest that even purely vegetable diets provide less than 6 mg/d of salicylates, and no measurable acetylsalicylate. These amounts are probably too low to affect coronary heart disease risk, and worries about adverse effects of dietary salicylates on the behaviour of children may be unfounded.

    Others found that dietary flavonoids were associated with a reduced risk of coronary heart disease and stroke. This might be due to effects on haemostasis, because flavonoids have been reported to inhibit platelet aggregation in vitro . We found that concentrations of 2.5 μM of the flavone apigenin inhibited collagen- and ADP-induced platelet aggregation in vitro by about 26%, whereas the flavonols quercetin and quercetin-3-glucoside had no effect. No effects were found on platelet aggregation, thromboxane production, or other haemostatic parameters in 18 healthy subjects after they had consumed large amounts of quercetin- (onions) and apigenin-rich (parsley) foods daily for 7 d each. We conclude that claims for anti-aggregatory effects of flavonoids are based on the in vitro use of concentrations that cannot be attained in vivo . Our findings suggest that it is unlikely that reported effects of dietary flavonoids on coronary vascular disease risk are mediated through platelet aggregation or cyclo-oxygenase activity. Possible effects on known risk indicators for coronary heart disease from the coagulation cascade or the fibrinolytic system should be examined in a larger study.

    It has been claimed that ginger consumption exerts an anti-thrombotic effect by inhibiting platelet thromboxane production. We, however, found no effects on platelet thromboxane production in a placebo-controlled cross-over study in 18 healthy subjects after consumption of raw (-1±9%, mean±sd) or cooked ginger (1±8%).

    We conclude that contents of (acetyl)salicylate in foods are too low to affect disease risk. We could not confirm the putative anti-thrombotic effect of ginger, onions and parsley on haemostatic parameters in humans.

    Absorptie- en dispositiekinetiek van quercetine- glycosiden bij de mens
    Hollman, P.C.H. ; Leeuwen, S.D. van; Gaag, M.S. van der; Mengelers, M.J.B. ; Trijp, J.M.P. van; Vries, J.H.M. de; Katan, M.B. - \ 1996
    Voeding 57 (1996)3. - ISSN 0042-7926 - p. 28 - 28.
    bloedstoornissen - hart- en vaatziekten - hart- en vaatstoornissen - chemische analyse - chemische samenstelling - chlorofyl - ziektepreventie - flavonen - flavonoïden - voedingsmiddelen - isoprenoïden - metabolisme - planten - porfyrinen - preventie - preventieve geneeskunde - quercetine - steroïden - vaatziekten - blood disorders - cardiovascular diseases - cardiovascular disorders - chemical analysis - chemical composition - chlorophyll - disease prevention - flavones - flavonoids - foods - isoprenoids - metabolism - plants - porphyrins - prevention - preventive medicine - quercetin - steroids - vascular diseases
    Homocysteine, B-vitamins and cardiovascular disease : epidemiologic evidence
    Verhoef, P. - \ 1996
    Agricultural University. Promotor(en): F.J. Kok; M.J. Stampfer. - S.l. : Verhoef - ISBN 9789054855002 - 167
    cystine - cysteïne - methionine - aminozuren - chemie - nicotinamide - vitamine b complex - riboflavine - pantoteenzuur - choline - myo-inositol - vaatziekten - bloedstoornissen - hart- en vaatziekten - hart- en vaatstoornissen - epidemieën - epidemiologie - cystine - cysteine - methionine - amino acids - chemistry - nicotinamide - vitamin b complex - riboflavin - pantothenic acid - choline - myo-inositol - vascular diseases - blood disorders - cardiovascular diseases - cardiovascular disorders - epidemics - epidemiology
    Background Cardiovascular disease constitutes a major public health problem in the Netherlands and other Western countries. Elevated plasma homocysteine has attracted growing interest as a "new" risk factor for cardiovascular disease. Homocysteine is formed from the essential amino acid methionine. Defective Homocysteine, metabolism may lead to elevation of plasma total homocysteine (tHcy). Genetic enzyme deficiencies or inadequate intake of vitamins B 6 , B 12 , and folate, all important cofactors in homocysteine metabolism, may result in elevation of tHcy. Accumulation of tHcy can possibly promote atherosclerotic or thrombotic processes.

    Methods The epidemiologic studies presented in the thesis, aimed to find additional evidence for the hypothesis that elevated plasma tHcy is an independent risk factor for cardiovascular disease. We addressed various disease endpoints, with data of prospective and retrospective studies, from Dutch, European, and US populations. The role of the B-vitamins and of a genetic enzyme defect, predisposing to high tHcy levels, were studied.

    Results Overall, in line with other findings, most of our studies showed that elevated tHcy is an independent risk factor for cardiovascular disease. Results indicated that the risk increased with rising levels of tHcy, with no threshold effect. The estimated average % increase in risk for 5 μmol/L (about 1 SD) increase in fasting tHcy varied between 20% and 60% in the various studies. In a large European case-control study, we found that elevated tHcy was a strong risk factor in women, both in pre- and postmenopausal women.

    Folate concentrations in plasma or expressed per haematocrit, and dietary folate were found to be important determinants of plasma tHcy in several studies. In one of our studies, in concordance with findings of others, tHcy reached its nadir at a folate intake of 400 μg/day. Furthermore, we observed that homozygosity for a mutation in 5,10-methylenetetrahydrofolate reductase, in combination with low folate status, predisposed to particularly high tHcy levels, and may thereby increase risk of cardiovascular disease.

    Conclusions & implications Dietary folate intake of a large segment of the general population is lower than 400 μg/day, and tHcy may be generally increased. Several studies have already shown that elevated tHcy can be normalized by supplementation with folate, even at a dose of 650 μg/day. Thus, increased folate intake seems an important way to decrease tHcy in populations, thereby possibly reducing incidence of cardiovascular disease. Large-scale prevention trials are warranted to demonstrate the efficacy of tHcy-lowering, and the minimal folate intake required. At this moment, based on the available epidemiologic evidence, it is advisable to increase consumption of fruits and vegetables in the general population. Results from prevention trials will indicate whether additional measures, such as fortification of food or supplementation are justified as well.

    Prospective studies on coronary heart disease in the elderly : the role of classical and new risk factors
    Weijenberg, M.P. - \ 1996
    Agricultural University. Promotor(en): D. Kromhout; E.J.M. Feskens. - S.l. : Weijenberg - ISBN 9789090092096 - 161
    vaatziekten - bloedstoornissen - hart- en vaatziekten - hart- en vaatstoornissen - epidemieën - epidemiologie - ouderen - ouderdom - nederland - vascular diseases - blood disorders - cardiovascular diseases - cardiovascular disorders - epidemics - epidemiology - elderly - old age - netherlands
    In this thesis associations between biological risk factors and the occurrence of coronary heart disease in elderly persons are described. The focus is on classical (i.e. total and high density lipoprotein cholesterol and blood pressure) and some new (i.e. homocysteine, white blood cell count and serum albumin) biological risk factors. The studies are based on two Dutch cohorts. One is a cohort of 292 men and women, aged 64 to 87 years in 1971, from a general practice in Rotterdam, with a mortality follow-up of 17 years. The other is the Dutch cohort of the Seven Countries Study which consists of 939 men aged 64 to 84 years in 1985 from the town of Zutphen. The morbidity and mortality follow- up embraced five years.

    In general, the classical risk factors were important predictors of coronary heart disease occurrence in elderly people. Systolic blood pressure was a strong independent long-term predictor of coronary heart disease mortality in elderly women, but the long-term association was less clear in elderly men. Total cholesterol was also significantly associated with long-term mortality from coronary heart disease in elderly women, but in men the association tended to be inverted U -shaped, i.e. men with cholesterol levels in the median tertile of the cholesterol distribution had a higher risk than those with levels in the first and third tertile. Regarding the Zutphen study, the short-term associations with incidence of coronary heart disease were usually weaker than with mortality from the disease. Elevated systolic and diastolic blood pressure, and especially isolated systolic hypertension, were important short-term predictors of sudden cardiac death in elderly men. For mortality from coronary heart disease, which was not additionally recorded as sudden, U -shaped associations with systolic and diastolic blood pressure levels were observed, i.e. men with the lowest blood pressure levels and those with the highest blood pressure levels and using antihypertensive medication had the highest risk. Serum total cholesterol was related to short-term coronary heart disease mortality in elderly men. For incidence of the disease, an association was only observed in a subgroup of the population with serum albumin levels below the median. High density lipoprotein cholesterol was not predictive of mortality from coronary heart disease, but there appeared to be an association with the incidence of the disease.

    Concerning the new risk factors, serum homocysteine appeared to be associated with mortality from coronary heart disease in elderly men in the first one-and-a-half years of follow-up only. A strong association with mortality from cerebrovascular disease was observed in normotensive men. In addition, an association with an increased risk of cognitive impairment was suggested. Both white blood cell count and serum albumin were important predictors of coronary heart disease independent of the classical risk factors for coronary heart disease. The association with serum albumin could only partly be explained by baseline health status indicators.

    The experience obtained from the studies described in this thesis has made clear that elderly people are a heterogenous group with respect to risk factor levels as well as coronary heart disease risk. It would therefore be desirable to have a measure of susceptibility for coronary heart disease to identify elderly people who are at increased risk of the disease. Our studies suggest that white blood cell count and serum albumin, routine clinical blood chemistry values, may be useful in this respect in addition to the classical risk factors. Future studies should aim at assessing the effectiveness of a multifactorial approach of risk factor management on coronary heart disease and all-cause mortality as well as on quality of life in older men and women.

    Dietary fatty acids and risk factors for coronary heart disease : controlled studies in healthy volunteers
    Zock, P.L. - \ 1995
    Agricultural University. Promotor(en): J.G.A.J. Hautvast; M.B. Katan. - S.l. : Zock - ISBN 9789054853282 - 190
    vaatziekten - bloedstoornissen - hart- en vaatziekten - hart- en vaatstoornissen - vetzuren - voedselhygiëne - bloedvetten - lipoproteïnen - plantaardige vetten - plantaardige oliën - voeding - cholesterol - vascular diseases - blood disorders - cardiovascular diseases - cardiovascular disorders - fatty acids - food hygiene - blood lipids - lipoproteins - plant fats - plant oils - nutrition - cholesterol

    High levels of LDL cholesterol, blood pressure and Lp(a), and low levels of HDL cholesterol increase the risk for coronary heart disease (CHD). This thesis describes the effects of dietary fatty acids on these risk factors. In each of three trials we fed diets with tailored fatty acid composition to about 60 healthy men and women. Each diet within a trial was supplied to every volunteer for 3 weeks.

    In the first study we compared the effects of monounsaturated trans fatty acids with those of linoleic acid, the fatty acid from which trans fatty acids are formed upon partial hydrogenation, and with those of stearic acid, a product of complete hydrogenation of linoleic acid. Relative to linoleic acid, both trans fatty acids and stearic acid raised LDL and lowered HDL cholesterol. Thus, partial as well as complete hydrogenation of linoleic acid produces fatty acids that unfavorably affect serum lipids relative to linoleic acid itself. Trans fatty acids and stearic acid did not influence blood pressure, but trans fatty acids modestly raised Lp(a).

    The second study addressed the relative cholesterol-raising potentials of two specific saturates, myristic and palmitic acid. Relative to oleic acid, myristic acid was about 1.5 times as cholesterol-raising a's palmitic acid, due to increases in both LDL and HDL cholesterol. The differences between myristic and palmitic acid were statistically significant. However, both saturates caused high LDL cholesterol levels and raise the LDL to HDL cholesterol ratio.

    In the third study we examined the effect of the positional distribution of fatty acids within dietary triglycerides. Two diets had identical total fatty acid composition, but a major contrast in fatty acid configuration. Total, LDL, and HDL cholesterol levels were the same on both diets. The position of the dietary fatty acids was partly reflected in fasting plasma lipids, but the fatty acid configuration had no important effect on lipoprotein levels.

    In conclusion, monounsaturated trans fatty acids and the saturates myristic and palmitic acid have adverse effects on the serum lipoprotein risk profile for CHID. People at high risk for CHD should replace the hard fats in their diets by carbohydrates or unsaturated oils.

    Epidemiology of stroke : the role of blood pressure, alcohol and diet
    Keli, S.O. - \ 1995
    Agricultural University. Promotor(en): D. Kromhout; E.J.M. Feskens. - S.l. : Keli - ISBN 9789054854173 - 91
    hersenziekten - vaatziekten - bloedstoornissen - hart- en vaatziekten - hart- en vaatstoornissen - bloeddruk - alcoholische dranken - voedselhygiëne - voedingstoestand - consumptiepatronen - preventieve geneeskunde - ziektepreventie - preventie - epidemieën - epidemiologie - nederland - nederlandse antillen - brain diseases - vascular diseases - blood disorders - cardiovascular diseases - cardiovascular disorders - blood pressure - alcoholic beverages - food hygiene - nutritional state - consumption patterns - preventive medicine - disease prevention - prevention - epidemics - epidemiology - netherlands - netherlands antilles

    This thesis evaluates the recent trends in stroke mortality in the Netherlands Antilles, and the role of long-term blood pressure, alcohol and diet as risk factors for stroke incidence. The official mortality statistics and population data from the Netherlands Antilles over the period 1981-1992 were used to study trends in stroke mortality. The association of long-term blood pressure, alcohol and diet were studied with data from the Zutphen Study, a longitudinal study on risk factors for chronic diseases in the Netherlands. Repeated blood pressure measurements were collected yearly between 1960 and 1970. Information on alcohol and diet was collected in 1960, 1965 and 1970 with the crosscheck dietary history method. Stroke incidence data were present for the period 1970-1985.

    Age-adjusted stroke mortality declined over the period 1981-1986 in men and women in the Netherlands Antilles. Over the period 1987-1992 a slow down occurred in men, and in older women even an increase was observed. The average of individual repeated systolic blood pressure measurements over a period of 10 years was shown to be a better predictor of stroke incidence than single measurements. The latter understimated the stroke risk by 55%. Moderate alcohol consumption was associated with a nonsignificant 34% lower stroke risk. Consumption of one serving of fish per week was associated with a 50% lower stroke incidence compared with the consumption of less fish. Men with high intake of dietary flavonoids and men who drank their main source tea frequently had a 70% lower stroke incidence compared with men with a lower intake of flavonoids or tea. Men with high intake of beta-carotene had a 46% lower incidence of stroke, although this was not statistically significant. The effects of blood pressure, fish and flavonoids were independent from each other, and from other risk factors for stroke.

    We conclude that the decrease in stroke mortality in the Netherlands Antilles came to a standstill, and that long-term blood pressure and diet are important predictors of stroke.

    Blood cholesterol : a public health perspective
    Verschuren, W.M.M. - \ 1995
    Agricultural University. Promotor(en): D. Kromhout. - S.l. : Verschuren - ISBN 9789054854234 - 169
    vaatziekten - bloedstoornissen - hart- en vaatziekten - hart- en vaatstoornissen - bloed - cholesterol - lipiden - epidemieën - epidemiologie - nederland - vascular diseases - blood disorders - cardiovascular diseases - cardiovascular disorders - blood - cholesterol - lipids - epidemics - epidemiology - netherlands
    Changes in total cholesterol levels (TC) were studied using data from three epidemiological studies: about 30,000 men and women aged 37-43 were examined between 1974 and 1980 (CB Project), about 80,000 men aged 33-37 between 1981 and 1986 (RIFOH Project) and 42,000 men and women aged 20-59 from 1987 to 1992 (Monitoring Project on CVD Risk Factors). In men a decline in TC of 6.5% was observed between 1974 and 1992. However, the largest decrease took place between 1981 and 1986 in men in a limited age range (33-37 years), and there were indications that this decrease was not generalizable to other age groups. From 1987 to 1992, a decrease of 7% in HDL cholesterol levels (HDL-C) was observed in men, leading to an increase in the non-HDL-C/HDL-C ratio. In women, no changes in TC and HDL-C were observed.

    Analyses of data from 36,000 men and women aged 20-59 years showed that between ages 30 and 50 about 19-38% of the gender difference in TC was explained by differences in body mass index (BMI) and cigarette smoking between men and women. After age 50, the higher TC in women compared to men was largely due to the effect of the menopause. The TC increase associated with menopause was 0.45 mmol/l in non-smokers and 0.28 mmol/l in smokers. The difference between a low-risk and a high-risk lifestyle was 0.58 mmol/I for TC and 0.38 mmol/l for HDL-C in men, and 0.40 mmol/l for TC and 0.45 mmol/l for HDL-C in women.

    Twelve year follow-up of 50,000 men and women aged 30-54 (CB Project) showed that the adjusted relative risk for coronary heart disease (CHD) mortality for the highest compared to the lowest cholesterol quintile was 3.0 (95% CI 1.8-5.1) in men and 3.8 (95% Cl 1.1-13.1) in women. It was estimated that a TC reduction of 0.6 mmol/l was associated with a 20% lower CHD mortality. Low TC was not associated with non-cardiovascular mortality. All-cause mortality was positively related to total cholesterol, with a 60% and 46% higher risk in the highest compared to the lowest TC quintile for men and women respectively.

    Twenty-five year follow-up of the Seven Countries Study, in which over 12,000 men aged 40-59 at baseline participated, showed that relative risks for CHD mortality were similar in different cultures, but the absolute risks were strikingly different. At a cholesterol level of about 5.4 mmol/l agestandardized CHD mortality rates varied from 4% to 5% in Japan and Mediterranean Southern Europe to 15% in Northern Europe after adjustment for age, smoking and blood pressure. It was concluded that other factors, such as diet, typical for low-risk countries, modify the effect of TC on CHD mortality. In the Seven Countries Study, in non-smokers no association of TC with cancer mortality was observed, while non-cardiovascular/non-cancer mortality was elevated only at TC below 4.15 mmol/l. In smokers, cancer mortality and non-cardiovascular/non-cancer mortality were inversely associated with TC. All- cause mortality showed a J-shaped association with TC in non-smokers (lowest all-cause mortality for TC between 4.15 and 5.15 mmol/l), while all-cause mortality was unrelated to TC in smokers. Absolute mortality rates were higher in smokers than in non-smokers for all endpoints.

    Lowering the average TC level in the population is concluded to contribute to a reduction in the burden of CHD. Low cholesterol levels are not considered an important public health concern in the Netherlands. Changes in the lipid profile should preferably be achieved by lifestyle interventions such as a diet low in saturated fat and rich in fruits and vegetables, no cigarette smoking, a desirable body mass index (less than 25 kg/m 2) and a physically active lifestyle. Such a lifestyle will not only have a favorable impact on coronary heart disease, but is also compatible with recommendations on the prevention of other chronic diseases such as diabetes and cancer.

    Haemostase en het effect van voedingsvet.
    Cavelaars, A.E.J.M. ; Mennen, L.I. ; Verhoef, P. ; Dekker, J.M. ; Kok, F.J. - \ 1992
    Voeding 53 (1992)6. - ISSN 0042-7926 - p. 151 - 154.
    bloedstolling - bloedstoornissen - hart- en vaatziekten - hart- en vaatstoornissen - vetten - voeding - vaatziekten - blood coagulation - blood disorders - cardiovascular diseases - cardiovascular disorders - fats - nutrition - vascular diseases
    Een hoge consumptie van visolie die rijk is aan eicosapentaeenzuur, vermindert de bloedplaatjesaggregatie en daarmee het riisco op hart- en vaatziekte
    Inspanning en voeding bij diabetes, hart- en vaatziekten, overgewicht
    Erp-Baart, A.M.J. van; Katan, M.B. ; Kemper, H.C.G. ; Laan, J.A.M. van der; Morris, J.N. ; Nobel, E. de; Saris, W.H.M. ; Weeda, H.W.H. - \ 1985
    Alphen a/d Rijn : Samsom - ISBN 9789060165461 - 115
    bloedstoornissen - hart- en vaatziekten - hart- en vaatstoornissen - suikerziekte - diabetes mellitus - energiebehoeften - moeheid - voeding - obesitas - overgewicht - lichamelijke activiteit - vaatziekten - blood disorders - cardiovascular diseases - cardiovascular disorders - diabetes - diabetes mellitus - energy requirements - fatigue - nutrition - obesity - overweight - physical activity - vascular diseases
    Determinants of total and high density lipoprotein cholesterol in boys and men with special reference to diet
    Knuiman, J.T. - \ 1983
    Landbouwhogeschool Wageningen. Promotor(en): J.G.A.J. Hautvast, co-promotor(en): C.E. West. - Wageningen : Knuiman - 99
    bloed - bloedstoornissen - hart- en vaatziekten - hart- en vaatstoornissen - cholesterol - consumptiepatronen - voedselhygiëne - mannen - voedingstoestand - vaatziekten - blood - blood disorders - cardiovascular diseases - cardiovascular disorders - cholesterol - consumption patterns - food hygiene - men - nutritional state - vascular diseases
    At present it is assumed that atherosclerosis begins in childhood and that this process may ultimately result in the manifestations of coronary heart disease later in life. For this reason it is relevant to study the distribution of risk indicators for coronary heart disease (CHD) in children from different countries and to seek possible determinants of these risk indicators.

    In Chapter 1 a general overview is given of coronary heart disease and its determinants. The reasons and objectives for research on CHD and the risk indicators for CHD are also discussed.

    In Chapter 2 the results are presented of a study on the distributions of mean total and HDL cholesterol concentrations in boys aged 7 and 8 years from urban and rural regions in 16 countries. A standardized protocol was used for the collection of samples with the analyses being carried out in one laboratory. The results of this study showed that the concentrations of total cholesterol in Dutch boys are similar to those of boys from Denmark, Austria, Ireland and Sweden but are lower than those of Finnish boys and higher than those of African and Asian boys. The mean concentrations of HDL cholesterol of the boys appeared to increase linearly with that of total cholesterol. This would indicate that both the concentrations of total and HDL cholesterol increase under the influence of a westernized diet. It would also indicate that the mean concentration of HDL cholesterol would be positively related to the incidence of coronary heart disease when different populations are compared, provided that the findings in boys could be extrapolated to adults.

    Chapter 3 deals with the concentrations of total and HDL cholesterol in two age-categories of adult men from thirteen countries. The concentrations of total and HDL cholesterol were on average higher in the groups of men from the European countries than in those from Asia and Africa. Although the tendency for a concomitant increase of mean HDL cholesterol and total cholesterol concentrations was less clear in the adult men than it was in the boys, there was no tendency for lower HDL cholesterol concentrations in men with higher total cholesterol concentrations. The body mass index appeared to be positively related with the concentrations of total cholesterol and negatively with that of HDL cholesterol.

    Chapter 4 deals with the concentrations of total and HDL cholesterol in macrobiotic, vegetarian and non-vegetarian men and boys. The concentrations of both total and HDL cholesterol were lower in the macrobiotic men and boys than in the other groups except for the concentration of HDL cholesterol in the non-vegetarian men. The variation between groups in the concentration of HDL cholesterol appeared to be largely due to variations in the concentration of cholesterol in the HDL 2 fraction (1.063 < ρ 20 < 1.125).

    In Chapter 5 the results are described of a more in depth study on the determinants of total and HDL cholesterol in boys from Finland, the Netherlands, Italy, the Philippines and Ghana. Positive correlations were found between the intake of fat, saturated fatty acids, monounsaturated fatty acids and dietary cholesterol and the concentrations of total and HDL cholesterol within several groups. Using the regression coefficients from a multiple regression analysis on the pooled data, it could be calculated that on average 24 percent of the inter-country differences in the levels of total cholesterol is explained by differences in the intakes of saturated fatty acids. Differences between the groups of the different countries 'in the intakesof carbohydrate explained on average 29 percent of the differences in the concentrations of HDL cholesterol. The results support the hypothesis that higher concentrations of total and HDL cholesterol are associated with western types of diets which are rich in saturated fatty acids and relatively poor in complex carbohydrates.

    Chapter 6 contains a general discussion of the various studies. The main conclusions were the following:
    - young boys from countries like Finland, the Netherlands, Denmark, Austria and Sweden are likely to be at a higher risk of developing coronary heart disease than boys from Greece or Portugal and boys from Asian and African countries;
    - the negative relationship between HDL cholesterol concentration and mortality or incidence from coronary heart disease as found within populations is not incompatible with the absence of a negative or even the presence of a positive relationship between HDL cholesterol and mortality from coronary heart disease when different countries are compared;
    - the changes induced by diet in the concentrations of total and HDL cholesterol tend to be parallel;
    - high concentrations of HDL cholesterol associated with a high intake of animal fat probably reflect a higher capacity to handle large amounts of dietary fat;
    - low concentrations of HDL cholesterol associated with a high intake of animal fat probably reflect a lower capacity to handle large amounts of dietary fat or when associated with a low intake of fat a normal capacity to handle dietary fat;
    - diets with relatively high proportions of food from vegetable origin, especially those relatively rich in complex carbohydrates and relatively poor in saturated fat, together with a considerable proportion of physical activity and an optimum level of body fatness might be beneficial for the prevention of the development of atherosclerosis in childhood.

    Thus it has been shown that epidemiological studies can play an important role in elucidating the relationship between diet and coronary heart disease. In particular, it has been possible to develop hypotheses on the significance of the concentration of HDL cholesterol as a risk factor for coronary heart disease.

    Doelgroepsegmentatie in de primaire preventie van cardiovasculaire ziekten
    Kok, F.J. - \ 1982
    Landbouwhogeschool Wageningen. Promotor(en): A.W. van den Ban; J.G.A.J. Hautvast. - Wageningen : Kok - 103
    vaatziekten - bloedstoornissen - hart- en vaatziekten - hart- en vaatstoornissen - mortaliteit - gezondheid - doodsoorzaken - preventieve geneeskunde - ziektepreventie - preventie - gezondheidseducatie - vascular diseases - blood disorders - cardiovascular diseases - cardiovascular disorders - mortality - health - causes of death - preventive medicine - disease prevention - prevention - health education
    Profiles of target groups (target group segmentation) in the primary prevention of cardiovascular disease (CVD), can lead to an effective target group-directed approach in health education. Objectives in this thesis are: 1) To identify demographic and socioeconomic characteristics of such target groups. 2) To find personal and environmental determinants of preventive health behavior, which are useful as guidelines for intervention.

    Segmentation was performed on the basis of health behavior regarding cardiovascular risk factors like inadequate nutrition habits, smoking, obesity, and physical inactivity. Using linear discriminant analysis we examined for each of these life-style habits, which of a series of characteristics discriminated between the target group and a preventive group. This multivariate technique yields the independent contribution of a determinant by controlling for confounding.

    Data have been collected through a cross-sectional survey about knowledge, attitude and behavior regarding cardiovascular risk factors among the Dutch population in the age of 18 to 64 years. The study was carried out in 1978 by interviewing a national, stratified random sample of 889 men and 1,062 women. All participants were personally interviewed at their homes according to a partially structured questionnaire.

    Chapter 1 describes determinants of health and cardiovascular risk, in particular the role of life-style. Also the use of primary prevention and target group segmentation are discussed.

    In Chapter 2 we studied the interrelationship of different life-style habits. Although some risk habits were associated, the results did not suggest systematic clustering: a combination of three or four risk habits in one person did not occur more often than one would expect on the basis of probability. Because of the high prevalence of multiple risk habits and their cumulative effect on CVD risk, health education on a prudent life-style is still to be recommended. Segmentation identified as target group: men, with low level of education and occupation. Dissemination of knowledge and attitude change through audiovisual mass media can stimulate preventive health behavior.

    In Chapter 3 those individuals are characterized with dietary habits that were thought to increase CVD risk. Comparison with a group with a desirable food consumption pattern by means of discriminant analysis indicated that the target group included more men, in the age of 18 to 44 years, from large families and in the lower socioeconomic strata. According to the target group's preference, nutrition education methods should include audiovisual mass media as well as group counseling or face-to-face instruction directed at young families. Educational objectives are: increasing knowledge (composition of food products and meals), stimulating motivation for change and learning personal skills (food selection and preparation of wholesome meals).

    Chapter 4 deals with the dietary history recall method that evaluated the quality of the food consumption pattern. The questionnaire focussed on nutrients considered as important in a diet aiming at prevention of CVD: fats, polyunsaturated fats, simple carbohydrates, cholesterol, dietary fiber, and alcohol. To assess the preventive value of the diet, a food scoring system based on the criteria of a prudent diet was constructed. The rationale behind the scoring procedure was that frequent use of foods which are optimal from a preventive point of view leads to a high score.

    The method was validated on quantitative seven-day-record data and seems to be applicable in nutrition education programs. For the analysis in Chapter 3 the upper 30 percent of the nutrition score distribution was labeled desirable and the lowest 30 percent as undesirable food consumption pattern.

    In Chapter 5 results are presented of the relationship between body mass index (BMI) and sociodemographic and life-style characteristics. Because of the U-shaped relationship with overall mortality, BMI was introduced as continuous variable in a linear regression to avoid an arbitrarily chosen reference group.

    In both sexes, a strong positive association was found with age and a negative one with level of education. Irrespective of own level of occupation and education women with high familial social class had a lower BMI. Sedentary living was positively related to overweight in women. Among men an inverse relationship was revealed for unemployment and a U-shaped pattern for smoking: non-smokers and heavy smokers had the highest BMI. No effects were identified for alcohol consumption and leisure time physical activity. An inventory of opinions relating to dietary habits and physical exercise may be useful for therapy.

    The differences of smokers, who failed in one or more cessation attempts of at least one month and ex-smokers - those who quitted at least a year ago - are reported in Chapter 6. This contrast was studied because the increase of non-smokers in the Netherlands in the seventies was hardly the consequence of a rise in the number of ex- smokers.

    The profile of the failing quitter could aid to give up the smoking habit successfully. Failing attempts were associated with men, younger age (18-34 year), a low educational level and divorced/widowed status. The fact that several univariate differences disappeared in a multivariate model, was in agreement with other findings of intercorrelation among smoking predictor variables e.g., tobacco consumption, number of inhalers, alcohol intake, skipping breakfast, obesity and leisure-time physical inactivity. These and other findings may be useful to design more effective smoking cessation programs.

    In Chapter 7 we identified those individuals who did not exercise regularly in leisure time. Sixty minutes per week engaging in sports or its equivalents in cycling (75 min/week) or walking (90 min/week) were cut-off points in classifying active and inactive subjects. Inactivity was defined as limited or not regular practice of any activity. Those who regularly participated in at least two activities and exceeded the time limits were classified as active.

    After adjustment for sedentary living, independent determinants of the target group were older age (55-64 yr), lower educational attainment and large families. Therefore programs promoting physical fitness, stimulating motivation, and encouraging social support, should address older people and large families.

    Chapter 8 includes a general discussion and guidelines for health education. Sources of bias (selection, information, and confounding bias) that may affect the validity of the results, the choice of the contrasts for segmentation, and the importance of multivariate analysis are discussed.

    Our study with its shortcomings is placed in a framework for planning of health education in solving health problems. For target group-directed educational programs, we gave guidelines for contents and methods and arguments to prefer a 'population-strategy' over a 'high-risk-strategy' in a prevention policy.

    Finally we dealt with a topic of discussion in health education: to advise or to inform the public.

    comparison of various cholesterol lowering diets in young healthy volunteers : effects on serum lipoproteins and on other risk indicators for cardiovascular diseases
    Brussaard, J.H. - \ 1981
    Landbouwhogeschool Wageningen. Promotor(en): J.G.A.J. Hautvast, co-promotor(en): M.B. Katan. - Wageningen : Brussaard - 109
    voeding - cholesterol - voedselhygiëne - voedingstoestand - consumptiepatronen - vaatziekten - bloedstoornissen - hart- en vaatziekten - hart- en vaatstoornissen - dieet - diëtetiek - nutrition - cholesterol - food hygiene - nutritional state - consumption patterns - vascular diseases - blood disorders - cardiovascular diseases - cardiovascular disorders - diet - dietetics
    This thesis deals with the effect of type and amount of dietary fat on the concentration and composition of serum lipoproteins, colonic function, plasma glucose and serum insulin levels and blood pressure in healthy human volunteers.

    Two experiments were carried out. In the first experiment with 60 volunteers a moderate fat diet with a high proportion of polyunsaturated fatty acids (as recommended by several advisory bodies), was compared with three other diets during a test period of 5 weeks. One diet was low in total fat with a low proportion of polyunsaturated fatty acids, one diet was high in total fat with a high proportion of polyunsaturated fatty acids and one was high in total fat with a low proportion of polyunsaturated fatty acids. In the second experiment with 35 volunteers the moderate fat diet rich in polyunsaturated fatty acids and the low fat, low polyunsaturated fatty acid diet were compared again, but this time the test period lasted 13 weeks. The diets were composed of regular foodstuffs and differed in carbohydrate and fat content or fatty acid composition only. There were only minor differences in intake of dietary fiber and other nutrients known to affect cholesterol metabolism. Subjects in both studies were under strict dietary control. All foodstuffs, except for 100 kcal (0,4 MJ) per day were supplied individually according to each person's energy need. Actual food intake was measured by food records and analysis of double portions. The fatty acid composition of cholesterol esters in serum was analysed in the second experiment in order to check adherence to the diets.

    The serum lipoprotein composition and concentration observed during the experiments are given in Chapters 2 and 3. In serum, total cholesterol , triglycerides, apolipoprotein-A I and -B were measured; in high-density-lipoprotein (HDL), cholesterol was measured; in low-density-lipoprotein (LDL), cholesterol and triglycerides were measured and in very-low-density-lipoprotein (VLDL), triglycerides, apolipoprotein-B and the apolipoprotein-C II /C III ratio were measured. From these experiments two conclusions can be drawn. Firstly, that both a low fat diet, low in polyunsaturated fatty acids and a moderate fat diet, high in polyunsaturated fatty acids lower total serum cholesterol levels when compared with the habitual diet of affluent communities. Secondly, that a low fat diet causes lower HDL-cholesterol and higher fasting VLDL-triglyceride levels than a moderate-fat diet, high in polyunsaturated fat.

    It is by no means certain that changes in the concentration of HDL and VLDL really result in changes in the risk of death from cardiovascular diseases. In long-term intervention trials, such a hypothesis has not been tested; only the effect of changes in serum total cholesterol has been studied in intervention trials.

    Chapter 4 deals with effects on colonic function. No changes in mean transit time through the gut, fecal wet and dry weight, frequency of stools and concentration of fecal steroids were found. This shows that the intake of dietary fiber had been roughly equal in all diet groups within each experiment. Because there were no consistent short- or long-term changes in fecal bile acid or neutral steroid excretion, it is concluded that changes at the intestinal level do not explain the changes in total serum cholesterol concentration.

    Chapter 5 gives the results of measurements of fasting and postprandial serum insulin and glucose concentrations. The results show, that neither the amount nor the type of dietary fat had a strong influence on these variables in healthy subjects.

    Chapter 6 describes the effect of type and amount of dietary fat on blood pressure as well as the effect of dietary fiber from various sources and type of protein. None of these dietary components had a demonstrable effect on blood pressure in young normotensive subjects.

    The results of these experiments do not call for changes in the dietary recommendations of the Netherlands Nutrition Council, as far as the risk of death from cardiovascular diseases is concerned.

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