Epidemiological study on risk factors and risk reducing measures for campylobacter infections in Dutch broiler flocks.

From September 1991 until August 1993 an epidemiological study involving 20 Dutch broiler farms was conducted to identify risk factors and risk reducing measures for campylobacter infections in broiler flocks. Campylobacter spp. were detected in 64 (57%) of the 112 broiler flocks and in 25 (63%) of the 40 broiler cycles examined. Univariate analysis of farm management data was performed followed by logistic regression analysis of selected risk and risk reducing factors. The presence of other farm animals, including pigs, cattle, sheep and fowl, other than broilers, was found to be independently associated with an increased risk of campylobacter infections in broiler flocks (odds ratio (OR) = 11.81; P = 0.041). Further, the results indicate that application of specific hygiene measures during the rearing period, such as washing hands before tending the broiler flocks, the use of separate boots for each broiler house and the use of footbath disinfection when entering a broiler house, may significantly reduce the risk of campylobacter infections in broiler flocks.

Alcohol, fish, fibre and antioxidant vitamins intake do not explain population differences in coronary heart disease mortality.

BACKGROUND: Within the Seven Countries Study data we investigated whether population differences in 25-year mortality rates from coronary heart disease could be explained by population differences in alcohol, fish, fibre and antioxidant intake. METHODS: Baseline surveys were carried out between 1958 and 1964, on 12 763 middle-aged men constituting 16 cohorts in seven countries. In 1987 and 1988 equivalent food composites representing the average food intake of each cohort at baseline were collected locally and analysed for their fibre and antioxidant content in one central laboratory. The vital status of all participants was verified at regular intervals over 25 years. RESULTS: Alcohol and fish intake were inversely related to 25-year mortality from coronary heart disease in univariate analyses. These associations became non-significant when the confounding effects of saturated fatty acids, flavonoids and smoking were taken into account. Fibre and antioxidant vitamins intake were not related to coronary heart disease mortality in either uni- or multivariate analysis. CONCLUSION: These cross-cultural analyses show that alcohol, fish, fibre and antioxidant vitamins do not explain population differences in coronary heart disease mortality, independently of saturated fatty acids and flavonoids intake and cigarette smoking.

Coffee consumption, alcohol use, and cigarette smoking as determinants of serum total and HDL cholesterol in two Serbian cohorts of the Seven Countries Study.

The associations between serum total and HDL cholesterol and three lifestyle factors--consumption of Turkish coffee, consumption of alcohol, and cigarette smoking--were examined in two Serbian cohorts of the Seven Countries Study. In 1988 and 1989, 319 men from Zrenjanin and Belgrade, 65 to 84 years old and free of myocardial infraction, participated. The men from Zrenjanin were originally working in a large cooperative, and the men from Belgrade were faculty members of the university. HDL cholesterol, alcohol consumption, and cigarette smoking were significantly higher in Zrenjanin than in Belgrade. Serum total cholesterol levels and coffee consumption were not different. ANCOVA showed that serum total cholesterol levels were 8.2% higher (P < .05) in men consuming two small cups of coffee per day compared with abstainers, and this was also seen after adjustment for cigarette smoking, age, body mass index, cohort, and alcohol consumption. In men consuming one or more alcoholic drinks per day (more than 10 g/d alcohol), HDL cholesterol levels were increased by 0.19 mmol/L (15.4%) compared with men consuming no alcohol (P < .001). This association was stronger in the Zrenjanin cohort than in the Belgrade cohort (P < .05). Smoking was not associated with total cholesterol or with HDL cholesterol levels. In Serbian men, boiled Turkish coffee and alcohol consumption are independently associated with serum total and HDL cholesterol levels, respectively.

Stability of blood (pro)vitamins during four years of storage at -20 degrees C: consequences for epidemiologic research.

We studied the effects of frozen storage on (pro)vitamin concentrations in EDTA-plasma and whole blood. Aliquots from 55 samples were analyzed before storage and after 3, 6, 12, 24, 36 and 48 months at -20 degrees C. Dramatic decreases occurred for EDTA-plasma concentrations of vitamin E between 6 and 12 months, vitamin A, total carotenoids and beta-carotene after 1 year, and whole blood niacin. A smaller decrease was observed for folic acid at 1 year of storage, but the level remained constant thereafter. The vitamins D, B6, B12 (EDTA-plasma), B1 and B2 (whole blood) showed no decline during 4 years of storage. With the exception of folic acid, the observed decreases varied considerably among subjects. Therefore using EDTA-plasma stored longer than 1 year at -20 degrees C will result in highly attenuated odds ratios when assessing the relationship between vitamin A, carotenoids, or vitamin E with a given disease. Attenuation will also occur when using niacin concentrations in whole blood stored for 4 years at -20 degrees C.

Serum total cholesterol and long-term coronary heart disease mortality in different cultures. Twenty-five-year follow-up of the seven countries study.

OBJECTIVE: To compare the relationship between serum total cholesterol and long-term mortality from coronary heart disease (CHD) in different cultures. DESIGN: Total cholesterol was measured at baseline (1958 through 1964) and at 5- and 10-year follow-up in 12,467 men aged 40 through 59 years in 16 cohorts located in seven countries: five European countries, the United States, and Japan. To increase statistical power six cohorts were formed, based on similarities in culture and cholesterol changes during the first 10 years of follow-up. MAIN OUTCOME MEASURES: Relative risks (RRs), estimated with Cox proportional hazards (survival) analysis, for 25-year CHD mortality for cholesterol quartiles and per 0.50-mmol/L (20-mg/dL) cholesterol increase. Adjustment was made for age, smoking, and systolic blood pressure. RESULTS: The age-standardized CHD mortality rates in the six cohorts ranged from 3% to 20%. The RRs for the highest compared with the lowest cholesterol quartile ranged from 1.5 to 2.3, except for Japan's RR of 1.1. For a cholesterol level of around 5.45 mmol/L (210 mg/dL), CHD mortality rates varied from 4% to 5% in Japan and Mediterranean Southern Europe to about 15% in Northern Europe. However, the relative increase in CHD mortality due to a given cholesterol increase was similar in all cultures except Japan. Using a linear approximation, a 0.50-mmol/L (20-mg/dL) increase in total cholesterol corresponded to an increase in CHD mortality risk of 12%, which became an increase in mortality risk of 17% when adjusted for regression dilution bias. CONCLUSION: Across cultures, cholesterol is linearly related to CHD mortality, and the relative increase in CHD mortality rates with a given cholesterol increase is the same. The large difference in absolute CHD mortality rates at a given cholesterol level, however, indicates that other factors, such as diet, that are typical for cultures with a low CHD risk are also important with respect to primary prevention.

Changes in major risk factors for cardiovascular diseases over 25 years in the Serbian cohorts of the Seven Countries Study.

The Serbian cohorts of the Seven Countries Study were examined four times during a 25-year period. Large changes were observed in average serum cholesterol, blood pressure and the prevalence of smoking in these ageing cohorts. Comparison of men of the same age strata e.g. men aged 50-59 examined at baseline and after 10 years of follow-up and of men aged 65-69 examined after 10 and 25 years of follow-up showed that serum cholesterol increased by about 45% in Zrenjanin, 35% in Velika Krsna and 15% in Belgrade over the last 25 years. Systolic blood pressure increased by 9% in Zrenjanin and 7% in Velika Krsna. No significant increase in systolic blood pressure was observed in Belgrade. There was no major secular trend in smoking and the changes observed during 25 years were mainly due to ageing. No major change was observed in body mass index. The increases in serum cholesterol and blood pressure observed in the Serbian cohorts during the last 25 years are compatible with the increase in cardiovascular disease mortality observed in Yugoslavian men aged 30-69 during the period 1970-1984.

Serum cholesteryl ester fatty acids and their relation with serum lipids in elderly men in Crete and The Netherlands.

This study describes dietary fatty acid intake, as assessed from serum cholesteryl ester composition, and its relation to serum lipoprotein levels in 100 age-matched elderly men from Crete and Zutphen. All were survivors of the respective cohorts of the Seven Countries Study [Keys A (1980) Seven countries: a multivariate analysis of death and coronary heart disease. Cambridge, MA: Harvard University Press]. A significantly higher percentage of oleic acid and a significantly lower percentage of linoleic acid in the cholesteryl esters was observed in the Cretan compared with the Zutphen men. The mean serum total cholesterol levels of the elderly men in Crete and Zutphen were similar (5.98 and 5.92 mmol/l, respectively), but in the Cretans the HDL cholesterol level was significantly higher (1.28 vs 1.09 mmol/l). The percentage of smokers and the average body mass index did not differ between the Cretan and Zutphen men, but the percentage of severely overweight men was three times higher in the Cretan cohort. Among men in Zutphen the oleic acid content of the cholesteryl esters was positively associated with the HDL cholesterol level, independent of the effects of age, body mass index, cigarette smoking and alcohol intake. However, the difference in HDL cholesterol level between Zutphen and Crete could be explained to only a minor extent by differences in serum cholesteryl oleic acid, smoking, or obesity.(ABSTRACT TRUNCATED AT 250 WORDS)

The impact of the Guidelines for a Healthy Diet of The Netherlands Nutrition Council on total and high density lipoprotein cholesterol in hypercholesterolemic free-living men.

To study the impact of dietary intervention on the plasma total and high density lipoprotein cholesterol (HDL cholesterol) levels in hypercholesterolemic men, the authors selected 80 male participants in a monitoring risk factor project carried out in Amsterdam, The Netherlands. These men had plasma total cholesterol levels of between 6.5 and 10.0 mmol/liter (between 251 and 387 mg/dl) and were randomly assigned to either the intervention (n = 39) or the control (n = 41) group. At the start of the intervention period, after 5 weeks, and after 26 weeks, both the intervention and the control groups were examined. This examination consisted of a measurement of height, weight, plasma total and HDL cholesterol, and a dietary interview. The intervention program consisted of a personalized dietary advice to the respondent, based on the report of the Netherlands Nutrition Council. The study took place between September 1987 and November 1988. Because of this intervention program, the plasma total and HDL cholesterol levels decreased. The difference in change in plasma total cholesterol between the intervention and control groups was 0.47 mmol/liter (18 mg/dl) after 5 weeks and 0.30 mmol/liter (12 mg/dl) after 26 weeks. For HDL cholesterol, a significant difference in change after 5 weeks disappeared after 26 weeks. The public health implications of the decrease in plasma total cholesterol are discussed.

The prevalence of selected physical activities and their relation with coronary heart disease risk factors in elderly men: the Zutphen Study, 1985.

Physical activity patterns and their relation with coronary heart disease risk factors are described for a representative sample of 863 Dutch men, 65-84 years old, who participated in the 1985 survey of the Zutphen cohort of the Seven Countries Study. Cross-sectional results revealed a median total of reported physical activity of about 1 hour and 20 minutes per day; only 5.8% reported no physical activity. The percentage of participation and total weekly time spent in physical activity decreased as age increased; the decrease was less pronounced for walking, bicycling, gardening, and doing odd jobs than for sports, hobbies, and work. Statistically significant mean differences were found among quartiles of total weekly physical activity for both total cholesterol and high-density lipoprotein cholesterol (HDL cholesterol); however, only the differences for HDL cholesterol remained significant (p = 0.045) after adjusting for potential confounders. Statistically significant regression coefficients (p less than 0.05) were found for the independent association between walking and total cholesterol and between gardening and total cholesterol, HDL cholesterol, and systolic blood pressure, after adjusting for confounders. Total weekly physical activity and specific activities, e.g., gardening and walking, demonstrated generally favorable associations with cholesterol and systolic blood pressure.

Long-term prospective studies: the only solution?

One of the advantages of prospective studies in nutritional epidemiology is that dietary patterns and nutrient intake data are collected before the occurrence of the disease. With such a design it is possible to study the contribution of dietary variables in explaining the occurrence of diseases between different cultures and within populations. In order to make a good estimate of the relation between a dietary variable and the occurrence of a disease in long-term prospective studies, it is necessary to have insight in the changes of dietary variables with time. For prospective cohort studies also information about the reproducibility of a dietary variable is needed. Long-term prospective studies with repeated dietary measures provide a powerful tool in studying diet-disease relations, but practical limitations may prevent the implementation of such designs.

Changes in food and nutrient intake in middle-aged men from 1960 to 1985 (the Zutphen Study).

Within the Zutphen Study dietary surveys using the cross-check dietary history method were carried out in 1960, 1965, 1970, and 1985. Of the 872 men aged 40-59 y examined in 1960, 315 participated in all four surveys. In 1985 a small random sample of 51 men aged 40-59 y was also investigated. Between 1960 and 1985 the consumption of bread, potatoes, and edible fats decreased and the consumption of fruits, pastries, nuts, and alcoholic beverages increased in both the aging cohort and in the two independent samples of middle-aged men examined 25 y apart. These changes were accompanied by a substantial decrease in the intake of monounsaturated fat, polysaccharides, and potassium and a substantial increase in animal protein and alcohol. Small changes were observed in the intake of saturated fatty acids, polyunsaturated fatty acids, dietary cholesterol, and dietary fiber. Since 1960 some changes in a nutritionally desirable direction were observed but the diet of the Zutphen men in 1985 departs substantially from the guidelines for a healthy diet formulated by The Netherlands Nutrition Council in 1986.

The reproducibility of dietary intake data assessed with the cross-check dietary history method.

The reproducibility of food intake data from elderly men in the Zutphen Study (Zutphen, The Netherlands) was investigated in repeated dietary surveys carried out three (n = 115) and 12 (n = 145) months after the initial survey (April 1985). The differences in the reproducibility estimations for the two different time periods were generally small. The ratios of the interindividual and intraindividual variance were large for carbohydrates (2.6 and 2.7 for three months and 12 months, respectively) and small for vitamin A (1.1 and 0.4 for three months and 12 months, respectively). The larger this ratio, the higher the probability of detecting an existing relation. Information about inter- and intraindividual variation was used to calculate the attenuation factor. For most nutrients, the attenuation factor was about 0.8. This implies that a simple correlation between a nutrient and a risk factor will be only slightly lowered because of measurement error and the temporal variability of the dietary measurement when the cross-check dietary history method is applied once (e.g., a "real" correlation of 0.40 would be expected to be lowered to 0.32).

The relative validity of retrospectively assessed energy intake data in cases with myocardial infarction and controls (the Zutphen Study).

The relative validity of energy intake data, retrospectively collected after a 15-year period, was investigated. In 1970 dietary data were obtained by the cross-check dietary history method among 615 men aged 50-69. Between 1970 and 1985, 43 of these men had a non-fatal myocardial infarction. As controls 86 healthy men were selected. Of these 129 men, 112 were interviewed about their usual food intake in 1985 and in 1970. The retrospectively collected food intake data were compared with the data obtained in 1970. Retrospectively the average energy intake was overestimated by approximately 300 kcal/day. The amount of overestimation was statistically associated with change in energy intake, education and interviewer. The data collected in 1970 showed a significantly lower energy intake in cases compared with controls. However, the retrospectively assessed energy intake data showed no significant difference. A difference in energy intake between cases and controls may not be found when dietary intake data are assessed retrospectively.