Fruits and vegetables and the risk of epithelial cancer

In this thesis, prospective studies on fruit and vegetable consumption in relation to epithelial cancer risk were described. The main research question was whether higher intakes were related to lower risks of epithelial cancers, mainly of lung cancer.In the Seven Countries Study, at the population level, consumption of fruits, vegetables and total plant foods was not related to colorectal cancer risk, whereas a difference of 10 g/d of fiber intake was associated with a 33% lower risk. Average population consumption of fruit was inversely and of refined grains positively related to population stomach cancer risk. Low consumption of fruits was however strongly correlated with high refined grain consumption.Fruit but not vegetable consumption was inversely associated with 25-year lung cancer mortality among European smoking men. This association was confined to heavy cigarette smokers. In Dutch men and women aged 20-59, vegetable consumption was inversely associated with lung cancer incidence, particularly of adenocarcinomas. Fruit consumption was not related to lung cancer after adjustment for smoking.Adherence to the dietary guidelines for fruits and vegetables was inversely associated with cancer incidence in Dutch elderly men. Consumption of the recommended amount of fruit was related to a 38% lower risk, while vegetables were not associated. Variety in vegetable intake was however inversely related to total and non-lung epithelial cancer.Plasma carotenoid concentrations were only crude indicators of usual vegetable and fruit intake in Dutch men and women aged 20-59. Plasmaβ-cryptoxanthin indicated fruit intake and total intake of vegetables, fruits and juices, whereas lutein was a marker for vegetable intake. Concentrations of carotenoids coul d not differ between all four quartiles of intake.During 1987/88-1997/98, the mean fruit and vegetable consumption (excluding juices) decreased with 34 g/d (12%) in Dutch men and 23 g/d (8%) in Dutch women. The consumption was lowest and decreased most in those aged 19-35 with a low level of education. Using a computer simulation model, the maximum theoretically reduction in cancer incidence, i.e., when all would consume the recommended 400 grams daily, was estimated to be 14 to 22% for this group.Valid assessment of fruit and mainly of vegetable intake, residual confounding by smoking and enough power of the study are major methodological concerns. In recent cohort studies weaker associations were observed compared to earlier risk estimates. Taken all evidence together, an inverse association between fruit and vegetable intake and cancer of the lung, stomach and colon/rectum is still indicated. There is not enough evidence yet to point at specific fruits and vegetables or plant compounds as responsible actors.</p

Etiology of atopy in infancy: the KOALA Birth Cohort Study.

PG - 679-84 AB - The aim of the KOALA Birth Cohort Study in the Netherlands is to identify factors that influence the clinical expression of atopic disease with a main focus on lifestyle (e.g., anthroposophy, vaccinations, antibiotics, dietary habits, breastfeeding and breast milk composition, intestinal microflora composition, infections during the first year of life, and gene-environment interaction). The recruitment of pregnant women started in October 2000. First, participants with 'conventional lifestyles' (n = 2343) were retrieved from an ongoing prospective cohort study (n = 7020) on pregnancy-related pelvic girdle pain. In addition, pregnant women (n = 491) with 'alternative lifestyles' with regard to child rearing practices, dietary habits (organic, vegetarian), vaccination schemes and/or use of antibiotics, were recruited through organic food shops, anthroposophic doctors and midwives, Steiner schools, and dedicated magazines. All participants were enrolled between 14 and 18 wk of gestation and completed an intake questionnaire on family history of atopy and infant care intentions. Documentation of other relevant variables started in the pregnant mother and covered the first and third trimester as well as early childhood by repeated questionnaires at 14-18, 30, and 34 wk of gestation and 3, 7, 12, and 24 months post-partum. A subgroup of participants, including both conventional and alternative lifestyles, was asked to consent to maternal blood sampling, breast milk and a faecal sample of the infant at 1 month post-partum, capillary blood at age 1 yr, venous blood and observation of manifestation of atopic dermatitis during home visits at the age of 2 yr (using the UK working party criteria and the severity scoring of atopic dermatitis index), and buccal swabs for DNA isolation from child-parent trios. From the start, ethical approval and informed consent procedures included gene-environment interaction studies. Follow-up at 3 and 7 months post-partum was completed with high response rates (respectively 90% and 88% in the conventional group, and 97% and 97% in the alternative group). The home visits at 2 yr of age will be completed in 2005. Preliminary results show that we have succeeded in recruiting a large population with various lifestyle choices with a fairly large contrast with regard to dietary habits (including organic foods, vegetarian diet), vaccination schemes and/or use of antibiotics. We have also been able to collect a large number of faecal samples (n = 1176) and capillary blood samples at age 1 yr (n = 956). Furthermore, a large proportion of the participants have consented with genetic studies. Mid 2006 we expect to report our first results on the relationship between the various exposures in early life and childhood atopy. An outline of the focus and design of the KOALA Birth Cohort Study is presented. AD - Department of Epidemiology, Care and Public Health Research Institute (Caphri), Maastricht University, Maastricht, The Netherlands. [email protected]