Plain language summary
Population and animal studies suggest that fat in the diet may have an influence on the development of breast cancer, but the results of studies in humans are inconsistent. This randomised controlled trial aimed to determine the effects of a lower-fat diet during childhood and adolescence on markers associated with breast cancer risk in adults. Female participants were initially recruited at age 8-10 years old, as part of a study to test the effects of lower-fat diets on cholesterol levels in children. The study diet limited total fat intake to 28% of calories (<8% saturated fat, <9% polyunsaturated fat, remainder monounsaturated), cholesterol was limited to 150mg/day and consumption of fibre was encouraged. The children followed the diet for 7 years, when the trial was terminated. This follow-up study was conducted 9 years later, when the participants were aged 25 to 29 years old. After adjusting for current diet, the lower-fat diet group had significantly higher oestradiol levels and bone mineral density. Progesterone concentrations and breast density did not differ between the two groups. The authors concluded that consumption of a lower-fat diet during adolescence does not appear to affect factors associated with breast cancer risk. Current diet may be more important than adolescent diet in determining hormone levels in premenopausal women.
Abstract
BACKGROUND Adolescent diet is hypothesized to influence breast cancer risk. We evaluated the long-term effects of an intervention to lower fat intake among adolescent girls on biomarkers that are related to breast cancer risk in adults. METHODS A follow-up study was conducted on 230 girls who participated in the Dietary Intervention Study in Children (DISC), in which healthy, prepubertal, 8 to 10 year olds were randomly assigned to usual care or to a behavioral intervention that promoted a reduced fat diet. Participants were 25 to 29 years old at follow-up visits. All tests of statistical significance are two-sided. RESULTS In analyses that did not take account of diet at the time of the follow-up visit, the only statistically significant treatment group difference was higher bone mineral content in intervention group participants compared with usual care group participants; their mean bone mineral contents were 2,444 and 2,377 g, respectively. After adjustment for current diet, the intervention group also had statistically significantly higher bone mineral density and luteal phase serum estradiol concentrations. Serum progesterone concentrations and breast density did not differ by treatment group in unadjusted or adjusted analyses. CONCLUSIONS Results do not support the hypothesis that consumption of a lower fat diet during adolescence reduces breast cancer risk via effects on subsequent serum estradiol and progesterone levels, breast density, or bone mineral density. It remains unclear, however, if the results are specific to the DISC intervention or are more broadly applicable. IMPACT Modest reductions in fat intake during adolescence are unlikely to lower later breast cancer risk via long-term effects on the biomarkers measured.
Methodological quality
Jadad score
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2
Allocation concealment
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Not applicable
