Low Fat Diet :: Low fat diets reduce breast cancer risks
The first experiment ever to show low-fat diets could help prevent a return of breast cancer now reveals, with longer followup, that the benefit was almost exclusively to women whose tumour growth was not driven by hormones.
Five servings of fruit and vegetables per day and a diet low in fat reduced the risk of breast cancer by nine per cent, a figure dismissed as not significant and due to ?chance?.
Several epidemiological, animal and population-based studies have associated high-fat diets with higher rates of breast cancer, but the link had never been tested by a clinical intervention trial.
The Women’s Health Initiative (WHI) Dietary Modification Trial enrolled 48,835 post-menopausal women with an average age of 62.3 between 1993 and 1998. The average follow-up time was 8.1 years.
Dietary intervention for 19,541 women entailed cutting down fat intake to less than 20 per cent, eating five servings of fruit and vegetables, and six portions of grains per day. The other 29,294 women ate a normal diet.
The intervention trial, reported in the Journal of the American Medical Association (Vol. 295, pp. 629-642), succeeded in reducing fat intake by 8.2 per cent and increasing vegetable intake by 1.1 servings.
“After approximately eight years of follow-up, breast cancer incidence was nine per cent lower in the dietary intervention group compared with women in the comparison group,” said lead researcher Ross Prentice from the Fred Hutchinson Cancer Research Center.
However, “because incidence rates did not differ between the intervention group and the comparison group at the conventional 0.05 level of significance, chance provides an explanation for the modestly lower breast cancer incidence rates in the intervention group,” said Prentice.
The disagreement between earlier studies and this new intervention study highlight the limitations of the present study. Thirty-five per cent of the volunteers were overweight, based on BMI measures, while over thirty per cent were obese.