Trans-fats harm may extend to prostate: study
non-aggressive prostate tumours by about 100 per cent, suggests new
research from Harvard.
The study followed almost 15,000 men over 13 years and piles further pressure on the fatty acids after significant prostate cancer risk increases were observed for higher intakes of the trans isomers of oleic and linoleic acids. "Blood levels of trans isomers of oleic and linoleic acids are associated with an increased risk of non-aggressive prostate tumours," wrote lead author Jorge Chavarro in the journal Cancer Epidemiology Biomarkers & Prevention. "As this type of tumours represents a large proportion of prostate cancer detected using prostate-specific antigen screening, these findings may have implications for the prevention of prostate cancer." Though trace amounts of trans fats are found naturally, in dairy and meats, the vast majority are formed during the partial hydrogenation of vegetable oil that converts the oil into semi-solids for a variety of food applications. Trans-fatty acids (TFAs) are attractive for the food industry due to their extended shelf life and flavour stability, and have displaced natural solid fats and liquid oils in many areas of food processing. But scientific reports that trans fatty acids raise serum levels of LDL-cholesterol, reduce levels of HDL-cholesterol, can promote inflammation can cause endothelial dysfunction, and influence other risk factors for cardiovascular diseases (CVD), has led to a well-publicised bans in New York City restaurants, and other cities, like Boston and Chicago, considering similar measures. The new study adds to a small number of previous studies reporting that increased levels of markers of trans-fat intake are associated with an increase risk of cancer of the prostate. The researchers, from Harvard School of Public Health, Brigham and Women's Hospital and Harvard Medical School, obtained blood samples from 14,916 apparently health men in 1982 and, among the 476 men who developed prostate cancer during 13 years of follow-up, quantified the blood levels of fatty acids. These measurements were subsequently compared with healthy controls, matched by age and smoking status. Chavarro and co-workers report that, in general, no link was observed between total trans-fats levels and overall prostate cancer risk. However, when they considered blood levels in relation to the aggressiveness of the tumours, they observed significant and positive increases in the risk of non-aggressive prostate tumours. Indeed, the highest blood levels of trans oleic acid and linoleic acids (18:1n-9t and 18:2t) were associated with a 116 and 97 per cent increase in the risk of non-aggressive prostate tumours, respectively, compared to the lowest levels. On the other hand, no link was observed with aggressive prostate tumour risk, reports Chavarro and co-workers. At last year's IFT in Chicago, Walter Willett from Harvard School of Public Health said that limiting and labelling trans fatty acids in food is not enough, and they should be banned. Professor Willett, who was also co-author on the new study, told food manufacturers and food professionals in Chicago that Denmark had taken the right approach to the trans-fatty acid issue - Denmark introduced legislation in 2004 that required locally and imported foods to contain less than two per cent industrially made TFAs, a move that effectively abolished the use of partially hydrogenated vegetable oils in the country. "Human life is more important that shelf life," said Willett. "Food scientists are capable of creating products that are free of trans fats and still have shelf life." According to the European School of Oncology, over half a million news cases of prostate cancer are diagnosed every year world wide, and the cancer is the direct cause of over 200,000 deaths. More worryingly, the incidence of the disease is increasing with a rise of 1.7 per cent over 15 years. Source: Cancer Epidemiology Biomarkers & Prevention 1 January 2008, Volume 17, Pages 95-101, doi: 10.1158/1055-9965.EPI-07-0673 "A Prospective Study of Trans-Fatty Acid Levels in Blood and Risk of Prostate Cancer" Authors: J.E. Chavarro, M.J. Stampfer, H Campos, T. Kurth, W.C. Willett, J. Ma