Fats and breast cancerMILAN, ITALY. The association between the intake of various fats and oils and the risk of breast cancer has been the subject of several studies. There is still no real consensus as to which fats are beneficial and which are not. The evidence for a protective role of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), the main components of fish oils, is probably the strongest.Researchers at the Italian National Cancer Institute have just completed an investigation aimed at clarifying the association between fat intake and breast cancer risk. A total of 4052 postmenopausal women were followed for an average of 5.5 years. During this time 71 cases of invasive breast cancer were diagnosed. The cancer patients were matched with 141 controls. All study participants had blood samples drawn and red blood cell (erythrocyte) membranes were analyzed for their fatty acid content. The researchers point out that erythrocyte membranes are good biomarkers for not only dietary fat intake, but also for other dietary and hormonal factors.Women with DHA concentrations in the highest tertile had less than half the risk of breast cancer than did women in the lowest tertile. Polyunsaturated fatty acids overall were also protective with omega-3 acids being somewhat more protective than omega-6 acids. Saturated fatty acid concentrations were not significantly related to breast cancer risk. A higher concentration of monounsaturated fats, especially oleic acid, was associated with a significantly increased risk. The researchers point out that most oleic acid in mammalian tissue is derived from saturated stearic acid through a process involving the enzyme delta 9-desaturase. Saturated fatty acids, cholesterol, carbohydrates, insulin, testosterone, and estrogen all activate this enzyme whereas dietary polyunsaturated fatty acids and fasting deactivate it. The researchers conclude that the delta 9-desaturase enzyme may be an important link between breast cancer risk and dietary fat consumption and urge further research in the field.Pala, Valeria, et al. Erythrocyte membrane fatty acids and subsequent breast cancer: a prospective Italian study. Journal of the National Cancer Institute, Vol. 93, July 18, 2001, pp. 1088-95
Breast cancer risk linked to fatty acid profile
CHAPEL HILL, NORTH CAROLINA. Breast cancer rates differ greatly between countries. They are 5 times higher in the United States than in Japan and twice as high in France as in neighbouring Spain. Differences in overall fat consumption in these countries have been extensively studied, but no link to breast cancer incidence has been detected so far. A large team of researchers from the Netherlands, Ireland, Spain, Finland, Switzerland, Germany and the United States now report that, while overall fat consumption may not be significant, the make-up of the fats could be. As part of the large EURAMIC Study the researchers investigated the link between the content of polyunsaturated fats in adipose (fat) tissue of postmenopausal women and breast cancer incidence. A total of 291 women with breast cancer and 351 controls were included in the study which involved 5 European medical centers. The women all had samples of adipose tissue taken (from the buttocks) and analyzed to determine the concentration of the main polyunsaturated fatty acids: the omega-3 acids - alpha-linolenic acid (ALA), eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), and the omega-6 acids - linoleic acid (LA) and its metabolite arachidonic acid (AA).
The study found no significant correlation between omega-3 fatty acid levels and breast cancer incidence, but did find a trend to increasing incidence with increasing levels of omega-6 fatty acids in the adipose tissue samples. The researchers also found a significant association between the ratio of EPA and DHA to LA levels and breast cancer incidence in 4 out of 5 of the medical centers involved in the study. Pooling all results showed that women with the highest ratio had a 35% lower breast cancer incidence than women with the lowest ratio. In other words, women with a relatively high adipose tissue level of EPA and DHA (the main components of fish oils) and a relatively low level of LA and its metabolites had a lower breast cancer risk. The researchers note that LA (linoleic acid) is the precursor of certain eicosanoids which may promote tumour growth. EPA and DHA inhibit the production of these harmful compounds and may also, on their own, inhibit tumour growth. The researchers also point out that several epidemiological studies have found an inverse correlation between fish consumption and breast cancer incidence and urge further studies to determine the relationship between the dietary intake of specific fatty acids and breast cancer risk.Simonsen, Neal, et al. Adipose tissue omega-3 and omega-6 fatty acid content and breast cancer in the EURAMIC Study. American Journal of Epidemiology, Vol. 147, No. 4, 1998, pp. 342-52
Fat consumption and cancer
LONDON, UNITED KINGDOM. Several major epidemiologic studies have found a clear association between a high dietary fat intake and the risk of developing breast and colon cancer. The correlation is particularly strong in the case of animal fats. One study found that a high fish or fish oil consumption is protective against later stage colon cancer in men, but has no effect on mortality from breast cancer. British medical researchers now report that fish and fish oils not only protect against colon cancer in men, but also against colon and breast cancer in women. This protective effect, however, is only apparent in countries where the intake of animal fats is high. In other words, a high intake of fish or fish oils counteracts the detrimental effects of a high animal fat consumption.
The study compared cancer mortality rates in 24 European countries, Canada and the USA with fish consumption and the intake of animal fats. In countries where the animal fat intake was high the researchers found a clear inverse correlation between the ratio of fish fat to animal fat and the risk of developing breast cancer in women and colon cancer in both men and women. A similar correlation was found between cancer risk and the ratio of fish fat to total fat intake.
The researchers conclude that a 15% decrease in animal fat intake combined with a 3-fold increase in fish oil intake could possibly reduce male colon cancer risk by as much as 30% in countries with a high animal fat intake. A 3-fold increase in fish oil intake could be achieved by eating fish three times a week or by taking two standard fish oil capsules daily.Caygill, C.P.J., et al. Fat, fish, fish oil and cancer. British Journal of Cancer, Vol. 74, No. 1, July 1996, pp. 159-64
The researchers conclude that a 15% decrease in animal fat intake combined with a 3-fold increase in fish oil intake could possibly reduce male colon cancer risk by as much as 30% in countries with a high animal fat intake. A 3-fold increase in fish oil intake could be achieved by eating fish three times a week or by taking two standard fish oil capsules daily.Caygill, C.P.J., et al. Fat, fish, fish oil and cancer. British Journal of Cancer, Vol. 74, No. 1, July 1996, pp. 159-64
No comments:
Post a Comment