NEWS2U Health & Wellness
Living Healthy in an Unhealthy World

Tuesday, September 30, 2008

Cancer Omega-6 fatty acids
linked to high risk of breast cancer

By David Liu, Ph.D.

Nutritionists have been saying for years that Americans' ratio of omega-6 fatty acids to omega 3 fatty acids is way too high. The ideal ratio is believed to be about 4:1 or less. But currently Americans have a ratio of about 18 to 1.

A new study in the October 1, 2008 issue of the International Journal of Cancer showed high omega 6 fatty acids in the diet could raise risk of breast cancer. And good news is that heterocyclic amines commonly formed in protein-rich foods such as meat and fish prepared at high temperature do not appear to increase the risk.

Heterocyclic amines have been recognized as carcinogens by the U.S. National Toxicology Program after Japanese scientists proposed that these chemicals should be listed as cancer-causing agents a few years ago.

The study is not a trial, a scientist who was not involved with the study cautioned, meaning that the study did not reveal any causal relationship between omega-6 fatty acid and increased risk although the possibility could not be ruled out either.

The study led by Dr. Emily Sonestedt, of Lund University, Malmo, and her colleagues was meant to examine the association between intake of heterocyclic amines and breast cancer risk in postmenopausal women and the role of omega-6 fatty acid in the relationship.

The researchers found low intake of the carcinogenic heterocyclic amines together with high intake of omega-6 polyunsaturated fatty acids, which are found high in most types of vegetable oil, was associated with a high likelihood of developing breast cancer in the study women.

Sonestedt and her associates could not explain why there was such an interaction, but suggested that it is important to consider the effect of food patterns, not simple food items on the risk.

Early studies showed that a fatty diet with high omega 6 was linked with high risk of tumors in rats compared to those that used a low fat diet.

In the current study, the researchers followed 11,699 women ages 50 or older for an average ten years and 430 women were diagnosed with breast cancer during the follow-up.

They found women who had highest amounts of heterocyclic amines were at no greater risk of breast cancer than those who had lowest intake of the by-products induced by food preparation.

Among women who had low intake of heterocyclic amines, those who had high intake of omega 6 fatty acids are at higher risk of the disease than those who had low intake.

One possible explanation for this finding is that women who had low intake of heterocyclic amines ate more low fiber bread, cookies and cakes, which were associated with high blood fats and high insulin levels in a previous analysis of the same set of data. The increase blood fats and insulin levels were already associated with elevated risk of breast cancer.

Regardless, one risk associated with use of omega-6 fatty acids in processed food is that they are not thermally stable and can be decomposed and transformed into certain toxic chemicals that can ultimately lead to cause cancer.

The scientist suggested that thermally processed food with high vegetable oil can be toxic. In addition to the decomposition products from omega-6 fatty acids, starch based food used commonly by those who had low intake of meat or low heterocyclic amines can also contain other cancer-causing agents such as acrylamide, which has been linked to breast cancer.