In some studies, omega-3 PUFAs, such as the short-chain alpha linolenic acid (ALA) common in flax seed or the long-chain fish oil FUFAs, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), reduced cancer in human and mice. Earlier work in cell cultures showed that all of PUFAs suppressed the growth of cancer cells.
A large French study (reference below) began in 1993. Approximately 100,000 women between the ages of 40 and 65 volunteered to provide dietary and breast malignancy information and ca. 75,000 qualified for the study (the French component of EPIC, European Investigation of Cancer and Nutrition) . The dietary data provided information on the fatty acid composition of meals and revealed who was eating vegetable antioxidants and vitamins.
- Neither omega-6 nor omega-3 fatty acids were related directly to breast cancer risk.
- Long chain omega-3 fatty acids (EPA and DHA) reduced breast cancer in the group of women with the highest consumption of omega-6 PUFAs.
- High LA or ALA consumption in the form of vegetable oils or vegetables reduced cancer incidence.
- High LA or ALA consumption in the form of processed foods or nuts was associated with a higher incidence of breast cancer.
- Longer chain PUFAs were not associated with increased risk, regardless of source.
What does this mean?
- The source of the PUFA is of paramount importance. This study may apply more specifically to cancers and less to other inflammation-based degenerative diseases. The general anti-inflammatory diet may need refinement. I would suggest the following additions:
- Retain the preference for the more omega-3 friendly olive oil or perhaps flax oil versus the omega-6 rich vegetable oils (corn, soy, safflower), but focus on freshness and do not heat these oils.
- The data seem to be in favor of saturated fats for cooking. That means a shift to coconut oil.
- Vegetable antioxidants may be most important in the gut during digestion. Do these antioxidants even enter the blood stream? Certainly some alkaloids get to the brain, but much of the impact of the less mobile, large molecules may be restricted to the gut.
- An extension of this discussion may be to encourage eating more leafy vegetables with meat. That may be the paleo-diet connection.
Thiébaut AC, Chajès V, Gerber M, Boutron-Ruault MC, Joulin V, Lenoir G, Berrino F, Riboli E, Bénichou J, Clavel-Chapelon F. 2009. Dietary intakes of omega-6 and omega-3 polyunsaturated fatty acids and the risk of breast cancer. Int J Cancer. Feb 15;124(4):924-31.