In the newspaper I have read that conjugated linoleic acids might help to protect against cancer, is that true? What are conjugated linoleic acids and which foods contain them?

Conjugated linoleic acids (CLAs) are natural components of animal foods derived from linoleic acid. They are found in milk fat, dairy foods and meats derived from ruminant animals. Since current dietary recommendations include eating less animal fat, there are questions being raised about a possible decline in dietary CLA consumption and the implications for health.

Research into CLAs has been undertaken in several areas including cancer, heart disease, diabetes and weight control. The evidence in all areas is far from conclusive.

Early research with animal models demonstrated that CLAs could inhibit cancer formation and growth, and there is now some evidence to suggest that CLAs may help to protect against certain types of cancer. Most of the evidence investigating the effects of CLAs on breast as well as skin, liver and colon cancers has, however, come from animal and human tissue studies. Although clinical studies are limited, recent work has found that a low risk of breast cancer is associated with high intakes of CLAs, high consumption of cheese and high blood levels of CLAs. Associations do not, however, prove cause-effect relationships and further human studies are needed to follow up these promising results.

You will find CLAs in fatty foods from ruminant animals such as full fat milk and dairy products and fatty meats. While the research appears promising, no firm conclusions can be made regarding the ideal CLA content of the diet and there are as yet no dietary recommendations for CLA intake. One of the areas that remains to be addressed is an evaluation of upper levels of intake. As with many other discoveries in the dynamic area of nutrition, more research is needed.