Can you tell me about eggs and breast cancer

Q. Is the intake of eggs associated with breast cancer risk? I had heard mention of this as I had also heard that the greater the intake of protein and animal products in a society's diet, the greater the cancer rate.

A. First, there is direct evidence that intake of eggs during the earlier stages of life-especially adolescence-may actually lower the risk of breast cancer in women. With respect to egg consumption during other parts of life, several large-scale studies have found no increase in risk of breast cancer associated with egg consumption. In terms of breast cancer treatment, we are not aware of any research studies demonstrating adverse effects of this food when included in a healthy overall meal plan.

The issue of estrogen residues

With animal meats, estrogen residues found in the edible portions of the food have been associated with the use of estrogen hormone implants in the animals. Because these estrogen implants can promote quicker growth and better yield, they are widely used in the non-organic meat industry. However, estrogen implants are prohibited in the production of certified organic products, including milk, eggs, and meats. Once again, we have not seen any research suggesting additional health risks posed from estrogen residues in certified organic meat, milk, or egg.

The role of protein

Greater protein intake is not categorically associated with increased cancer risk. There is some evidence (although it is not clearcut) that excessive protein intake may be associated with increased cancer risk. However, there is no reason we can see why the inclusion of eggs in a weekly meal plan would necessarily result in excessive protein intake. An egg white contains approximately 6 grams of protein. Since the recommended intake level for adult women is 46 grams of protein per day, one egg white would "use up" approximately 13% of the day's allotment. That amount should leave room for plenty of other protein-containing foods during the course of the day without driving total protein intake to an excessive level.

The role of saturated fats

While we would agree that excessive saturated fat intake and excessive fat intake overall can be associated with increased cancer risk, we do not believe that inclusion of eggs in a weekly meal plan necessarily results in excessive saturated fat or excessive total fat intake. One large egg yolk contains about 5 grams of total fat. While some of this fat is indeed saturated, some of the saturated fat found in egg yolk is not the long-chain saturated fat (like palmitic acid) associated with increased health problems. In addition, egg yolk contains unsaturated fat in important amounts. Oleic acid (a monounsaturated fatty acid considered heart-protective) is also provided by egg yolk, as are varying amounts of some omega-3 fatty acids. This last category is particularly interesting, because the amount of omega-3 fatty acids contained in an egg yolk depends on the hen's diet. Many organic chicken farmers have been experimenting with their chicken feed to increase the percentage of omega-3 fatty acids that turn up in the eggs. Omega-3 fatty acid intake has repeatedly been shown to lower the risk of many cancers, including breast cancer.

For more information on this topic, please see:

• Eggs

References:

Frazier AL, Ryan CT, Rockett H, et al. Adolescent Diet and Risk of Breast Cancer. Breast Cancer Res. 2003;5(2):R59-64.

Holmes MD, Colditz GA, Hunter DJ, et al. Meat, Fish and Egg Intake and Risk of Breast Cancer. Int J Cancer. 2003;104(2): 221-7.

Lewis NM, Seburg S, Flanagan NL. Enriched Eggs As a Source of N-3 Polyunsaturated Fatty Acids for Humans. Poult Sci. 2000;79(7):971-4.

Missmer SA, Smith-Warner SA, Spiegelman D, et al. Meat and Dairy Food Consumption and Breast Cancer: a Pooled Analysis of Cohort Studies. Int J Epidemiol. 2002;31(1):78-85.

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