Chicken eggs are a good dietary sources of choline, lutein and selenium. Consumers previously were warned away from eating eggs due to their high cholesterol content, but it has been found that consumption of up to one egg per day is unlikely to have substantial overall impact on the risk of coronary heart disease or stroke for otherwise healthy men and women. There have been numerous population-based studies that sought to determine whether the consumption of eggs was related to the risks of various cancers, however very few associations have been found. One U.S. study found that a high intake of eggs was associated with an increased risk of non-Hodgkin lymphoma. Past studies reported conflicting results as to the relationship between eggs and ovarian cancer, however more recent population studies and study reviews have concluded that egg consumption does not appear to increase the risk of ovarian cancer.
Breast cancer-related effects of eating eggs
Choline consumption has been found to be associated with lower risk of breast cancer in some studies. In addition, lutein consumption and circulating lutein levels have been found to be associated with reduced risk of breast cancer in several epidemiological studies. Lutein has been shown to inhibit the progression of both ER+ and ER+ breast cancer cells under hypoxia, a low-oxygen condition in which solid breast tumors can thrive. Lutein has also been shown to potentiate the effect of taxane chemotherapy drugs (Taxol and Taxotere) in breast cancer cells.
A case-control study of the participants in the Nurses' Health Study found that consumption of eggs during high school was associated with lower risk of breast cancer for the women in adulthood. A major study combining the data in eight previous prospective North American and European studies found breast cancer risk was slightly decreased for women who consumed fewer than two eggs per week but slightly increased among women who consumed one or more eggs per day compared to women who did not eat eggs. A case-control study of women in Shanghai found that egg consumption was associated with significantly lower risk of breast cancer. However, a 2014 meta-analysis of previous studies reported that women who consumed eggs had a slightly elevated risk of breast cancer.
Whether fried in butter or oil, fried eggs should be avoided. Fried eggs and meat have been associated with increased risk of cancers of the upper digestive track, stomach, colon, rectum, ovaries and breast, among others. Several kinds of carcinogenic compounds are produced during the process of frying protein-rich foods, particularly when the cooking temperature is very high. The fats used for frying appear to further increase the mutagenic activity of some of these compounds.
Preserved or salted eggs also should be avoided. Salted egg is a Chinese preserved food made by soaking eggs in brine, or packing eggs in damp, salted charcoal paste. Asian population studies have found a positive association between oral cancer, nasopharyngeal cancer, stomach cancer, and intestinal cancer and the consumption of salted preserved foods, including salted eggs.
Raw eggs and uncooked foods (such as salad dressings) made with raw eggs are also not recommended due to the risk of salmonella infection.
Free range organic eggs appear to be the healthiest choice for those who consume eggs. The most humane egg-laying conditions are provided for hens producing American Humane Certified, Certified Humane or Animal Welfare Approved eggs. Based on the studies we have reviewed, there was once a protective effect of egg consumption on breast cancer risk that appears to have declined over time. This may be due in part to modern egg production practices.
Omega-3 enriched eggs have enhanced levels of omega-3 fatty acids, which are produced by modifying the laying hens' diets to include foods such as flaxseed. Such eggs appear safe, but may contain relatively low amounts of omega-3 fatty acids.
Below are links to recent studies concerning this food. For a more complete list of studies, please click on eggs.