Chicken eggs are an excellent dietary source of choline, a very good source of lutein and zeaxanthin, a good source of riboflavin and selenium, and also incorporate some iodine and vitamin B12. Most of these micronutrients have been linked to lower risk of breast cancer. Eggs also contain high levels of arachidonic acid.
Consumers previously were warned away from eating eggs due to their high cholesterol content. However, it appears that consumption of up to one egg per day might not have substantial overall impact on the risk of coronary heart disease or stroke for otherwise healthy women (although not all research is in agreement with this conclusion). There have been numerous population-based studies that sought to determine whether egg intake was related to the risks of various cancers.
One U.S. study found that a high intake of eggs was associated with increased risk of non-Hodgkin lymphoma. Past studies reported conflicting results as to the relationship between eggs and ovarian cancer, however more recent epidemiological and other studies have concluded that egg consumption does not appear to increase the risk of ovarian cancer.

Breast cancer-related effects of eating eggs

Most human population studies have reported either no association between egg consumption and breast cancer risk, or a small reduction or increase in risk. Major egg micronutrients choline, lutein and zeaxanthin have been linked to reduced breast cancer risk. However, the high level of arachidonic acid in eggs may not be beneficial.

Epidemiological studies

Several population studies have examined possible associations between egg consumption and breast cancer:
  • 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 reported that 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.
  • A 2020 meta-analysis of previous studies reported that women who consumed two to five eggs per week had a slightly elevated risk of postmenopausal breast cancer compared to those consuming less than one egg per week.


Choline is a compound similar to folate that is normally classified with B vitamins. Attempts to measure a clear association between choline and breast cancer have produced mixed results. Choline consumption has been found to be associated with lower risk of breast cancer in some studies. However, other studies have found no link.
Dietary choline deficiency has been shown to alter gene expression for important genes involved in DNA repair, resulting in increased mutation rates. One carefully controlled animal study found that choline-supplemented rats produced offspring with a favorable genetic profile with respect to mammary tumor development. The offspring overexpressed six genes that are known to confer favorable prognosis in human cancers and underexpressed 10 genes associated with aggressive cancer. The same study found that while choline supplementation of the mothers did not reduce the incidence of mammary tumors in the rat offspring, it did reduce the tumor growth rate and improved survival.

Lutein and Zeaxanthin

Lutein and zeaxanthin have identical chemical composition but slightly different molecular structures (they are chemical isomers). These structural differences can result in slightly different activities in the body. Lutein and zeaxanthin are often found in the same food, although one usually predominates. However eggs are the exception; eggs have only about 10% more lutein than zeaxanthin. Egg yolks contain approximately 2.5 times the lutein and zeaxanthin as whole eggs. Lutein and zeaxanthin both help prevent age-related eye diseases.
Lutein and zeaxanthin intake has been found to be associated with reduced risk of breast cancer in multiple studies. For example, one study reported an inverse association between high levels of lutein/zeaxanthin consumption over five years and breast cancer risk among premenopausal women. Another study found that intake of lutein/zeaxanthin was inversely associated with risk of estrogen receptor negative (ER-), but not ER+, breast cancer. However, not all population studies have reported a link.
Lutein has been demonstrated to reduce the viability of ER+/PR+ and triple negative (ER-/PR-/HER2-) cells by activating programmed cell death through antioxidant defense response-linked cell survival signaling. Lutein has also been shown to inhibit the progression of both ER+/PR+ and triple negative breast cancer cells under hypoxia, a low-oxygen condition in which solid breast tumors can thrive. In addition, lutein has been shown to enhance the effect of taxane chemotherapy drugs (Taxol and Taxotere) in breast cancer cells.
Zeaxanthin has been reported to induce programmed cell death in triple negative breast cancer cells made resistant to chemotherapy through MDR-1, one type of multidrug resistance protein. MDR proteins are present in a majority of human tumors and are an important cause of eventual treatment failure.

Arachidonic acid can promote breast cancer

Arachidonic acid is an omega-6 fatty acid found in eggs (especially the yolks). Several studies have demonstrated that arachidonic acid can promote breast cancer. For example, arachidonic acid has been shown to induce the migration and invasion of triple negative breast cancer cells. Note that eggs laid by pasture-raised chickens contain approximately 70% of the arachidonic acid eggs from commercial chickens.

Eggs should not be fried

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, and ovaries, among others, as well as breast cancer. Carcinogenic compounds (such as heterocyclic amines (HCAs) and polycyclic aromatic hydrocarbons (PAHs)) 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.

Select eggs carefully

Organic eggs laid by pastured (or free range), corn- and soy-free chickens appear to be the healthiest choice. The majority of commercial hens are housed in factory farm buildings under severely cramped and unsanitary conditions that require use of antibiotics and antimicrobial drugs to maintain their health. More humane egg-laying conditions are provided for hens producing American Humane Certified, Certified Humane or Animal Welfare Approved eggs.
The use of chicken feed consisting primarily of corn produces eggs with relatively high omega-6 fatty acid levels. This in turn results in less favorable omega-6 to omega-3 fatty acid ratios in the eggs. Several studies have reported that lower dietary omega-6/omega-3 ratios are associated with reduced risk of breast cancer. By law, U.S. egg laying hens are not given steroid hormones such as estrogen. However, use of feed incorporating soybeans or supplemental soy isoflavones has been demonstrated to transfer potentially estrogenic isoflavones from the feed into the eggs.
Based on the studies we have reviewed, it appears that 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 commercial egg production practices.

Bottom line

Based on the available evidence, consuming up to three carefully selected eggs per week is likely to be safe for breast cancer patients and survivors and might be beneficial.

Additional comments

Limit century eggs

Preserved or salted eggs also should be limited or avoided. Century eggs are a Chinese preserved food traditionally made by soaking eggs in brine, or packing eggs in damp, salted charcoal paste. This typically results in high salt content. 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.
Perhaps more concerning are reports of contamination of century eggs with harmful chemicals such as industrial copper sulphate (which typically incorporates heavy metals) or lead oxide, which have been used by unscrupulous makers to speed up the egg-festering process.

Sources of information provided in this webpage

The information above, which is updated continually as new research becomes available, has been developed based solely on the results of academic studies. Clicking on any of the underlined terms will take you to its tag or webpage, which contain more extensive information.
Below are links to 20 recent studies concerning this food and its components. For a more complete list of studies, please click on eggs.