Some observational studies suggested that a high intake of eggs may be associated with an increased risk of cancers such as gastrointestinal cancers, upper aero-digestive tract cancers and ovarian cancer, however, many other studies suggested no association between egg consumption and risk of cancers such as brain cancer, bladder cancer and non-hodgkin lymphoma. The positive associations found between ovarian cancer and egg consumption may be because the studies might not have adjusted for other risk factors such as lifestyle, obesity/overweight etc. A moderate intake of eggs should not cause cancer and may also provide great nutritional benefits. In any case, it is always better to limit the intake of fried eggs.
Eggs are eaten as part of a healthy and balanced diet since thousands of years. Eggs are considered as an inexpensive, economical source of high quality protein.There are many types of edible eggs in different sizes and tastes, from chicken, ducks, quails and others, but chicken’s eggs are the most popular and commonly consumed. Whole eggs are loaded with many nutrients and are hence considered as one of the most nutritious foods we can find.
Eggs are a good source of proteins, vitamin D, vitamin B6, vitamin B12, selenium, lutein, zeaxanthin, choline and minerals such as zinc, iron and copper. Eggs also contain cholesterol and hence have been under controversy for many years regarding the impact of their regular consumption on heart health.
Health Benefits of Eggs
When taken in moderate quantities, eggs can provide great nutritional benefits. The health benefits of consumption of eggs include:
- Helps to produce energy
- Helps in maintaining a healthy immune system
- Increases HDL which is the good cholesterol that do not adversely impact heart health
- Good source of proteins which help in maintaining and repairing different body tissues including muscles
- Helps the brain and the nervous system to function effectively
- Contains folic acid and choline which plays an important role in brain and spinal cord development during pregnancy, cognitive development in infants and helps prevent cognitive decline in the elderly.
- Helps to protect bones and prevent diseases such as osteoporosis and rickets
- Reduce age-related blindness
- Promote healthy skin
Even though eggs contain some cholesterol, they may not adversely affect blood cholesterol levels. A high intake of saturated fats from other sources such as red meat, has a more significant impact on the cholesterol levels in our blood. Eating eggs in moderate quantities should not lead to any health issues. However, it is better to reduce the intake of fried eggs.
Egg Consumption and Cancer Risk
Different observational studies and meta-analyses have been carried out to evaluate the association between consumption of eggs and risk of different types of cancers. We have collated some of these studies in this blog to find out whether there is any evidence that suggests avoiding intake of eggs to stay away from cancer.
Egg Consumption and Brain Cancer Risk
Recently, the researchers from the Ningxia University in China evaluated the association of poultry and egg consumption with brain cancer risk. To study this association, they used data from 10 articles (6 articles for poultry and 5 articles for egg) obtained through literature search in online databases including PubMed, Web of knowledge and Wan Fang Med Online. Based on the results of the analysis, the researchers concluded that poultry and egg consumption may not be associated with an increased risk of brain cancer. (Haifeng Luo et al, Cell Mol Biol (Noisy-le-grand)., 2019)
Egg Consumption and Risk of Upper Aero-Digestive Tract Cancers
A meta-analysis was conducted by the researchers of Iran to investigate the association between egg intake and the risk of Upper Aero-Digestive Tract cancers. The meta-analysis included data from 38 studies with a total of 164,241 subjects including 27,025 cases, obtained through literature search in Medline/PubMed, ISI web of knowledge, EMBASE, Scopus, and Google Scholar databases. (Azadeh Aminianfar et al, Adv Nutr., 2019)
The study found that a high daily egg consumption of ≥1 meal/day may be associated with an increased risk of Upper Aero-Digestive Tract cancers. However, they found this association only in hospital based case-control studies, but not in population-based cohort studies.
Egg Consumption and Gastro-Intestinal Cancers
In a study done by the researchers of the University of Sydney in Australia, they evaluated the relationship between egg consumption and the risk of gastrointestinal (GI) cancers. The analysis obtained data from 37 case-control and 7 cohort studies involving 424,867 participants and 18,852 GI cancer cases, through literature search in electronic databases until January 2014. (Genevieve Tse et al, Eur J Nutr., 2014)
The findings from the study suggested that egg consumption may have a positive dose-response association with the development of gastrointestinal cancers.
Egg Consumption and Ovarian Cancer Risk
Researchers from Hebei Medical University, Cangzhou in China did a meta-analysis to investigate whether there is any association between egg consumption and ovarian cancer risk. The meta-analysis used data from 12 eligible studies involving 629,453 subjects and 3728 ovarian cancer cases, obtained through literature search in PUBMED, EMBASE, and Cochrane Library Central database up to August 2013.
The study mentioned that compared to those with low intake of eggs, women with high intake of eggs may be associated with an increased risk of ovarian cancer. However, they found this association only in case-control studies, but not in population based studies.
Also, these studies might not have adjusted for many other factors such as being overweight, which can also increase ovarian cancer risk. An analysis by the American Institute for Cancer Research also found that current evidence is too limited to support any conclusion.
Egg Consumption and Breast Cancer Risk
- A study published in 2014 by the researchers from the Gansu Provincial Hospital in China evaluated the relationship between egg consumption and breast cancer risk. The analysis included data from 13 studies obtained through literature search in PubMed, EMBASE and ISI Web of Knowledge databases. The findings of this analysis suggested that increased egg consumption may be associated with increased breast cancer risk among the European, Asian and postmenopausal population especially in those who consumed 2 to 5 eggs per week. (Ruohuang Si et al, Breast Cancer., 2014)
- However, two previously published studies had found that women who ate eggs had a lower risk of developing breast cancer.
- A study published in the Breast Cancer Research Journal in 2003 by the researchers at Dana-Farber Cancer Institute, Harvard Medical School in the United States, based on data from the Nurses’ Health Study found that women who ate one egg per day during adolescence may be associated with 18% reduced risk of breast cancer. (A Lindsay Frazier et al, Breast Cancer Res., 2003)
- Another study done on Chinese women which was published in the Cancer Epidemiology, Biomarkers & Prevention Journal in 2005 by the researchers of Oregon Health and Sciences University in the United States found that, the risk of developing breast cancer was 44% lower in women who ate at least six eggs per week compared to those who ate two or fewer eggs per week. (Jackilen Shannon et al, Cancer Epidemiol Biomarkers Prev., 2005)
Hence, based on these conflicting results, we cannot conclude whether egg consumption may be associated with increased breast cancer incidence.
Egg Consumption and Bladder Cancer Risk
In a study published in 2013, the researchers from the Nanfang Hospital, Southern Medical University, Guangzhou in China conducted a meta-analysis to evaluate the association between egg consumption and bladder cancer risk. The researchers used data from 4 cohort studies and 9 case-control studies involving 2715 cases and 184,727 participants, obtained through literature search in the PubMed database till February 2012. (Fei Li et al, Nutr Cancer., 2013)
The study found no significant association between egg consumption and bladder cancer risk. However, the study suggested a possible relationship with increased intake of fried eggs with bladder cancer risk based on a limited number of studies. The researchers hence suggested to do large prospective cohort studies to confirm these findings.
Egg Consumption and Prostate Cancer Risk
Researchers from the Tongde Hospital of Zhejiang Province, Hangzhou in China evaluated the association between dietary egg intake and prostate cancer risk. To study this association, they obtained data from 9 cohort studies and 11 case-control studies, by carrying out literature search to identify peer-reviewed manuscripts published up to July 2012. The study didn’t find any association between prostate cancer incidence and egg consumption. The study also found no association between egg consumption and prostate cancer-specific mortality. (Bo Xie et al, Asian Pac J Cancer Prev., 2012)
A previous study however mentioned that men who consumed 2.5 or more eggs per week had an 81% increased risk of lethal prostate cancer compared with men who consumed less than 0.5 eggs per week (Erin L Richman et al, Cancer Prev Res (Phila)., 2011). However, the life-style factors of these men such as age, higher body mass index indicating obesity/overweight, smoking and eating red and processed meats might also have contributed to prostate cancer.
Egg Consumption and Non-Hodgkin Lymphoma Risk
In a study done by the researchers of the Huazhong University of Science and Technology and Xiangyang Hospital Affiliated to Hubei University of Medicine in China, they carried out a meta-analysis to evaluate the association of poultry and eggs consumption with Non-Hodgkin Lymphoma risk. The meta-analysis included data from 9 case-control and 3 population-based studies, including 11,271 Non-Hodgkin Lymphoma cases, obtained through literature search in MEDLINE and EMBASE databases till March 2015. Results from the meta-analysis indicated that consumption of poultry and eggs may be not associated with Non-Hodgkin Lymphoma risk. (Y Dong et al, Eur J Cancer Care (Engl)., 2017)
While some observational studies suggested that a high intake of eggs may be associated with an increased risk of cancers such as gastrointestinal cancers, upper aero-digestive tract cancers and ovarian cancer, many other studies suggest no association between egg consumption and risk of cancers such as brain cancer, bladder cancer and non-hodgkin lymphoma. Also, the positive associations found between cancers such as ovarian and prostate cancers and egg consumption may be because these studies might not have adjusted for many other risk factors such as being overweight and life-styles.
Hence, one need not completely stop taking eggs to stay away from heart diseases and cancer. A moderate intake of eggs as part of a healthy diet may provide great nutritional benefits. Also, we can limit the intake of fried eggs. Taking an egg instead of red and processed meats, sugary beverages and polished grains may be more healthy.
Cancer patients often have to deal with different chemotherapy side effects which affect their quality of life and look out for alternative therapies for cancer.Taking the right nutrition and supplements based on scientific considerations (avoiding guesswork and random selection) is the best natural remedy for cancer and treatment related side-effects.