Viva!’s Veronika Powell serves you all the facts you need to know about the effect of eggs on health…
In the current maelstrom of media articles both warning against and recommending eating eggs, it’s hard to know what to believe. So what’s the truth behind all the conflicting stories about eggs and their effect on us?
Eggs have never been an essential part of the human diet, merely an addition. There is no recommended egg intake simply because we don’t need to eat any!
Eggs contain saturated fat and cholesterol and the science is clear – consumption of these increases your risk of heart disease. All major health bodies agree, regardless of sensationalist media stories.
Professor Spence, director of the Stroke Prevention and Atherosclerosis Research Centre in Ontario, Canada, warns that eating eggs can be equally as detrimental to your blood vessels as smoking (Spence et al., 2012). Regular egg yolk consumption contributes to an increased build-up of arterial plaques – cholesterol deposits on artery walls – which poses a serious risk for causing stroke and heart attack. Cholesterol by-products resulting from egg cooking further increase the risk and can be toxic, causing DNA damage (Mili evi et al., 2014).
On top of that, eggs contain choline – an essential nutrient we need in small amounts. Too much, however, can be damaging, and eggs are by far the richest source. People who frequently consume eggs have a very high choline intake. One of the by-products of choline (TMAO) is associated with the build-up of arterial plaques and the higher the levels of TMAO, the higher the risk of stroke and heart attack (Tang et al., 2013).
People who eat an egg a day have up to double the risk of developing type-2 diabetes compared to people who eat eggs only occasionally (Djoussé et al., 2009). Egg consumption affects blood sugar metabolism and increases the risk of developing type-2 diabetes, mostly due to the cholesterol in eggs (Lee et al., 2014). Cholesterol not only suppresses insulin production (the hormone responsible for sugar metabolism), but can also lower the body’s sensitivity to it.
Food poisoning and contaminants
Salmonella food poisoning is one of the most common and widespread diseases carried by food, affecting millions of people across the world every year and eggs are the main source (Miranda et al., 2015). In the UK, egg-laying hens on farms subscribing to the British Lion Code have to be vaccinated against salmonella – this means about 85 per cent of eggs. It follows that 15 per cent of eggs on the UK market come from farms that don’t have to vaccinate. Farms that have fewer than 350 hens don’t have to comply with the Salmonella National Control Programme, so are largely unregulated where salmonella is concerned.
Eggs can also carry other dangerous bacteria, such as listeria and campylobacter that have been known to cause serious illness in people.
Laying hens treated with drugs and given feed containing pesticides tend to produce contaminated eggs. Traces of many of these dangerous pollutants are usually present even in free range and organic eggs.
Egg consumption has been strongly linked to hormone-sensitive cancers. Eating five or more eggs a week has been associated with a worrying increase in the risk of breast, prostate and ovarian cancers (Pirozzo et al., 2002). This could be due to the cholesterol and choline content. Cholesterol can increase the levels of sex hormones – testosterone and oestrogens – and excessive amounts of these are a well-known risk factor in hormone-sensitive cancers. Cholesterol and choline are also essential components of cell membranes and a plentiful supply might help cancerous cells grow.
High concentrations of choline are characteristic for prostate cancer cells. One study showed that men with the highest choline intake had a 70 per cent increased risk of lethal prostate cancer. Another study revealed that 2.5 eggs per week increased men’s risk of prostate cancer by 81 per cent (Richman et al., 2011).
The relationship between eggs and the risk of developing ovarian cancer is also very strong. Women eating more than two eggs a week had an 82 per cent higher risk of developing ovarian cancer compared to women who rarely eat eggs.
Take home message?
It’s best to steer clear of eggs! Many recipes can be easily adapted to be egg-free and delicious. Ditching eggs is not only a healthy choice but an ethical one too – the conditions at modern egg farms are appalling and as Viva!’s investigations show, free range hens suffer just as much, living in crowded sheds and barns; the advert idyll a mere fantasy.
Please note that this article is an excerpt taken from Viva!Health’s “Cracked” guide. For the fully reference article, please see Viva!Health’s guide which includes the full list of references for the claims made in this article: http://bit.ly/2yKTbsS.
- Djoussé L, Gaziano JM, Buring JE and Lee IM. 2009. Egg consumption and risk of type 2 diabetes in men and women. Diabetes Care. 32 (2) 295-300.
- Lee CT, Liese AD, Lorenzo C, Wagenknecht LE, Haffner SM, Rewers MJ and Hanley AJ. 2014. Egg consumption and insulin metabolism in the Insulin Resistance Atherosclerosis Study (IRAS). Public Health Nutrition. 17 (7) 1595-1602.
- Mili evi D, Vrani D, Maši Z, Parunovi N, Trbovi D, Nedeljkovi – Trailovi J and Petrovi Z. 2014. The role of total fats, saturated/unsaturated fatty acids and cholesterol content in chicken meat as cardiovascular risk factors. Lipids in Health and Disease. 13, 42.
- Miranda JM, Anton X, Redondo-Valbuena C, Roca-Saavedra P, Rodriguez JA, Lamas A, Franco CM and Cepeda A. 2015. Egg and egg-derived foods: effects on human health and use as functional foods. Nutrients. 7 (1) 706-729.
- Pirozzo S, Purdie D, Kuiper-Linley M, Webb P, Harvey P, Green A and Bain C. 2002. Ovarian cancer, cholesterol, and eggs: a casecontrol analysis. Cancer Epidemiology, Biomarkers and Prevention. 11 (10 Pt 1) 1112-1114.
- Richman EL, Kenfield SA, Stampfer MJ, Giovannucci EL and Chan JM. 2011. Egg, red meat, and poultry intake and risk of lethal prostate cancer in the prostate specific antigen-era: incidence and survival. Cancer Prevention Research. 4 (12) 2110-2121.
- Spence JD, Jenkins DJ and Davignon J. 2012. Egg yolk consumption and carotid plaque. Atherosclerosis. 224 (2) 469-473.
Viva!Health is part of the charity Viva! that monitors scientific research linking diet to health, providing accurate information so that you can make informed choices on the food you eat. www.vivahealth.org.uk