So what’s the deal with eggs…? They were in favour, out of favour, are they in again?
Egg yolks contain cholesterol, so it was thought that eating them would increase cholesterol-related illnesses (eg. heart attacks, strokes).
One study from 2002 (with the tagline “Eggs Are Nearly As Bad For Your Health As Cigarettes”) looked at >1000 patients in Canada attending vascular prevention clinics. The researchers found that with aging, plaque builds up gradually in the arteries, and that egg yolks make it build up faster – about two-thirds as much as smoking.
Some limitations with this study:
- Did not assess or adjust for other dietary or lifestyle factors;
- Did not examine hard cardiovascular disease endpoints;
- The cross-sectional nature of the study also limited causal interpretation of the data.
Fast forward to the present day, and to a dose-response meta-analysis of prospective cohort studies published in the British Medical Journal (essentially a higher-quality study).
This study found no evidence of an association between egg consumption and risk of coronary heart disease or stroke. Interestingly, people with the highest egg consumption had a 25% lower risk of developing haemorrhagic stroke (when there’s a bleed in the brain).
In a subgroup analysis of diabetic populations, there was an increased risk of coronary heart disease among diabetic patients. Among diabetic populations, there are decreased levels of apolipoprotein which lead to abnormal cholesterol transport. Therefore the adverse effect of egg consumption on lipoprotein profile and glycaemic (sugar) control may contribute to the elevated risk of coronary heart disease in diabetic populations.
(Apolipoproteins are proteins that bind lipids – oil-soluble substances such as fat and cholesterol – to form lipoproteins. They transport the lipids through the lymphatic and circulatory systems.)
The study concludes that higher consumption of eggs (up to one egg per day) is not associated with increased risk of coronary heart disease or stroke.
Here are some other benefits of eggs:
- Help prevent macular degeneration: due to the carotenoid content, specifically lutein and zeaxanthin;
- Lower the risk of developing cataracts: also because of the lutein and zeaxanthin;
- Contain 6g high-quality protein and all 9 essential amino acids (the building blocks of protein);
- Are a good source of choline: helps regulate the brain, nervous system, and cardiovascular system;
- Contain good fats: one egg contains 5g fat of which only just over 1g is saturated;
- Contain vitamin D (all you hear about these days is how the whole planet is suffering from vitamin D deficiency – eggs can save the world);
- Promote healthy hair and nails (’cause there’s no reason you can’t look faaaaabulous while improving your health).
Bottom line: having up to one egg per day does not increase your risk of heart attack or stroke, unless you are diabetic (in which case there are other factors at play, like abnormal cholesterol transportation).
If you have any doubt at all about the benefits of eggs, check out this YouTube video “I Love Egg”. Very educational.
Rong Y, Chen L, Zhu T, Song Y, Yu M, Shan Z, Sands A, Hu FB, Liu L. Egg consumption and risk of coronary heart disease and stroke: dose-response meta-analysis of prospective cohort studies. BMJ. 2013 Jan 7;346:e8539. doi: 10.1136/bmj.e8539.
Spence JD, Jenkins DJ, Davignon J. Egg yolk consumption and carotid plaque. Atherosclerosis 2012;224:469-73.
Zampelas A. Still questioning the association between egg consumption and the risk of cardiovascular diseases. Atherosclerosis2012;224:318-9.
Fielding CJ, Castro GR, Donner C, Fielding PE, Reaven GM. Distribution of apolipoprotein E in the plasma of insulin-dependent and noninsulin-dependent diabetics and its relation to cholesterol net transport. J Lipid Res1986;27:1052-61.
Venkatesan S, Imrie H, Read S, Halliday D. Apo C subclasses from non-insulin-dependent diabetic patients—a quantitative comparison with control subjects. Biochem Soc Trans1995;23:278S.