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Going to work on an egg


Bandolier did a quick survey of attitudes to and knowledge of the perceptions people have about egg consumption and the way it affects risk of heart disease. Responses varied from no effect at all, to just about lethal. What's the truth? Analysis of two large epidemiological studies tells us that eating up to one egg a day in unlikely to have any substantial impact on risk of heart disease or stroke [1].

Study


There were actually two prospective studies. One looked at just under 38,000 US male health professionals over eight years. The other collected data from 80,000 US nurses for 14 years. Both had obvious exclusions (hyperlipidaemia or diabetes where diet could radically be changed, prior heart disease or cancer), and both collected information from participants about their diets, including consumption of eggs.

Outcomes


The outcomes were fatal and non-fatal coronary heart disease and stroke (analysed separately) by using biennial questionnaires. They used sensible diagnostic criteria and had high (98%) follow-up rates. A wealth of additional information was collected about diet and lifestyle to adjust for risk factors other than egg consumption.

Results


At the beginning of the study men averaged 2.3 and women 2.8 eggs a week. At the end consumption had declined to about 1.5 eggs a week. There were still considerable numbers of men and women who consumed up to and above one egg a day.

There were 866 cases of coronary heart disease in men and 939 in women. Compared with eating less than one egg per week, eating up to and above one egg per day did not increase the risk of developing coronary heart disease (Table) for women or men.

There were 258 cases of stroke in men and 563 in women. Compared with eating less than one egg per week, eating up to and above one egg per day did not increase the risk of suffering a stroke (Table) for women or men.

  Relative risk for coronary heart disease Relative risk for stroke
Eggs per week Women Men Women Men
<1 1.0 1.0 1.0 1.0
1 0.82 (0.67 to 1.00) 1.06 (0.88 to 1.27) 0.89 (0.70 to 1.13) 1.06 (0.76 to 1.49)
2 - 4 0.99 (0.82 to 1.18) 1.12 (0.88 to 1.33) 0.83 (0.66 to 1.05) 0.95 (0.69 to 1.31)
5 - 6 0.95 (0.70 to 1.29) 0.90 (0.63 to 1.27) 0.89 (0.60 to 1.32) 1.43 (0.85 to 2.43)
≥7 0.82 (0.60 to 1.13) 1.08 (0.79 to 1.48) 0.89 (0.60 to 1.31) 1.07 (0.66 to 1.75)
Relative risks were obtained after adjustment for factors like age, body mass index, smoking, family history, vitamin supplements, alcohol, energy intake and other factors


When information from other groups was included, there did appear to be a higher risk of coronary heart disease for diabetic men eating more than one egg a day compared with those eating less than one a week. The relative risk was 2.0 (1.05 to 3.9).

Comment


The lesson seems to be that eggs may have cholesterol in them, but they probably have other important nutrients too. There is no evidence here that eating eggs has much effect on risks of heart disease or strokes, with the possible exception of diabetic men.

This does not mean that a daily ritual of fried bacon, fried sausage, black pudding and fried bread with plenty of toast and butter is advised. Rather it means that we can enjoy the occasional cooked breakfast, or enjoy a nice boiled egg and soldiers without feeling guilty. Bandolier intends to not feel guilty on a more regular basis.


Reference:

  1. FB Hu et al. A prospective study of egg consumption and risk of cardiovascular disease in men and women. JAMA 1999 281: 1387-94.
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