Simon Brown
Jun 1, 2021
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Journal
Post Reproductive Health
Abstract
Eggs, however cooked on the breakfast menu, have had a mixed press over the years, mostly negative. Most studies – and dietary advice have concentrated on the high cholesterol content of the yolks, although that effect seems less than that of the fried bacon and sausage served alongside. Indeed, the evidence of any deleterious effect of the eggs themselves seems less than clear. Some studies, for example, have found that while eating eggs on a daily basis may well lead to marginal increases in LDL cholesterol, other results show increased levels of HDL – and thus that the total cholesterol to HDL ratio, an important predictor of heart disease, remains steady. Overall, observational studies have reported inconsistent results, and most meta-analyses have found nonsignificant associations between eggs, CVD or all-cause mortality in the general population. In the bad old Edwina Currie days, most dietary recommendations, following the lead of the American Heart Association, advised consumption of no more than 300 mg of cholesterol per day, around half of which might be found in a single egg yolk; no more than three eggs a week was the usual advice. However, the eggs fought back and a large population study in 1999 (from the ever buoyant Nurses’ Health Study) found no difference in cardiovascular risk between those eating one egg a day and one egg a week. Indeed, in 2020 the AHA revised its advice to state that healthy people could safely eat a whole egg a day. They also approved two eggs a day for healthy older adults because of the overall nutritional benefits of eggs. However, despite the intuitive advice that skipping breakfast (or eating a very low energy version) appears to increase the risk of atherosclerosis, and despite the moderate rehabilitation of eggs, eggs may still not offer a golden start to the day – at least not in mid-life and in older women as defined by the Women’s Health Initiative trial. More than 90,000 subjects from the original WHI recruitment have provided dietary information in a follow-up of almost 20 years to indicate, first, a moderate association of dietary cholesterol with incident CVD, and a significant association with ischaemic heart disease, ischaemic stroke and cardiovascular mortality and second, an association between ‘higher egg consumption’ and a moderately higher risk of incident CVD and all-cause mortality. These are conclusions similarly seen in other recent studies – albeit not in postmenopausal women. A pooled cohort study from 2019 (almost 30,000 participants) also found that a higher consumption of dietary cholesterol or eggs was significantly associated with a greater risk of incident CVD and all-cause mortality in a dose-response manner. And more recently, a huge prospective cohort study from the USA (n1⁄4 521,120), in which women aged 50–70 years were 40% represented, has also found that intakes of eggs and cholesterol were associated with higher all-cause, CVD, and cancer mortality. Both the 2021 studies ask if their results should be considered in any update of dietary guidelines, which have apparently remained without specific restriction since 2000. Current guidelines, including the UK, suggest that a healthy individual will likely suffer no harm from eating up to seven eggs per week, while benefitting from a nutritional content relatively low in calories and saturated fat, and rich in protein, vitamins, and minerals.