A debate over eggs has raged for years, with successive studies either promoting or denouncing the breakfast staple.
Its detractors point to the cholesterol content of eggs but this claim is widely refuted.
A new study makes a strong case for upping your daily egg consumption.
The study, published in the Journal of Nutrition, showed that eating more than one egg a week was associated with a lower risk of Alzheimer's disease.
To examine the association of egg consumption with Alzheimer's dementia risk, researchers asked 1024 older adults to fill out a food questionnaire.
The participants, who did not have any signs of dementia at the outset of the study, were recruited from the Memory and Aging Project (MAP) - a longitudinal study of dementia and other chronic diseases of ageing.
39 percent of the total effect of egg intake on Alzheimer's dementia was down to dietary choline
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After conducting their analysis, which included tracking cases of dementia and comparing this with rates of egg consumption, the researchers found that consuming more than one egg was associated with a 47 percent reduced risk of Alzheimer’s disease - the leading cause of dementia.
Specifically, they found that chomping down on eggs was associated with a lower risk of Alzheimer's pathology in the brain.
A mediation analysis - a tool used for describing, discovering, and testing possible causal relationships -also showed that 39 percent of the total effect of egg intake on Alzheimer's dementia was down to dietary choline.
The finding comes after an analysis of nearly 2,500 middle-aged adults, published in The American Journal of Clinical Nutrition, found evidence that dietary intakes of choline were associated with better performance in cognitive tests assessing verbal fluency and memory.
The lecithin found in egg yolk may also be playing a hand here. One study followed 3,227 people and about 250 developed dementia over the course of several years.
Analysing the food intake of these people revealed that eating food with lecithin every day significantly reduced their risk of developing dementia.
An older study in rats also suggested dietary lecithin elevates choline levels.
Lecithin is a mixture of fats that are essential to cells in the human body. It can be found in many foods, including soybeans and egg yolks.
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Although people with heart disease used to be warned against eating eggs, this hasn’t been the case for 20 years
PAIn the diet, lecithin is the main source of choline, a nutrient similar to the B vitamins. Lecithin is converted into acetylcholine, a substance that transmits nerve impulses.
It's worth noting that a controversial debate over egg yolks has raged for years. A flashpoint came in 2019 when a large study of almost 30,000 people linked egg consumption to an increased risk of heart disease and death.
The finger was pointed at the cholesterol content of eggs. This contradicts current thinking that the cholesterol in foods isn’t a cause for concern, as eating saturated fat (the kind found in butter, cheese and meat) does more to your levels of cholesterol, explains the British Heart Foundation (BHF).
Although people with heart disease used to be warned against eating eggs, this hasn’t been the case for more than 20 years, and UK guidelines on healthy eating do not recommend a limit on the amount of cholesterol we should be consuming.
Commenting on the study at the time, Victoria Taylor, Senior Dietitian at the British Heart Foundation, said: “There has been much debate about the role of eggs in relation to heart and circulatory disease. This study suggests that people who ate more eggs were at a greater risk of heart disease because of the cholesterol that’s in them.
"However, this type of study can only show an association rather than cause and effect and more research is needed for us to understand the reasons behind this association.
"Eating healthily is all about balance. If you’re eating too much of one thing it leaves less room in the diet for other foods that may have more health benefit.
"Eggs are a nutritious food, while this study focuses on the amount that we’re eating it’s still important to pay attention to how the eggs are cooked and to the trimmings that come with them. For example, poached eggs on wholegrain toast is a much healthier meal than a traditional fry up.”
Indeed, most healthy people can eat up to seven eggs a week without increasing their risk of heart disease, according to the Mayo Clinic.
In addition to boosting the brain, some studies have shown that this level of egg consumption might even help prevent certain types of stroke and a serious eye condition called macular degeneration that can lead to blindness.
