Eating as many as a dozen eggs a week as part of a healthy diet carries no adverse risks for people with pre-diabetes or type 2 diabetes, Australian research has shown.
A study published in the American Journal of Clinical Nutrition finds that among the target population cardiovascular risk factors including cholesterol, blood sugar and blood pressure are unaffected by diets that vary between one and 12 eggs a week.
To make the finding, a team led by Nick Fuller of Sydney University’s Boden Institute of Obesity, Nutrition, Exercise and Eating Disorders established two cohorts of volunteers, all with either pre-diabetes or type 2 diabetes. Members of one cohort ate fewer than two eggs a week, while the other enjoyed a dozen.
For the first three months, the volunteers were asked to maintain their weight. For the next three they were asked to lose weight, and for the final six they could choose their own weight goals. Egg consumption remained fixed throughout.
At each phase of the experiment, none of the participants showed any increase in adverse markers for diabetes or cardiovascular risk, and the weight loss outcomes were identical across both the low egg and high egg cohorts.
“Despite differing advice around safe levels of egg consumption for people with pre-diabetes and type 2 diabetes, our research indicates people do not need to hold back from eating eggs if this is part of a healthy diet,” Fuller says.
The association between egg consumption and diabetes risk arose during the 1970s, due to an incomplete understanding of the effects of cholesterol in relation to cardiovascular disease. This led to recommendations that healthy people should restrict their intake to four a week. People with diabetes or a history of heart disease should eat even fewer.
The advice became a dietary maxim for decades, and, as a result influenced the design of many subsequent studies into the relationship between eggs and illness.
A meta-analysis published in 2013 found that no randomised control trial data were available on the relationship between egg consumption and the risks of either diabetes or cardiovascular disease. Most of the literature available was in the form of observational studies, with only a few controlled diets into other aspects of egg consumption and health being available.
The review found no association between cardiovascular disease and egg consumption among healthy people. It did find some evidence linking egg eating and diabetes risk. It noted, however, that results of studies in the area were inconsistent, and called for more research.
Referring specifically to diabetes, the authors concluded, “the results of this meta-analysis should be interpreted with caution and may not justify changes in current dietary advice on egg consumption until more scientific data become available”.
The new work by Fuller and his colleagues appears to provide at least some of the missing data.
“While eggs themselves are high in dietary cholesterol – and people with type 2 diabetes tend to have higher levels of the ‘bad’ low density lipoprotein (LDL) cholesterol – this study supports existing research that shows consumption of eggs has little effect on the levels of cholesterol in the blood of the people eating them,” Fuller says.
“Eggs are a source of protein and micronutrients that could support a range of health and dietary factors including helping to regulate the intake of fat and carbohydrate, eye and heart health, healthy blood vessels and healthy pregnancies.”
The research was funded by poultry industry lobby group Australian Eggs. The researchers state the funder had no input into the design, conduct or analysis of the research.