Researchers from Denmark performed a detailed survey of studies published between 2005 and 2015 on the associations between egg consumption, cardiovascular diseases and type 2 diabetes (European Journal of Nutrition, published online September 27, 2017). They concluded that "up to seven eggs per week can safely be consumed, but in patients with established cardiovascular diseases or type 2 diabetes, only with special emphasis on a prudent diet and proper medical treatment."
The scientific literature is loaded with conflicting articles that show both increased risk and no increased risk for heart attacks or diabetes in people who eat eggs daily, compared with those who eat fewer than three eggs per week. Here is a sample of the conflicting findings:
• In healthy men and women, eating three or more eggs per week was associated with increased size and number of plaques in arteries and the more eggs they eat, the more extensive were the plaques that formed in their arteries (Atherosclerosis, October 2012;224:469–473). However, other authors found no association (Am J Clin Nutr, Mar 2016;103(3):895-901).
• In healthy men and women, no association was found between eating one egg per day regularly and risk for heart attacks and strokes, but for diabetics eating one egg per day was associated with increased risk for heart attacks (Am J Clin Nutr, 2013;98:146–159; BMJ, 2013;346:e8539).
• In healthy men, three or more eggs per week was linked to higher levels of sugar stuck on cells (HbA1C) that measures cell damage from high blood sugar levels, but no increased risk for heart attacks or premature death; and in diabetics, eating three eggs per week was associated with higher blood sugar levels and increased risk of stroke (European Journal of Nutrition, Nov 2, 2017). This study following 2512 men for an average 22.8 years.
• In diabetics, three or more eggs was associated with increased heart attack risk, but in healthy men and women, no increased risk (BMJ, 2013 Jan 7;346:e8539).
• In healthy men and women, six eggs per week increased risk for diabetes (Diabetes Care, Feb 2009;32(2):295–300).
• Healthy North Americans who eat more than two eggs per week appear to be at increased risk for diabetes, but studies from Spain, France, Finland and Japan showed no increased risk for diabetes (Journal of Clinical Nutrition, Jan 6, 2016).
• Replacing eggs with plant-based protein led to a 19 percent reduction in death risk (JAMA Internal Medicine, October 2016). This study followed 130,000 men and women for 36 years.
Overall Diet and Lifestyle are More Important
Many researchers feel that the entire diet is far more important than whether you eat eggs on occasion or not (Nutrients, 2015 Sep 3;7(9):7399-420). The Danish researchers quoted above say, "The suggestion of egg consumption by itself promotes the risk and development of heart disease and diabetes seems improbable compared with the general complexity of the dietary pattern, physical activity and genetic predisposition."
Based on the many conflicting studies, I believe that at this time people can eat eggs in moderation but should not eat them every day, and that diabetics should eat eggs only on occasion. For some of the possible mechanisms, see Why I STILL Restrict Meat, Eggs and Milk