People around the world love eggs for breakfast. We like them poached, boiled, fried, scrambled. Eggs are one of the most nutritious foods providing best quality protein, all essential amino acids, vitamins, and minerals. This high-protein food is a must in low-carb diets targeting weight loss, managing glucose impairment, controlling insulin resistance, and muscle-building.
However, a recent report from multiple national news media discussing the results from a 2020 study that tracked data from 1991 to 2009 fuelled the ongoing egg-diabetes debate. Involving around 8,400 Chinese adults, the study reported that consumption of one egg (50 g) or more per day increased the risk of developing diabetes by 60 per cent.
Can this study be considered as scientifically sound evidence? No. Here’s why.
First, the study is longitudinal and not a randomised control trial to prove a cause-and-effect relationship between eggs and increased risk of diabetes. Second, the study used a 3-day-24-hour dietary recall method to collect data that often produced misleading conclusions as respondents might provide incomplete information. Third, the transition in dietary habits of the Chinese cohort from 1991 to 2009 didn’t account for consumption of other foods including refined carbs, ultra-processed foods, sugary drinks, etc., which are directly linked to insulin resistance and elevated risk of type 2 diabetes.
This article aims to assess the existing evidence on egg consumption and increased risk of type 2 diabetes.
Let’s check nutrition
Eggs are nutritionally dense. One large egg provides 6.25 grams of protein, 4.74 grams of fat, 0.35 grams of carbs, 65 calories, all nine essential amino acids that can’t be produced by our body, vitamin A, D, E & K, vitamin B12, omega 3 fats, antioxidants such as lutein and choline, and minerals – iron, zinc, selenium, potassium. Eggs are affordable and can be eaten in diverse forms including salads, soups, vegetables, whole grains, and much more. Eggs have a balanced nutrition profile, making them an ideal food for people of all ages.
A note on egg cholesterol
Cholesterol is portrayed as a potential cardiovascular risk. Heart-healthy diets often recommend low-cholesterol foods. But cholesterol chemistry is more complicated than we thought. Recent findings have challenged the decade-old guidelines associating dietary cholesterol with blood cholesterol. Egg yolks are rich sources of cholesterol and were advised to be eliminated as a part of a healthy diet. Current evidence refuted this claim considering multiple research studies that reported no association as such. In fact, some studies suggest that consuming one egg per day may reduce the risk of cardiovascular illnesses.
Evidence on egg-diabetes connection
A large prospective study from the United States involving 20,703 men and 36,295 women reported that high consumption of 1 to 7 eggs per week was associated with increased risk of type 2 diabetes. This study included a follow-up for 20 years (1992-2007). However, the authors mentioned it was unclear if consumption of eggs alone led to the development of type 2 diabetes because the dietary pattern of this cohort included processed meat, refined grains, sugary beverages, French-fries, desserts, ultra-processed snacks, and refined grains along with eggs. A Japanese prospective study, on the other hand, found no association between egg intake and type 2 diabetes risk among 27,248 men and 36,218 women. Similarly, a Swedish study in 2016 found no elevated risk of type 2 diabetes in 39,610 men who consumed 1 to 5 or more eggs/week for 15 years.
The randomised control trials (RCTs) reported no link between egg consumption and increased risk of type 2 diabetes. A 12-week-long RCT involving 42 overweight or obese adults with pre-diabetes and type 2 diabetes found that participants in egg group reported significant reduction in insulin resistance and improved fasting blood glucose marker. The authors in fact recommended consuming one large egg per day because it could reduce the risk of diabetes without causing any adverse effects on lipid profile. Another RCT from Australia reported that participants with pre-diabetes or type 2 diabetes who consumed a 3-month high-egg weight loss diet with a 6-month follow up demonstrated no negative effect in cardiovascular health markers compared to those who were on a low-egg weight loss diet.
Well-designed intervention studies are limited to associated egg consumption with increased risk of type 2 diabetes. Most of the studies that reported an increased risk of diabetes in long-term consumption of eggs are either epidemiological, population-based prospective studies or longitudinal studies that failed to include the contribution of other food groups on the manifestation of type 2 diabetes.
Eggs can be included in a healthy, balanced diet plan designed for people living with diabetes. However, moderation is the key. The amount of egg per day or per meal is individual specific, aligned to total protein need, and best to be determined by a nutrition expert.
Dr Subhasree Ray is Doctoral Scholar (Ketogenic Diet), a certified diabetes educator, and a clinical and public health nutritionist. She tweets @DrSubhasree. Views are personal.
(Edited by Prashant)