It’s no yolk. Americans eat a lot of eggs — nearly 300 per person per year, according to the U.S. Department of Agriculture ─ and egg consumption has been going up. Europeans eat even more. Part of the reason for the rise in egg consumption is that new nutrition research has pretty much ended eggs’ reputation as unhealthful cholesterol delivery systems. Now many consumers perceive them as healthful (in moderation) ─ not to mention that they are affordable.
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The study, which was done in cooperation with researchers at China Medical University and Qatar University, lasted from 1991 to 2009. It analyzed data from Chinese adults (average age of 50) who took part in an initiative called the China Health and Nutrition Survey (CHNS). The CHNS was founded as a joint endeavor of the University of North Carolina at Chapel Hill and the Chinese Academy of Preventive Medicine, now called the China Center for Disease Control and Prevention (CCDC). Its main purpose is to analyze how the rapid social and economic changes in China over the last few decades have affected the health and nutrition of the population. From the beginning, the data collected by the CHNS has been made publicly available without cost to researchers all over the world.
The researchers compared egg consumption with blood sugar levels in more than 8,545 participants. They found that those who ate the most eggs had an increased risk of diabetes compared to those who ate the fewest. According to lead researcher Ming Li, “What we discovered was that higher long-term egg consumption (greater than 38 grams per day) increased the risk of diabetes among Chinese adults by approximately 25%. Furthermore, adults who regularly ate a lot of eggs (over 50 grams, or equivalent to one egg per day) had an increased risk of diabetes by 60%.”
The authors could only speculate on why eating eggs seems to be connected to diabetes. They conjectured the risk might be related to oxidation and inflammation from choline found in egg yolks or that chemicals in egg whites hindered carbohydrate absorption. But they also suggested possible contributing factors besides the eggs themselves. For one thing, the subjects who consumed the most eggs also consumed more fat and animal protein. Also, they were less physically active and had higher cholesterol levels. The researchers also pointed out that during the last few decades in China a more Western-type diet (low in vegetables, high in meats and fat) has been becoming more common, which could contribute to rising diabetes rates.
After reviewing the new study, registered dietitian and diabetes educator Amy Campbell, MS, RD, LDN, CDCES, pointed out that it has some limitations. First, she said, “This was a longitudinal study, which means they followed individuals over a particular period of time. This was not a randomized controlled trial, which is the ‘gold standard.’” She also reiterated the authors’ observation that many people in China have moved away from a traditional diet of grains and vegetables “to a more processed diet with more meat, snacks and energy-dense food.” The more processed diet, she said, “could very likely be contributing to the increased diabetes risk as well.” Furthermore, she said, “What is also not mentioned is any change in body weight ─ in other words, were people also gaining weight over this period which could also contribute to the increase in diabetes?”
Her advice? “My take is that it’s wise to be cautious about egg intake, but other research indicates that eggs, in moderation, can be part of a healthy diet and may even lower the risk of diabetes. It’s important to take a more global look at a person’s overall diet, plus other factors such as body weight, change in activity level, stress, and so on, to help determine causes of diabetes.”