Eggs take a beating…linked to diabetes, heart disease

June 15, 2013 in Diabetes & Diabetes Prevention, Heart Health, Nutrition Topics in the News

Eggs take a beating…linked to diabetes, heart disease

A new study about eggs suggests you might make some of you swap sunny-side up for a whites-only omelet. While eating an egg a day  didn't increase the risk of cardiovascular disease in healthy people, it did increase the likelihood of developing Type 2 diabetes.  Among people who already had diabetes, an egg-a-day habit substantially upped the likelihood of heart attack or stroke.

The new report, published online in the American Journal of Clinical Nutrition, combined the results of 16 studies, lasting 7 to 20 years, which included participants ranging in number from 1,600 to 90,735. The researchers found that eating one or more eggs a day did not increase the risk of heart disease or stroke among healthy people.  

It did, however, increase the odds of developing Type 2 diabetes, a major risk factor for heart disease and stroke. Participants who ate at least one egg each day were 42 per cent more likely to develop Type 2 diabetes compared to people who never ate eggs or ate less than one per week.

When the researchers analyzed studies conducted in people with diabetes, they found that daily egg eaters - versus those who didn't eat eggs or ate less than one per week - had a 69 per cent increased risk of cardiovascular disease.

Eggs have long been vilified for their high cholesterol content. One large egg has 183 milligrams of cholesterol, almost an entire day's worth (200 milligrams) for someone with heart disease, diabetes or high blood cholesterol.  Healthy people are advised to limit daily cholesterol intake to 300 milligrams.

Although high blood cholesterol is an established risk factor for heart attack and stroke, the link between cholesterol in foods and cardiovascular disease remains unclear. Most studies have found dietary cholesterol has little, if any, impact on blood cholesterol levels.

While eggs may have little effect on your fasting blood cholesterol level, that may not be the case for your "after meal", or postprandial, blood cholesterol. (A fasting blood cholesterol is measured after consuming no food or drinks, with the exception of water, for 9 to 12 hours.) 

There's mounting evidence that, depending on what you eat, postprandial blood fats can damage blood vessels and promote atherosclerosis (hardening and narrowing of the arteries).  Small studies have shown that eating a cholesterol-rich meal can enhance the blood cholesterol-raising effects of saturated (animal) fat and increase the chance your LDL (bad) blood cholesterol becomes oxidized. Once oxidized, LDL cholesterol can cause inflammation in blood vessels. These harmful "after meal" changes can persist for at least four hours after eating.

Postprandial impairments to blood fats appear to be more frequent in people with diabetes, which may help explain the higher risk of cardiovascular disease associated with diabetes. There's also speculation that individuals with diabetes absorb higher amounts of cholesterol from foods. As well, animal studies suggest that high cholesterol intakes impair the pancreas's ability to release insulin, the hormone that removes excess sugar from the bloodstream.

People at high risk for cardiovascular disease - e.g. people with diabetes, high cholesterol, and/or hypertension and smokers - should definitely limit their intake of egg yolks, and some experts advise avoidance. 

Instead of eating a two-egg omelet with 366 milligrams of cholesterol, have a cholesterol-free white-only omelet for a good source of protein, riboflavin (a B vitamin) and selenium.  Try a cholesterol-free egg product sold in the egg case at grocery stores.

But most of all, let's not forget preventing cardiovascular disease is about a whole lot more that cutting back on egg yolks.  Limiting refined (white) starchy foods and added sugars, reducing saturated and trans fats, emphasizing monounsaturated fats (e.g. olive oil, avocado, almonds), increasing omega-3 fats from fish oil, limiting sodium intake, getting regular exercise and maintaining a healthy weight are key strategies to guard against heart disease and stroke.

All research on this web site is the property of Leslie Beck Nutrition Consulting Inc. and is protected by copyright. Keep in mind that research on these matters continues daily and is subject to change. The information presented is not intended as a substitute for medical treatment. It is intended to provide ongoing support of your healthy lifestyle practices.