The Good Egg: Serum Cholesterol and Diabetes

Diabetes is a major risk factor for the development of cardiovascular disease (CVD) and if current trends in the incidence of diabetes continue, it is possible the recent decline in rates of CVD may be reversed.

The projected burden of diabetes in Australia predicts there will be at least 2 million Australian adults with diabetes by 2025. If the incidence of obesity and diabetes, specifically type 2 diabetes continue to increase, and mortality rates continue to decline, up to 3.5 million Australians will have type 2 diabetes by 2033.

Elevated serum LDL cholesterol levels are an important treatable risk factor and need to be aggressively treated in people with type 2 diabetes. Consequently, eggs - a food containing dietary cholesterol - have previously been targeted as one that should be limited when advising patients to lower serum cholesterol levels.

Some epidemiologic studies suggest an increased risk of CVD and mortality with increased egg consumption in people with type 2 diabetes. However, confounding factors across several studies did not adjust for baseline dietary cholesterol intake, total and saturated fat intake, glycaemic index, nor the intake of wholegrains or fibre; known factors that reduce the risk of type 2 diabetes and CVD.

The few clinical studies to have been conducted in this area support the health benefits of eggs in people with insulin resistance or diabetes. Few studies have examined the effect of egg consumption on other indicators of diabetes control such as blood glucose or HbA1C levels. Moreover, there is no consistent evidence that increased egg consumption has an independent association with risk of CVD. 

One of the key barriers to including eggs in the diet is the perceived contribution of eggs to elevating serum cholesterol levels. Early animal studies used simple regression models that demonstrated a linear relationship between dietary cholesterol and serum cholesterol. Studies have since concluded that saturated fat in the diet has a far greater effect on serum cholesterol than dietary cholesterol.

Endocrinologist Dr Tania Markovic and colleagues (2007) examined the literature to assess the effect of dietary cholesterol from eggs on serum cholesterol levels and the risk of CHD. Dr Markovic now advises her patients with diabetes that they may include as many eggs as they like in their diet, "provided this is within a healthy diet low in saturated fat that also meets the guidelines for diabetic management".

Eggs are a highly nutritious food providing:

• 11 vitamins and minerals
• negligible trans fat
• 10.5 g total fat
o 4.5 g monounsaturated fat
o 1.0 g polyunsaturated fat
o 3.2 g saturated fat
• 13.3 g of protein per serve
• minimal carbohydrates (0.3 g); and
• antioxidants lutein and zeaxanthin

Cardiologists and all healthcare professionals are encouraged to reassure those concerned about egg consumption and the risk of CVD. It is prudent to communicate The Heart Foundation recommendation:

Up to six eggs a week may be consumed as part of a healthy balanced diet, low in saturated fat without increasing the risk of heart disease.

www.heartfoundation.org.au
Egg Nutrition Council Roundtable Report 2010
www.enc.org.au/enc-roundtable-report
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