Cardioprotective Activities of Whole Eggs in Prediabetic Adults

Featured article in the March, 2018 Issue of Nutrition Research Update; written by Josh D. McDonald, PhD Candidate, Ohio State University

Cardiovascular disease (CVD) continues to be the leading cause of death in the United States (US).¹ While numerous risk factors contribute to the progression of CVD, epidemiological evidence demonstrates that postprandial hyperglycemia (PPH), or increases in blood sugar following a meal, are a better predictor of CVD-related mortality compared with fasting blood sugar.² PPH results in the generation of chemicals that impair blood vessel function to increase CVD risk.³ Dietary modification targeting PPH and/or downstream chemicals are leading strategies to limit PPH-mediated increases in CVD risk.⁴

Studies demonstrate that consumption of whole eggs limit increases in blood sugar⁵ and chemicals that damage blood vessels,⁶ suggesting eggs may serve as an effective dietary approach to protect against PPH-mediated CVD risk. We hypothesized that co-ingestion of egg-based meals with glucose would protect against PPH-mediated impairments in vascular function. To test this hypothesis, we conducted a 4-arm study in which prediabetic men (n = 20) consumed meals equal in calories (400 kcal) consisting of glucose alone or in the presence of 1.5 whole eggs, 7 egg whites, or 2 egg yolks after an overnight fast. At baseline (0 min) and at 30 min intervals for 180 min postprandially, we evaluated vascular function using ultrasound and collected blood to measure parameters related to PPH and vascular health.

Glucose ingestion alone resulted in the greatest decline in vascular function. Impairments in vascular function due to glucose ingestion alone were similarly attenuated when glucose was co-ingested with whole eggs or egg whites, but not egg yolks. Protection against impairments in vascular function by whole egg- and egg white-based meals was likely due to limiting increases in blood sugar and chemicals that damage blood vessels. Attenuation of blood sugar responses may be in part due to greater levels of cholecystokinin, a gastric hormone that functions to slow the release of contents of the stomach, which would be expected to slow the rate of glucose absorption and rise in blood sugar. Importantly, vasoprotective activities of whole eggs and egg whites occurred without increasing circulating cholesterol levels, which until recently, the dietary guidelines recommended limiting egg consumption due to their cholesterol content.

Findings demonstrate that replacing a portion of carbohydrate as glucose with either whole eggs or egg whites helps to protect against decreases in vascular function otherwise induced by glucose ingestion alone. Additionally, results suggest a potential vasoprotective role of the gut in limiting blood sugar and related chemicals that would otherwise impair vascular health. Thus, co-ingestion of carbohydrate-based meals with whole eggs or egg whites may serve as an effective dietary strategy to reduce PPH-mediated CVD risk. This is of public health importance as there are over 800,000 CVD-related deaths per year in the US,⁽¹⁾ and humans spend much of their day in a non-fasted state.

Josh D. McDonald is a recipient of the Egg Nutrition Center Young Investigator Award.

References

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