Cholesterol watch: Egg consumption does not increase the risk of stroke, says research

21 May 2019 --- A moderately high intake of dietary cholesterol, equivalent to the consumption of up to one egg per day is not associated with an elevated risk of stroke, according to a new study from the University of Eastern Finland, published in the American Journal of Clinical Nutrition. Furthermore, no association was found in carriers of the APOE4 phenotype, which affects cholesterol metabolism and is remarkably common among the Finnish population.

Findings from earlier studies addressing the association of dietary cholesterol or egg intake with the risk of stroke have been contradictory. Some have found an association between high dietary cholesterol intake and an increased risk of stroke, while others have associated the consumption of eggs, which are high in cholesterol, with a reduced risk of stroke. For most people, dietary cholesterol plays a very small role in affecting their serum cholesterol levels, the researchers note.

However, in carriers of the apolipoprotein E phenotype 4 – a genetic indicator linked to cholesterol metabolism – the effect of dietary cholesterol on serum cholesterol levels is greater. In Finland, the prevalence of APOE4, which is a hereditary variant, is exceptionally high, with approximately one third of the population presenting as carriers. Yet, research data on the association between a high intake of dietary cholesterol and the risk of stroke in this population group have not been available until now.

In a separate egg study conducted by the same research team earlier last January, it was concluded that the consumption of one egg per day may in fact prove beneficial in its association with a blood metabolite profile linked to a lower risk of Type 2 diabetes. Published in Molecular Nutrition and Food Research, this previous study called for further research to observe the health effects of egg consumption. The authors note that eggs are a rich source of many bioactive compounds that may benefit overall health.

NutritionInsight reached out to authors of the study to discuss further applications of these findings.

Neither dietary cholesterol nor egg consumption was associated with stroke
The dietary habits of 1,950 men aged between 42 and 60 years with no baseline diagnosis of a cardiovascular disease were assessed at the onset the Kuopio Ischaemic Heart Disease Risk Factor Study, KIHD, between 1984 to 1989 at the University of Eastern Finland. APOE phenotype data were available for 1,015 of the men participating in the study. Of those, 32 percent were known carriers of APOE4.

During a follow-up of 21 years, 217 men were diagnosed with stroke. The study found that neither moderate dietary cholesterol nor egg consumption was associated with the risk of stroke – not even in carriers of APOE4 who are said to be predisposed to a greater effect of dietary cholesterol on serum cholesterol levels. 

In the highest control group, the study participants had an average daily dietary cholesterol intake of 520 mg and they consumed an average of one egg per day, meaning that the findings cannot be generalized beyond these levels. One egg contains approximately 200 mg of cholesterol. In this study, about a fourth of the total dietary cholesterol consumed came from eggs. Furthermore, the generalizability of this study is also weakened by the fact that the study population did not have a pre-existing cardiovascular disease at baseline and the size of the study population was relatively small. 

As such, the researchers were able to conclude that the findings of the study must be verified in a larger cohort, as well as in people with a pre-existing cardiovascular disease who are currently advised to limit their intake of cholesterol and eggs.

Nutrition-linked coronary health
While findings across separate studies evaluating egg consumption may yield discrepancies, a general verdict on the subject of coronary disease is that nutrition, aside from genetic makeup, remains a pivotal factor in determining heart health. Last January, a joint study published by Germany’s Martin Luther University Halle-Wittenberg (MLU), the Friedrich Schiller University Jena, the nutriCARD competence cluster and the University of Washington, US, linked a percentage of European deaths to unbalanced diets, such as those lacking in whole grain products, vegetables, nuts and seeds and high salt intake.

In the same month, a University of South Australia found that a dairy-enhanced Mediterranean diet significantly increases health outcomes for those at risk of cardiovascular disease, even proving more effective than a low-fat diet. The results from the study revealed that the dairy-supplemented Mediterranean diet (“MedDairy”) significantly improved blood pressure, heart rate, cholesterol, mood and cognitive function – challenging common perceptions of what is considered “healthy.”

By Benjamin Ferrer