The study, involving almost 2,500 Finnish men, aimed to test a suggested link between intakes of cholesterol (and eggs as a major source of dietary cholesterol) and cognitive decline in both the general population and in a group of people genetically ‘at risk’ of dementia.
Led by Maija Ylilauri from the University of Eastern Finland, the team found that a relatively high intake of dietary cholesterol, or eating one egg every day, was not associated with an increased risk of dementia or Alzheimer's disease.
Furthermore, no link was found in people carrying the APOE4 gene – a gene that is known to affect cholesterol metabolism and increase the risk of memory disorders.
“Neither cholesterol nor egg intake is associated with an increased risk of incident dementia or AD in Eastern Finnish men,” said the team. “Instead, moderate egg intake may have a beneficial association with certain areas of cognitive performance.”
Writing in the American Journal of Clinical Nutrition, the Finnish research team said the results suggest that a high-cholesterol diet, or frequent consumption of eggs, does not increase the risk of memory disorders – even in persons who are genetically predisposed to a greater effect of dietary cholesterol on serum cholesterol levels than others because of the APOE4 gene.
A beneficial effect?
Instead, the research data suggested that a moderate intake of eggs may actually offer certain cognitive benefits.
“We investigated the associations of cholesterol and egg intakes with incident dementia, Alzheimer disease (AD), and cognitive performance in middle-aged and older men from Eastern Finland,” explained the team.
A total of 2,497 dementia-free men, aged between 42 and 60 years old during the recruitment window (1984–1989) were enrolled in the study, however Ylilauri and colleagues noted that information on the Apo-E phenotype was available for 1,259 men.
During an average follow-up time of almost 22 years, the team reported that 337 men were diagnosed with dementia, while 266 men were diagnosed with AD.
While neither cholesterol nor egg intake was found to be associated with a higher risk of incident dementia or AD, the team did identify a possible link between egg consumption and better memory.
“Egg intake was associated with better performance on neuropsychological tests of the frontal lobe and executive functioning, the Trail Making Test, and the Verbal Fluency Test,” Ylilauri and colleagues wrote.
They concluded that while the current study found no link between dietary cholesterol and the incidence of dementia or Alzheimer’s disease, since the study participants with the highest daily intake consumed an average of 520 mg of dietary cholesterol, the findings cannot be generalised beyond these levels.
Source: American Journal of Clinical Nutrition
Published online ahead of print, doi: 10.3945/ajcn.116.146753
“Association of dietary cholesterol and egg intakes with the risk of incident dementia or Alzheimer disease: the Kuopio Ischaemic Heart Disease Risk Factor Study”
Authors: Maija PT Ylilauri, et al