Metabolites from the Mediterranean diet may help prevent cognitive decline

Share on Pinterest
Metabolites from healthier diets may help protect brain health, new research suggests. Ivan January/Stocksy
  • Studies show that levels of certain blood metabolites, which are intermediate or end products of human metabolism, are associated with cognitive function.
  • Blood metabolite levels are influenced by health status, genetics and environmental factors, and may differ between different ethnic or racial groups.
  • A recent study characterized blood metabolites associated with cognitive function among various ethnic/racial groups.
  • The study’s findings suggest that dietary habits could potentially influence the levels of these metabolites and subsequently cognitive performance, highlighting the importance of a healthy diet.

Individuals from minority ethnic or racial groups are often underrepresented in research, making it difficult to understand the risk factors and effectiveness of treatments for diseases in these minority groups.

A recent study published in the journal Alzheimer’s and dementia found that levels of six plasma metabolites were associated with lower cognitive function in all racial/ethnic groups, and levels of most of these blood metabolites were associated with adherence to a Mediterranean diet.

talking with Today’s Medical NewsThe study’s corresponding author, Dr. Tamar Sofer, a professor at Brigham and Women’s Hospital at Harvard University, said:

“We have identified a number of metabolites (small molecules) in the blood whose levels are correlated with cognitive function and all of them are related to diet. Although there are clinical trials showing that diet can influence cognitive function, identifying specific metabolites can help identify them [a] specific mechanism, specific components of [a] diet that are more important than others, and biomarkers to measure [the] success of dietary changes”.

However, Dr. Sofer added that “there is still work to be done to take these steps, but this is a good start, especially since the results held up in a few different studies, so the findings are very reliable.” .

Technological advances have made it possible to profile hundreds of metabolites at once and identify metabolites associated with a disease state. For example, studies have shown that plasma metabolite levels are associated with cognitive function and dementia.

Characterizing metabolites associated with cognitive function can help researchers to understand the mechanisms underlying the development of dementia. In addition, blood metabolites can be easily measured and could serve as biomarkers of cognitive function.

A previous study with Puerto Rican adults enrolled in the Boston Puerto Rico Health Study (BPRHS) showed that levels of 13 blood metabolites were associated with global cognitive function, which is a composite measure of multiple cognitive abilities.

Metabolite levels are influenced by the interplay between genetics, health status, and environmental factors, including diet, other lifestyle factors, and socioeconomic factors, which may differ between and even within ethnic groups. / racial

Given the influence of such a multitude of factors on blood metabolite levels, the study authors examined whether the BPRHS results could be replicated in a different sample of individuals of Puerto Rican heritage in the United States. The researchers also investigated whether these findings could be generalized to the broader Hispanic/Latino population and other ethnic groups.

Several metabolites identified by BPRHS have been shown to be influenced by dietary habits. Therefore, modifying dietary habits could help preserve cognitive health.

Therefore, the study authors also examined the causal role of blood metabolites and dietary habits in influencing cognitive function.

To assess the generalizability of the BPRHS findings to the broader US Hispanic/Latino population, researchers used data from 2,222 adults enrolled in the Community Health Study/Latino Study (HCHS/SOL). HCHS/SOL is a longitudinal cohort study examining the health of individuals of diverse Hispanic/Latino origins, including those of Cuban, Dominican, Puerto Rican, Mexican, Central American, and South American descent.

Using blood samples from the HCHS/SOL cohort, the researchers were able to estimate the level of 11 of the 13 metabolites assessed by the BPRHS.

They found that the direction of effects of blood metabolites on cognitive function in Puerto Rican HCHS/SOL and all HCHS/SOL participants was similar to that observed in BPRHS.

In addition, there was a significant correlation between the levels of certain metabolites with global cognitive function in Puerto Rican HCHS/SOL and all HCHS/SOL participants.

Among these metabolites, higher levels of beta-cryptoxanthin and lower levels of gamma-CEHC glucuronide were associated with cognitive function in both HCHS/SOL Puerto Ricans and all HCHS/SOL participants.

To examine the association between blood metabolites and cognitive function in other racial/ethnic groups, the researchers used data from 1,365 European Americans and 478 African Americans enrolled in the Atherosclerosis Risk in Communities (ARIC) to study. The researchers then conducted a meta-analysis to assess the association between blood metabolite levels and cognitive function using data from the BPRHS, HCHS/SOL, and ARIC studies.

The meta-analysis showed that six blood metabolites were associated with lower cognitive function in all ethnic/racial groups. Four of the six metabolites associated with global cognitive function were sugars, including glucose, ribitol, mannose, and mannitol/sorbitol.

Because the previous analysis only showed a correlation between metabolites and cognitive function, the researchers conducted additional analyzes to determine whether any of the blood metabolites had a causal effect on cognitive function.

Of the six metabolites, the analysis revealed a potential causal effect of only ribitol on cognitive function.

The researchers also assessed the association between dietary habits, including adherence to a Mediterranean diet, and food group intake (i.e., intake of legumes, fruits, vegetables, meat, fish, etc.) and blood metabolite levels.

They found that adherence to a Mediterranean diet or its component food groups correlated with several blood metabolites assessed in the study.

In particular, the strongest association between beta-cryptoxanthin and fruit intake was observed in HCHS/SOL Puerto Ricans and all HCHS/SOL participants.

Beta-cryptoxanthin is a carotenoid with antioxidant properties found in fruits and vegetables, and levels of beta-cryptoxanthin are associated with a lower risk of insulin resistance and liver dysfunction.

The researchers then examined whether the intake of specific food groups had a causal effect on cognitive performance.

Although food groups played a causal role in cognitive performance, cognitive function had a much stronger causal effect on the intake of specific food groups. Cognitive function is associated with socioeconomic status, which may mediate the effects of cognitive status on dietary habits.

In summary, these results suggest that dietary habits could potentially influence cognitive performance by modulating blood metabolite levels.

The authors acknowledge that the study had some limitations. They noted that the BRPHS, HCHS/SOL, and ARIC studies used different methods to assess cognitive function, and causal effects of metabolites on cognitive function should be interpreted with caution.

Dr. Perminder Sachdev, professor of neuropsychiatry at the University of New South Wales, who was not involved in this study, said MNT:

“There are several challenges in interpreting these results in relation to the role of specific nutritional groups and brain health. This is a cross-sectional study from which causal relationships cannot be drawn. Nutrition may not only affect health of the brain, but poor cognitive function may also influence nutrition, suggesting a bidirectional relationship.”

In addition, Dr. Sachdev also pointed out that “metabolites in the blood have multiple determinants, with diet only one of them. Genetic factors, health comorbidities and lifestyle are important. Therefore, a direct attribution to diet is difficult.”

“[T]their study is a step in the right direction in examining the role of diet and body metabolism in brain health. It provides suggestive evidence that adherence to a good diet such as the Mediterranean-style diet may be beneficial for brain health across a wide age range.”
—Dr. Perminder Sachdev

Dr. Sachdev added that much more work was needed.

“We need to better understand the plasma metabolome to know what determines its blood levels before we can begin to interpret these studies. We need longitudinal studies with multiple measurements in large samples, followed by intervention studies, so that a relationship can be established causal,” he said.

Leave a Reply