Mediterranean and MIND diets benefit brain health during midlife

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• A new study showed that a Mediterranean or MIND diet resulted in better cognitive health for females.
• The study of 509 twins found that those following these diets better preserved episodic and visuospatial working memory after 10 years.
• The possible mechanisms by which the diets are helping preserve cognitive health are specific gut bacteria and short-chain fatty acids.

A new study analyzing data from middle-aged females investigates the potential benefits of a Mediterranean or a MIND diet on cognitive health.

The research included genetically identical (monozygotic) twins and fraternal (dizygotic) twins.

The study finds that among monozygotic twin pairs, the twin with a higher adherence to either the Mediterranean or MIND diet retained slightly stronger episodic and visuospatial working memory.

This observation was significant for twins with a greater adherence to the Mediterraneandiet.

Monozygotic twins both develop from a single egg, or “ovum.” Fraternal, or “dizygotic,” twins are born together but do not come from the same egg. They are sometimes referred to as co-twins or birth partners. Monozygotic twins are genetically identical. Dizygotic twins share roughly 50% of their genes.

In this study, the researchers analyzed data from 509 female twins who had enrolled with the UK Adult Twin Registry between 1992 and 2004. Of this group, 34% were monozygotic, and 66% were dizygotic.

The study cohort included healthy twins with a complete set of baseline data regarding diet — via questionnaires — and cognitive performance. Approximately 10 years later, between 2008 and 2010, twins took new cognitive tests, and participants’ fecal samples were analyzed.

A higher adherence to the MIND diet at baseline was associated with a greater abundance of the bacteria Ruminococcaceae and short-chain fatty acids at follow-up.

However, this association was not significant after adjusting for dietary fiber intake.

The study is published in the journal Alzheimer’s Research & Therapy.

“This study sets itself apart by honing in on female twins, offering a unique perspective on the interplay between diet and cognitive health,” said Michelle Routhenstein, a registered dietitian nutritionist who specializes in heart disease at EntirelyNourished, and who was not involved in this study.

“By factoring in shared genetics and early life experiences, it delves deeper into the potential cognitive advantages associated with Mediterranean and MIND diets, particularly as individuals reach midlife,” she added.

Dr. Thomas Holland, from the Department of Internal Medicine, Division of Digestive Diseases and Nutrition at Rush University, also not involved in the study, commented on its significance for Medical News Today.

“This study provides further evidence that our dietary habits in midlife can significantly impact our cognitive health,“ he told us. “It goes beyond the assumption that such habits are only beneficial later in life, emphasizing their relevance during midlife.”

He noted that when we think about cognitive development, we often view it as “a trajectory of improvement from childhood through adulthood and into midlife, with the expectation of some decline as we age.”

Importantly, he said: “This study suggests that we possess the potential to enhance our cognitive resilience and build cognitive reserve during midlife. These benefits may extend into older age, enabling us to better maintain our cognitive abilities over time.”

The benefits in cognitive health reported in this study were less dramatic than are sometimes seen in studies of older people.

This may be because, as Dr. Holland suggested: “It’s commonly assumed that individuals in this stage are already operating at higher levels of cognitive function, approaching a theoretical ceiling. This dynamic contributes to the diminished observable effect in this demographic.”

Cognitive health is generally measured through the testing of various functions, of which episodic and visuospatial memory are just two.

“Episodic memory refers to our capacity to utilize personal experiences for learning new information, retaining it, and recalling it when necessary,” explained Dr. Holland.

“Meanwhile,” he said, “visuospatial memory involves the ability to recognize objects and their spatial locations, internalize this information, and subsequently process and retain specific details about the objects.”

“These cognitive functions are crucial quasi-biomarkers of eventual cognitive health,” noted Routhenstein, “as deficits in them often manifest early in neurodegenerative diseases like Alzheimer’s, making their preservation indicative of lower risk for cognitive decline.”

Such cognitive abilities, and others, collectively contribute to global cognition.

“While a deficiency in one cognitive domain may not necessarily signify an overall decline in global cognition,” said Dr. Holland, “it can serve as a valuable indicator of cognitive health or trajectory.”

Both the Mediterranean and MIND diets are anti-inflammatory, healthy diets.

The study’s authors may present an additional clue explaining the mechanistic connection between these diets and strong cognitive reserve: Ruminococcaceae and short-chain fatty acids.

Routhenstein explained: “Ruminococcaceae bacteria in the gut produce short-chain fatty acids (SCFAs) like acetate, propionate, and butyrate through dietary fiber fermentation, contributing to gut health and exerting anti-inflammatory effects crucial for protecting neuronal function.”

“These SCFAs, in turn, play a role in modulating immune system activity by reducing the recruitment of monocytes and neutrophils, thus exhibiting anti-inflammatory properties.”

— Dr. Thomas Holland, physician scientist

“Additionally,” Routhenstein noted, “SCFAs act as energy substrates for gut epithelial cells and may cross the blood-brain barrier, providing energy to brain cells and modulating neurotransmitter levels, potentially enhancing cognitive function.”

Nevertheless, the experts pointed out that people should prioritize more than just their dietary habits to maintain brain health as they age.

“While diet plays a pivotal role, it’s merely one component of a comprehensive healthy lifestyle,” said Dr. Holland.

He cited the following lifestyle interventions for preserving cognitive health:

• engaging in moderate to vigorous physical activity
• cultivating an active social circle
• participating in mentally stimulating activities (i.e., visiting museums or exploring new hobbies)
• prioritizing sleep quality and quantity
• implementing stress reduction techniques