In the news: Studies Highlight Key Nutrients in Maintaining Cognitive Function

Three newly published studies lend credence to previous findings that dietary intake of flavonoids, omega-3 fatty acids, and select vitamins and minerals play an important role in preserving cognition or slowing cognitive decline with age.

Omega-3 Blood Levels & All Cause Dementia

The largest study to date examining the relationship between omega-3 biomarkers and dementia tapped the UK Biobank, a prospective, population-based cohort of approximately 500,000 people. In that study – with available data on omega-3 and incident dementia in 102,722 participants – both plasma DHA and total omega-3 were linked to a significantly lower risk of incident dementia.

With the recent release of additional metabolic data from 157,000 UK Biobank participants, the researchers updated those associations(1). They confirmed the favorable relationships between DHA and dementia risk and found evidence that non-DHA omega-3 (e.g. EPA, DPA) may also be beneficial.

Comparing the highest vs. lowest levels of total omega-3 showed a 13% lower risk of Alzheimer’s and a 21% decrease in risk of all-cause dementia.

According to the authors, the stronger association seen for non-DHA omega-3 vs. DHA suggests that the effect of omega-3 is likely greater for non-Alzheimer’s dementias, such as vascular dementia, Lewy body dementia, and frontotemporal dementia.

Stronger associations were also observed for men compared to women; and for those over age 60 at baseline compared to those in their 50s. Thus, this research helps better define groups who might gain the greatest cognitive benefits in omega-3-based interventions.

Nutrients & Cognitive Function in AREDS 1&2

Numerous large-scale studies provide evidence that certain dietary patterns and nutrients support cognition as we grow older. A study published in 2020, for example, reported that participants in AREDS 1 and 2 who adhered most closely to the Mediterranean (Med) diet had a significantly lower risk of cognitive impairment, though not a slower decline in cognitive function. Fish intake was also associated with higher cognitive function.

The AREDS research group recently published a study analyzing associations between nutrients and altered function or decline(2). Echoing the findings from the Med diet investigation, some nutrients were linked with lower risk of cognitive impairment or higher cognitive function scores, but not slower cognitive decline.

Nutrients with the strongest and most consistent favorable associations included: Vitamins A, C, E and several B-vitamins. The minerals copper, magnesium, selenium, and zinc. The carotenoids lutein, zeaxanthin, beta-carotene and lycopene, as well as the lipids DHA, EPA, and fiber. Nutrients with harmful associations included MUFA, oleic and saturated fatty acids, as well as diets with a high glycemic index or load.

Higher Flavonoid Intake & MCI / Dementia Risk

Previous research has reported a link between cognition and flavonoid intake. [See SBH.com, EduFacts Vol. 26, Flavonols May Slow Memory Decline]. Briefly, a newly published meta-analysis of 13 observational studies reports that higher flavonoid intake was associated with a 17% lower risk of cognitive impairment/dementia(3).

The dose-response analysis indicated a lower dementia risk with higher total flavonoid intake up to about 250 mg daily. For individual flavonoid types, anthocyanins (-27%) and flavones (-23%) had the highest impact on risk reduction. Anthocyanins are abundant in berries, grapes, currants, and red to purplish leafy vegetables. Flavones are found in herbs, teas and many fruits and vegetables.

References

1. Sala-Vila A, et al. Plasma omega-3 fatty acids and risk for incident dementia in the UK BioBank Study: A closer look. Nutrients. 15(23):4896, Nov. 2023.
2. Keenan TDL, et al. Dietary nutrient intake and cognitive function in the Age-Related Eye Disease Studies 1 and 2. Alz Dement. 19:4311-24, Oct.,2023.
3. Godos J, et al. Dietary (poly)phenols and cognitive decline: A systematic review and meta-analysis of observational studies. Mol Nutr Food Res. E2300472, Oct. 2023.