Diets rich in protein and anti-inflammatory foods may protect against cognitive decline

Soon nutrients The journal study evaluates the effects of a protein-enriched diet (PED) and anti-inflammatory diet (AID) on cognitive impairment (CI) in older adults in China.

To work: Anti-Inflammatory Diet and Protein-Enriched Diet May Reduce the Risk of Cognitive Impairment in Older Adults: A Nationwide Cross-Sectional Study. Image Credit: Ruslan Huzau / Shtuterstock.com

The link between diet and dementia

Age-related CI in older adults can range from mild CI to severe dementia. Recently, the Lancet Commission concluded that diet and nutrition may delay or prevent 40% of dementia worldwide through the effects of certain dietary compounds.

For example, beta-carotene is very important in maintaining mental health, whereas polyphenols have a neuroprotective effect and omega-3 fatty acids positively affect CI. Eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) are also very important for brain structure and function.

The Dietary Inflammatory Index (DII) assesses dietary inflammation by calculating the correlation between systemic pro-inflammatory cytokine levels and nutrients. To this end, diets with higher pro-inflammatory dietary potential have been associated with a higher incidence of dementia.

Previous studies have documented the beneficial effects of AIDs on mental health disorders. Protein intake has also been associated with better cognitive performance.

Protein-enriched Mediterranean diet is associated with healthy neurocognitive aging in the elderly population; However, these results are inconclusive as some studies have failed to detect a significant relationship between protein intake and cognitive function. Additionally, previous studies have systematically established a PED and investigated its relationship with CI.

About the study

Since the role of AID and PED on CI remains unclear, it is important to establish two dietary indices of AID and PED and measure their associations with CI. To this end, the current study included a cohort of older adults from the China Longitudinal Health and Longevity Study (CLHLS) to evaluate the effects of AID and PED on CI.

The study group consisted of 8,692 adults aged 60 and over. Anti-inflammatory foods included fruits, vegetables, legumes, tea and nuts. Food sources rich in protein include eggs, fish, meat, dairy products and bean products.

Binary logistic regressions and restrictive cubic splines were used to investigate linear and nonlinear relationships. Sensitivity and subgroup analyzes revealed robustness.

Study findings

Older adults with higher PED and AID scores were less likely to suffer from CI, and the relationship between AID, PED, and CI was linear. Subgroup and sensitivity analyzes also provided significant reliability to the findings. Taken together, these results have important implications for the future management of CI in terms of diet and nutrition.

Consistent with previous research, the CI was different between women and men. AID and PED scores also differed by gender. Sex differences in CI may be attributed to sex differences in dietary intake or smoking habits.

The incidence of CI was found to be reduced in older adults, suggesting that the combined effect of lifestyle factors plays a beneficial role and diet may be a promising approach to delay or prevent CI.

Besides diet, some digestive problems and malabsorption may also be associated with CI. For example, malabsorption of vitamin B-12 has been shown to alter cognitive performance and lead to some intestinal disorders.

There is a high incidence of folate deficiency in older people due to poor intestinal malabsorption and decreased dietary intake. Low folate levels have been associated with depression, mild CI, and dementia, especially Alzheimer’s. In the current study, the protective effect was more significant when AID and PED consumption was more than three units. Therefore, more than three protein-rich and anti-inflammatory foods should be consumed regularly to prevent CI. Consuming more of these foods linearly reduces the risk of CI; However, excessive consumption cannot be recommended due to problems with digestion and absorption.

Results

Increased consumption of AIDs and PEDs was associated with reduced risk of CI among older adults in China. However, a key limitation of the current study is the self-reported data, which may be subject to bias regarding CI. Additionally, due to the cross-sectional nature of the study, a causal relationship could not be established.

Considering the linear relationship between these diets and CI, the optimal dosage of PED and AID needs to be determined. Therefore, future cohort studies are needed to determine precise dosage recommendations for these two dietary patterns.