Medical Bulletin 05/ April/ 2024

A recent Nutrients journal study evaluated the effects of a protein-enriched diet (PED) and an anti-inflammatory diet (AID) on cognitive impairment (CI) in older adults.

The Lancet Commission suggested that specific dietary compounds could delay or prevent 40% of dementia worldwide. Beta-carotene supports mental health, polyphenols have neuroprotective effects, and omega-3 fatty acids benefit cognitive function.

The Dietary Inflammatory Index (DII) assesses dietary inflammation, with higher scores correlating to increased dementia risk. Adequate protein intake is linked to better cognitive performance, and the protein-enriched Mediterranean diet may support healthy ageing, although results vary. Previous studies also highlighted the beneficial effects of specific dietary patterns on cognitive impairment.

The study cohort comprised 8,692 adults 60 years of age or older. The anti-inflammatory foods included fruits, vegetables, legumes, tea, and nuts. Protein-rich food sources included eggs, fish, meats, dairy products, and bean products. Data analysis was conducted to obtain results.

The results showed that higher protein-enriched diet and anti-inflammatory diet scores were associated with lower cognitive impairment risk in older adults, with a linear relationship observed. Gender differences in CI may be due to varying dietary intake or smoking habits. Lifestyle factors, including diet, play a role in reducing CI incidence. Folate deficiency, common in older adults, is linked to depression and dementia.

The findings suggested that consuming more than three units of protein-rich and anti-inflammatory foods regularly may help prevent CI, but excessive intake is not advised due to digestive issues.

Reference: Wang, L., Xian, X., Zhou, M., et al. (2024). Anti-Inflammatory Diet and Protein-Enriched Diet Can Reduce the Risk of Cognitive Impairment among Older Adults: A Nationwide Cross-Sectional Research. Nutrients 16(9); 1333. doi:10.3390/nu16091333.

According to a new study published in the journal Biological Psychiatry, a genetic propensity to higher circulating levels of lipids containing arachidonic acid, an omega-6 polyunsaturated fatty acid found in eggs, poultry, and seafood, has been found to be linked with a lower risk for bipolar disorder.

Bipolar disorder is a debilitating mood disorder characterized by recurring episodes of mania and depression. Although its etiology is still unclear, previous studies have shown that bipolar disease is highly heritable.

Given its presence in human milk, arachidonic acid is considered essential for infant brain development and is added to infant formula in many countries. Therefore, it may exert an effect on bipolar disorder risk by affecting neurodevelopmental pathways, which would be consistent with contemporary views of bipolar disorder as a neurodevelopmental disorder. Arachidonic acid can be sourced directly from meat and seafood products or synthesized from dietary linoleic acid (e.g., nuts, seeds, and oils).

“Accumulating evidence indicates a role for metabolites in bipolar disorder and other psychiatric disorders. By identifying metabolites that play causal roles in bipolar disorder, we hoped to be able to highlight potential lifestyle or dietary interventions," said Lead investigator David Stacey.

In the study, by applying Mendelian randomization the researchers identified 33 out of 913 metabolites present in the blood that were associated with bipolar disorder, most of them lipids.

They found that a bipolar disorder risk gene cluster, which encodes enzymes associated with lipid metabolism, mediated the association between bipolar disorder and the levels of arachidonic acid and other metabolites.

"To our knowledge, this is the first study to highlight a potential causal role between arachidonic acid and bipolar disorder. Preclinical studies and randomized controlled trials will be necessary to determine the preventive or therapeutic value of arachidonic acid supplements, perhaps with a particular focus on people with a compromised arachidonic acid synthesizing pathway or with poor natural dietary sources. Our findings also support potential avenues for precision health interventions focused on early life nutrition to ensure that infants and children are receiving enough arachidonic acid and other polyunsaturated fatty acids to support optimal brain development, which may also reduce the risk of bipolar disorder,” concluded Stacey.

Reference: David Stacey, Beben Benyamin, S. Hong Lee, Elina Hyppönen; A Metabolome-Wide Mendelian Randomization Study Identifies Dysregulated Arachidonic Acid Synthesis as a Potential Causal Risk Factor for Bipolar Disorder; Biological Psychiatry; DOI:https://doi.org/10.1016/j.biopsych.2024.02.1005

A survey published in Menopause, the journal of The Menopause Society suggested that premature surgical menopause can lead to an increased risk of muscle disorders.

Premature menopause, particularly due to surgical intervention, can induce musculoskeletal pain through hormonal disruptions and associated physiological changes. Estrogen, a key hormone affected by menopause, plays a crucial role in maintaining bone density and muscle mass. Its decline accelerates bone resorption, leading to osteoporosis, and contributes to muscle atrophy and weakness.

Weakened bones and muscles are more susceptible to strain and injury, resulting in pain. Furthermore, estrogen deficiency can impact joint health, promoting inflammation and cartilage degradation, which may exacerbate conditions like osteoarthritis. Thus, premature menopause disrupts the intricate hormonal balance, precipitating accelerated bone loss, muscle weakness, and joint deterioration, culminating in musculoskeletal discomfort.

The study examined how various types of menopause affect muscle discomfort and function in women aged 55 years and older. It involved nearly 650 late-postmenopausal women and found that those who underwent premature surgical menopause were more prone to developing musculoskeletal discomfort and sarcopenia compared to those who experienced natural menopause at age 45 years or older. The researchers proposed that hormone deficiency, rather than chronological age alone, played a more significant role in the pain and decline of muscle mass during the late post menopause stage.

“This study highlights the potential long-term musculoskeletal effects of premature surgical menopause, which causes a more abrupt and complete loss of ovarian hormones, including estrogen and testosterone, than natural menopause. The use of hormone therapy until the natural age of menopause has the potential to mitigate some of the adverse long-term effects of early estrogen loss,” said Dr. Stephanie Faubion, medical director for The Menopause Society.

Reference: New study underscores the potential significance of hormone levels in influencing musculoskeletal health during the postmenopause phase; Menopause: THE MENOPAUSE SOCIETY; DOI: 10.1097/GME.0000000000000002367