New evidence underscores the importance of dietary nutrients in slowing cognitive decline in older adults.
One study, published in the American Journal of Clinical Nutrition, showed that older adults taking a daily multivitamin containing more than 20 essential micronutrients had less memory impairment than those taking a dummy pill or placebo.
The research was part of the parent COcoa Supplement and Multivitamin Outcomes Study (COSMOS) that’s testing a cocoa extract and a daily multivitamin-mineral supplement for cardiovascular disease and cancer prevention. This current analysis included 573 participants, average age almost 70 years, who were randomized to take the daily supplement or a placebo and completed comprehensive cognitive tests at the beginning of the study and after two years.
After adjusting for age and other factors that can affect cognition, the study found that participants assigned to the supplement group had a modest benefit in global cognition (a composite of average scores from 11 cognitive tests) and a statistically significant more favourable change in memory over two years compared to those taking a placebo.
Researchers carried out an additional analysis of more than 5,000 participants across three COSMOS sub-studies (the current one used in-person cognitive assessments, while the two others tested cognition using telephone-based and web-based assessments). That analysis showed clear evidence of the benefits of the supplement on both global cognition and memory that may translate to a reduction by two years in cognitive aging.
The results make sense, the authors said. Combinations of vitamins and minerals interact with multiple biologic pathways that support cognitive health, while the study’s older subjects are more likely to have nutritional and micronutrient deficiencies that put them at increased risk of cognitive decline.
The authors also note that long-term multivitamin supplements are accessible and have no negative side effects.
The study was unable to determine whether individual vitamins or minerals in the supplement explain the cognitive benefits. It’s also unclear whether supplements other than those used in the study (Centrum Silver) would have the same favourable results.
In addition to taking multivitamins, following the Mediterranean diet also supports healthy brain aging. A lengthy study that used food-intake biomarkers found that older people who adhered to the Mediterranean diet had significantly less cognitive decline.
The study, published in Molecular Nutrition & Food Research, included a total of 840 older people without dementia in two centres in France (Bordeaux and Dijon) who provided blood samples at the beginning of the study and completed cognitive assessments at regular follow-up visits.
Previous studies used self-reported questionnaires to examine dietary patterns, which rely on recall. Here, researchers developed a Mediterranean diet metabolomic score (MDMS) based on biomarkers of food-related metabolites in the blood samples, which provides a more accurate picture of food consumption.
The biomarkers provide evidence of adherence to seven key food groups of the Mediterranean diet (vegetables, legumes, fruits, cereals, dairy, fats and fish) that more accurately capture dietary patterns than questionnaires.
The total MDMS ranged from 0 (minimal adherence) to 14 (maximal adherence).
After 12 or so years, a higher MDMS was associated with about a 10 per cent lower risk of cognitive decline in both study samples. This was after considering possible confounders such as demographics (age, sex, race), modifiable risk factors for dementia (diabetes, alcohol intake, smoking status, etc.), genetic factors and medications.
The diet could prevent cognitive decline directly (through the brain-boosting power of individual nutrients) or indirectly by reducing other risk factors such as high blood pressure and type 2 diabetes.
