The effects of the supplementation were more significant in elderly who already suffer from mild cognitive impairment.
Researchers added that large, high-quality, long-term trials are needed to confirm the findings.
Nonetheless, they believe that B-vitamins and essential fatty acids supplementation could be “promising strategies” in minimising age-related cognitive decline in Asia.
Findings of the meta-analysis were recently published in Critical Reviews in Food Science and Nutrition.
This is said to be the first complete overview of nutrition intervention trials for the prevention of cognitive impairment in East Asia, including Brunei, Cambodia, China, Fiji, Indonesia, Lao’s, Malaysia, Myanmar, Singapore, Vietnam.
Eighteen RCTs were included in the meta-analysis.
They assessed five types of intervention, including micronutrient supplementation, essential fatty acids supplementation, chicken essence supplementation, nutraceuticals, and nutritional and lifestyle counselling.
Of which, only B-vitamins and essential fatty acids supplementation showed significant evidence in reducing cognitive decline.
In the case of B-vitamins, it was found that elderly with elevated homocysteine levels are more likely to benefit than those with normal homocysteine levels.
Homocysteine is an amino acid which is linked to heart disease and Alzheimer’s disease when present in the blood in high level.
The researchers said that for the next step, large trials are needed to identify at which homocysteine level should supplementation of B-vitamins start to reduce dementia incidence.
On the other hand, EPA/DHA supplementation was found to be beneficial for improving attention and orientation in elderly with mild cognitive impairment.
“In conclusion, several promising strategies, such as B-vitamin and EPA/DHA supplementation, seem to be able to decrease age-related cognitive decline in East-Asia.
“These nutritional strategies appear to be more effective in older subjects with impaired cognitive function,” the researchers said.
No significant effects
The supplementation of chicken essence, certain nutraceuticals, and adapting a nutritional and lifestyle counselling did not lead to significant reduction in cognitive decline amongst elderly.
Chicken essence was found to improve single neuropsychological test scores, but researchers said the overall quality of the trials was low, thus, there was a lack of evidence.
“We did not find any additional evidence in favour of chicken essence and conclude that based on the current data chicken essence does not seem a promising strategy for prevention of cognitive impairment,” they said.
Some nutraceuticals assessed in the meta-analysis, such as L-carnitine and soy-isoflavone also did not lead to significant improvement.
Only one RCT covered in the meta-analysis studied the effects of L-carnitine supplementation.
The researchers believe that as the study had a small sample size of 50 subjects and a short intervention duration of 10 weeks, this could have led to the inability to detect beneficial effect of L-carnitine.
On the other hand, since soy is already a staple food in Asia, the researchers said that supplementation is unlikely to lead to improvements.
“It seems more effective to focus on nutrients that are lacking in the general diet of East-Asian population, than nutrients that are already consumed in a relatively high amount,” they said.
Source: Critical Reviews in Food Science and Nutrition
Nutritional interventions for the prevention of cognitive impairment and dementia in developing economies in East-Asia: a systematic review and meta-analysis
Authors: Andrea McGrattan, Carla van Aller, Alla Narytnyk, Daniel Reidpath, Hannah Keage, Devi Mohan, Tin Tin Su, Blossom Stephan, Louise Robinson and Mario Siervo