A claim you hear on longevity podcasts
The claim checked: B vitamins slow brain decline only when omega-3 levels are good Hear it at 1:14:27
Two reports from the VITACOG trial found B vitamins slowed brain shrinkage or cognitive decline only in people with high omega-3 levels. A Dutch trial found the reverse: folic acid helped those with lower omega-3. Three more found a weaker interaction or none.
Computed from 6 studies that test this point, each judged by two readers, in full. 9 more studies are waiting for a full read and do not count yet.
The study behind the claim tested something else. See what it tested
“But there are now at least three randomized control trials that have shown that omega-3 status and B vitamin status interact and they're dependent on one another.”
On tape: VITACOG first, then B-PROOF, then OmegAD, at least three trials. This is the VITACOG analysis. It found the interaction he describes, in people with mild cognitive impairment, as a post hoc split of one trial. Brain atrophy in cognitively impaired elderly: the importance of long-chain ω-3 fatty acids and B vitamin status in a randomized controlled trial. Am J Clin Nutr, 2015. Retrospective analysis of a randomized, placebo-controlled trial (VITACOG): B vitamins for 2 years, effect split by baseline omega-3 level, 168 people aged 70 and over with mild cognitive impairment in Oxford.
What it found
“In subjects with high baseline ω-3 fatty acids (>590 μmol/L), B vitamin treatment slowed the mean atrophy rate by 40.0% compared with placebo (P = 0.023).”
How the authors extend it
“The beneficial effect of B vitamin treatment on brain atrophy was observed only in subjects with high plasma ω-3 fatty acids.”
Not stated in the text we read. Two readers agreed on the label, and the paper was read in full.
controlled trial · 2015 · cited on tape
“Conclusions: The beneficial effect of B vitamin treatment on brain atrophy was observed only in subjects with high plasma ω-3 fatty acids.”
Brain atrophy in cognitively impaired elderly: the importance of long-chain ω-3 fatty acids and B vitamin status in a randomized controlled trial. Am J Clin Nutr
Who: Elderly people aged 70 or older with mild cognitive impairment in the VITACOG trial
PMID 25877495
controlled trial · 2016
“In conclusion, when plasma omega-3 fatty acid concentrations are low, B vitamin treatment does not slow cognitive decline in people with MCI.”
Omega-3 Fatty Acid Status Enhances the Prevention of Cognitive Decline by B Vitamins in Mild Cognitive Impairment. J Alzheimers Dis
Who: Older adults aged >=70 y with mild cognitive impairment (VITACOG trial, Oxford UK), mean baseline tHcy ~12 umol/L
PMID 26757190
systematic review · 2018
“However, there is limited evidence regarding the interaction of blood biomarkers such as n-3 fatty acid status and genetic risk factors including APOE4, which suggests the potential benefits of nutraceuticals may be dependent on multiple factors.”
Effect of long-term nutraceutical and dietary supplement use on cognition in the elderly: a 10-year systematic review of randomised controlled trials. Br J Nutr
Who: Systematic review of double-blind RCTs in adults with mean age 65 or older, n of at least 100, duration of at least 1 year
PMID 29310724
controlled trial · 2022
“This post-hoc analysis indicated that efficacy of B-vitamin supplementation in slowing cognitive decline relates to DHA status, with individuals with higher plasma DHA levels benefitting more from vitamin B12 and folic acid use.”
DHA status influences effects of B-vitamin supplementation on cognitive ageing: a post-hoc analysis of the B-proof trial. Eur J Nutr
Who: Cognitively healthy Dutch adults aged >=65 y with elevated plasma homocysteine (>=12 umol/L), Wageningen subsample of the B-proof trial
PMID 35704085
controlled trial · 2011
“Overall, there were no statistically significant main effects of group assignment on cognitive function (all P > 0.1).”
Cognitive function after supplementation with B vitamins and long-chain omega-3 fatty acids: ancillary findings from the SU.FOL.OM3 randomized trial. Am J Clin Nutr
Who: 1748 French men and women aged 45-80 y with a history of myocardial infarction, unstable angina, or ischemic stroke (SU.FOL.OM3 ancillary sample); homocysteine largely within the normal range
PMID 21593490
controlled trial · 2021
“Individuals with a lower ω-3 fatty acid status at baseline benefited from folic acid treatment, while individuals with a higher ω-3 fatty acid status did not.”
Positive effects of folic acid supplementation on cognitive aging are dependent on ω-3 fatty acid status: a post hoc analysis of the FACIT trial. Am J Clin Nutr
Who: Cognitively healthy Dutch men and postmenopausal women aged 50-70 y with elevated plasma homocysteine (13-26 umol/L) and vitamin B12 >=200 pmol/L (FACIT trial)
PMID 33564824
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