Evidence for Supplements #

Every substantive claim on the Supplements page is checked against current research. Here is each claim, how well today’s evidence supports it, and the sources. The full, de-duplicated source list lives on the references page.

Supported · moderate evidence — For cognitively healthy, well-nourished adults there is no dietary supplement with convincing evidence that it improves learning or memory.

Cochrane reviews of vitamin and mineral supplementation for cognition in non-demented adults find no convincing benefit; this matches the broad 2026 consensus that supplements do not enhance cognition in healthy, well-fed people. The debunk of the enhancement claim is the well-supported position.

Sources: Rutjes, A. W. S., et al. (2018), Vitamin and mineral supplementation for maintaining cognitive function in cognitively healthy people in mid and late life. Cochrane Database of Systematic Reviews — https://doi.org/10.1002/14651858.CD011906.pub2 · full reference ›

Supported · moderate evidence — Omega-3 (fish oil) supplementation does not produce a clear improvement in cognition or memory in cognitively healthy older adults.

The Cochrane review of omega-3 PUFA for cognition in cognitively healthy older people found no benefit on standard cognitive tests over follow-up; subsequent large trials (e.g. the VITAL cognitive substudy) reinforce the null in 2026. The page’s debunk of an omega-3 memory benefit is supported.

Sources: Sydenham, E., Dangour, A. D., & Lim, W.-S. (2012), Omega 3 fatty acid for the prevention of cognitive decline and dementia. Cochrane Database of Systematic Reviews — https://doi.org/10.1002/14651858.CD005379.pub3 · full reference ›

Supported · strong evidence — Ginkgo biloba does not reliably improve memory or thinking, and does not prevent cognitive decline, in healthy adults.

The Cochrane review concluded the evidence that ginkgo has predictable, clinically significant benefit for cognitive impairment or dementia is inconsistent and unreliable, and large prevention trials (GEM, GuidAge) found no effect on cognitive decline; this is the firm 2026 view. The page contradicts the old marketing claim, which is the supported stance.

Sources: Birks, J., & Grimley Evans, J. (2009), Ginkgo biloba for cognitive impairment and dementia. Cochrane Database of Systematic Reviews — https://doi.org/10.1002/14651858.CD003120.pub3 · full reference ›

Mixed · moderate evidence — Multivitamin supplementation has no convincing effect on cognition in well-nourished people.

Cochrane and most trials find no cognitive benefit of multivitamins in well-nourished adults; however, some recent large trials (e.g. COSMOS-Mind/COSMOS-Web, published 2022-2023) reported small effects on certain memory measures in older adults, so the picture is not entirely settled. Rated ‘mixed’ because the page’s blanket ’no convincing effect’ is broadly right but a few recent results qualify it.

Supported · moderate evidence — Correcting a genuine nutrient deficiency (e.g. B12, iron, vitamin D) can improve how a person feels and functions, but topping up a nutrient already at adequate levels does not push cognition beyond normal.

It is well established that deficiency states (notably B12 and iron-deficiency anaemia) impair cognition and are reversible with treatment, whereas supplementation above sufficiency yields no enhancement in the trial evidence; this deficiency-versus-enhancement distinction is standard in 2026 nutrition guidance.

Supported · moderate evidence — Even mild dehydration impairs attention and short-term memory, so adequate hydration supports cognitive performance.

Meta-analytic and experimental work shows mild dehydration (around 1-2% body-mass loss) degrades attention, executive function and short-term memory; this is well accepted in 2026 though individual effect sizes vary by task.

Sources: Wittbrodt, M. T., & Millard-Stafford, M. (2018), Dehydration impairs cognitive performance: A meta-analysis. Medicine & Science in Sports & Exercise — https://doi.org/10.1249/MSS.0000000000001682 · full reference ›

Supported · moderate evidence — The brain depends on a steady supply of glucose, and low blood glucose (e.g. from skipping a meal before study) impairs memory and attention.

It is basic neuroscience that glucose is the brain’s primary fuel and that hypoglycaemia impairs cognition; experimental glucose-and-memory studies show modest enhancement when glucose is restored, supporting ‘steady supply matters’ without endorsing sugar loading. Well established in 2026.

Sources: Mergenthaler, P., Lindauer, U., Dienel, G. A., & Meisel, A. (2013), Sugar for the brain: the role of glucose in physiological and pathological brain function. Trends in Neurosciences — https://doi.org/10.1016/j.tins.2013.07.001 · full reference ›

Supported · strong evidence — Sleep consolidates newly learned material into lasting memory, and no supplement substitutes for adequate sleep.

Sleep-dependent memory consolidation is one of the most robust findings in cognitive neuroscience (Rasch & Born 2013 and a large subsequent literature); it remains firmly established in 2026 and dwarfs any supplement effect.

Sources: Rasch, B., & Born, J. (2013), About sleep’s role in memory. Physiological Reviews — https://doi.org/10.1152/physrev.00032.2012 · full reference ›

Supported · moderate evidence — Regular aerobic exercise supports brain health and memory.

Meta-analyses of randomised trials show aerobic and combined exercise produce small-to-moderate improvements in cognition, particularly executive function, in adults; the direction is well supported in 2026 though effect sizes are modest and vary by population.

Sources: Northey, J. M., Cherbuin, N., Pumpa, K. L., Smee, D. J., & Rattray, B. (2018), Exercise interventions for cognitive function in adults older than 50: a systematic review with meta-analysis. British Journal of Sports Medicine — https://doi.org/10.1136/bjsports-2016-096587 · full reference ›

Supported · moderate evidence — A balanced whole-diet pattern (e.g. Mediterranean-style: vegetables, fish, whole grains) is more convincingly linked to better long-term brain health than any single supplement.

Systematic reviews of dietary patterns find that higher adherence to Mediterranean-type diets is associated with better cognitive outcomes and slower decline, an association more consistent than single-nutrient supplementation; this whole-diet emphasis is the mainstream 2026 position, though much of the evidence is observational.

Sources: van den Brink, A. C., et al. (2019), The Mediterranean, Dietary Approaches to Stop Hypertension (DASH), and MIND diets and the risk of cognitive decline and dementia. Advances in Nutrition — https://doi.org/10.1093/advances/nmy078 · full reference ›

Supported · strong evidence — Caffeine reliably improves alertness, reaction time and vigilance, which can indirectly aid learning, especially when tired or on simple/repetitive tasks.

The performance-enhancing effects of caffeine on alertness, reaction time and vigilance (particularly under fatigue) are among the best-replicated findings in psychopharmacology and are well established in 2026; it is an arousal aid rather than a memory enhancer.

Sources: McLellan, T. M., Caldwell, J. A., & Lieberman, H. R. (2016), A review of caffeine’s effects on cognitive, physical and occupational performance. Neuroscience & Biobehavioral Reviews — https://doi.org/10.1016/j.neubiorev.2016.09.001 · full reference ›

Supported · moderate evidence — Caffeine has a half-life of roughly six hours, so consuming it before bed disrupts sleep and is counterproductive.

Caffeine’s typical half-life of about 5-6 hours and its disruption of sleep when taken even several hours before bedtime are well documented (e.g. Drake et al. 2013 found caffeine 6 hours before bed significantly disturbed sleep); established in 2026, with individual variation in metabolism.

Sources: Drake, C., Roehrs, T., Shambroom, J., & Roth, T. (2013), Caffeine effects on sleep taken 0, 3, or 6 hours before going to bed. Journal of Clinical Sleep Medicine — https://doi.org/10.5664/jcsm.3170 · full reference ›