Supplements for Brain Fog: What Studies Show

What the evidence shows

Vitamin C improved some attention measures in a small trial of healthy adults with low blood levels.
Creatine may help short-term memory and reasoning, but results for many other skills conflicted.
ME/CFS supplement studies reported some fatigue changes, but bias and mixed results limit confidence.
These studies do not show that supplements identify or correct the underlying cause of brain fog.

What brain fog studies actually measured

Brain fog is a broad complaint, but these papers did not test it as one condition. They measured attention, task performance, fatigue, or disease-specific symptoms instead. That difference limits what supplement findings can mean for everyday fog. None of these abstracts describes a trial in people recruited for unexplained brain fog.

The studies below cover healthy adults, healthy people in creatine trials, and people with ME/CFS. Their results cannot show whether a supplement identifies or corrects an underlying cause of someone's fog.

Vitamin C: a signal in adults with low blood levels

One study first examined 214 healthy adults aged 20 to 39. Higher blood vitamin C levels were linked with better attention (r = 0.16, p = 0.02; adjusted beta = 0.21, p = 0.003). The study found no significant links with fatigue or mood.

A separate randomized, double-blind trial included 46 healthy adults with low blood vitamin C. Low meant below 50 micromoles per liter. Twenty-four received vitamin C, and 22 received a dummy pill, for four weeks. Compared with the dummy pill, vitamin C improved attention and work absorption (both p = 0.03). Fatigue and overall work engagement showed trends, but not significant results (p = 0.06 and p = 0.07). Vitamin C did not change mood or blood BDNF, a marker measured in the study. The vitamin C group also did better on the Stroop attention and processing-speed test (p = 0.04).

This result applies to a small, selected group. It does not establish a benefit for people with brain fog generally. Vitamin C supplementation promotes mental vitality in healthy young adults: results from a cross-sectional analysis and a randomized, double-blind, placebo-controlled trial. (European journal of nutrition, 2022)

Creatine: possible gains, with mixed results

A review covered six randomized studies with 281 healthy people. It found possible improvements in short-term memory and intelligence or reasoning. Results conflicted for long-term and spatial memory, and memory scanning. They also conflicted for attention, executive function, response inhibition, and word fluency. Reaction time and mental fatigue results also conflicted.

Cognitive task performance stayed unchanged in young people. Vegetarians did better than meat-eaters on memory tasks, but not on other cognitive areas. The review suggested possible benefits for aging or stressed people. It called creatine safe, while also asking for larger studies. It said researchers should test creatine in people with dementia or cognitive impairment. Effects of creatine supplementation on cognitive function of healthy individuals: A systematic review of randomized controlled trials. (Experimental gerontology, 2018)

ME/CFS supplements: possible fatigue changes, weak evidence

A review included 14 studies with 809 people with ME/CFS. The studies used different designs, and the review found high risk of bias. Missing data and selection bias were common problems.

Some interventions showed significant reductions in fatigue: L-carnitine, guanidinoacetic acid, oxaloacetate, CoQ10 with selenium, NADH, and NADH with CoQ10. Results for cognitive function and inflammatory markers were mixed. Six studies reported adverse effects, including nausea and insomnia. The review said these limits prevent firm conclusions. It called for better diagnostic criteria and more diverse study groups. Dietary Supplementation for Fatigue Symptoms in Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS)-A Systematic Review. (Nutrients, 2025)

What these findings cannot tell us

These studies do not show that a supplement fixes the reason someone feels foggy. They did not test supplements against a cause-focused assessment. The vitamin C trial studied healthy adults with low blood levels. The creatine review covered healthy people. The fatigue review focused on people with ME/CFS.

Those groups are not the same as people with unexplained brain fog. The findings also use different measures, such as attention tests, memory tasks, and fatigue scores. Mixed results and study limits leave no firm answer for people outside the groups studied.

Sources

About this article

NootroWorld publishes research summaries, not medical advice. This article describes what studies have and have not established; it does not tell you what to take. Supplements can interact with medication, pregnancy and existing health conditions, and study populations often differ from your own situation. Discuss any personal decision with a qualified healthcare professional.