Research library / 174 articles
Evidence-aware explainers, practical supplement guides, and cognitive health research, written to show where confidence ends.
Caffeine has the clearest short-term evidence for alertness. Iron may ease fatigue in people with low iron stores, while extra B12 has not helped people with normal levels. Ginseng findings remain mixed.
Human studies of lion’s mane, reishi and cordyceps are small and mixed. Lion’s mane has the clearest direct cognition trials, including one in people with mild cognitive impairment, but results in healthy adults are inconsistent. A trial combining reishi and cordyceps found no cognitive benefit in healthy young adults.
Small, short-term trials in healthy adults report better performance on some attention-switching tasks after caffeine and L-theanine together. Results vary by task, and the evidence does not establish that the combination reliably outperforms caffeine alone. A 2025 review found possible benefits versus placebo, with uncertainty in the size and consistency of effects.
Randomized human studies consistently show that caffeine can reduce vigilance failures during acute sleep deprivation, especially on psychomotor attention tests. The benefit is incomplete, varies by task and person, and may be offset by poorer recovery sleep or cardiovascular effects.
Human research on bovine colostrum in physically active adults suggests possible effects on exercise-related gut-permeability markers, but findings are inconsistent. Immune biomarker changes are generally small, while recovery and performance evidence remains limited and dependent on narrow laboratory outcomes.
Human trials suggest lactoferrin can affect some iron-related and immune markers, but findings vary by population, formulation, comparator, and study design. Evidence is strongest for short-term laboratory changes, not for broad clinical benefits.
Human studies consistently show that trimethylglycine, also called betaine, can lower circulating homocysteine under some conditions. Evidence for better exercise performance is weaker and varies by outcome, training status, study duration, and test protocol.
Human studies of inositol suggest possible effects on panic symptoms and glucose-related measures, but the evidence is uneven. Small psychiatric trials, mixed metabolic studies, and PCOS research do not establish a consistent benefit across populations or outcomes.
Human research links higher beta-cryptoxanthin exposure with some favorable bone measures and lower inflammatory markers, but most evidence is observational. Small intervention studies have measured bone-turnover markers, not fractures or lasting changes in bone density.
Human trials suggest that some standardized Boswellia serrata extracts may improve pain, stiffness, and function in adults with knee osteoarthritis. Evidence for inflammatory-marker changes is less consistent, and differences between extracts, small samples, short follow-up, and industry involvement limit certainty.
This evidence review compares human trials of ginger extract for nausea in pregnancy, after surgery, and during chemotherapy with studies of inflammatory blood markers. It separates symptom outcomes from surrogate biomarkers, identifies studied populations and trial strengths, and explains why the findings do not establish broad clinical benefits.
Controlled human studies suggest pomegranate extract or juice can transiently affect measured blood flow and may improve performance in some exercise tests. Recovery findings are mixed: small trials report both reduced soreness and no benefit. Results are limited by small, young, mostly athletic samples and differing products, protocols, and outcomes.
Human research links lycopene with some vascular and cognitive-aging markers, but the evidence is limited by small or selective populations, surrogate outcomes, observational designs, and a lack of long-term cognitive intervention trials.
Human trials have not established chromium picolinate as a consistent way to improve glycemic markers. Cognitive evidence is limited to one small older-adult trial, so claims of reliable cognitive enhancement remain unproven.
Human trials suggest iodine supplementation can improve some cognitive measures in iodine-deficient schoolchildren, especially when deficiency is moderate or severe. Evidence is weaker and mostly null for offspring of mildly deficient pregnant women, while cognitive benefits in iodine-sufficient adults remain unestablished.
Human research suggests vitamin C may influence attention and short-term stress responses, especially when status is low, but evidence does not establish broad cognitive enhancement or durable protection against decline. This review separates deficiency-related findings from studies in vitamin C–replete adults.
Human studies often associate lower folate or higher homocysteine with poorer cognition in older adults, but association does not establish causation. Randomized trials reliably lower homocysteine more often than they improve memory, executive function, or global cognition.
Human research suggests riboflavin may reduce migraine frequency in some adults, but the evidence base is small, heterogeneous, and not yet sufficient to establish how mitochondrial biology translates into reliable clinical benefit.
Human trials suggest that L-ornithine may influence subjective fatigue, mood, and some sleep-related measures in healthy adults, but the evidence remains small, short-term, and mostly from Japanese study populations. Cortisol findings are inconsistent, objective sleep evidence is limited, and clinical benefits for diagnosed conditions have not been established.
Human research suggests L-carnosine may influence selected glycation-related and metabolic biomarkers, but evidence remains limited, short-term, and concentrated in people with diabetes or metabolic risk. Healthy-aging findings often involve beta-alanine or anserine-carnosine mixtures rather than isolated L-carnosine.
Human research on alpha-ketoglutarate and aging remains early. A small uncontrolled formulation study and a larger observational cohort reported lower DNA-methylation-based biological-age measures, but neither establishes that AKG slows aging or improves healthspan. A randomized trial has been conducted, yet published results have so far focused on recruitment rather than efficacy.
Human research suggests resistant starch may modestly improve some glucose and insulin-resistance markers, but results vary by starch type and population. Direct evidence for improved cognition is sparse and does not yet establish a causal benefit.
Human studies suggest that inulin and related prebiotic fibres can influence some mood, memory, cognitive-flexibility, and food-decision outcomes, but the findings are mixed and population-specific. Microbiome changes often accompany these effects, yet no study has firmly established that microbiome changes cause the psychological outcomes.
Human trials suggest that some probiotic formulations may influence perceived stress, selected mood measures, and performance on certain cognitive tests. However, results vary by strain, population, outcome, and study design, so broad claims about probiotics as general mood or cognition enhancers are not established.
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