Evidence & research
Every claim in the library is tied to the literature. Here are all 110 research summaries in one place, each rated for evidence strength and linked to the underlying studies. Search by supplement or filter by how strong the evidence is.
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Showing 110 of 110 studies
B12 and homocysteine reduction
B12 supplementation lowers homocysteine, especially when combined with folate and B6.
Label accuracy of melatonin supplements
Independent testing has found actual melatonin content ranges from a fraction of to several times the labeled dose, with gummies the most variable.
Vitamin K2 and arterial calcification
A 2-year RCT of MK-7 plus vitamin D found no significant effect on arterial calcification progression; evidence for arterial benefits remains weak.
NAC and OCD / compulsive behaviours
Early small trials suggested benefit, but a phase III RCT found no evidence that NAC reduces OCD symptoms compared with placebo.
Arginine and blood pressure
Meta-analysis of RCTs shows arginine supplementation significantly reduces systolic and diastolic blood pressure.
Tongkat Ali and testosterone
Reviews of human trials report increases in testosterone, especially in men with low baseline levels.
Vitamin D and respiratory infections
Supplementation appears to modestly lower the risk of acute respiratory infections, with the largest benefit in deficient individuals.
Magnesium and sleep
Reviews suggest modest improvements in sleep parameters, especially in older adults or those with low intake.
Creatine safety and long-term supplementation
Long-term use shows no adverse effects on kidney or liver function in healthy adults across controlled trials.
Caffeine as an ergogenic aid
Consistently enhances endurance and high-intensity exercise performance.
Ashwagandha and stress
Standardized extracts reduce perceived stress and cortisol versus placebo in several RCTs.
Collagen peptides and skin aging
A review of randomized trials found oral collagen improved skin hydration, elasticity, and wrinkle depth.
Taurine and exercise performance
Some trials report small improvements in endurance and recovery, though results are mixed.
Magnesium and metabolic health
Higher dietary magnesium is consistently associated with improved insulin sensitivity and lower type-2 diabetes risk.
Magnesium for muscle cramps and recovery
A Cochrane review found magnesium unlikely to provide clinically meaningful cramp prevention in older adults; evidence in pregnancy and exercise-related cramps is mixed.
Creatine for muscle preservation in older adults
Improves lean mass and strength gains when combined with resistance training in aging adults.
Ashwagandha and sleep
Trials report improvements in sleep quality and onset latency.
MTHFR variants and folate metabolism
The C677T and A1298C MTHFR polymorphisms reduce enzyme activity by 40–70%, impairing conversion of folic acid and raising homocysteine levels.
B12 deficiency in vegans and older adults
B12 deficiency is prevalent in vegans without supplementation and in older adults with reduced gastric acid.
B12 supplementation and cognitive decline
Correcting deficiency supports cognition; benefit in already-replete adults is not established.
Berberine for weight loss
Small trials and pooled analyses show modest reductions in body weight and waist circumference; effects are real but smaller than social media suggests.
Vitamin D and bone fracture prevention
The largest meta-analysis (33 RCTs) found vitamin D with calcium was not associated with lower fracture risk in community-dwelling older adults; any benefit appears concentrated in institutionalized or deficient people.
Omega-3 and triglycerides
Consistent dose-dependent reductions in triglycerides across many trials.
Omega-3 and depression
EPA-predominant formulations show modest benefit as an adjunct in depressive symptoms.
Creatine loading, dosing, and muscle saturation
Daily 5 g saturates muscle creatine within a few weeks; a loading phase speeds saturation but is optional.
L-theanine and stress
Small studies suggest reduced stress and improved relaxation markers.
Citicoline and attention
A randomized trial in healthy adolescent males found improved attention and psychomotor speed with citicoline.
Calcium, vitamin D, and fractures
Large meta-analyses find calcium plus vitamin D does not significantly reduce fracture risk in community-dwelling older adults; benefit appears limited to institutionalized or deficient populations.
Homocysteine reduction with methylfolate
Active folate forms (methylfolate, folinic acid) are more effective than folic acid alone at lowering homocysteine in MTHFR carriers.
Glycine and collagen synthesis
Glycine supplementation increases collagen synthesis markers, supporting joint and skin health.
Arginine and erectile dysfunction
Supplemental arginine (3–6 g/day) improves erectile function scores in mild to moderate ED in multiple controlled trials.
Collagen for joint pain
Trials in athletes and osteoarthritis patients report reduced joint pain with daily collagen peptides.
Berberine for type 2 diabetes
Meta-analyses of randomized trials report significant reductions in fasting glucose, post-meal glucose, and HbA1c, though trial quality varies.
Magnesium for migraine prevention
Randomized trials support magnesium for reducing migraine frequency in some patients.
Creatine and cognition
Early studies suggest cognitive benefits, particularly under stress such as sleep deprivation.
Probiotics and IBS
Some strains improve IBS symptoms, though benefits are strain- and individual-specific.
L-Methylfolate and depression
L-Methylfolate as an adjunct to antidepressants improves outcomes in patients with major depressive disorder, particularly those with MTHFR polymorphisms.
NAC and glutathione
Oral NAC reliably increases blood and tissue glutathione levels across a wide range of populations and conditions.
B12 and energy metabolism
B12 is a cofactor in energy metabolism; supplementation raises energy only when someone is deficient.
Glucosamine sulfate for knee osteoarthritis
Reviews find glucosamine sulfate offers small benefits for pain and function, with the sulfate form outperforming hydrochloride.
Glucosamine and joint space narrowing
Meta-analysis finds little to no effect on joint-space narrowing, though a small pain benefit is possible.
Psyllium and cholesterol
Meta-analyses confirm psyllium lowers LDL and total cholesterol in a dose-dependent way.
Rhodiola and stress
A standardized extract improved self-reported stress and related symptoms over several weeks in stressed adults.
Ginseng and fatigue
Reviews of randomized trials report reductions in mental and physical fatigue with Panax ginseng versus placebo.
Taurine and cardiovascular function
Reviews suggest taurine supports blood pressure regulation, endothelial function, and cardiac output.
CoQ10 and statin myopathy
Reviews of trials report mixed results for CoQ10 easing statin-associated muscle symptoms, with some benefit in subsets.
Berberine in PCOS
Early trials report improved insulin resistance and hormonal markers in women with polycystic ovary syndrome.
Vitamin K2 and bone density
Some trials report improved bone mineral density and reduced fracture markers, though results vary by population and dose.
Magnesium and blood pressure
Meta-analyses show modest reductions in blood pressure with magnesium supplementation.
Magnesium, anxiety, and stress
Reviews link low magnesium status to higher subjective anxiety and stress measures.
Zinc and the common cold
Evidence is mixed: some meta-analyses find high-dose zinc lozenges started within 24 hours shorten colds, while others conclude the evidence is still lacking; dose and formulation matter.
Alternate-day iron dosing
Spacing doses may increase fractional absorption by reducing hepcidin spikes.
Creatine for strength and power
Decades of trials confirm improvements in strength, power, and lean mass with resistance training.
ISSN position stand on creatine supplementation
The International Society of Sports Nutrition concludes creatine monohydrate is the most effective and safe ergogenic supplement for high-intensity work and lean mass.
Citicoline and age-related cognition
Reviews suggest benefits for memory and cognition in older adults and in post-stroke recovery.
Probiotics and antibiotic-associated diarrhea
Specific strains reduce the risk of antibiotic-associated diarrhea in reviews.
NAC and COPD
High-dose NAC reduces exacerbations and improves lung function in chronic obstructive pulmonary disease.
Glutamine and gut permeability
Supplementation reduces markers of intestinal permeability in critically ill patients, surgical patients, and endurance athletes.
Citrulline malate and resistance exercise
Trials are mixed: some report more repetitions and less soreness with 8 g before training, while a controlled study found no improvement in muscle recovery.
Riboflavin for migraine prevention
High-dose riboflavin (400 mg/day) reduces migraine frequency in adults and children.
B6, homocysteine, and cardiovascular risk
B6 supplementation lowers homocysteine, especially when combined with folate and B12.
Inulin and gut bacteria
Trials show inulin-type fructans increase Bifidobacteria and support a healthier microbiome.
Rhodiola and fatigue
Standardized extracts reduced symptoms of stress-related and chronic fatigue versus placebo in multiple randomized trials.
Melatonin in older adults
Reviews find improved sleep quality in older adults, whose natural production declines, particularly with prolonged-release formulations.
Berberine and blood lipids
Trials show reductions in LDL cholesterol and triglycerides, partly through increased LDL-receptor expression.
Iron and fatigue in deficiency
Supplementation improves fatigue and work capacity in iron-deficient individuals, even without full anemia.
Caffeine and cognitive performance
Improves alertness, vigilance, and reaction time, especially when fatigued.
Curcumin and osteoarthritis
Trials suggest reduced joint pain and improved function, often comparable to NSAIDs with fewer GI effects.
Tryptophan and sleep
Supplemental tryptophan modestly shortens sleep latency and increases sleep efficiency in several small controlled trials.
Zinc and copper balance
Sustained high-dose zinc induces copper deficiency, supporting combined supplementation.
Folate and neural tube defect prevention
Periconceptional folate supplementation reduces neural tube defect risk by 50–70% in clinical trials and population studies.
Tyrosine and stress-induced cognitive decline
Supplementation attenuates the decline in working memory and information processing seen under cold-stress and sleep deprivation.
Glutamine and immune function
Perioperative glutamine supplementation reduces infection rates and hospital stay duration in multiple clinical trials.
Citrulline vs arginine for blood arginine levels
Oral citrulline raises plasma arginine levels more effectively than equimolar arginine due to better intestinal absorption and reduced splanchnic extraction.
B12 forms: methylcobalamin and cyanocobalamin
Common forms are similarly effective at correcting deficiency at adequate doses.
Boron and mineral metabolism
Boron supplementation reduces urinary calcium and magnesium loss and supports vitamin D status.
Boron and hormones
Short human trials report increases in free testosterone and changes in estrogen and inflammatory markers with daily boron.
Alpha-GPC and power output
Small studies report increases in lower-body power and force after acute alpha-GPC dosing.
Phosphatidylserine and memory in older adults
Trials and reviews report modest improvements in memory and cognition in older adults with age-related decline.
Vitamin C and iron absorption
Co-ingestion markedly increases non-heme iron absorption in controlled studies.
Tryptophan, serotonin, and mood
Acute tryptophan depletion reliably worsens mood in vulnerable individuals, supporting the role of the serotonin pathway.
Niacin and lipid profile
High-dose niacin favourably alters HDL, triglycerides, and LDL in dyslipidaemia.
Pantethine and lipids
Pantethine supplementation shows modest reductions in LDL and triglycerides in some trials.
Psyllium for constipation and IBS
Soluble fiber from psyllium improves stool consistency and symptoms in constipation and IBS.
CoQ10 in heart failure (Q-SYMBIO)
A randomized trial found CoQ10 added to standard therapy reduced major adverse cardiovascular events and symptoms in heart failure.
Vitamin C and the common cold
Regular supplementation modestly shortens cold duration but does not reliably prevent colds.
Huperzine A and cognition
Reviews of trials in Alzheimer's disease and cognitive decline report memory benefits, but caution that study quality is low.
Piperine as a bioavailability enhancer
Increases absorption of several nutrients and drugs by inhibiting their metabolism and transport.
Tyrosine and working memory
Improves working memory and cognitive flexibility in demanding but not routine cognitive tasks.
Betaine and athletic performance
Several RCTs report gains in power, strength, or body composition with ~2.5 g/day betaine, though findings are inconsistent across protocols.
Thiamine deficiency and neuropathy
Thiamine deficiency is a well-documented cause of peripheral neuropathy and Wernicke encephalopathy.
Vitamin B12 and neurological function
B12 maintains myelin; deficiency causes reversible and, if prolonged, irreversible neurological damage.
Tongkat Ali and stress hormones
A standardized extract reduced cortisol and improved mood scores in moderately stressed adults.
Alpha-GPC and cognition
Trials in older adults and after stroke suggest alpha-GPC may support memory and attention; data in healthy young adults is more limited.
Melatonin for sleep onset and insomnia
Meta-analyses of randomized trials find melatonin reduces sleep-onset latency and modestly improves total sleep time, with larger effects in delayed sleep phase.
Glycine and sleep quality
3 g of glycine before bed improves subjective sleep quality and reduces daytime sleepiness and fatigue in controlled trials.
Uridine for mood
Small early studies, sometimes combined with omega-3s, suggest possible mood benefits but are limited in size and quality.
L-theanine, caffeine, and attention
The combination improves attention and reduces task-switching errors more than caffeine alone.
5-HTP and serotonin synthesis
5-HTP readily crosses the blood-brain barrier and is decarboxylated to serotonin, raising central serotonin more directly than tryptophan.
Ginseng and cognition
Trials suggest Panax ginseng can improve some aspects of cognitive performance and mood, especially under stress or fatigue.
Uridine, DHA, and synaptic membranes
Mechanistic and animal studies show uridine combined with DHA and choline increases synaptic membrane phospholipids and synaptic proteins.
Inulin and mineral absorption
Prebiotic fibers can improve calcium absorption and bone mineral density in some studies.
Huperzine A mechanism
Pharmacology studies confirm it is a reversible inhibitor of acetylcholinesterase that crosses the blood-brain barrier.
Betaine and homocysteine
Betaine supplementation lowers plasma homocysteine in a dose-dependent manner via BHMT-mediated remethylation, independent of folate status.
Phosphatidylserine and exercise cortisol
A randomized study found PS supplementation did not significantly affect cortisol responses to exercise.
5-HTP and mood
Small controlled trials suggest 5-HTP may improve low mood, but evidence quality and trial sizes are limited.
Melatonin for jet lag
A Cochrane review concluded melatonin taken at the target bedtime is remarkably effective at preventing or reducing jet lag across multiple time zones.
Curcumin bioavailability with piperine
Piperine substantially increases curcumin absorption in pharmacokinetic studies.
Biotin for brittle nails
2.5 mg/day biotin improved nail thickness and reduced splitting in people with brittle nails.
Copper-zinc balance
Maintaining copper intake offsets the copper depletion seen with sustained high-dose zinc.
Reviewed by Vital Matrix Research Team. Research summaries are plain-language interpretations of the cited sources and are for educational purposes only, not medical advice. Many links point to PubMed searches so you can review the wider body of evidence yourself.