Research & Clinical Studies

Every recommendation on this site is backed by peer-reviewed research. Browse the clinical evidence behind our supplement profiles and guides.

16
Studies Cited
4
Meta-Analyses
7
RCTs
12
Ingredients

Evidence Hierarchy

Meta-Analysis
Highest quality — pools multiple studies
RCT
Gold standard — randomized controlled
Systematic Review
Comprehensive review of all evidence
Cohort Study
Observational — tracks groups over time
Narrative Review
Expert summary of current knowledge

Showing 16 of 16 studies

Systematic ReviewCreatineCognitive Function2018

Effects of creatine supplementation on cognitive function: a systematic review and meta-analysis

Avgerinos KI, Spyrou N, Bougioukas KI, et al. — Experimental Gerontology

RCTAshwagandhaStress & Anxiety2012

A prospective, randomized double-blind, placebo-controlled study of safety and efficacy of a high-concentration full-spectrum extract of ashwagandha root

Chandrasekhar K, Kapoor J, Anishetty S. — Indian Journal of Psychological Medicine

Systematic ReviewCollagenSkin Health2019

Oral collagen supplementation: a systematic review of dermatological applications

Choi FD, Sung CT, Juhasz ML, Mesinkovsk NA. — Journal of Drugs in Dermatology

Meta-AnalysisVitamin DMood & Depression2014

Vitamin D supplementation for depressive symptoms: a systematic review and meta-analysis

Shaffer JA, Edmondson D, Wasson LT, et al. — Psychosomatic Medicine

Meta-AnalysisOmega-3 / Fish OilDepression2019

Efficacy of omega-3 PUFAs in depression: a meta-analysis

Liao Y, Xie B, Zhang H, et al. — Translational Psychiatry

Cohort StudyMagnesiumDepression2015

Magnesium intake and depression in adults

Tarleton EK, Littenberg B. — Journal of the American Board of Family Medicine

RCTVitamin DEnergy & Muscle Function2013

Improving the vitamin D status of vitamin D deficient adults is associated with improved mitochondrial oxidative function in skeletal muscle

Sinha A, Hollingsworth KG, Ball S, Cheetham T. — Journal of Clinical Endocrinology & Metabolism

RCTLion's ManeCognitive Function2011

Effects of Hericium erinaceus on amyloid β(25-35) peptide-induced learning and memory deficits in mice

Mori K, Inatomi S, Ouchi K, et al. — Biomedical Research

Narrative ReviewCreatineAthletic Performance2017

International Society of Sports Nutrition position stand: creatine supplementation and exercise

Kreider RB, Kalman DS, Antonio J, et al. — Journal of the International Society of Sports Nutrition

RCTBacopa MonnieriMemory & Learning2001

A double-blind, placebo-controlled, randomised study on the effects of a standardised Bacopa monnieri extract on cognitive performance

Stough C, Lloyd J, Clarke J, et al. — Psychopharmacology

Meta-AnalysisZincAcne / Skin Health2020

Effects of zinc supplementation on the incidence of acne: a meta-analysis

Yee BE, Richards P, Sui JY, Marsch AF. — Journal of Clinical and Aesthetic Dermatology

Systematic ReviewRhodiola RoseaFatigue & Mental Performance2012

Rhodiola rosea for physical and mental fatigue: a systematic review

Ishaque S, Shamseer L, Bukutu C, Vohra S. — BMC Complementary and Alternative Medicine

RCTCurcumin / TurmericDepression2014

Curcumin for the treatment of major depression: a randomised, double-blind, placebo controlled study

Lopresti AL, Maes M, Maker GL, et al. — Journal of Affective Disorders

Meta-AnalysisProbioticsAnxiety & Stress2019

Probiotic supplementation reduces stress and anxiety: a meta-analysis

Liu RT, Walsh RFL, Sheehan AE. — Neuroscience & Biobehavioral Reviews

RCTAshwagandhaTestosterone2019

Effect of ashwagandha (Withania somnifera) root extract on testosterone and luteinizing hormone in men

Lopresti AL, Drummond PD, Smith SJ. — American Journal of Men's Health

RCTCollagenBone Health2018

Specific collagen peptides improve bone mineral density and bone markers in postmenopausal women

König D, Oesser S, Scharla S, et al. — Nutrients

Our Research Methodology

Every supplement recommendation on BestSellingSupplements.com is grounded in peer-reviewed clinical research. We prioritize meta-analyses and systematic reviews as the highest form of evidence, followed by randomized controlled trials (RCTs), cohort studies, and expert reviews.

We evaluate studies based on: sample size and statistical power, study design and methodology, conflict of interest disclosures, reproducibility across multiple trials, and clinical relevance of the outcomes measured.

Our evidence ratings reflect the overall body of research, not individual studies. A "Strong" rating means multiple high-quality trials with consistent results. "Moderate" means good evidence with some limitations. "Emerging" means promising early research that needs more confirmation.

This page is regularly updated as new research is published. Last updated: February 2026.