The Internet's Most Trusted Encyclopedia of Dietary Supplements

Evidence-graded research on 250+ ingredients, 200+ product categories, and 800+ in-depth articles. Reviewed by licensed clinicians. Updated monthly.

5,000+ peer-reviewed citations · 12 licensed medical reviewers · Trusted by 1.2M readers

Browse by Category

Every ingredient organized by what it does — find what's right for your goal.

Vitamins

A through K — fat-soluble, water-soluble, methylated forms, dosages, and deficiency signs.

Minerals

Macro, trace, and ultra-trace minerals. Bioavailable forms and absorption science.

Amino Acids & Proteins

EAAs, BCAAs, creatine, collagen, whey, plant proteins — what works for whom.

Herbs & Adaptogens

Ashwagandha, rhodiola, ginseng, turmeric, and 80+ other clinically-studied botanicals.

Omega Fatty Acids

EPA, DHA, omega-3 vs 6, fish vs algal vs krill — bioavailability and dosing.

Probiotics & Prebiotics

Lactobacillus, Bifidobacterium, spore-forming strains, and the prebiotics that feed them.

Longevity Compounds

NMN, NR, spermidine, fisetin, urolithin A, calcium AKG — the science of healthy aging.

Specialty & Phytochemicals

CoQ10, astaxanthin, quercetin, resveratrol, sulforaphane, and other targeted compounds.

Most-Searched Ingredients

The ingredients our readers ask about most this month.

Mineral

Magnesium

Sleep, muscle, anxiety, migraines — and which form to choose.

Adaptogen

Ashwagandha

Stress and cortisol — KSM-66 vs Sensoril vs raw root.

Vitamin

Vitamin D3

Dosing, blood levels, K2 stacking, and seasonal variation.

Creatine

Strength, cognition, hair-loss myths, monohydrate vs HCl.

Metabolic

Berberine

Blood sugar, cholesterol, gut microbiome, and "nature's metformin" claims.

Longevity

NMN

NAD+ precursor — research, dosage, and the NMN vs NR debate.

Nootropic

Lion's Mane

Cognition, nerve growth factor, and the BDNF research.

Anti-Inflammatory

Turmeric / Curcumin

Bioavailability problem solved — Meriva, Theracurmin, BCM-95.

Latest Research-Backed Articles

Long-form, citation-dense breakdowns of the questions our readers care about.

Magnesium Glycinate vs Citrate: Which Is Better?

Absorption data, ideal use cases, side-effect profile, and cost-per-dose breakdown.

NMN vs NR: Which NAD+ Booster Works?

22 clinical trials reviewed. Why the answer is more nuanced than influencers claim.

Best Fish Oil Supplement of 2026

We tested 18 brands for EPA/DHA accuracy, oxidation, and heavy metals.

Ashwagandha Side Effects & Who Should Avoid It

Liver concerns, thyroid interactions, and pregnancy contraindications explained.

How to Improve Gut Health in 30 Days

A protocol built from 50+ studies — what to add, what to remove, and what to measure.

Best Magnesium for Sleep — A 2026 Buyer's Guide

Glycinate, threonate, taurate — which form actually helps you fall asleep.

Free Tools

Practical calculators built on the same evidence base as our articles.

Dosage Calculator

Personalized dosing for 50+ supplements based on weight, age, and goal.

Interaction Checker

Check supplement-drug and supplement-supplement interactions instantly.

Supplement Quiz

Answer 12 questions to get a personalized stack recommendation.

Deficiency Symptom Checker

Map your symptoms to the most likely vitamin or mineral gap.

Why Trust Us

Independent. We don't sell supplements. Our editorial team is structurally separated from any commercial relationships, and every affiliate link is disclosed at the top of the page where it appears.

Reviewed by clinicians. Every health claim is reviewed by at least one licensed clinician — MDs, PharmDs, RDs — whose names, credentials, and full bios are public on each article.

Citation-dense. Every "may help" or "studies suggest" is backed by a linked, peer-reviewed source. We average 18 citations per article.

Living documents. Every page shows the date of last review. We update major pages every 90 days, all pages within 12 months.

Read our full editorial policy →