Supplement Buying Guides
Every supplement we cover is scored on the same 6-metric rubric — so you can see exactly why one magnesium, probiotic, or multivitamin ranks ahead of another. Read the scoring methodology →
Best Magnesium Supplements, Scored on a Public Rubric
We scored 7 top-selling Amazon magnesium supplements on a public 6-metric rubric — third-party testing, form, value, transparency, and more.
Best Probiotic Supplements, Scored on a Public Rubric
Side-by-side scoring of six probiotics on our 6-metric rubric: named strains, CFU dose, third-party testing, shelf-stability, and value.
Best Fish Oil Supplements, Scored on a Public Rubric
We scored six fish oil supplements on our 6-metric rubric: EPA/DHA dose, oxidation, third-party testing, and value per gram of omega-3.
Best Vitamin D Supplements, Scored on a Public Rubric
We scored six vitamin D3 supplements on our 6-metric rubric: dose accuracy, K2 pairing, third-party testing, and value per IU.
Best Collagen Peptides, Scored on a Public Rubric
Six top-selling collagen peptide supplements compared on our 6-metric rubric — molecular weight, source, third-party testing, and value.
Best Ashwagandha Supplements, Scored on a Public Rubric
Five ashwagandha supplements scored on our 6-metric rubric: extract type (KSM-66, Sensoril), withanolide content, and third-party testing.
Best Multivitamins, Scored on a Public Rubric
Six multivitamins compared on our 6-metric rubric: bioavailable forms (methylated folate, MK-7, methylcobalamin), third-party testing, and value.
Best Berberine Supplements, Scored on a Public Rubric
Berberine has real, modest evidence for blood sugar and cholesterol — and it is not "nature's Ozempic." Its biggest problem is absorption, not marketing. We scored seven widely-available options on a 6-metric rubric weighted toward the dose the trials used and the forms that survive first-pass metabolism.
Best Vitamin C Supplements, Scored on a Public Rubric
Your plasma saturates near 200 mg a day, and above 1 g absorption falls below 50% — so most of a mega-dose is urine. We scored seven vitamin C options on the dose that actually absorbs, not the number on the front of the bottle.
Best Zinc Supplements, Scored on a Public Rubric
The adult RDA is 11 mg. The upper limit is 40 mg. Most of the aisle sells 50 and 100 mg — and 50 mg for weeks quietly starves your copper. We scored seven zinc supplements on the dose that respects the ceiling, not the number on the front.
Best Iron Supplements, Scored on a Public Rubric
Iron is the one supplement you should not buy on a hunch — get the blood test first. Then take less, every other day: 60 mg on alternate days absorbed more total iron than the same dose taken daily. We scored seven iron supplements on dose, form, and tolerability.
Best CoQ10 Supplements, Scored on a Public Rubric
Ubiquinol is rarely the upgrade the label promises, and CoQ10 won't reliably fix statin muscle pain. We scored seven CoQ10 supplements on form, dose, third-party testing, and honest value.
Best Vitamin B12 Supplements, Scored on a Public Rubric
The methylcobalamin premium isn't earned and B12 won't give a non-deficient person energy. We scored seven B12 supplements on form-neutral value, third-party testing, and honest dosing.
Best Turmeric Supplements, Scored on a Public Rubric
Curcumin barely absorbs on its own, so the formulation is the whole game. We scored seven turmeric supplements on standardized curcuminoids, real absorption enhancers, testing, and honest claims.
Best Biotin Supplements, Scored on a Public Rubric
Biotin deficiency is rare and the aisle sells 10,000 mcg for a 30 mcg need. We scored seven biotin supplements on honest dosing, third-party testing, and the FDA lab-interference warning you need to know.
Best Glucosamine Supplements, Scored on the Evidence
The big trials are mixed and rheumatology guidelines now advise against it — but glucosamine is cheap and low-risk. We scored seven on form (sulfate over HCl), clean labels, and third-party testing.
The Best Greens Powders — and Why a Plate of Vegetables Still Wins
Greens powders don't replace vegetables, and most of the marketing is proprietary-blend fairy dust. We rank the ones with real greens, honest labels, and third-party testing — and say plainly where the money is wasted.
The Best Fiber Supplements — and Why Food Comes First
Psyllium has the best evidence — for regularity, cholesterol, and blood sugar. We rank fiber supplements by fiber type, tolerability, and value, and say plainly that whole food should come first.
The Best Calcium Supplements for Bone Health
Food is the best calcium source, and more isn't better. We rank calcium citrate and carbonate supplements, explain the absorption differences, and are honest about the 500 mg-per-dose limit and the vitamin D pairing.
The Best Tart Cherry Supplement for Inflammation, Recovery, and Sleep
The best tart cherry supplement for inflammation, ranked: Montmorency capsules, cold-pressed concentrate vs 10:1 extracts, live prices, and honest evidence.
The Best Prebiotic Supplements for Gut Health
A prebiotic feeds the good bacteria you already have — it's not a probiotic and it's not magic. We rank inulin, GOS, resistant starch, and acacia picks on evidence, tolerability, and value, food-first throughout.
The Best Mushroom Supplements, Judged on What's Actually in the Bottle
Functional-mushroom supplements are one of the most oversold categories on the shelf. We rank lion's mane, cordyceps, reishi, and blends on the one number that matters — verified beta-glucans from a real fruiting body — with the evidence stated plainly.
The Best Nootropic Supplements, Ranked by What They Actually Disclose
Most 'brain supplements' hide their doses inside a proprietary blend. We rank nootropics on the one thing that predicts whether they'll work — every milligram disclosed — and name the best-evidenced option, which costs about six cents a day.
Best Joint Supplements, Ranked by How Good the Evidence Actually Is
The joint aisle is built on the one ingredient rheumatology now recommends against. We ranked seven joint supplements across five ingredient classes by how good the evidence actually is.
Best Hair Growth Supplements, Scored on a Public Rubric
We scored seven hair-growth products on evidence, trial independence, and label honesty. The uncomfortable finding: the only option with FDA approval behind it is not a supplement at all.
The Best Supplements for Muscle Recovery, Ranked by Evidence
Most recovery supplements are marketing. We rank seven on what the research actually supports for recovery — protein and creatine first, tart cherry and collagen last — and name the ones to skip.
The Best Supplements for Energy, Ranked by What the Evidence Supports
Most energy supplements only work if you were deficient to begin with. We rank seven on the actual evidence — caffeine first, iron and B12 only with a blood test, CoQ10 last.
The Best Supplements for Immune Support, Ranked by the Actual Evidence
You cannot boost a healthy immune system — and the aisle's flagship 50 mg zinc caplet can reduce immune function. We rank six on the actual trial evidence, dose ceilings included.
The Best Supplements for Gut Health, Ranked by What the Trials Actually Show
Most adults eat about half the fiber they need, and no expert body recommends probiotics for healthy people. We rank seven gut supplements on outcome trials, not mechanism stories.
The Best Supplements for Men Over 50, Ranked by the Evidence That Actually Applies After 50
After 50 the evidence points at muscle, not testosterone: creatine plus lifting added 1.37 kg of lean mass in 22 trials. We rank seven picks on age-specific trials and call out the boosters.
The Best Supplements for Women Over 50, Ranked by the Evidence That Was Actually Run on Women This Age
After menopause the evidence points at muscle and bone, not hormone blends. We rank seven picks on trials run in postmenopausal women — creatine, protein, calcium, D, B12, magnesium, omega-3.
The Best Supplements for Inflammation, Ranked by What the Trials Actually Measured
Omega-3 fish oil is the best supplement for inflammation for most people who train hard — our pick is Nordic Naturals Ultimate Omega. We rank six picks on trial evidence, absorption, label honesty and live price.