Stop guessing
which supplement
to actually buy.
Vitfacts compares the supplements Chemist Warehouse, iHerb and Amazon stock side by side — on active dose, bioavailability, and price per gram of useful nutrient. Cited sources, no sponsored order.
Prices updated weekly · Affiliate links help fund this site · No extra cost to you
Three editorial principles
that every comparison follows.
Cite every claim
Every product, dose, and price links to a verifiable source. We name the date and URL.
Bioavailability first
A 500 mg dose that absorbs 80% beats a 1000 mg dose that absorbs 10%. We rank absorption, not label size.
Per-effective-dose pricing
Same dollar amount in your hand gives very different useful nutrient depending on the form. We normalize by active dose.
Pick a category. Browse or arrow.
Every comparison is built from the same data set: peer-reviewed sources, retailer-verified prices, and per-effective-dose math. ← Use arrows or drag →
Vitamin C
Ascorbic acid vs Liposomal vs Ester-C vs Sodium Ascorbate vs Calcium Ascorbate. Ranked on bioavailability, dose, and price per effective mg.
Magnesium
Glycinate vs Citrate vs Oxide vs L-Threonate vs Malate vs Taurate vs Chloride. Which form actually absorbs, and which is a waste of money.
Whey Protein
Concentrate vs Isolate vs Hydrolyzed vs Plant blends. Protein per dollar, leucine threshold, taste and mixability.
Omega-3
EPA/DHA content, oxidation (TOTOX), and the top brands compared on freshness, dose, and price per gram of usable omega-3.
Creatine HMB vs Mono
Does adding HMB to creatine actually build more muscle than plain creatine monohydrate? The evidence is clear: most combo products are a waste of money.
Probiotic
Multi-strain blends, Saccharomyces boulardii, and spore-based Bacillus — scored on strain identity, CFU per serving, and what the evidence actually says.
Vitamin D
Cholecalciferol (D3) vs calcifediol (25(OH)D) vs lichen-D3 for vegans. Ranked on bioavailability, dose per capsule, and price per 1000 IU.
Retinol
Retinol vs retinal vs HPR vs bakuchiol. Ranked on irritation, clinical evidence, and price per ml. The only AU/TH comparison covering all 6 retinoid forms.
Iron
Ferrous sulfate vs bisglycinate vs fumarate. Ranked on absorption, GI tolerance, and price per elemental mg. Covers the 1-in-4 women who are deficient.
Ashwagandha
KSM-66 vs Sensoril vs Shoden — ranked on RCT evidence for stress, cortisol, sleep, and athletic performance. Includes the thyroid caveat.
Collagen
Marine vs bovine vs multi-collagen vs topical skincare. Ranked on dose, evidence, and cost per gram of effective peptide.
Sleep Stack
Melatonin vs magnesium glycinate vs L-theanine vs ashwagandha. The right ingredient at the right dose for your specific sleep problem.
Zinc
Picolinate vs bisglycinate vs citrate vs sulfate vs oxide vs gluconate. Ranked on bioavailability, dose, and the copper-depletion trap.
CoQ10
Ubiquinone vs ubiquinol. Ranked on absorption, dose-by-indication (heart, statin users, fertility), and price per 100 mg.
L-Theanine
Free-form vs Suntheanine vs combo with magnesium. Ranked on alpha-wave evidence, dose, and the classic caffeine-stacking combo.
B-Complex
Standard vs activated/methylated vs high-potency vs stress-formulated. Ranked on B12/folate methylation, doses, and the MTHFR factor.
Topical Vitamin C
L-ascorbic acid vs MAP vs SAP vs THD vs ascorbyl glucoside. Ranked on stability, irritation, pH, and price per ml — for brightening, photoaging, and acne.
Sunscreen
Chemical vs mineral vs hybrid vs tinted. Ranked on UVA-PF (PPD), water resistance, reef safety, and price per ml — covering SPF 30 to SPF 50+.
Niacinamide
2% vs 5% vs 10% vs 20% concentrations. Ranked on irritation, clinical evidence, and price per ml — the only AU/TH comparison covering all 6 niacinamide formats.
Hyaluronic Acid
Multi-MW vs single-MW vs hydrolyzed vs sodium hyaluronate. Ranked on hydration depth, molecular weight, and price per ml — the molecular weight makes the difference.
Salicylic Acid (BHA)
BHA 2% vs AHA+BHA peels vs BHA cleansers vs BHA toners. Ranked on irritation, clinical evidence, and price per ml — the only OTC active that penetrates pores.
Azelaic Acid
AZA 10% vs 15% vs multi-active combos. Ranked on irritation, clinical evidence, and price per ml — the multi-tasker for acne, rosacea, and hyperpigmentation.
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Vitamin C,
ranked on what
actually absorbs.
5 forms · 12 products · ranked by bioavailability, dose, and price per effective mg. Liposomal vs Ester-C vs Ascorbic acid vs Sodium Ascorbate vs Calcium Ascorbate.
Coming next
Glycolic acid (AHA) is the next skincare comparison in the research queue.
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supplement to start with?
The Supplement Finder asks 5 questions and recommends a category based on your goal, diet, and stack. Takes 30 seconds.