Top 20 Supplements backed by medical journals — and where to find them on Amazon.ca.

The most-studied performance supplement in history — 1,000+ trials. Improves strength, lean mass, anaerobic capacity, and possibly cognition under sleep deprivation. 3–5 g/day, every day, any time. Kreider 2017 · ISSN Position Stand

A convenient way to hit your protein target — 1.6–2.2 g/kg/day for active adults. Whey is the fastest-absorbing protein with the most complete amino-acid profile and the highest leucine content per dollar. Morton 2018 · BJSM Meta-analysis

Slow-digesting milk protein. 20–40 g before bed measurably increases overnight muscle protein synthesis — useful when your final meal is >3 h before sleep. Trommelen 2016 · Nutrients

Reliably improves endurance, strength, power, and reaction time across 21 meta-analyses. 3–6 mg/kg, 30–60 min pre-training. Tablets give precise dosing; coffee works just as well if your gut tolerates it. Grgic 2020 · BJSM Umbrella Review

Buffers muscle acidity in 1–4 minute efforts. Best for HIIT, Hyrox, and high-rep training. Builds over weeks; effects plateau around 4–6 weeks. 4–6 g/day split into smaller doses to minimise harmless skin tingling. Trexler 2015 · ISSN Position Stand

Nitric oxide precursor that modestly improves submaximal endurance. Works best as concentrated juice "shots" 2–3 hours pre-effort. Domínguez 2017 · Nutrients

Modest but reliable cardiovascular and anti-inflammatory benefit. 1–3 g combined EPA + DHA daily. Look for products with the IFOS (International Fish Oil Standards) seal — third-party tested for purity and oxidation. Aung 2018 · JAMA Cardiol meta-analysis

Wide deficiency in Canadians from October to April. Linked to bone, immune, and mood outcomes. 1,000–2,000 IU/day typical, ideally individualised by serum level (your physician can run a 25(OH)D test). Holick 2007 · NEJM

Involved in 300+ enzymatic processes. Most North Americans run on the low end of adequate intake. Glycinate is best tolerated and supports sleep; citrate is well-absorbed but laxative at higher doses. 200–400 mg/day.

Deficiency common in vegans, vegetarians, older adults, and those on metformin or PPIs (acid blockers). Methylcobalamin is the active, well-absorbed form. 500–1000 mcg/day if deficient. Test, don't guess — easy bloodwork.

Common deficiency in menstruating women, vegetarians, and endurance athletes. Causes fatigue and lowered VO₂max. Bisglycinate is gentler on the gut than older ferrous-sulfate forms. Do not supplement without lab confirmation — iron overload (hemochromatosis) is dangerous.

For training over 60 min, heavy sweaters, hot summer sessions, or recovery from gut illness. Look for sodium 500–1,000 mg per serving — most "low-sodium" electrolyte powders are too dilute to do meaningful work. ACSM 2007 · Position Stand

Emerging evidence that 15 g of collagen with vitamin C, 30–60 min before mechanical loading, supports tendon collagen synthesis. Useful for those rehabbing tendinopathies or training in repetitive sports. Shaw 2017 · Am J Clin Nutr

Effective for short-term sleep onset and jet lag at 0.3–1 mg. Higher doses are not better and may impair next-day alertness. Most off-the-shelf doses (3–10 mg) are far above what the research supports. Costello 2014 · Nutr J

Won't replace a quality diet, but a basic multi can fill gaps if your eating is inconsistent. Look for USP Verified or NSF on the label.

Important for immune function, wound healing, and testosterone in men. Heavy sweaters lose zinc through sweat. 15–25 mg/day max from supplements; higher chronic doses can interfere with copper absorption.

Strain matters more than CFU count. Lactobacillus and Bifidobacterium strains have the most clinical-trial evidence for general gut and immune support. Useful around antibiotic courses or after gut illness.

Adaptogen with small-but-real RCT evidence for cortisol reduction and perceived stress. The two extracts with the most clinical research are KSM-66 and Sensoril. 300–600 mg/day. Avoid in pregnancy and with thyroid disease.

Real ergogenic aid for short-burst events of 1–7 minutes (rowing test, 800m, certain Hyrox stations). Hard to dose without GI distress; emerging buffered or split-dose forms help. Generic baking soda is the same active ingredient at 1/100th the cost. Hadzic 2019 · J Sports Sci Med

Most pre-workout benefit comes from caffeine and beta-alanine — both of which you can buy individually for less. If you prefer a single-scoop convenience, choose a third-party-tested product to avoid the high contamination rate in this category.