100+ Supplements Reviewed: What the Human Trials Actually Support
After five years of reading the literature for his book, Siim Land sorts more than 100 supplements into three buckets: strong human-trial evidence, weak or absent evidence, and promising but unproven. The pattern that emerges is consistent: the effects are real but modest, and most nutrients only move the needle when you were low to begin with.
Overview
This session is a full pass through the supplement landscape, filtered through one standard: randomised human clinical trials rather than animal or observational work. The top tier includes creatine, omega-3s, glycine, NAC, taurine, magnesium, vitamin D, vitamin K, zinc, vitamin C, melatonin, turmeric, berberine, the carotenoids and the caffeine-theanine pair. For each one, the headline benefit is often not the one social media talks about: creatine's clearest effect is power and recovery rather than muscle size, berberine's is cholesterol rather than blood sugar, and ashwagandha's hormone effect runs through lowered cortisol.
A second bucket collects the popular products where trials have looked and found little: BCAAs and essential amino acids for muscle growth, tribulus and horny goat weed for testosterone, oral carnitine for performance, glutathione for skin, and pterostilbene for longevity. A third bucket holds the promising-but-thin evidence, including spermidine, senolytics, urolithin A, lion's mane, shilajit and nattokinase, where sample sizes are often tiny and doses inconsistent.
Several long-standing myths get checked against the data, most notably the claims that creatine causes hair loss or kidney damage and that omega-3s raise inflammation, none of which hold up in controlled trials. The recurring message is one of proportion: supplements support a baseline, they do not replace training, sleep or diet. Everything here is educational wellness content, not medical advice.
Key quotes
5Creatine alone without resistance training does not build muscle.
Creatine helps to make up for lost sleep in terms of restoring your cognition to a normal baseline.
Contrary to popular belief, omega-3s lower inflammation.
Berberine is worse in lowering blood sugar than metformin, but better in lowering cholesterol than metformin.
In an actual clinical study where they gave people creatine, there was no effect on hair loss.
Key ideas
9Human trials set the bar
The whole ranking rests on randomised controlled trials in people, not on animal or observational data. That single filter removes a large share of what circulates online as supplement science.
Creatine's headline is power, not size
The strongest trial evidence is for muscle power, speed and explosiveness, followed by reduced muscle damage and faster recovery. Strength and a modest amount of mass follow from that, not the other way round.
Carotenoids work on skin and eyes
Astaxanthin, lutein and zeaxanthin accumulate in tissues rich in mitochondria and show trial evidence for UV resilience, eye fatigue and inflammation. Beta-carotene is the weak member of the family.
Precursors beat pre-made antioxidants
Glycine and NAC raise glutathione and let the body regulate how much it makes, which supports a healthy redox balance. Swallowing glutathione directly gives up that self-regulation.
Triglycerides come before high blood sugar
High triglycerides are described as the first step on the road to insulin resistance, which is why omega-3s matter metabolically as well as for the brain and heart. Blood omega-3 status is presented as a biomarker worth tracking.
Berberine is a lipid supplement
Its largest measured effect is on cholesterol, not glucose, where it underperforms metformin. It also nudges blood pressure, inflammation and visceral fat, and it acts on gut bacteria.
Most nutrients only work if you are low
Vitamin D and zinc raise testosterone only from a deficient starting point, magnesium supports sleep mainly in deficiency, and B vitamins and multivitamins do most of their work in people with poor intake. Sufficiency turns the effect off.
Prebiotics have broader evidence than probiotics
Inulin, beta-glucans, psyllium, pectin and resistant starch show effects on cholesterol, constipation, blood sugar and inflammation across the general population. Probiotic strains are more context-specific, with the clearest results around diarrhoea.
Longevity hype outruns the data
Resveratrol, pterostilbene, alpha-ketoglutarate, spermidine and urolithin A all carry lifespan claims that human trials do not yet support. Where signals exist they rest on small samples, surrogate markers or sedentary participants.
Practical takeaways
7- 1
Pair creatine with training 4:30
Treat creatine as an amplifier of resistance training rather than a substitute for it. Without the training stimulus, the muscle effect largely disappears.
- 2
Lean on creatine after short nights 6:10
The cognitive rescue effect shows up specifically in sleep-deprived states. It is a patch for a bad night, not a replacement for a good one.
- 3
Track omega-3 status and triglycerides 16:00
Both are measurable and both sit upstream of metabolic and cardiovascular risk markers. Eating fish regularly covers the same ground as supplementing.
- 4
Mind the timing around workouts 21:00
Resveratrol is described as blunting exercise adaptations, and nicotine constricts blood vessels and reduces blood flow. Keep both away from training sessions.
- 5
Measure before you add 28:00
Vitamin D, zinc, magnesium and B vitamins mostly deliver when a shortfall exists. Testing first avoids paying for effects you cannot get.
- 6
Start with prebiotic fibre 32:00
For a general audience, fermentable fibres have a wider evidence base than any single probiotic strain. Reach for strains when there is a specific gut issue to address.
- 7
Read the sample size, not the headline 44:00
The much-shared urolithin A mitophagy result came from six reported responders inside a small study. A striking mechanism in a handful of people is a research lead, not a conclusion.
Topics & chapters
14Why review 100+ supplements
Five years of reading for a book on supplement science. The stated goal is separating what is true from what is repeated online.
The evidence standard
Randomised human trials outrank animal and observational studies. Everything that follows is sorted by that criterion.
Creatine: power, recovery, sleep debt
The most researched supplement in the world, with its clearest effects on power, muscle damage and sleep-deprived cognition. Muscle growth requires training alongside it.
Astaxanthin and skin resilience
A carotenoid with trial evidence for UV protection, skin ageing, inflammation, eye health and a small lipid effect. The framing is resilience to sun, not avoidance of it.
Garlic, glycine and NAC
Aged garlic extract on lipids, blood pressure, blood sugar and liver health. Glycine and NAC raise glutathione, with NAC carrying near-medical uses in lung conditions and liver support.
Omega-3s across organ systems
Triglycerides, blood omega-3 status, inflammation and mental health, with effects spanning brain, heart, skin and endothelium. The vilification of fish oil is addressed directly.
Taurine, ashwagandha, melatonin
Taurine targets the metabolic syndrome cluster and aerobic performance. Ashwagandha lowers stress and cortisol; melatonin covers sleep, antioxidant and lipid effects at higher doses.
Turmeric, berberine, vitamin D
Turmeric on inflammation and joint pain, berberine on cholesterol first and glucose second, vitamin D on bone, immunity and testosterone in deficiency.
The everyday basics
HMB, B vitamins, caffeine, chromium, collagen peptides, magnesium, glucosamine, lithium and the multivitamin. A recurring theme of context and deficiency runs through all of them.
Gut: probiotics and prebiotics
Three probiotic strains carry the most human evidence, mainly for diarrhoea and IBS. Prebiotic fibres show broader general-population effects.
The weak-evidence list
BCAAs and EAAs for growth, pterostilbene and AKG for lifespan, beta-carotene, oral carnitine, tribulus and horny goat weed all come up short in trials.
Needs more research
Spermidine, senolytics, NMN and NR, urolithin A, boron, hyaluronic acid, lion's mane, nattokinase and shilajit sit in the promising-but-thin category.
Creatine myths checked
Hair loss, DHT and kidney damage are examined against the trial data. None survive in people with normal kidney function.
Closing note on selection
The list leans toward supplements that have evidence, by design. Anything unmentioned is more likely to lack support than to have been forgotten.