Supplements: what has evidence and what doesn't
Eight supplements with what the literature says, the doses used in studies and what you can skip.
Creatine monohydrate
The one thing almost everyone agrees on
STRONG EVIDENCEWHAT IT DOES
It tops up the muscle's phosphocreatine stores, which is where energy for short intense efforts comes from. In practice: an extra rep here and there, and over time a bit more strength and muscle.
WHEN IT HELPS
If you lift consistently. It is one of the few supplements whose effect actually shows up in your logged numbers.
DOSES USED IN STUDIES
In the studies, 3-5 g a day, every day, training or not. Timing does not matter and no loading phase is needed: filling the stores takes a few weeks either way.
WATCH OUT
Monohydrate and nothing else: the “advanced” forms cost more and have shown no advantage. With kidney problems, ask first.
Protein powder
Not magic: convenient food
STRONG EVIDENCEWHAT IT DOES
It delivers decent-quality protein in a format that fits in a bag. What builds muscle is hitting your daily total; powder just helps you get there.
WHEN IT HELPS
When you are 30-40 g short of your target and cooking is not happening. If food already covers it, you do not need it.
DOSES USED IN STUDIES
One scoop (20-30 g of protein) for whatever gap you have. Whey if you tolerate dairy; isolate or plant-based if you do not.
WATCH OUT
Read the label: protein per scoop, not the size of the tub. And be wary of blends with twenty ingredients.
Caffeine
What pre-workouts are actually made of
STRONG EVIDENCEWHAT IT DOES
It lowers perceived effort and improves both strength and endurance performance. It is the ingredient doing the work in nearly any pre-workout; the rest is usually filler.
WHEN IT HELPS
On hard sessions or when you arrive tired. You do not need it daily — in fact taking it daily blunts what you feel.
DOSES USED IN STUDIES
In the studies, 3-6 mg per kilo about 45 minutes before. At 80 kg that is 240-480 mg, or two to four coffees. Start at the low end.
WATCH OUT
Half-life around five hours: an afternoon dose costs you sleep at night, and sleeping worse costs more than the session gains. If it spikes your blood pressure or makes you jittery, use less.
Vitamin D
Only if you are short, and plenty of people are
STRONG EVIDENCEWHAT IT DOES
It plays a part in bone, muscle and immune function. Fixing a deficiency improves measurable things; taking it with normal levels does nothing.
WHEN IT HELPS
If you get little sun, work indoors all day or live somewhere with long winters. The sensible move is a blood test.
DOSES USED IN STUDIES
Supplementation studies typically use 1,000-2,000 IU a day with a meal containing fat, adjusted afterwards by blood work.
WATCH OUT
It is fat-soluble: excess accumulates and can do harm. This is not one to take blind at high doses.
Omega-3 (EPA/DHA)
More for general health than for muscle
MODERATE EVIDENCEWHAT IT DOES
Fatty acids with reasonably solid effects on cardiovascular health and inflammation. On muscle gain specifically, the data are weak.
WHEN IT HELPS
If you eat oily fish less than twice a week.
DOSES USED IN STUDIES
Studies typically use 1-2 g a day of EPA+DHA combined — not total oil, which is the big number on the label.
WATCH OUT
On blood thinners, ask first. And keep it sealed and cool: rancid oil is useless.
Beta-alanine
For long sets, not for your triples
MODERATE EVIDENCEWHAT IT DOES
It raises muscle carnosine, which helps buffer acidity. The effect shows up in efforts of one to four minutes: sets of 15-20, rowing, cycling. On sets of 5 it does nothing.
WHEN IT HELPS
If your training has a lot of high-rep or metabolic work.
DOSES USED IN STUDIES
Studies use 3-6 g a day over weeks; it works by accumulation, not by taking it before training.
WATCH OUT
It causes tingling in the face and arms — annoying but harmless, and it goes away if you split the dose.
Citrulline malate
Maybe an extra rep, at best
MODERATE EVIDENCEWHAT IT DOES
It raises nitric oxide and blood flow. Some studies see a couple of extra reps on the last sets and less soreness; others see nothing. The famous pump is real, and it is cosmetic.
WHEN IT HELPS
If creatine, protein and sleep are already handled and you fancy trying something else. Not before that.
DOSES USED IN STUDIES
Studies use 6-8 g of citrulline malate around 40-60 minutes before.
WATCH OUT
High doses can upset your stomach. And beware pre-workouts advertising a “nitric oxide matrix” with 500 mg in it: that does nothing.
Magnesium
Useful if you are short; not a booster
LIMITED EVIDENCEWHAT IT DOES
It takes part in muscle and nerve function. Fixing a deficiency can improve cramps and sleep. As a performance enhancer in people who already eat well, the evidence is poor.
WHEN IT HELPS
If you eat few nuts, legumes and leafy greens, get cramps or sleep badly.
DOSES USED IN STUDIES
Studies use 200-400 mg a day, better in the evening. Citrate or bisglycinate absorb better than oxide, which is the cheapest and the worst.
WATCH OUT
Too much has a laxative effect. If you are on medication, check for interactions.
What you can skip
BCAAs
If you hit your daily protein, you are already getting them. Buying them separately is paying for a fraction of what you already have.
Fat burners and thermogenics
What they do is caffeine with extras. The deficit comes from food; these just make you notice it less for a while.
Testosterone boosters
Tribulus, D-aspartic acid, ZMA and friends: in men with normal levels they raise neither testosterone nor strength. What does move it is sleeping, eating and not carrying excess weight.
Glutamine
Well studied in clinical settings and extreme endurance work. For hypertrophy in healthy people, nothing.
Where to check it
Examine.com
Every supplement with what the literature says and how good that evidence is. The place to check before buying any tub.
Stronger by Science
Long, honest articles on strength and hypertrophy, with the statistics in plain sight.
MASS Research Review
Monthly review of new studies, explained. Paid, and worth it once you have read the free stuff.
Barbell Medicine
Doctors who also lift. The place for pain, injury and getting back to training.
Renaissance Periodization
Where the per-muscle volume ranges everyone quotes originally come from.
PubMed
The original studies. When someone tells you “it is proven”, this is where you check.
ACSM
Official position stands from the American College of Sports Medicine: what there is consensus to say.
This is general information written from the training literature, not medical advice or a personalised plan. If you take medication, have a health condition or something genuinely hurts, the person to ask is a healthcare professional.