Supplements that actually work: the short list, the maybes, and the marketing

This page replaces a 2012 post on this site titled “Sport Nutritional Supplements & Vitamins Key for Good Health Fitness!” Joe has been a gym member since the 1990s, so the question here is the one any lifter should ask at checkout: what has evidence behind it, what depends on the person, and what is a label with a story attached. The tiers below come from position stands (ISSN, ACSM, the Endocrine Society), large randomized trials and systematic reviews, and every claim names its source, with links in the Sources list at the bottom of the page.

What counts as “actually works” on this page

Three tests, in order:

1. Is there a position stand or a meta-analysis of randomized trials? Single seller-funded studies do not move a supplement into the top tier.
2. Does it help someone who already eats reasonably and trains? Fixing a deficiency is a medical decision, not a gym purchase.
3. Is the effect large enough to notice?

Pass all three: short list. Pass the first but not the second: a maybe. Fail the first: marketing.

The short list: strong evidence

Creatine monohydrate, 3-5 g every day

The ISSN position stand (Kreider 2017) is direct: creatine raises intramuscular creatine stores, which explains the consistent improvements in high-intensity performance and the larger training adaptations that follow. It reports short- and long-term use, up to 30 g a day for five years in studies, as safe and well tolerated in healthy people, and a habitual 3 g a day as potentially beneficial across the lifespan.

Practical notes: buy plain monohydrate, not a buffered or other specialty form, since the position stand found none of them retains more creatine than monohydrate; take it daily including rest days, since the effect comes from saturated stores, not timing; expect a pound or two of water weight inside the muscle early on. Loading works but is optional.

Protein, up to about 1.6 g per kg of body weight per day

Morton’s 2018 meta-analysis pooled 49 trials with 1,863 participants. Protein supplementation on top of resistance training added 2.49 kg to one-rep-max strength and 0.30 kg of fat-free mass on average, with larger effects in trained lifters and smaller effects with age. The break-point analysis found no further fat-free-mass gain once total daily protein passed about 1.62 g/kg/day.

A 180 lb (82 kg) lifter lands at roughly 130 g a day. If meals already get you there, powder buys convenience, not muscle. If not, whey isolate, casein or a plant blend all work once the daily total is met.

Caffeine, 3-6 mg per kg, about an hour before training

The ISSN caffeine position stand (Guest 2021) reports small-to-moderate improvements in muscular endurance, strength, sprinting, jumping and throwing, and the most consistent moderate-to-large benefit in aerobic endurance. The effective range is 3-6 mg per kg, the minimal dose may be as low as 2 mg/kg, and doses around 9 mg/kg bring side effects without added benefit. Usual timing is 60 minutes before exercise; caffeinated gum acts faster.

For an 82 kg person that is about 245-490 mg. The FDA lists 113-247 mg of caffeine in a 12-ounce cup of regular brewed coffee, so about two cups land in that range, depending on the brew. The FDA also cites 400 mg a day as the amount not generally associated with negative effects for most adults, so the top of the study range is above that line. The position stand notes that sleep disruption and anxiety vary with genetics and habitual intake, so your ceiling may be lower than the study’s. Check the caffeine line on any pre-workout and price it against coffee.

Beta-alanine, 4-6 g a day for at least 2-4 weeks

The ISSN beta-alanine position stand (Trexler 2015) found that four weeks at 4-6 g a day raises muscle carnosine, which buffers acid inside the muscle. Gains show up most clearly in efforts lasting 1-4 minutes (400-800 m repeats, hard rowing intervals, high-rep sets near failure). The only reported side effect is paresthesia, the tingling in the face and hands, reduced by splitting the dose into 1.6 g servings or using a sustained-release form. Effects on strength and on efforts longer than 25 minutes remain unproven. Like creatine, it is the daily total over weeks that matters, not a scoop before a workout.

The short list at a glance

Supplement	Effective dose	Time to work	What it helps	Main side effect	Source
Creatine monohydrate	3-5 g/day, every day	3-4 weeks (5-7 days with a loading phase)	High-intensity and repeated-effort performance, training adaptation	Water weight inside muscle	ISSN 2017
Protein (as a gap-filler)	Enough to reach about 1.6 g/kg/day total	Over a training block	Strength (+2.49 kg 1RM) and fat-free mass (+0.30 kg) on average	Cost; no added lean mass past about 1.6 g/kg/day	Morton 2018
Caffeine	3-6 mg/kg, 60 min pre-workout	Same session	Endurance most, plus strength, power, sprinting	Sleep, anxiety at higher doses	ISSN 2021
Beta-alanine	4-6 g/day, split into 1.6 g doses	2-4 weeks minimum	Efforts of 1-4 minutes	Tingling (paresthesia)	ISSN 2015

The maybes: it depends on your history, diet and sweat

Vitamin D, only with a specific reason

The VITAL trial (Manson 2019) randomized 25,871 U.S. adults (men 50 and older, women 55 and older) to 2,000 IU of vitamin D3 a day or placebo for a median of 5.3 years. Vitamin D did not lower the risk of invasive cancer or major cardiovascular events. The VITAL fracture study (LeBoff 2022) found no reduction in total, nonvertebral or hip fractures either, and no difference by baseline vitamin D level, in adults not selected for deficiency. The 2024 Endocrine Society guideline (Demay 2024) suggests empiric supplementation for children and adolescents, adults 75 and older, pregnancy, and high-risk prediabetes. A healthy 40-year-old who trains is not on that list. If you think you may be low (little sun, a restrictive diet, a condition that affects absorption), ask a clinician whether testing is warranted. The same guideline advises against routine 25-hydroxyvitamin D testing in people without a specific reason.

Omega-3 (fish oil)

The omega-3 arm of VITAL (Manson 2019) randomized the same 25,871 adults to 1 g a day of marine n-3 fatty acids or placebo. It did not lower the primary endpoints, major cardiovascular events and invasive cancer, compared with placebo. A secondary analysis reported a difference in one individual heart outcome, but the trial’s own conclusion is that omega-3 did not lower the incidence of major cardiovascular events or cancer, and a secondary endpoint in a null trial is a reason for a clinician conversation, not a supplement-aisle decision.

Electrolytes

The ACSM position stand on fluid replacement (Sawka 2007) is careful: sweat rates and sweat sodium vary a lot between people, so plans should be individualized; beverages with electrolytes and carbohydrate can beat plain water “under certain circumstances”; and the goal during exercise is to avoid losing more than 2% of body weight. The test is simple: weigh yourself before and after a hard session. Lose more than about 2% (3.5 lb for a 180 lb person) and you need to drink more during training; on long or very sweaty sessions, an electrolyte drink is the kind of “certain circumstances” case the ACSM describes. A 45-minute lift in an air-conditioned gym rarely needs one. Puerto Rico in August, where this site is run from, is a different calculation than Denver in January.

The marketing: weak, mixed or overclaimed

Collagen

Collagen peptides are sold as a protein and as a joint product. The 2021 systematic review by Khatri (15 randomized trials, 12 in recreational athletes) found collagen did not raise muscle protein synthesis compared with the same amount of higher-quality protein, so it is not a protein source. Its most consistent findings were for joint function and joint discomfort, with collagen synthesis markers rising at 15 g a day. Those are small trials in narrow groups. If you buy collagen, buy it for the joint question and know the evidence is early.

BCAAs

Wolfe’s 2017 review searched for human studies measuring muscle protein synthesis after oral BCAAs alone and found none. The two available intravenous studies showed BCAAs decreased muscle protein synthesis, because the other essential amino acids needed to build new protein were missing. His conclusion: the anabolic claim for BCAAs alone is unwarranted. Whey, meat, eggs and dairy already contain them. Flavored BCAA powders are expensive water flavoring.

Fat burners

The ingredient in a typical fat burner with performance evidence is caffeine, covered above; check every other ingredient’s dose against the study the brand cites for it. The FTC’s Health Products Compliance Guidance says claims about the health benefits of dietary supplements require competent and reliable scientific evidence, and its health-claims page counts 120 cases filed against supplement health claims in a single decade. The FDA keeps a list of weight-loss products found to contain hidden drug ingredients and warns that many products sold for weight loss, including diet pills, fat-burning pills and weight-loss supplements, are likely to be contaminated with dangerous hidden ingredients. If you want the proven part, drink coffee.

NMN and NR

Nicotinamide mononucleotide (NMN) and its cousin nicotinamide riboside (NR) are sold on the NAD+ story. The one point that holds up: NMN raises blood NAD concentrations. The 2023 randomized trial by Yi and colleagues (80 healthy middle-aged adults, 60 days, 300-900 mg) showed the increase and a longer six-minute walk distance in the NMN groups. Read the disclosure line first: the trial was fully funded by Aba Chemicals and Abinopharm, the two companies that developed and manufactured the NMN, and three of the authors work for them. One short manufacturer-funded trial with a walking test is not evidence that a monthly capsule changes how you train, look or age. This page does not review NR trials.

Ashwagandha

The 2021 Bayesian meta-analysis by Bonilla found ashwagandha outperformed placebo on physical-performance variables across 12 small trials with a low-to-moderate risk of bias. That is a real signal. It sits in this tier for a different reason: the Björnsson 2020 case series in Liver International documented five cases of liver injury attributed to ashwagandha-containing supplements, with jaundice appearing 2-12 weeks after starting and liver tests taking 1-5 months to normalize. Rare and self-limited in these cases, and still a reason to tell your clinician you take it and to stop and get checked if you notice yellowing skin or eyes, itching or nausea.

How to read a label without getting fooled

• Third-party certification on the tub. NSF Certified for Sport checks that a finished product contains what the label says and screens it for banned substances. Informed Sport and Informed Choice test finished products for banned substances, and Informed Protein checks protein label claims. The FDA states it is not authorized to approve dietary supplements for safety and effectiveness before they are marketed, so a third-party certification is the main independent check on what is in the tub.
• Amounts, not blends. A “proprietary blend” hides how much of each ingredient is in the scoop. Every strong-tier supplement has a known effective dose; if the label will not show the number, assume it is under-dosed.
• Price per effective dose. Creatine at 5 g a day from a 1 kg tub is about 200 servings. Compare that to a 30-serving pre-workout with 3 g per scoop before calling the pre-workout “convenient.”

Where to buy / how to save

What each merchant is good for, checked on 09/28/2026 (Legion and Momentous subscription terms rechecked on 09/29/2026):

• Transparent Labs. Whey isolate, creatine and pre-workouts with full-dose labels and Informed Choice / Informed Protein certification shown on the site. Free U.S. shipping over $99. They also sell BCAAs and fat burners, so buy from the short list, not the whole catalog.
• Legion Athletics. Whey, casein, plant protein, creatine and a caffeine pre-workout. On 09/28/2026 the site advertised Subscribe & Save at 30% off the first subscription order and 15% off every later one, free shipping on a first U.S. order and over $80 after that, a give-20%-get-$20 referral program, and a money-back guarantee with no returns required.
• Momentous. The premium option: creatine, whey and magnesium with NSF Certified for Sport on several products and downloadable certificates of analysis. 25% off the first subscription order and 10% off later deliveries, and free U.S. shipping over $99. You pay for the testing; if you compete in a tested sport, that is the point.
• The Vitamin Shoppe. The multi-brand store, online and in person. Free shipping over $45, Auto Delivery savings of at least 15% (20% on the house brands), rotating BOGO 50% deals by brand, and the Healthy Awards points program. Best for comparing creatine and whey price-per-gram across brands in one cart.

The simplest way to spend less: pick two or three short-list products, subscribe at one merchant, and stop buying the tier-three tubs.