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Supplements: what the evidence supports, and what to skip

Guides · Nutrition

The supplement aisle is one of the loudest, most over-promised corners of fitness. Almost everything on the shelf claims to burn fat, build muscle, or boost energy — and most of it does very little. The honest, useful truth is smaller and calmer than the marketing: a short list of products has genuinely good evidence behind it, a couple more help in specific situations, and a great deal is safe to skip. This guide walks through that list plainly, so you can spend your money — if you spend it at all — on the few things that tend to earn their place.

The single most important frame to keep in mind: supplements are optional extras, not essentials. The word is literal — they supplement a diet and a training plan that are already doing the real work. No powder, capsule or scoop out-works consistent training, enough sleep, and a sensible diet built mostly from whole food. Nothing on this page is a shortcut, and none of it is required to get results. With that settled, here's what the evidence actually says.

Before we start: this is general educational information, not medical advice, and individual needs vary a lot with body size, health, diet and training. Supplements can interact with medications and medical conditions, and the industry is loosely regulated in many places — "natural" does not mean proven or safe. If you have a health condition, take medication, are pregnant or breastfeeding, or compete under anti-doping rules, check with a doctor, pharmacist or registered dietitian before adding anything.

On this page

  1. The whole guide, at a glance
  2. Creatine — the most-studied one that works
  3. Protein powder — convenience, not magic
  4. Electrolytes — situational, not daily
  5. Vitamin D — fix a deficiency, don't chase a high
  6. What to skip for most people
  7. A worked routine you can copy
  8. Takeaways, and how Strathlon fits

1. The whole guide, at a glance

Here's the punchline first, because it saves you money and reading time. Supplements sort cleanly into three tiers by how strong the evidence is and how many people they actually help. Everything after this section simply explains each row in depth.

Supplement Verdict The honest one-liner
Creatine monohydrate Good evidence Well studied for supporting strength and higher-intensity training; cheap, safe for healthy people, and simple to use.
Protein powder Good evidence — as a tool A convenient way to hit a protein target, not a muscle-building drug. Useful only if you'd otherwise fall short.
Electrolytes Situational Genuinely helpful around long, hot, or heavy-sweat sessions; unnecessary for everyday training, where water is enough.
Vitamin D Situational Worthwhile mainly if you're actually low — little sun, darker skin, winter, or a tested deficiency. Not a performance booster for the already-sufficient.
BCAAs, fat-burners, "test boosters" Skip for most Weak, mixed, or no good evidence for healthy people eating enough protein. Save your money.

Notice what dominates the list: the things that work are cheap, boring, and few. That's the opposite of how supplements are usually sold. If you take nothing else from this page, take the table — and the reminder that a good diet and consistent training make every row here optional.

2. Creatine — the most-studied one that works

If there is a single supplement with strong, repeatedly replicated evidence for training, it's creatine monohydrate. It's also one of the most researched sports supplements in existence, which is exactly why it can be recommended calmly rather than hyped.

What it does

Your muscles use a molecule called ATP as their immediate energy currency, and for short, hard efforts they lean on a fast-recharge system built around phosphocreatine. Supplementing creatine tends to raise the amount of phosphocreatine your muscles store, which helps you regenerate ATP a little faster between hard efforts. In plain terms: it can support your ability to do slightly more high-intensity work — an extra rep or two on a heavy set, a bit more quality in repeated sprints — and it's that extra accumulated training, over weeks, that tends to translate into strength and muscle gains. Creatine doesn't build muscle directly; it helps you train a touch harder, and the training builds the muscle.

How to take it — the simple approach

This is refreshingly uncomplicated. A common, well-supported approach is a steady 3–5 g per day, every day, of plain creatine monohydrate. Take it at whatever time you'll remember — timing around your workout is a minor detail, and consistency across the week is what matters. You do not need to "load" (the higher-dose first week you'll see on labels); loading fills your muscle stores faster, but a steady daily dose gets you to the same place within a few weeks with less fuss. Monohydrate is the form with the most evidence and the lowest price — the fancier, pricier forms don't reliably out-perform it.

The simplest version: 5 g of creatine monohydrate, once a day, every day — including rest days. Stir it into water or any drink. No loading phase, no cycling, no special timing. That's the whole routine, and it's about as cheap as supplements get.

Is it safe?

For healthy people with healthy kidneys, creatine monohydrate has a long track record and is generally considered well tolerated at these everyday doses. The main visible effect is a small amount of water drawn into the muscle, which can nudge scale weight up a little at the start — that's intramuscular water, not fat. As always, the caveat that earns the disclaimer at the foot of this page: if you have kidney disease or another relevant medical condition, or you're pregnant or breastfeeding, clear it with a professional first.

Common myths, corrected. "Creatine is a steroid" — no. It's a compound your body already makes and that you get from foods like meat and fish; it works through energy metabolism, not hormones. "It damages your kidneys" — not supported for healthy people with healthy kidneys at normal doses; the concern applies to those with existing kidney disease, who should follow medical advice. "The weight gain is fat" — the early gain is mostly water pulled into muscle, not body fat. "You have to cycle on and off" — there's no established need to cycle; a steady daily dose is the norm. "You must load in the first week" — loading is optional and just fills stores faster; a plain daily dose gets you there.

3. Protein powder — convenience, not magic

Protein powder has good evidence behind it, but it's important to be precise about what the evidence supports. Powder isn't a special muscle-building substance. It's simply a convenient, concentrated source of dietary protein — and the benefit comes from the protein, not the powder. If your total daily protein is already where it should be from food, adding powder does little.

What protein actually does

Protein supplies the amino acids your body uses to build and repair tissue, including muscle. Eating protein — especially sources rich in the amino acid leucine — briefly raises muscle protein synthesis, the process of building new muscle protein. Paired with resistance training, adequate protein helps you build muscle when you're eating enough, and helps protect muscle when you're eating in a deficit. Whey, casein, and blended plant powders (soy, pea, rice) are all just efficient ways to deliver that protein when whole food is inconvenient.

Do you need it?

Only if you'd otherwise miss your protein target. Most people can hit their needs from food — eggs, dairy, fish, poultry, lean meat, legumes, tofu, tempeh — without any powder at all. Where a scoop genuinely helps is the practical stuff: you're busy, travelling, not very hungry after training, or you simply find it easier to close a daily gap with a shake than to cook another protein-heavy meal. That's a real, honest use case. It just isn't a requirement, and it isn't worth spending heavily on.

For how much protein to actually aim for — the evidence-based per-kilogram range, why it protects muscle in a deficit, and where the internet overstates it — see our deeper guide to protein and muscle. The one-line version: get most of your protein from food, spread across the day, and use powder only to top up if you fall short.

Common myths, corrected. "You need a shake right after training or you 'waste' the workout" — the so-called anabolic window is far wider and more forgiving than it's sold as; your total daily protein matters far more than the exact minute you drink it. "More protein per scoop always means more muscle" — beyond the point of sufficiency, extra protein mostly just adds calories; muscle growth is driven by training, with enough protein as a requirement, not an accelerator. "Powder is better than food" — it's more convenient, not superior; whole foods bring other nutrients a powder doesn't.

4. Electrolytes — situational, not daily

Electrolytes — chiefly sodium, along with potassium, magnesium and chloride — are minerals your body uses to manage fluid balance, nerve signalling and muscle contraction. You lose some of them in sweat, mostly sodium. This is where electrolyte drinks and tablets have a real, legitimate role — and also where they're wildly over-sold as an everyday health drink.

When they genuinely help

The honest rule of thumb is about duration, heat, and sweat. Electrolytes tend to matter when a session is long, hot, or leaves you visibly sweaty and salt-crusted — think an hour-plus of hard work, training in the heat, or being a naturally heavy or salty sweater. In those cases, replacing sodium (and drinking to your thirst) helps you maintain fluid balance and hold performance better than water alone. For the everyday short-to-moderate session, though, plain water is enough, and a normal diet already contains plenty of sodium.

A neat way to think about it, and one Strathlon's day-by-day view maps onto naturally, is to match your hydration approach to the kind of day you're having:

Day type Sensible approach
Rest or light day Water is plenty. Electrolyte products aren't doing anything useful here.
Long or hard session An electrolyte drink (mainly sodium) around the session can help, especially past the hour mark. Drink to thirst.
Hot day / heavy-sweat session The clearest case for electrolytes. Adjust intake up if you're sweating a lot or the weather is hot — and pay attention to how you feel.

For most people, most weeks, that means electrolytes are an occasional tool for specific sessions — not a daily supplement, and certainly not a substitute for water.

Common myths, corrected. "You need electrolytes every day to stay hydrated" — for most people eating a normal diet and doing everyday training, water covers it; sodium is rarely the missing piece. "Cramp is always an electrolyte problem" — cramp has several possible causes (fatigue, unaccustomed effort, and more), and it isn't reliably fixed by electrolytes for everyone; treat "electrolytes cure cramp" as unproven, not a rule. "More electrolytes are always better" — they're a replacement for what you lose, not a health tonic to pile on; there's no bonus for topping up sodium you didn't sweat out.

5. Vitamin D — fix a deficiency, don't chase a high

Vitamin D matters for bone health, muscle function and the immune system, and your body makes it when skin is exposed to sunlight. This is the key to reading the evidence honestly: the benefit of supplementing comes almost entirely from correcting a genuine shortfall — not from pushing an already-normal level higher.

Who tends to benefit

Low vitamin D is genuinely common, and more likely if you get little sunlight (indoor lifestyle, covered skin, high latitude, winter months), have darker skin (which makes less vitamin D for a given amount of sun), are older, or spend most daylight hours indoors. For people who are actually low, supplementing to restore a healthy level is sensible and can support bone and muscle health. For people who are already sufficient, the evidence that more vitamin D adds anything — including any performance boost — is weak. The gain is in fixing the deficiency, not in exceeding it.

The sensible approach

Because it depends entirely on your own level, the accurate advice is: if you suspect you're low, the best move is to get it tested and let a professional advise a dose to correct it, rather than guessing. Vitamin D is fat-soluble, which means the body stores it and it's possible to take too much over time, so more-is-better does not apply here — a modest, appropriate dose to restore a normal level is the goal, not a mega-dose. Many people in low-sun conditions reasonably take a modest daily amount over winter; if in doubt, a test removes the guesswork.

Common myths, corrected. "Vitamin D boosts everyone's performance and immunity" — the clear benefit is in correcting a deficiency; topping up an already-sufficient level doesn't reliably do much. "If some is good, more is better" — no; because it's stored in the body, excessive intake over time can be harmful, so dose to your actual need. "A supplement is the only way to get it" — sensible sun exposure and some foods contribute too; a supplement is one tool, most useful when sun and diet fall short.

6. What to skip for most people

Being even-handed means saying plainly what the evidence doesn't support, too. For most healthy people eating enough protein, the following are safe to skip — not because they're necessarily dangerous, but because the evidence that they help is weak, mixed, or absent, and the money is better kept.

There's an honest nuance worth keeping: "skip for most people" isn't "useless for everyone." A clinician might recommend a specific supplement for a diagnosed deficiency — for example B12 for some people eating fully plant-based, or iron for tested low iron. Those are targeted fixes for an identified gap, decided with a professional — a very different thing from buying a general "booster" off a shelf on the promise of an edge.

Common myths, corrected. "BCAAs build muscle" — if you eat enough total protein they add little, because you're already getting those amino acids. "Fat-burners burn fat" — the deficit burns fat; the pill mostly burns money, and sometimes adds stimulant side effects. "Natural boosters raise your testosterone" — over-the-counter "test boosters" have weak-to-no evidence in healthy people; real low testosterone is a medical matter.

7. A worked routine you can copy

To make all of this concrete, here are two simple, honest examples. They're illustrative starting points to adjust to your own body and needs — not prescriptions.

Everyday: the one-supplement routine

For most people training regularly, the entire evidence-based supplement plan can be a single line:

5 g of creatine monohydrate, once a day, every day — rest days included. Stir it into water, coffee, or a protein shake if you're having one. No loading, no cycling, no special timing. That's it. Everything else is optional and situational.

If your protein intake from food runs low on busy days, add a scoop of protein powder only to top up the shortfall — a convenience, not a second "must-take." That's a complete, defensible routine for a large majority of active people.

Match day / big session: electrolytes plus post-session protein

Now the situational pieces come in — but only because the day calls for them. Picture a long, hard match or a heavy training session, on a warm day, where you'll sweat a lot:

And here's the reassuring part that corrects the biggest timing myth: the post-session protein window is wide, not a sprint. You don't need to slam a shake within minutes of the final whistle. Getting a solid protein meal in within a few hours — and, more importantly, hitting your total protein for the whole day — is what actually matters. The "eat-immediately-or-lose-your-gains" urgency is marketing, not physiology.

The through-line of both examples: the everyday driver is simple and constant (creatine, if anything at all), the situational tools appear only when the session demands them (electrolytes for long/hot/sweaty days), and protein is about the daily total, not the stopwatch. Nothing here is urgent, expensive, or complicated.

8. Takeaways, and how Strathlon fits

Where it's honest to say so: Strathlon doesn't sell supplements and doesn't need you to buy any. What it does do is handle the part that actually moves the needle — building your training and nutrition around your body and goals, and giving you a personalised protein target and an energy-balance view so you can see whether the fundamentals are in place. Get those right and, for most people, the supplement question shrinks to a short, cheap answer: maybe some creatine, protein powder if it's convenient, electrolytes on the hard days, and vitamin D if you're low. If you'd like the food side that all of this sits on top of, our guide to eating for results is the companion to this one.

References

Numbered sources for the specific figures and ranges above. Where a point reflects agreed guidance rather than a single trial, the citation is to the position stand or consensus statement of the body concerned, with the country or international remit named. Supplements are the area with the widest gap between marketing and evidence, so this list leans on position stands and on the AIS classification system, which grades products by how well supported they actually are.

  1. Maughan RJ, Burke LM, Dvorak J, Larson-Meyer DE, Peeling P, Phillips SM, et al. IOC consensus statement: dietary supplements and the high-performance athlete. British Journal of Sports Medicine. 2018;52(7):439–455. IOC consensus statement on dietary supplements and the high-performance athlete — the framing source for treating supplements as optional extras and for the short list that has real support. PubMed 29540367 · PMC5867441 full text
  2. Australian Institute of Sport (AIS, Australia). AIS Sports Supplement Framework. The Australian Institute of Sport Sports Supplement Framework, which grades supplements by evidence and is the basis for this guide's short list. AIS Sports Supplement Framework
  3. Kreider RB, Kalman DS, Antonio J, Ziegenfuss TN, Wildman R, Collins R, et al. International Society of Sports Nutrition position stand: safety and efficacy of creatine supplementation in exercise, sport, and medicine. Journal of the International Society of Sports Nutrition. 2017;14:18. ISSN position stand on the safety and efficacy of creatine supplementation — the source for 3 to 5 g/day of monohydrate with no loading or cycling needed. PubMed 28615996 · PMC5469049 full text
  4. Kazeminasab F, Kerchi AB, Sharafifard F, Zarreh M, Forbes SC, Camera DM, et al. The Effects of Creatine Supplementation on Upper- and Lower-Body Strength and Power: A Systematic Review and Meta-Analysis. Nutrients. 2025;17(17). Systematic review and meta-analysis of creatine on upper- and lower-body strength and power, the recent effect-size check behind calling creatine the standout. PubMed 40944139 · PMC12430374 full text
  5. Persky AM, Brazeau GA, Hochhaus G. Pharmacokinetics of the dietary supplement creatine. Clinical Pharmacokinetics. 2003;42(6):557–74. Pharmacokinetics of creatine, supporting the point that a loading phase changes how fast you saturate, not the end point. PubMed 12793840
  6. Jäger R, Kerksick CM, Campbell BI, Cribb PJ, Wells SD, Skwiat TM, et al. International Society of Sports Nutrition Position Stand: protein and exercise. Journal of the International Society of Sports Nutrition. 2017;14:20. ISSN position stand on protein and exercise, the source for protein powder being a way to hit a target rather than a separate mechanism. PubMed 28642676 · PMC5477153 full text
  7. Morton RW, Murphy KT, McKellar SR, Schoenfeld BJ, Henselmans M, Helms E, et al. A systematic review, meta-analysis and meta-regression of the effect of protein supplementation on resistance training-induced gains in muscle mass and strength in healthy adults. British Journal of Sports Medicine. 2018;52(6):376–384. Morton and colleagues' meta-analysis of protein supplementation, supporting the claim that powder works only insofar as it raises total intake. PubMed 28698222 · PMC5867436 full text
  8. Guest NS, VanDusseldorp TA, Nelson MT, Grgic J, Schoenfeld BJ, Jenkins NDM, et al. International society of sports nutrition position stand: caffeine and exercise performance. Journal of the International Society of Sports Nutrition. 2021;18(1):1. ISSN position stand on caffeine and exercise performance — the source for the dose range and the performance effect. PubMed 33388079 · PMC7777221 full text
  9. Guest N, Corey P, Vescovi J, El-Sohemy A. Caffeine, CYP1A2 Genotype, and Endurance Performance in Athletes. Medicine and Science in Sports and Exercise. 2018;50(8):1570–1578. Study of caffeine, CYP1A2 genotype and endurance performance, supporting the point that response varies between individuals. PubMed 29509641
  10. European Food Safety Authority (EFSA, European Union) Panel on Dietetic Products, Nutrition and Allergies. Scientific opinion on the safety of caffeine. EFSA Journal. 2015;13(5):4102. EFSA scientific opinion on the safety of caffeine, the European source for the intake ceilings quoted. doi:10.2903/j.efsa.2015.4102
  11. Sawka MN, Burke LM, Eichner ER, Maughan RJ, Montain SJ, Stachenfeld NS. American College of Sports Medicine position stand. Exercise and fluid replacement. Medicine and Science in Sports and Exercise. 2007;39(2):377–90. ACSM position stand on exercise and fluid replacement, the basis for electrolytes being situational rather than routine. PubMed 17277604
  12. Barnes KA, Anderson ML, Stofan JR, Dalrymple KJ, Reimel AJ, Roberts TJ, et al. Normative data for sweating rate, sweat sodium concentration, and sweat sodium loss in athletes: An update and analysis by sport. Journal of Sports Sciences. 2019;37(20):2356–2366. Normative sweat rate and sweat sodium data, supporting 'reach for them on long, hot, heavy-sweat days' rather than every session. PubMed 31230518
  13. Georgiou GD, Antoniou K, Antoniou S, Michelekaki EA, Zare R, Ali Redha A, et al. Effect of Beta-Alanine Supplementation on Maximal Intensity Exercise in Trained Young Male Individuals: A Systematic Review and Meta-Analysis. International Journal of Sport Nutrition and Exercise Metabolism. 2024;34(6):397–412. Systematic review of beta-alanine and maximal-intensity exercise, cited for a supplement with real but narrow application. PubMed 39032921
  14. Silva KVC, Costa BD, Gomes AC, Saunders B, Mota JF. Factors that Moderate the Effect of Nitrate Ingestion on Exercise Performance in Adults: A Systematic Review with Meta-Analyses and Meta-Regressions. Advances in Nutrition. 2022;13(5):1866–1881. Systematic review with meta-analysis of factors moderating the effect of nitrate on exercise performance, cited for the same reason. PubMed 35580578 · PMC9526841 full text
  15. Thomas DT, Erdman KA, Burke LM. Position of the Academy of Nutrition and Dietetics, Dietitians of Canada, and the American College of Sports Medicine: Nutrition and Athletic Performance. Journal of the Academy of Nutrition and Dietetics. 2016;116(3):501–528. Joint ACSM / AND / DC position on nutrition and athletic performance, the source for diet and training doing the real work. PubMed 26920240
  16. National Health Service (NHS, United Kingdom). Physical activity guidelines for adults aged 19 to 64. NHS physical activity guidance, the baseline against which any supplement claim should be judged. NHS physical activity guidelines

This is general educational information, not medical or dietetic advice. Individual variation is large, and figures such as the 3–5 g/day creatine dose and the illustrative post-session protein serving are approximate, evidence-based starting points rather than exact prescriptions. Supplements can interact with medications and medical conditions, the industry is loosely regulated in many places, and "natural" does not mean proven or safe. Anyone with a health condition — including kidney disease — anyone who is pregnant or breastfeeding, anyone on medication, and anyone competing under anti-doping rules should consult a qualified physician, pharmacist or registered dietitian before adding any supplement. See our Terms for more.

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