The supplement industry turns over billions, but only a small part of the shelf is really backed by evidence. This section reviews vitamins, minerals and performance supplements one by one — what their physiological role is, who is really deficient, what the effective dose is compared with the marketing dose, and when a supplement does more harm than good.
In-depth articles for athletes
| Article | Key questions |
|---|---|
| Magnesium | What is known about sleep and cramps, and how do you read the dose on the label? |
| Berberine | What has really been proven about weight and blood sugar, and what does a 2026 trial teach us? |
| Creatine | Who does it help, do you need a loading phase, and what does the weight gain mean? |
| Caffeine | How do you tell apart research doses, safety limits and harm to sleep? |
| Whey protein | When is a powder useful, and how do you choose between product types? |
| Beta-alanine | In which efforts might it help, and why is tingling not a measure of effectiveness? |
Three questions before choosing a supplement
- What is the goal? Filling a nutritional gap, treating a deficiency and improving performance are different uses. There is no single list of supplements that suits everyone.
- What exactly was tested? It is important to check the study population, the dose and the outcome that was measured, and not to settle for an explanation of the mechanism of action.
- Does it suit your personal situation? Take into account medications, underlying conditions, other products and the need for tests based on medical judgment.
The AIS framework for evaluating supplements emphasizes safety, evidence of effectiveness and compliance with the rules of sport. Even a useful supplement is only part of a nutrition and training plan. The AIS supplement framework.
Vitamins
Vitamin A · Vitamin B1 · Vitamin B6 · Vitamin B9 · Vitamin B12 · Vitamin C · Vitamin D · Vitamin E · Vitamin K · Choline
Minerals
Calcium · Magnesium · Potassium · Sodium · Iron · Zinc · Selenium · Iodine · Copper · Manganese · Phosphorus
Sports supplements and other substances
Creatine · Whey protein · Beta-alanine · Caffeine · Omega-3 · Turmeric and curcumin · Berberine · Insulin: information on a hormone and a drug, not a dietary supplement · Combining supplements into a stack
Frequently asked questions
Question: Which supplements are worth considering for sport? Answer: It depends on the goal. Creatine and caffeine have a substantial evidence base for certain uses, protein powder can fill a nutritional gap, and beta-alanine may suit certain efforts. Details and sources appear in the articles linked above.
Question: Can you take several supplements together? Answer: Every combination needs to be checked according to the ingredients, the amounts, medications and medical condition. Several products may contain the same ingredient and create a cumulative intake that goes unnoticed.
Question: Does a higher dose work better? Answer: Not necessarily. A distinction should be made between a studied dose, a safety limit and a personal target. Detailed examples appear in the articles on magnesium and caffeine.
Question: Is berberine a proven performance supplement? Answer: There is no basis for presenting it that way. The research deals mainly with metabolic markers in certain populations; you can’t infer from it a promise of improved performance in healthy athletes.