The supplement industry earns billions from athletes hoping for an extra edge. Many of those products are useless for most runners. But a handful of supplements do have a solid scientific basis. This article helps you tell the difference.
The starting point: a varied diet is the foundation. Supplements fill in where the foundation falls short. They never replace a poor diet.
Supplements with strong scientific substantiation
Vitamin D
Vitamin D is less of a supplement and more of a correction of a structural deficiency. In Belgium and the Netherlands, where sunshine is limited from October to April, a large part of the population is vitamin D deficient in the winter months. This is relevant for runners: vitamin D plays a role in bone health, muscle function and immune function.
The recommendation: 800 à 2,000 IU per day in autumn and winter, or all year round if you don't spend much time outside. If in doubt, have your blood level tested: a deficiency is easy to determine and easy to correct.
Iron
Iron deficiency is the most common nutrient deficiency in endurance athletes, especially in female runners. Symptoms include fatigue, declining performance, shortness of breath on exertion and concentration problems.
Iron is essential for hemoglobin, the protein that transports oxygen in the blood. Runners with an iron deficiency perform demonstrably worse. Supplementation helps quickly if there is a proven deficiency.
Important: Do not take an iron supplement based on suspicion alone. Too much iron is harmful. First have a blood test performed and discuss supplementation with your doctor.
Good dietary sources of iron: red meat, liver, dark leafy vegetables, legumes, quinoa. Vitamin C increases iron absorption from plant sources.
Creatine
Creatine is the most well-researched supplement in the sports world, with hundreds of studies proving its effectiveness on strength and explosiveness. For runners who also do strength training - which is recommended for most runners - creatine is worthwhile.
The evidence is weaker for pure endurance sports performance (pace, lactate threshold, VO2max). Creatine causes a slight weight gain due to water retention in muscles (1 & 2 kg), which is a consideration for lighter runners.
The recommendation: 3 à 5 grams of creatine monohydrate per day, daily. No "charging phase" necessary for long-term use.
Caffeine
Cafeïne is one of the best documented ergogenic drugs for endurance sports. It reduces perceived exertion, increases alertness and can improve endurance. Effective at doses of 3 à 6 mg per kilogram of body weight, 45 à 60 minutes before a training or match.
A cup of coffee contains 80à 100 mg caffeine. For a 70 kg runner, 3 mg/kg is good for 210 mg, or two à three strong cups of coffee.
Be aware of habituation: if you drink a lot of coffee every day, you will notice less effect. Consider reducing caffeine in the week before a competition to maximize the effect.
Omega-3 fatty acids (fish oil)
Omega-3, especially EPA and DHA from fish oil, has anti-inflammatory properties that are relevant for endurance athletes. Regular intake can reduce muscle soreness after intensive training and support recovery. The evidence is not as strong as for caffeine or creatine, but the risk of side effects is minimal.
Recommendation: 1 à 3 grams of EPA + DHA per day. Do you eat oily fish (salmon, mackerel, herring) twice a week? Then you probably don't need a supplement.
Supplements with Limited Evidence (But Popular)
Magnesium
Magnesium is widely recommended against cramps in runners. The scientific evidence for this specific effect is limited. Cramps while walking are more often caused by dehydration, electrolyte imbalance, overexertion or poor running technique than by a magnesium deficiency.
That said: magnesium deficiency occurs in athletes who sweat a lot, and plays a role in muscle function and sleep quality. If you have signs of deficiency (muscle cramps, poor sleep, fatigue), 200 à 400 mg magnesium bisglycinate or citrate per day is a sensible option.
Beet root extract (nitrates)
Beet root extract is rich in nitrates, which are converted into nitric oxide in the body. This improves oxygen efficiency in the muscles and can improve performance during certain forms of exercise. The effect is greatest at submaximal effort of 12 à 40 minutes (relevant for 5 à 10 km race runners).
Take it 2 à 3 hours before a training or competition. The same effect can be achieved by drinking beetroot juice every day.
Protein powders
Protein powder is not a panacea but a practical food. If you easily get enough protein through regular food (1.4 à 1.7 grams per kilogram per day), a shake adds nothing. If you don't achieve that (busy schedule, little appetite after training, vegetarian diet), a good whey or plant protein shake is a useful addition.
Supplements you can skip
Amino acid complexes and BCAAs
If you eat enough complete proteins, separate BCAA supplements are unnecessary. The amino acids they contain are present in any protein-rich food. Expensive and little added value for runners with a normal diet.
Fat burners
Products that claim to increase your fat burning through stimulant extracts (green coffee, raspberry ketones, garcinia cambogia) have no convincing scientific evidence of effectiveness in healthy athletes. The amount of caffeine in some of these products does have a marginal effect, but you can achieve that cheaper with a cup of coffee.
Most are glorified sports drinks with marketing packaging. Check the label and compare the ingredients with cheaper alternatives. In research, chocolate milk often scores as well as commercial recovery products.
Frequently asked questions
As a vegetarian or vegan runner, should I take supplements?
Are pre-workout supplements dangerous?
Do glutamine supplements help recovery?
Are supplements safe if I participate in competitive sports?
In summary
Four supplements have a solid scientific basis for runners: vitamin D (in case of deficiency), iron (in case of proven deficiency), caffeine (for performance), and creatine (in combination with strength training). Omega-3 is a sensible supplement for those who eat little oily fish. The rest: examine it critically, read the label, and compare with cheaper alternatives.
→ Back to the nutrition overview for runners for the complete picture.
→ Do you want to know how to combine recovery nutrition and supplements? Read nutrition after running.
Bart Vandenbussche is passionate about sport and never shies away from a sporting challenge. He has run several marathons (including sub-3h), is an Iron+Ultra Viking, and currently has the Hyrox bug.
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