This article is written by Amy from The Running Dietitian.
Introduction To Supplements For Runners
Supplements are products designed to provide nutrients that may be missing in your everyday diet. Supplements are tools to fill in the gaps when nutrition from food alone isn’t enough.
For some runners, certain supplements may offer advantages for energy, endurance, or recovery, but they are still not essential. Understanding which supplements are supported by research, and how to use them safely, can help you decide if they’re worth adding in to support your endurance running.
Do Runners Really Need Supplements?
As the name suggests, supplements are meant to supplement your diet, not replace it. A balanced, nutrient-rich diet should always come first since it forms the foundation for performance, recovery, and overall health. While supplements can help fill gaps or provide small benefits, most runners do not need them.
It’s also important to remember that not all supplements are created equal and regulation is limited. If you do choose to use supplements, look for products that have been third-party tested, such as those that carry the NSF Certified for Sport or Informed Sport seal, to ensure quality and safety.
What Supplements Are Best For Runners?
Collagen
Collagen is the most abundant protein in the body, providing structure to connective tissues like skin, tendons, ligaments, cartilage, and bones. The body makes collagen from the amino acids proline, hydroxyproline, and glycine.
For runners, collagen is especially important as it supports joint health and connective tissue resilience. Combining vitamin C with collagen can stimulate collagen synthesis in tendons and ligaments, which can aid in tissue repair and reduce injury risk.
Potential downside: Collagen is generally safe, but it’s not a complete protein (it lacks tryptophan), so it shouldn’t replace other protein sources in your diet.
Iron
Iron plays a critical role in running performance because it transports oxygen to working muscles. Without enough iron, the body can’t produce adequate red blood cells, which means your muscles receive less oxygen and you may experience fatigue, poor endurance, or shortness of breath. Runners are at a higher risk of iron deficiency due to losses through foot-strike hemolysis, sweat, and, for women, menstruation.
Dosage: Recommended Dietary Allowance (RDA): 8-18 mg per day, depending on age and sex.
Potential downside: Iron supplements can cause constipation or nausea. Forms like iron bisglycinate or ferrous sulfate are often better tolerated.
Myth-busting, “every runner needs an iron supplement”: Not every runner needs an iron supplement. Taking it without a diagnosed deficiency can cause iron overload. Blood work and medical guidance should dictate if supplementation is necessary.
Magnesium
Magnesium is often talked about for sleep, but for runners it plays a much bigger role. It supports bone health, muscle contraction and relaxation, heart function, and insulin sensitivity. Since magnesium is lost in sweat and it is common not to meet the RDA for magnesium, runners face a higher risk of deficiency.
Dosage: RDA for magnesium is 310-420 mg per day, depending on age and sex.
Electrolytes
When you sweat you lose not just water, but electrolytes. Sodium and chloride are lost in the greatest amounts, while potassium, magnesium, and calcium appear in smaller concentrations. Sweat losses vary by age, sex, body size, training conditions, and exercise intensity.
Myth-busting, “cramping is a sign of an electrolyte imbalance”: While cramping can be related to electrolyte imbalances, research suggests that muscle fatigue is often the more likely cause.
This doesn’t mean electrolytes aren’t important – replenishing them still supports hydration and performance – but it’s equally important to pay attention to your pace and effort to help reduce the risk of cramping.
Caffeine
Caffeine can help delay fatigue by supporting muscle contractions and improving how efficiently your body produces energy. Just as importantly, caffeine works on the brain by blocking signals that make you feel tired, which boosts alertness, focus, and even mood. This combination can help reduce how hard a run feels, making it easier to hold your pace for longer.
Dosage: 3 to 6 milligrams of caffeine per kilogram of body weight, taken about 60 minutes before exercise.
Potential downside: For some, caffeine can lead to gastrointestinal distress (upset stomach, diarrhea) and even heart palpitations.
Creatine
Creatine is best known for increasing muscle strength and power, making it especially popular among athletes in strength and power-based sports. However, research has also explored its potential benefits for endurance runners.
For runners, creatine may also improve muscle endurance and glycogen storage, helping runners sustain higher intensities during interval training or delay fatigue in the later stages of a race.
Dosage: 3-5 g per day
Myth-busting, “you need a loading phase”: The loading phase, 20g of creatine a day for 5 to 7 days, is intended to quickly saturate the muscles with creatine, aiming to reach optimal levels more rapidly than with regular maintenance dosing alone. Aiming for a maintenance phase of 3 to 5g of creatine per day will have the same effect, just at a slower rate.
Protein
Most runners can meet their protein needs through food alone, but supplementation can be helpful in certain situations. Adequate protein is essential for repairing muscle and supporting recovery. Needs can typically be met with a balanced diet that includes a variety of protein-rich foods.
Protein supplements, such as powders or bars, can be a convenient option for busy schedules, travel, or for athletes who struggle to get enough protein from food alone.
Dosage: Runners generally need about 0.8 to 2.2 grams of protein per kg of body weight every day.
Myth-busting, “the more protein the better”: More protein is not always better. Taking in amounts beyond what your body needs will not provide extra performance benefits and may even displace the carbohydrates needed to fuel training.
Supplements for a Race-Day Focus
Beetroot Juice
Beetroot juice works because it’s rich in nitrates, which your body converts into nitric oxide. This helps widen blood vessels and allows your muscles to use oxygen more efficiently. For runners, that means being able to sustain pace with less effort, which can improve endurance and make running feel easier, especially during longer efforts.
Dosage: 400 mg of nitrate taken 2 to 3 hours before exercise for a minimum of 5 days.
Sodium Bicarbonate
Sodium bicarbonate seems to be the new supplement world class track athletes are talking about. This supplement is used by runners because it helps buffer the lactic acid that builds up during high-intensity exercise lasting up to 10 minutes. A common downside to this supplement is gastrointestinal distress (bloating, nausea, or diarrhea).
Dosage: 200–300 mg per kg of body weight taken 1–2 hours before exercise.
Myth-busting, “half marathon and marathon runners should use sodium bicarbonate”: Sodium bicarbonate works best for high-intensity efforts lasting from 30 seconds up to 10 minutes.
Because half marathons and marathons are much longer endurance events, this supplement does not provide meaningful benefits for races of those distances. It’s better suited for track races or repeated sprint efforts, not long-distance running.
Takeaways
Supplements can provide benefits for some runners, but they are not a replacement for a well-balanced diet. The most important factors for improving your endurance performance include: consistent training, adequate fueling, hydration, and supporting recovery.
If you choose to use supplements, focus on those backed by research, pay attention to proper dosage and timing, and select products that are third-party tested for safety. Above all, remember that supplements should be just that, supplemental.