Safe and Research-Supported Supplements for Runners

Safe and Research-Backed Supplements for Runners

Supplements are popular amongst runners. We all want that magic pill that will give us that ultimate performance advantage. Unfortunately, that does not exist. No supplement will replace consistent, smart training (or genetic luck). However, there are some supplements for runners that the research suggests are effective and safe. This article delves into how runners should choose supplements, as well as safe and effective supplements for runners.

How to Pick Safe and Effective Supplements for Runners

Before taking any micronutrient supplement, it is essential to determine first if you need the supplement. 

1. Determine if you actually need the supplement.

Supplements should be taken based on need. The supplements that your running buddy takes may not be the best choice for you. If you can get it from whole foods, try that first. Then, opt for a supplement if you still have a deficiency, a gap in your diet, or extra performance needs.

For example, iron supplements are popular. Some runners have low ferritin or hemoglobin levels and require an iron supplement. However, if a runner with optimal levels supplemented iron pills, they could risk iron toxicity. You need to use bloodwork also, as symptoms such as fatigue can be indicative of both iron deficiency and toxicity – or other deficiencies or diseases. 

 2. Ensure you are choosing a high-quality supplement. 

  • Safety
  • Purity: This supplement is not contaminated with any substances, including illegal performance-enhancing drugs. 
  • Efficacy: The supplement contains the appropriate dosage of ingredients that are clinically demonstrated to be effective. 

Shop for supplements third-party tested supplements and/or brands using third-party testing. I highly recommend Momentous and Previnex for supplements for runners.

3. Weigh the risk vs benefits of taking the supplement. 

Sodium bicarbonate provides an excellent example of the risk vs reward analysis. Sodium bicarbonate is a known ergogenic aid, as it offers a 2-3% performance improvement for high-intensity running (particularly in the mile and shorter distances). However, sodium bicarbonate has a high risk of gastrointestinal distress associated with it. Common side effects of sodium bicarbonate supplementation include nausea, vomiting, bloating, and abdominal pain. Those side effects can be severe enough to outweigh any performance enhancements. 

When choosing supplements, it is prudent to look up any potential side effects. Then, consider for yourself: do the benefits outweigh the side effects? You may not know until after you try the supplement, which is why it’s important to test supplements in training, not close to or during goal races. 

4. Ensure the supplement does not interact with any medications or other supplements. 

You cannot look at supplements individually. Everything you take – supplements and medications – interact with each other. 

For example, ashwagandha supplements may interact with thyroid, diabetes, high blood pressure, and immunosuppressant medications. You can often find interactions between supplements and medications on WebMD; if you are unsure, speak with your healthcare provider, registered dietitian, or pharmacist. 

For more on supplements for runners, be sure to listen to Episode 7 of the Tread Lightly Podcast! We discuss more on how to choose supplements, plus popular supplements such as protein powder, creatine, and greens powders,

Safe and Effective Supplements for Runners

The following are some of the safest and most effective supplements for runners. As outlined above, you still need to weigh the risks and benefits of each and consider your individual situation before you start supplementing. 

Caffeine Supplements

You may not think of it as a supplement, but caffeine is one of the most widely used and effective supplements for runners. 

Sports nutrition products such as gels, chews, and sports drinks sometimes contain deliberate doses of caffeine. You may also find caffeine in supplements such as pre-workouts. Caffeine supplementation is legal for adult runners, but the NCAA does ban high doses. (So if you are a collegiate runner reading this, be careful with caffeine supplementation!)

Importantly, not every runner’s response to caffeine is the same. Caffeine response is genetically determined by CYP1A2 genotypes. Some people are high-responders, some low-responders, and others still non-responders. Likewise, some individuals may be more prone to the adverse effects of caffeine supplementation (see more below). 

Mechanisms of Action:

After ingestion, it is only a matter of minutes before caffeine appears in the bloodstream. However, peak caffeine levels occur approximately 45 min after ingestion (and may last up to 2 hours). 

Caffeine improves performance through multiple mechanisms of action. The primary mechanism is stimulation of the central nervous system. In the brain, caffeine blocks adenosine receptors; as a result, both neurotransmitters release (including dopamine and norepinephrine) and motor unit firing rates increase. This results in a reduced rate of perceived exertion and less pain during intense exercise. 

Additionally, caffeine favorably affects the working muscles. Caffeine enhances calcium ion mobilization, which in turn increases force production. Caffeine’s effect on calcium ions may also reduce muscular fatigue. 


Caffeine reduces rate of perceived exertion and pain perception during endurance exercise, such as running. The evidence suggests that caffeine supplementation can result in a 2-4% performance improvement in responding individuals. 

While not reported in the literature, many runners attribute caffeine before a race to aiding in pre-run bowel movements.

Potential side effects:

As many runners likely have learned the hard way, caffeine can come with adverse effects. The most common side effects of caffeine supplementation are gastrointestinal distress, such as nausea and runner’s trots. Others may experience anxiety, jitters, or palpitations. Some adverse effects may outweigh the performance benefits. As with any supplement, test in training. The higher dose you use, the more likely you are to have side effects. 

How to use:  

Caffeine supplementation is typically used twice on race day: prior to the race and during the race. In the 1-2 hours before a race, you may choose to have a cup of coffee, highly caffeinated tea, or a caffeinated sports drink. During the race, you want to take caffeinate supplements (such as a caffeinated gel) at 45-60 minutes before you anticipate needing it. So, if you want the boost during the final miles of the marathon, take your caffeine in the middle of the race. 

The International Society of Sports Nutrition recommends 3-6 mg of caffeine per kilogram of body weight. For a 65-kg runner (143 lbs), the recommendation equates to 195-390 mg of caffeine. That’s not at once – that’s over the course of the entire event. Always start on the lower end first when testing caffeine dosages. The ISSN notes that some individuals may benefit from low doses of 2 mg/kg (130 mg of caffeine). 

What does that recommendation actually look like in practice? If you have one cup of coffee before the race (95 mg) and one caffeinated Maurten gel during the race (100 mg), you hit the goal of 195 mg. Alternatively, you could have one cup of coffee and two 50-mg caffeinated gels during the race. 

Recommend Products

Skratch Hydration Mix offers caffeinated flavors (such as the delicious Raspberry Limemade), while also providing electrolytes and carbohydrates. Maurten 100 CAF gels provide a large dose of caffeine, to which many runners respond positively.

Probiotic Supplements

Surprisingly, probiotic supplements may be one of the most beneficial supplements for runners. Probiotics are beneficial microorganisms that live in the gut – and offer health and performance benefits when supplemented. 

Mechanisms of Action: 

Probiotic supplements introduce different strains of probiotics into the gut. These strains each serve slightly different functions. Probiotics promote mucus secretion in the gut, which improves the gut barrier integrity and function. Probiotics may also alter gene expression in a manner favorable to healthy gut muscosa. The gut muscoa plays a role in nutrient absorption, immune system regulation, and other physiological processes.     


For runners prone to the runner’s trots or suffering from IBS, probiotics may attenuate symptoms. Even if you do not experience GI upset on runs, probiotics can still be beneficial. Probiotic supplementation can improve gut barrier function, which results in better nutrient absorption. There is more novel research being explored, such as the role of gut bacteria on neurotransmitters (which could impact running motivation) and on cortisol levels. 

Probiotics may reduce the risk of upper respiratory infections. This benefit is important for runners, since URIs can disrupt training. Probiotics modulate T-cell production of cytokines and may downregulate certain inflammatory cytokines. Since the GI tract musoca is a line of defense of the immune system, improvement in the gut muscuosa integrity is another immune system benefit of probiotic supplementation. 

Potential side effects: 

When starting a probiotic, you may experience some gastrointestinal symptoms such as bloating. These symptoms will subside as you continue supplementation. If they do not, you may want to try a different strain of bacteria.  

How to Use:

Probiotic supplementation is generally straightforward: you take the supplement (typically a pill form) daily. It’s a safe practice to take a probiotic after your run, if you are worried about any potential GI upset on a run.  

Recommended Brands:

I highly recommend the Previnex Probiotics, which contain six clinically effective strains. I have tried dozens of brands of probiotics over the years and experienced the best results from these. You can use the code LNR15 for 15% off of your first order.

Omega-3 Fatty Acids: 

Omega-3 supplements are widely popular for both general population and athletes. For athletes, there are some benefits – particularly if you take a high-quality supplement. 

Mechanisms of Action:

Omega-3 supplements provide a particular type of polyunsaturated acid. Polyunsaturated acids have a double bond that allows them to incorporate into phospholipids. The changes in the phospholipids aid in blunting reactive oxygen species (ROS) and reducing pro-inflammatory cytokine production. Intense exercise elevates ROS and cytokine production; omega-3 supplements downregulate the ROS and cytokines in a way that reduces muscle soreness. 


Omega-3 fatty acids offer numerous benefits, such as improved cognitive function and better cardiovascular health. For athletes, the specific benefits may come in relation to muscle soreness. Studies, such as a 2021 randomized controlled trial in the Journal of the International Society of Sports Nutrition, found that four weeks of 3-grams daily omega-3 supplementation resulted in less perceived delayed onset muscle soreness and lower creatine kinase levels at 24-hours post-exercise. For athletes who struggle with soreness in big training blocks, omega-3 supplementation may help. (However, excessive soreness can be indicative of greater deficiencies in nutrition, such as low energy availability or inadequate protein intake, so check those first.)

Foods such as fatty fish and walnuts contain omega-3 fatty acids, so you may not need a supplement – you may be able to get enough in your diet. The research simply is not definitive yet if athletes need greater quantities than diet can offer. 

Potential side effects: 

Low-quality omega-3 supplements may be contaminated and include heavy metals. Low quality supplements can also cause gastrointestinal symptoms such as burping or heartburn. If you have a bleeding disorder, talk to your doctor before supplementing omega-3 fatty acids. 

Recommended Brands:

Previnex Omega Pure Plus supplements are tested to be free of heavy metals (which is a concern with fish oil supplements). Use the code LNR15 to save 15% off of your first order!

Collagen Supplements

Collagen supplements are most effective for joint and skin health. These supplements do not provide a complete amino acid profile – they are not a replacement for protein powders. However, they may benefit some athletes (more below). Even if you do not get direct performance benefits from the supplements, you may notice a difference in your skin, hair, and nails. 

Mechanisms of Action:

Collagen is the most abundant structural protein in the body, found in, bone, skin, muscle, tendons, ligaments, and cartilage. Collagen is made from the amino acids glycine, proline and hydroxyproline – which are found most protein-rich foods such as eggs, dairy, poultry, legumes, and red meat. Production of collagen does decline with age, which is why collagen supplements have become more popular.

When you take a collagen supplement, your body breaks it down into the separate amino acids. Those amino acids are then distributed throughout the body and form collagen wherever it is needed. Most collagen supplements also include vitamin C, which enhances collagen synthesis. 


Collagen is most effective for athletes suffering from joint pain. As outlined in a 2018 review in the International Journal of Sport Nutrition and Exercise Metabolism, collagen supplementation may benefit athletes with osteoarthritis, knee pain, or tendon injuries. The benefits occur over months, not days, so if you supplement collagen, you need to take it consistently for several weeks. 

Potential side effects: 

Collagen supplementation has very few side effects. However, you do want to ensure you choose a collagen supplement from a third-party tested brand to avoid heavy metal contamination. 

How to Use

Timing is vital with collagen supplements. Ideally, you want to take it within 30-60 minutes prior to starting exercise. As with most supplements, the dose makes the efficacy; the recommended dosage is 10-15 grams. Hydrolyzed collagen is the most bioavailable form of collagen supplement. Most collagen supplements dissolve in hot and cold liquids.

Recommended Brands

Momentous is an NSF safe-for-sport collagen peptide supplement. Gnarly Nutrition and Vital Proteins are also reputable brands.

Final Thoughts on Supplements for Runners

These are only a few supplements for runners! Importantly, sport nutrition should be individualized. Research may support these supplements, but that does not mean that you need to take them. You may have adverse reactions or see no results.

As discussed above, micronutrient supplements such as vitamin D or iron should be taken based on bloodwork. For runners who need them, they are beneficial – but toxicity can occur if supplemented inappropriately.

You can read more about other sports nutrition supplements in these articles: 


Collagen (Harvard Public Health)

Disclaimer: this article contains affiliate links. I am a certified sport nutrition, but I am not a registered dietitian or medical professional.

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