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What are the Best Supplements for Marathon Runners?

UK Fitness Pro
UK Fitness Pro
· 11 min read
People running a marathon

Besides a good training plan and a healthy diet, supplements can significantly impact your marathon performance. Below, I've included an overview of the scientific evidence supporting the use of different supplements when training and competing in marathons. You'll also find links to the most highly regarded versions of these supplements. 

The Best Supplements During Marathon Training

Fatty Acids

A recent study found that twelve weeks of omega-3 fatty acid supplementation during endurance training significantly improved running economy and V̇O2 peak in amateur long-distance runners (Tomczyk et al., 2023). Popular fatty acid supplements on Amazon include: 

If you'd like help training for an event, you could reach out to a UK-based online running coach. 

Another study found regular use of cod liver oil by recreational endurance athletes was associated with a significant reduction in exercise-induced C-reactive protein (CRP) levels, suggesting potential anti-inflammatory benefits that could improve recovery and reduce inflammation following a long run. There's also evidence that cod liver oil may reduce joint stiffness (Gruenwald et al., 2002). Here are some highly rated cod liver oil supplements on Amazon:

If you'd like guidance on how to reach peak performance with supplements and good nutrition, you could get in touch with one of these UK-based online personal trainers who help people understand their nutritional needs. You could also think about working with a UK-based online PT who specialises in injury prevention. 

Vitamin Supplements

Vitamin E: Consistent with vitamin E contributing to the health of the digestive system (Scorletti et al., 2022), a placebo-controlled trial published in Nutrition found that vitamin E supplementation for two weeks before a marathon was associated with a reduced incidence of gastrointestinal complaints, such as abdominal cramping and pain, in marathon runners (Buchman et al., 1999). Here are a few of the top-rated vitamin E supplements on Amazon: 

According to the NHS, male athletes should aim for 4 mg of vitamin E daily, whereas female athletes should aim for 3 mg. 

Vitamin C: There's also evidence that vitamin C supplementation for several weeks before a long-distance race may reduce the incidence of post-race upper-respiratory-tract infections (Peters et al., 1993). Popular vitamin C supplements on Amazon include: 

According to the NHS, the recommended dosage of vitamin C is 40 mg daily. As well as supplements, citrus fruits and certain berries (e.g., blackcurrants) are excellent sources of vitamin C. 

Vitamin D: Another trial published in Nutrients found that vitamin D supplementation before an ultramarathon reduced exercise-induced inflammation (Mieszkowski et al., 2021). Vitamin D also plays an important role in immune system health (Aranow, 2012), so nutritional supplements could minimise the risk of illness and help you complete all of your planned training sessions. If you suspect you might have a vitamin D deficiency, one of the following supplements (available on Amazon) could be of interest: 

According to the NHS, the health benefits of vitamin D also include healthy bones and muscles, and the recommended daily allowance is 10 micrograms (0.01 mg). 

Mineral Supplements

Iron: A study by researchers in Japan found that iron supplementation in female endurance runners significantly improved serum ferritin levels, running velocity at lactate threshold, onset of blood lactate accumulation, and 3000 m running performance during periods of rigorous training (Yoshida et al., 1990). If you suspect you might have an iron deficiency, one of these supplements (available on Amazon) may be of interest:

According to the NHS, low iron levels can contribute to headaches, shortness of breath, and fatigue. Regarding the recommended dietary allowance, the NHS suggests 8.7 mg daily for adult males and 8.7–14.8 mg daily for adult females (depending on age). 

The Best Supplements for Marathon Runners on Race Day

Pre-Workout Supplements

A study published in Nutrients found that a multi-ingredient pre-workout supplement containing caffeine, beta-alanine, taurine, and beetroot extract significantly increased time to fatigue in long-distance runners (Fye et al., 2021). Another study found that a pre-workout supplement containing caffeine, vitamin B, amino acids, creatine, and beta-alanine significantly improved muscular endurance by delaying fatigue and enhancing energy levels and focus during high-intensity exercise (Spradley et al., 2012). Top-rated pre-workout supplements on Amazon include:

If you'd prefer a ready-made pre-workout drink, you could check out those offered by Optimum Nutrition (4.4/5) or Warrior Rage (4.3/5). 

If you're interested in how sports supplements compare, you might like our article on branch-chain amino acids (BCAAs) and pre-workout supplements. 

Energy Drinks

Research published in the European Journal of Applied Physiology found that consuming a carbohydrate solution (containing glucose syrup, fructose syrup, and maltodextrin) improved marathon performance by allowing runners to maintain their speed throughout the race (Tsintzas et al., 1995). Popular sports drinks on Amazon include:

If you're interested in how other supplements can enhance sports performance, you might like our article on the benefits of BCAAs for different athletes. 

Energy Gels

A study published in the International Journal of Sport Nutrition and Exercise Metabolism found that marathon runners who followed a scientifically based nutritional strategy, including energy gels with water, maltodextrin, glucose, sodium, and caffeine, completed the race 4.7% faster than those using a freely chosen strategy (Hansen et al., 2014). Top-rated energy gels on Amazon include:

If you're interested in supplements that contribute to energy production, you might like our article comparing creatine pills and powders. 

Electrolyte Drinks

Research conducted at Loughborough University found that consuming glucose or fructose-based carbohydrate-electrolyte solutions during a 30-km treadmill run helped runners maintain their pace better than water alone (Williams et al., 1990). Consuming electrolytes could reduce the risk of a painful muscle contraction (i.e., cramp; Lau et al., 2022). Highly rated electrolyte drinks (and tablets for making drinks) on Amazon include:

If you're looking for electrolyte powders instead, you might like those offered by Science in Sport (4.6/5) or Freak Athletics (4.5/5).  

Essential Amino Acids

A study published in the Journal of Sports Science and Medicine found that national-level endurance runners ran significantly faster after consuming an essential amino acid (EAA) supplement an hour before running compared to a placebo (Cheng et al., 2016). Here are some of the top-rated EAA supplements on Amazon:

Sodium Bicarbonate

An investigation published in the Journal of Sports Science found that sodium bicarbonate ingestion significantly improved 1500-metre race times compared to a placebo (Bird et al., 1995). Similar results have been found for races between 400 metres and 40 kilometres (Schubert et al., 2013). Such findings may partially reflect how sodium bicarbonate can reduce lactic acid buildup (Mueller et al., 2013). Popular sodium bicarbonate supplements on Amazon include:

The Best Post-Race Supplements for Marathon Runners 

Protein Powder

Researchers in Taiwan found that whey protein supplementation after a marathon reduced muscle damage and promoted recovery from exercise injuries (Huang et al., 2017). Popular whey protein supplements on Amazon include:

While the above proteins are suitable for those on a vegetarian diet, they contain dairy products. If you're on a plant-based diet, you might like the plant-based proteins from Wyldsson (4.4/5) or The Protein Works (4.3/5). 

Common Questions About Running Marathons 

How much protein should marathon runners consume?

The American College of Sports Medicine recommends that anyone completing regular training runs should eat 1.2–1.7 grams of protein per kilo of body weight (about 0.5 to 0.8 grams per pound of body weight). While powders can help you meet your protein needs, you should also ensure your protein intake is sufficient by eating protein-rich foods that contain other important nutrients. For example, eggs are not only an excellent source of protein but are also rich in b vitamins (Iannotti et al., 2014).  

What's the ideal level of carbohydrate intake during a marathon?

As it's common to burn 2,000–3,000 calories during a marathon (Loftin et al., 2007), it's important to consume enough energy. A study on elite ultramarathon runners found that, on average, they consumed 70 grams of carbohydrates every hour to help maintain their muscle glycogen stores (Stellingwerff, 2016). Consuming protein in the form of peanut butter in addition to carbohydrates during or immediately after a marathon may reduce muscle soreness and fatigue (Saunders et al., 2018). 

What dietary supplements are good for post-marathon recovery?

As with whey protein, plant-based proteins can assist with muscle recovery (Kritikos et al., 2021) and athletic performance (Joy et al., 2013). These effects may be attributable, in part, to the presence of leucine in plant-based powders (Kalman, 2014), which promotes muscle protein synthesis (Garlick, 2005). Similarly, low-fat milk may facilitate recovery after running long distances (Pieterse et al., 2022). However, you may recover more quickly if you consume a drink with added sugar, such as chocolate milk (Spaccarotella & Andzel, 2011). 

Where can I find out more about marathon nutrition?

Top-rated books about marathon nutrition include Nutrition for Runners (4.5/5), The Runner's Cookbook (4.7/5), and Eat and Run (4.6). 

You might also like our article on the best pre-run supplements. 

About the Author

Dave Robinson is a co-founder of ukfitness.pro and has a background in psychology (BSc) and neuroscience (MSc, PhD). As well as strength training, he enjoys endurance challenges and has run marathons and ultramarathons, cycled across several countries, and completed the Three Peaks Challenge. When writing, he draws on scientific evidence to understand the pros and cons of different diets, supplements, and training regimes. 

As an Amazon Associate, the site earns from qualifying purchases.

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