Running places unique demands on your body — so which supplements are genuinely relevant?

Runners lose more iron than non-exercisers. They lose more magnesium through sweat. Repetitive impact stresses bones and joints over thousands of strides per session. Heavy training blocks suppress immune function. These are measurable, well-documented physiological demands.

Yet most "best supplements for runners" lists recommend ingredients with no regulatory basis for the claims being made. Under EU Regulation 432/2012, retained in UK law post-Brexit, only specific nutrients can carry authorised health claims. Everything else is marketing language.

This guide covers the nutrients and compounds with genuine relevance to runners — separating authorised claims from clinical evidence, and both from speculation.

Is iron the most important supplement for runners?

Iron is arguably the single most relevant mineral for endurance athletes. It contributes to normal oxygen transport in the body and contributes to the reduction of tiredness and fatigue — both authorised health claims under EU Regulation 432/2012.

For runners, the case is especially strong because exercise increases iron losses through multiple mechanisms. Peeling et al. (2008) reviewed the pathways of athletic iron deficiency, identifying foot-strike haemolysis (the mechanical destruction of red blood cells from repeated impact), increased gastrointestinal losses during prolonged exercise, and elevated sweat losses during training. The authors also highlighted how exercise-induced inflammation increases hepcidin — a hormone that reduces iron absorption — creating a compounding effect where runners both lose more iron and absorb less of it.

Female runners face particular risk. The National Diet and Nutrition Survey shows that 25% of women aged 19–64 have iron intakes below the Lower Reference Nutrient Intake. Combine menstrual losses with training-related iron depletion and the prevalence of suboptimal iron status in female runners is substantial.

Iron deficiency impairs performance even before clinical anaemia develops. When ferritin drops below optimal levels, oxygen delivery to working muscles is compromised, VO2 max declines, and perceived exertion increases at the same training intensity.

For a detailed comparison of iron supplement forms and bioavailability, see our guide to iron supplements: forms, absorption and how to choose. PARTICULAR uses ferrous gluconate — a well-absorbed form with fewer gastrointestinal side effects than ferrous sulphate. Read more about our iron.

Does magnesium help with running performance and muscle recovery?

Magnesium carries three authorised health claims directly relevant to runners: it contributes to normal muscle function, contributes to the reduction of tiredness and fatigue, and contributes to normal energy-yielding metabolism.

These are not trivial claims. Magnesium is a cofactor for over 300 enzymatic reactions, including those involved in ATP production — the primary energy currency during exercise. Every muscle contraction and relaxation cycle depends on adequate magnesium.

Nielsen and Lukaski (2006) reviewed the relationship between magnesium and exercise, finding that strenuous physical activity increases magnesium losses through urine and sweat, potentially raising requirements by 10–20% above sedentary levels. The authors noted that athletes with marginal magnesium intake may experience impaired performance and increased susceptibility to muscle cramps.

For runners, the combination of sweat losses during long runs and potential dietary insufficiency (particularly if restricting calories or following a plant-based diet) means magnesium status deserves attention. Symptoms of marginal deficiency — muscle cramps, fatigue, poor sleep quality — overlap significantly with what many runners attribute to "overtraining."

For more on magnesium and recovery, see our guide on magnesium and sleep, and learn about our magnesium formulation.

Why do runners need vitamin D for bones and muscle function?

Vitamin D contributes to the maintenance of normal bones and contributes to the maintenance of normal muscle function — both authorised claims under EU Regulation 432/2012. It also contributes to normal absorption and utilisation of calcium and phosphorus.

For runners, bone health is a direct performance concern. Stress fractures are among the most common serious injuries in distance running, and vitamin D status is a modifiable risk factor. Lappe et al. (2008) conducted a randomised, double-blind, placebo-controlled trial with 5,201 female Navy recruits and found that vitamin D and calcium supplementation reduced stress fracture incidence by 20% compared to placebo.

UK runners face a particular challenge. The government recommends that all adults consider taking a vitamin D supplement during autumn and winter, when UVB levels are insufficient for cutaneous synthesis. Runners who train early in the morning, late in the evening, or predominantly indoors on treadmills may have limited sun exposure even during summer months.

The muscle function claim is also relevant. Adequate vitamin D supports the fast-twitch muscle fibres involved in propulsion, and deficiency has been associated with increased injury risk and prolonged recovery times in athletic populations.

For a deeper look at vitamin D forms and dosing, see our guide on vitamin D3 versus D2. PARTICULAR uses vegan vitamin D3 derived from lichen. Read more about our vitamin D3.

Can CoQ10 support endurance performance?

Coenzyme Q10 (CoQ10) does not hold an authorised health claim under EU Regulation 432/2012, so no regulatory claim can be made. However, its biochemical role and the available evidence are worth examining for runners.

CoQ10 is a component of the mitochondrial electron transport chain — the pathway through which cells produce ATP. During sustained aerobic exercise, mitochondrial energy production is the primary fuel source. CoQ10's role in this process provides a clear mechanistic rationale for its relevance to endurance athletes.

Drobnic et al. (2022) published a systematic review in Nutrients examining CoQ10 supplementation and exercise performance. The authors concluded that while data are not yet definitive, CoQ10 supplementation may support exercise performance and recovery from fatigue, particularly through its role in reducing exercise-induced oxidative stress.

CoQ10 levels decline naturally with age, which may make supplementation more relevant for masters-category runners. It is worth noting that statins — taken by a significant proportion of the UK adult population — deplete CoQ10, making supplementation particularly relevant for runners on these medications.

Does MSM help with joint recovery for high-mileage runners?

Methylsulfonylmethane (MSM) does not hold an authorised health claim in the UK, so no regulatory claim can be made. However, for runners accumulating significant weekly mileage, the clinical evidence on MSM and joint and recovery support is worth reviewing.

Kalman et al. (2012) conducted a pilot study examining MSM supplementation at 3g per day for 30 days in healthy men following exercise-induced muscle damage. The results showed that MSM supplementation was associated with favourable changes in markers of exercise recovery, including antioxidant capacity.

Running is a repetitive-impact sport. Knees, ankles and hips absorb forces of 2–3 times bodyweight with every stride. Over a marathon training block, that amounts to millions of impact cycles. MSM is an organic sulphur compound — sulphur is a structural component of the amino acids methionine and cysteine, which are involved in the integrity of connective tissue.

For a broader look at joint-relevant supplements, see our guide on supplements for joint pain.

What does the evidence say about ashwagandha (KSM-66®) and running performance?

Ashwagandha (KSM-66®) does not hold an authorised health claim under EU Regulation 432/2012, so no regulatory claim can be made. However, a specific clinical trial on KSM-66® and cardiorespiratory endurance provides relevant evidence for runners.

Choudhary et al. (2015) conducted a randomised, double-blind, placebo-controlled trial examining KSM-66® ashwagandha root extract in healthy athletic adults. The study found a statistically significant improvement in VO2 max (P < 0.0001) in the KSM-66® group compared to placebo at both 8 and 12 weeks of supplementation.

VO2 max — the maximum rate of oxygen consumption during exercise — is one of the most important determinants of endurance running performance. Any supplement with evidence for improving VO2 max warrants serious attention from runners, though it is important to note that this was a single trial and larger replication studies would strengthen the evidence base.

KSM-66® is a standardised full-spectrum root extract of Withania somnifera, produced using a process that avoids chemical solvents. It is vegan-suitable and has been the subject of multiple clinical trials across different health outcomes.

Can vitamin C and zinc support runners' immune systems during heavy training?

Heavy training loads are associated with increased susceptibility to upper respiratory tract infections — a phenomenon well-documented in marathon and ultramarathon runners. Two nutrients with authorised immune-related claims are directly relevant.

Vitamin C contributes to the normal function of the immune system — an authorised health claim. It also contributes to the protection of cells from oxidative stress, which is elevated during intense exercise.

Hemilä and Chalker (2013) published a Cochrane systematic review examining vitamin C and the common cold. While the general population showed minimal benefit from supplementation, a subgroup analysis of five trials involving 598 marathon runners, skiers and soldiers under heavy physical stress found that vitamin C halved the incidence of colds (pooled RR 0.48, 95% CI 0.35–0.64). This is a substantial protective effect specifically relevant to endurance athletes.

Zinc contributes to the normal function of the immune system — also an authorised health claim. Zinc is lost through sweat during exercise, and marginal deficiency can impair immune cell function. For runners in heavy training blocks, ensuring adequate zinc intake is a practical immune-support strategy with a solid regulatory and evidence basis.

Why do runners need personalised supplementation?

A runner completing three 5K sessions per week has fundamentally different nutritional demands from someone training for an ultramarathon. Mileage, training intensity, sex, dietary pattern, and individual physiology all influence which nutrients are most relevant and at what levels.

Consider the differences:

Generic multivitamins apply a one-size-fits-all approach to a problem that is inherently individual. PARTICULAR builds your formulation around your specific answers — your training load, dietary patterns, health goals and biological considerations.

Take the questionnaire to find out which nutrients are most relevant to your running, or read more about the science behind personalised supplementation.

Key takeaways

PARTICULAR delivers these ingredients as loose vegan microgranules in a pouch — one daily scoop, tailored to your individual profile. No capsules, no tablets, no guesswork.

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