For most runners in the UK, a balanced diet will cover the vast majority of your nutritional needs. But when training ramps up, or your lifestyle, goals or diet change, certain supplements can help support performance, recovery, and overall wellbeing.
That said, the supplement market is overflowing with products promising faster recovery, fewer injuries and improved endurance. It can be hard to separate what’s useful from what’s just marketing hype. This guide breaks down the most evidence-backed supplements for runners – and when they might actually be worth adding to your routine.
Do Runners Need Supplements?
Not always. If you eat a varied, nutrient-rich diet and train moderately, you may not need any extras. But you might benefit from certain supplements if:
- You’re training for long-distance events like a half marathon or marathon
- You follow a vegetarian or vegan diet
- You often feel fatigued or struggle with recovery
- You train in the early morning or during darker UK winters
- Your blood tests show any deficiencies (especially iron or vitamin D)
Top Supplements for Runners
1. Vitamin D
With limited sunlight in the UK – especially during autumn and winter – vitamin D deficiency is common. This vitamin supports bone health, muscle function, and immune response.
Recommended dose: 10 micrograms (400 IU) daily during autumn and winter, or year-round if you get little sun exposure.
Signs you might need it: Low mood, fatigue, frequent colds, or a history of stress fractures.
2. Iron
Iron helps transport oxygen in the blood. Low iron can lead to fatigue, poor performance and anaemia – a common concern for female runners and those on plant-based diets.
Best taken when: Blood tests show low ferritin or iron levels. Avoid supplementing unless confirmed, as too much iron can be harmful.
Food tip: Pair iron-rich foods (like spinach, lentils, red meat) with vitamin C to boost absorption.
3. Magnesium
This mineral supports muscle function, energy production and helps with cramp prevention. Runners may use more magnesium through sweat, especially during hot weather or long races.
Signs you may need it: Muscle cramps, restless legs, difficulty sleeping, or regular soreness.
Form: Magnesium citrate or glycinate is generally better absorbed than magnesium oxide.
4. Omega-3 (Fish Oil or Algae Oil)
Omega-3 fatty acids have anti-inflammatory benefits, which can help reduce muscle soreness and support joint health. Great for recovery after hard sessions or longer races.
Ideal for: Runners who rarely eat oily fish (like salmon, mackerel, or sardines) or follow a vegetarian or vegan diet.
5. Protein Powder
Not essential for everyone, but protein shakes can be convenient for runners with busy lifestyles or those who struggle to eat enough protein post-run.
Use after: Long runs or strength training sessions, ideally within 30–60 minutes.
Tip: Look for a clean powder with 20–25g of protein per serving. Whey is fast-digesting, while pea, hemp and soy are good plant-based options.
6. Electrolytes
Important for hydration, especially during long summer runs, marathons, or training in heat. Electrolyte tablets or powders help replace sodium, potassium and magnesium lost through sweat.
When to take: On long or hot runs lasting over 60 minutes, or if you experience post-run headaches, fatigue, or cramping.
Supplements to Approach with Caution
- Pre-workout powders – Often packed with caffeine and artificial ingredients. Stick to a coffee or banana before a run.
- Multivitamins – May be useful occasionally but don’t replace a balanced diet.
- Fat burners or detox pills – Avoid completely. No benefit to runners, often full of nonsense.
Final Thoughts
Supplements can support your running, but they’re just that – a supplement to your training and nutrition, not a replacement. The most important things remain consistent running, smart recovery, sleep, and a well-rounded diet.
If in doubt, speak to a GP, registered dietitian, or sports nutritionist before adding anything new. And always choose high-quality, third-party tested supplements to ensure safety and purity.
