Best supplements for runners: what helps and what is hype

The sports supplement market is worth over $45 billion globally, and the majority of products marketed to runners are unnecessary. A 2018 IOC consensus statement on dietary supplements concluded that only a few supplements have good evidence for performance benefits in athletes, including caffeine and nitrate. Most of what lines the shelves of running stores falls into the category of probably harmless but unproven.

This guide separates the supplements with genuine evidence for runners from those riding marketing claims. It connects to the broader endurance nutrition framework that covers daily nutrition, race fuelling, and cellular energy.

Which supplements actually have evidence for runners?

Based on the current scientific consensus, five supplement categories have strong or moderate evidence supporting their use by endurance athletes. Everything else is either unproven, context-dependent, or marketing...

Supplement	Evidence level	What it does for runners	Effective dose
Iron (when deficient)	Strong	Supports oxygen transport capacity.	18 to 65 mg/day, under medical guidance
Caffeine	Strong	Reduces perceived effort and can improve endurance performance.	3 to 6 mg/kg, 30 to 60 min before exercise
Nitrates (beetroot juice)	Moderate to strong	Can improve oxygen efficiency and endurance performance.	6 to 8 mmol, 2 to 3 hours before exercise
Vitamin D (when deficient)	Strong	Supports immune function, bone health, and muscle function.	1,000 to 4,000 IU/day depending on baseline level
Magnesium	Moderate	Supports normal energy metabolism and muscle function.	300 to 500 mg/day, depending on individual needs

If your diet is adequate, most supplements are expensive urine. The exceptions are correcting genuine deficiencies and the handful of compounds with replicated evidence in controlled trials.

Dr. Trent Stellingwerff, Director of Performance Solutions, Canadian Sport Institute Pacific

What about antioxidant supplements for runners?

This is where the science gets interesting and where most supplement advice gets it wrong. High-dose synthetic antioxidants taken around training sessions can blunt some training adaptations. A study in the Journal of Physiology showed that vitamin C and E supplementation attenuated some of the cellular adaptations to endurance training.

But the picture changes when you look at polyphenolic antioxidants from whole food or plant-based sources. Unlike synthetic megadoses, compounds like oleuropein, quercetin, and catechins appear to support mitochondrial function without blocking adaptation. The mechanism matters: polyphenols modulate the oxidative stress response rather than eliminating it entirely.

A recent study in Cell Metabolism found that oleuropein directly activates mitochondrial calcium uptake and supports muscle energy metabolism. More recent human research also suggests that olive leaf extract can enhance the mitochondrial response to moderate exercise.

Which supplements should runners avoid?

Four categories of supplements that runners should approach with scepticism:

• BCAAs (branched-chain amino acids): redundant if protein intake is adequate. A review in the Journal of the International Society of Sports Nutrition concluded that BCAAs alone do not stimulate muscle protein synthesis more effectively than a complete protein source.
• Glutamine: once popular for immune support, but evidence for performance or recovery benefits in endurance athletes is weak.
• Proprietary blends: any product that hides individual ingredient doses behind a proprietary blend label makes it impossible to verify whether efficacious doses are present. Avoid.
• Fat burners and thermogenics: no good evidence for endurance performance improvement. They often contain stimulants that can impair sleep quality and recovery.

How should runners prioritise supplements?

A decision hierarchy, from most to least important:

1. Fix deficiencies first. Get blood work. Check iron, vitamin D, magnesium, B12, and folate. If anything is low, correct it.
2. Optimise daily nutrition. No supplement compensates for inadequate carbohydrate, protein, or micronutrient intake from food.
3. Support cellular energy. Address the mitochondrial layer with polyphenolic compounds that support energy production without blocking training adaptation.
4. Add performance-specific compounds. Use caffeine and nitrates on race day or for key sessions only.

The OLEUS Daily Shot was designed around step three: magnesium, oleuropein, vitamins B6, C, and D in a targeted formula for mitochondrial energy production. It is not a multivitamin. It is not a protein powder. It is a daily support formula for the cellular foundation of endurance training.

Sources

1. Maughan, R.J., et al. (2018). IOC consensus statement: dietary supplements and the high-performance athlete. British Journal of Sports Medicine, 52(7), 439-455. DOI: 10.1136/bjsports-2018-099027
2. Paulsen, G., et al. (2014). Vitamin C and E supplementation hampers cellular adaptation to endurance training. Journal of Physiology, 592(8), 1887-1901. DOI: 10.1113/jphysiol.2013.267419
3. Gherardi, G., et al. (2024). Mitochondrial calcium uptake declines during aging and is directly activated by oleuropein to boost energy metabolism and skeletal muscle performance. Cell Metabolism. DOI: 10.1016/j.cmet.2024.10.021
4. Lanfranchi, C., et al. (2026). Oleuropein-based olive leaf extract enhances muscle mitochondrial bioenergetics response to moderate but not maximal intensity exercise in humans. Journal of Physiology, 604(10), 3802-3824. DOI: 10.1113/JP290316
5. Wolfe, R.R. (2017). Branched-chain amino acids and muscle protein synthesis in humans: myth or reality? Journal of the International Society of Sports Nutrition, 14, 30. DOI: 10.1186/s12970-017-0184-9

This statement has not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.