A Dietitian’s Guide to Supplements: What Actually Matters?

The supplement industry is massive, and it’s easy to get pulled into the idea of a quick fix. But the reality is simple: supplements don’t replace a solid nutrition foundation. Food comes first, always.

That said, supplements can play a role when convenience, performance demands, or specific gaps come into play. The key is knowing what’s worth it, when to use it, and why it works.

Do You Actually Need Supplements If You Eat Well?

If your nutrition is consistent, balanced, and meeting your energy needs, you may not need supplements at all. But in real life, heavy training loads, travel, appetite changes, or time constraints, optimal nutrition isn’t always achievable.

That’s where supplements can fill the gap. In athletes, high training loads increase carbohydrate use, protein turnover, and micronutrient demands, making it harder to consistently meet needs through food alone, especially around training. Low energy availability (RED-S) further increases the risk of micronutrient deficiencies and poor recovery, making targeted supplementation more relevant in some athletes.

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The International Olympic Committee states that supplements cannot compensate for a poor diet, but may be useful in specific scenarios¹. Higher training loads increase carbohydrate oxidation, protein turnover, and micronutrient requirements, making both timing and total intake harder to achieve through food alone².

What Supplements Actually Have The Strongest Evidence?

Not all supplements are created equal. Some are backed by decades of research, while others are still emerging. Before looking at what works, it’s worth noting that supplements are not risk-free. Contamination, incorrect dosing and poor quality control are real concerns. Choosing batch-tested products (e.g. Informed Sport or HASTA certified) reduces this risk, particularly for competitive athletes.

Performance supplements with the strongest evidence;

• Caffeine → Improves endurance performance, power output and reduces perceived effort (3-6mg/kg) ³.

• Creatine monohydrate → One of the most extensively studied supplements; supports strength, power and lean mass adaptations (3-5g/day)⁴,⁵.

• Dietary nitrate (beetroot juice) → Improves exercise efficiency and endurance performance, particularly in submaximal efforts (300-600mg nitrate)⁶.

• Sodium Bicarbonate→ Acts as an extracellular buffer, helping to reduce the impact of metabolic acidosis during high-intensity exercise, which can improve performance in short, repeated or sustained efforts (0.2-0.3g/kg)⁷. 

• Vitamin D→ Supports bone health, muscle function and immune health. Supplementation may benefit those with deficiency, particularly for bone health and muscle function, with less consistent effects on performance⁸.

Endurance Essentials (often overlooked as “supplements”)

These are arguably the most important for performance in long events:

• Carbohydrate (gels, drinks, powders) → Primary fuel source; directly impacts pace, fatigue, and cognitive function.

• Electrolytes (especially sodium) → Support fluid balance and reduce risk of hyponatremia, particularly in long or hot conditions.

• Iron → Essential for oxygen transport and energy production; supplementation is effective when deficiency is determined through a blood test.

Recommended, Safe & Beneficial Supplements For Recovery

If there’s one supplement that consistently delivers across performance, recovery and safety, it’s protein. For convenience, protein powders (like whey isolate or plant blends) are one of the most practical ways to support recovery, particularly when appetite is low, time is limited or convenience matters. They don’t replace food, but they make it easier to get protein in when timing matters most after training.

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Protein ingestion post-exercise enhances muscle protein synthesis (MPS), with rapidly digested, leucine-rich proteins (like whey) producing the strongest response⁹. Meta-analyses show protein supplementation improves lean mass and strength adaptations when combined with training⁹. A leucine threshold of around 2-3g per serve with 20-40g of high quality protein is typically required to maximise MPS⁹,¹⁰.

Plant proteins are typically lower in essential amino acids and leucine, meaning a higher dose or blended sources may be needed¹¹. However, systematic reviews show that total daily protein intake is a primary driver of adaptation, although protein quality and leucine content can influence outcomes¹¹.

Is Fish Oil Worth Taking For Performance?

Fish oil isn’t a performance booster in the traditional sense, but it can support recovery and overall health. It’s also one of the most extensively researched supplements, with decades of data across cardiovascular health, inflammation and exercise recovery¹²,¹³.

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Omega-3 fatty acids (EPA/DHA) help regulate inflammation, immune function and cell membrane fluidity 12. Meta-analyses show reductions in inflammation and muscle soreness, although direct performance benefits are less consistent¹³.

What About “Extra” Supplements?

"Extra” supplements like tart cherry, French maritime pine bark extract, Nomio or ketones can be useful, but they’re not foundational. Think of them as performance add-ons, not essentials. They tend to work best when your fuelling, hydration and overall nutrition are already dialled in.

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Emerging / context-specific→

• Tart cherry juice → May reduce muscle soreness and support recovery via polyphenol content¹⁴.

• French maritime pine bark extract (e.g. Modex, Plasmaide) → May support blood flow and reduce oxidative stress, but performance data is limited¹⁵.

• Nomio (ITC broccoli extract) → Activates antioxidant pathways. Early evidence suggests reduced oxidative stress, but performance outcomes are still emerging¹⁶.

• Ketones → Mixed evidence, may improve brain health, endurance, heart health and cognitive performance. Keep in mind these studies have been done on a small scale with male athletes ¹⁷.

The Key Takeaway

Not all supplements serve the same purpose:

• Some support daily health and recovery (protein, omega-3, vitamin D)

• Some are performance tools used strategically (caffeine, creatine, nitrate)

• And some are non-negotiables in endurance (carbohydrates, electrolytes, iron when needed)

If the foundations, energy, carbohydrates and hydration, aren’t in place, supplements won’t fix the problem. They sit on top of it, not fix it.

Ash Miller
Dietitian and Nutritionist (Masters)
Bachelor of Physical and Health Education
Instagram: @ashthomo_nutrition

References

1. Maughan RJ, Burke LM, Dvorak J, et al. IOC consensus statement: dietary supplements and the high-performance athlete. Br J Sports Med. 2018.

2. Thomas DT, Erdman KA, Burke LM. Position of the Academy of Nutrition and Dietetics: Nutrition and Athletic Performance. J Acad Nutr Diet. 2016.

3. Southward K, Rutherfurd-Markwick KJ, Ali A. Effects of caffeine on endurance performance: systematic review and meta-analysis. Sports Med. 2018.

4. Chilibeck PD, Kaviani M, Candow DG, Zello GA. Effect of creatine supplementation during resistance training on lean tissue mass and muscular strength in older adults: a meta-analysis. J Strength Cond Res. 2017;31(8):2216-24.

5. Lanhers C, Pereira B, Naughton G, Trousselard M, Lesage FX, Dutheil F. Creatine supplementation and lower limb strength performance: a systematic review and meta-analysis. Br J Sports Med. 2017;51(11):868-75.

6. Senefeld JW, Wiggins CC, Regimbal RJ, et al. Ergogenic effect of nitrate supplementation: meta-analysis. Med Sci Sports Exerc. 2020.

7. Grgic J, Pedisic Z, Saunders B, Artioli GG, Schoenfeld BJ, McKenna MJ, et al. Effects of sodium bicarbonate supplementation on exercise performance: an umbrella review. J Int Soc Sports Nutr. 2021;18(1):61.

8. Sist M, et al. Effects of vitamin D supplementation on physical performance in athletes: a systematic review and meta-analysis of randomized controlled trials. Front Nutr. 2023;10:1289454.

9. Cermak NM, Res PT, de Groot LC, et al. Protein supplementation augments muscle mass and strength. Am J Clin Nutr. 2012.

10. Witard OC, Jackman SR, Breen L, Smith K, Selby A, Tipton KD. Myofibrillar muscle protein synthesis rates subsequent to a meal in response to increasing doses of whey protein at rest and after resistance exercise. Am J Clin Nutr. 2014;99(1):86‑95. doi:10.3945/ajcn.112.055517.

11. Lim MT, Pan BJ, Toh DWK, et al. Animal vs plant protein and skeletal muscle mass: systematic review and meta-analysis. Nutrients. 2021.

12. Gutiérrez S, Svahn SL, Johansson ME. Effects of Omega-3 Fatty Acids on Immune Cells. Int J Mol Sci. 2019 Oct 11;20(20):5028. doi: 10.3390/ijms20205028. PMID: 31614433; PMCID: PMC6834330.

13.  Lv Z‑T, Zhang J‑M, Zhu W‑T. Omega‑3 polyunsaturated fatty acid supplementation for reducing muscle soreness after eccentric exercise: a systematic review and meta‑analysis of randomized controlled trials. Biomed Res Int. 2020;2020:8062017.

14. Hill JA, Keane KM, Quinlan R, Howatson G. Tart Cherry Supplementation and Recovery from Strenuous Exercise: A Systematic Review and Meta‑Analysis. Int J Sport Nutr Exerc Metab. 2021;31(2):154-167.

15. Aldret RL, Bellar D. A double‑blind, placebo‑controlled, cross‑over study of maritime pine extract on exercise performance, post‑exercise inflammation, oxidative stress, and muscle soreness. J Diet Suppl. 2020;17(3):309-320.

16. Wang Y, et al. Glucosinolate‑rich broccoli sprouts and exercise: Activation of Nrf2 and antioxidant pathways. Food Chem Toxicol. 2023; (animal & small human studies).

17. Valenzuela PL, Castillo‑García A, Morales JS, Lucia A. Acute ketone supplementation and exercise performance: systematic review and meta‑analysis of randomized controlled trials. Int J Sports Physiol Perform. 2020;15(3):298-308.

Disclaimer:
The content in this blog is for general information only and is not a substitute for professional medical advice, diagnosis, or treatment. Always speak with your doctor or allied health team before changing your diet, exercise, or taking supplements, especially if you have a health condition or take medication. Please use this information as a guide only. Aid Station doesn't take responsibility for individual outcomes.