6 Best Supplements for Triathletes (That Actually Work)

Whether you’re a beginner or an experienced triathlete, the right nutrition plan can make a big difference in optimizing your performance and achieving your goals. But should supplements be part of that plan?

As a dietitian, I believe that fundamental nutrition concepts (like eating enough and balancing your plate) are often overlooked and will arguably make a bigger difference for most athletes. That said, there are a few supplements for triathletes that have some science behind ’em and could potentially improve performance. If you’ve already got a solid nutrition plan in place, adding one of these supplements to your routine may give you that extra edge.

Disclaimer: This post was written by Chrissy Carroll, MPH, RD, USAT Level I Short Course Triathlon Coach. It is for informational purposes only and should not be construed as advice. Consult a doctor or dietitian prior to starting any new supplement.

Best Supplements for Triathletes

Below you’ll find some supplements that I believe can be beneficial for triathletes, depending on your diet and training regimen.

You’ll see several photos of NOW Foods products, who I have worked with in the past, appreciate their commitment to quality. While I’ve linked to some of their Amazon products below, you can always order from their website and get a 20% discount on your entire order by using code CHRISSY. (That code is NOT valid on Amazon orders).

You can also find other brands that produce these products at a local nutrition shop or online. I’ve linked to some other recommended brands too!

Disclaimer: This section contains Amazon affiliate links. As an affiliate, I earn a commission on qualifying purchases.

1. Protein Powder

Protein is essential for muscle repair and recovery after a workout. It’s also involved in other functions, like supporting the immune system and helping you feel full after meals.

Endurance athletes need somewhere between 1.2 to 2 grams of protein per kilogram of body weight, depending on their training regimen, age, goals, and a few other factors. (Note – that range is assuming you don’t have medical conditions that impact your needs).

For a 70 kilogram (154 pound) athlete, that would be about 84 grams of protein on the low end (1.2 g/kg) up to 140 grams on the high end (2 g/kg).

Many people can meet these protein needs through foods in their diet, but others may struggle with getting enough. This is common during two times of day: breakfast and during a post-workout snack or meal.

If you struggle to meet your needs, a protein powder can help. Whey protein is the most well researched, and is highly regarded for its bioavailability and high leucine content. [Read more about whey protein for triathletes.]

But if you’re a vegan or dairy free athlete, you can also use a plant-based protein powder. I’m a fan of plant protein blends, as they often have a better amino acid profile compared to some of the individual plant protein powders.

You can find more of my favorite protein powder options here.

2. Caffeine (recommended in the form of coffee)

Caffeine has been well researched over the years, and is proven to be a performance enhancer. The International society of sports nutrition position stand on caffeine and performance suggests this may be because:

• Caffeine can bind to adenosine receptors in the brain. Since adenosine can make you feel tired when it binds to its receptors, caffeine blocks that action by binding to them instead, keeping you more alert and energized.
• It may increase the production of certain chemicals in the body that can reduce pain perception and perceived exertion during exercise.
• There may be a mechanism related to improved skeletal muscle performance, either through enhancing strength and/or neuromuscular function. 

The ISSN statement notes that doses of 3–6 mg/kg body mass are supported for performance enhancing effects, but minimal effective doses are unknown and could fall as low as 2 mg/kg body mass.

Keep in mind that your genetic makeup may affect how much you need and the degree of benefit that caffeine has as a performance enhancer. For example, variations in the CYP1A2 gene may affect how fast or slow you metabolize caffeine, which could affect how you respond to it.

[Read more about caffeine and genetic variations in this article about coffee before running.]

Although you can take caffeine in capsules or other supplements, I recommend getting your caffeine from coffee if you can tolerate it. Coffee provides polyphenols and antioxidants in addition to the caffeine, and can easily be included in a pre-workout meal.

One 8-ounce cup of coffee typically provides around 95 mg of caffeine, according to the USDA. The specific amount varies though based on several factors, like size of the grounds, brewing method, etc. For example, an 8-ounce medium roast from Starbucks contains 155 mg of caffeine.

If you consider the lower end of the caffeine recommendations at 3 mg/kg, and look at a 70 kg (154 lb) adult, that person would need about 210 mg of caffeine for a performance boost – or around 1 1⁄2 to 2 cups of coffee, depending on the type.

If you do choose to use a supplement instead, I would recommend you avoid using a caffeine powder, also called anhydrous caffeine. This can easily be mismeasured and is dangerous if done so.

3. Beta Alanine

Beta Alanine is an amino acid. We get it from eating foods and it is also naturally produced in the body. Beta alanine is involved in creating carnosine in your muscles.

Carnosine is important for triathletes because it…

Buffers acids produced in the muscle during high-intensity exercise, helping to delay fatigue and prolong the length of time the muscle can keep working at that intensity

Possibly reducing damage to muscle cells by acting as a free radical scavenger

Potentially affects calcium handling and muscle contractile function

The total amount of carnosine in your muscles is limited by your body’s beta alanine levels. So the thought behind beta alanine supplements is they’ll allow you to produce more carnosine, and then experience more of the benefits above.

Several studies on cycling have noted beneficial effects:

• This study found 24 weeks of supplementation improved high-intensity cycling capacity.
• Another study found supplementation increased time to exhaustion, anaerobic capacity, and time trial performance.
• A study on sprint interval training found that in a set of 4 cycling sprints, the beta alanine group had improved performance in the 3rd and 4th sprint. Over several weeks of supplementation, the supplement group had greater improvements in supramaximal cycling time to exhaustion.
• A 28-day supplementation study found beta alanine led to greater time to exhaustion and total work completed.
• Among middle aged individuals, beta alanine supplementation increased cycling exercise capacity.

Like most sports nutrition research, not every study out there shows benefits, but I think the majority of the evidence is positive.

Most research studies use dosages of 2 to 6.4 grams per day of beta alanine, so that may help you to determine a good starting point – though checking with an RD is your best bet!

[Read more about beta alanine for triathletes.]

4. Beet Juice Shots

Beets are a rich source of dietary nitrates. These are converted to nitric oxide in your body, which helps to increase blood flow by opening up the blood vessels more. This means possibly enhanced oxygen delivery to muscles during exercise, which could improve performance.

The research supports this. A 2017 systematic review concluded that “The available results suggest that supplementation with beetroot juice can improve cardiorespiratory endurance in athletes by increasing efficiency, which improves performance at various distances, increases time to exhaustion at submaximal intensities, and may improve the cardiorespiratory performance at anaerobic threshold intensities and maximum oxygen uptake (VO2max).”

Pretty cool, huh? Now of course the impact is fairly small, but still neat.

While you could down a bunch of beets prior to a workout, I’m guessing most athletes aren’t looking to eat a big plate of ’em right before going for a run or ride. Beet juice shots, which have concentrated the dietary nitrates, are easy to enjoy quickly before a workout. I really like the BEET IT shots.

You can also look at beet root powders. While most of the research is on beet juice, theoretically powders that have standardized amounts of dietary nitrates should also be beneficial. These can be mixed into smoothies or juices to mask the beet taste if you’re not a fan of it (I like it, my husband says it tastes like dirt – haha).

5. Vitamin D

Vitamin D is one of the most common nutrient deficiencies worldwide, and one of the supplements for triathletes that I find myself suggesting people look into often.

Research suggests more than 15 percent of people are clinically deficient in this vitamin, and other studies suggest only 12% of the population may meet what some consider “optimal levels”.

You’re probably aware that Vitamin D is involved in bone health, and this makes it key for preventing stress fractures – a common concern among runners and triathletes, especially female athletes. Studies have shown that prolonged low Vitamin D levels are linked to stress fracture risk.

Vitamin D may also be involved in recovery from exercise. For example:

• A single high dose Vitamin D supplement given 24 hours before an ultra marathon helped blunt the inflammatory response after exercise in this study.
• Research found men with optimal Vitamin D levels were found to have lower levels of inflammatory compounds and reduced muscle cell damage after downhill running.
• A study with 3 weeks of Vitamin D supplementation in ultra marathon runners led to decreased markers of skeletal muscle damage.

How do you know if you should supplement with Vitamin D? Get your levels checked! An easy blood draw will tell you if you’re deficient, which is when your Vitamin D falls under 30 ng/mL.

A doctor may recommend a prescription supplement regimen to bring your numbers back up initially. After that, a regular OTC supplement of 1000-2000 IU per day is often worthwhile, as it is quite difficult to meet needs through food alone (though fatty fish, egg yolks, and fortified foods are the best sources).

[Read more about Vitamin D for runners and triathletes.]

6. Omega-3s

Omega-3 fatty acids, specifically EPA and DHA, are known to have a wide range of benefits – from cardiovascular health to mental health to cognitive health. (Though specific benefits may apply to certain population groups).

For triathletes, omega-3s may play a role in exercise. A 2020 narrative review noted “Several studies suggest a potentially beneficial effect of EPA/DHA on performance by improved endurance capacity and delayed onset of muscle soreness, as well as on markers related to enhanced recovery and immune modulation. The majority of these studies are conducted in amateurs.”

Not all studies show these benefits, and the mechanism behind any improvements isn’t quite clear. One study postulates that omega-3s may increase nitric oxide concentration, which could be responsible due to its effects on opening up blood vessels and increasing blood flow to the muscles. Other research suggests it may have an antioxidant role that could be involved.

Regardless, most adults could benefit from getting more omega-3’s in their diet. The best way to do this (in my opinion) is by eating more seafood, which is rich in EPA and DHA! About 90% of adults do not meet the current guidelines to eat seafood twice a week, so that’s great to work towards.

Of course, if you don’t like seafood or you’re on a vegan diet, then it may be worth taking an omega-3 supplement. This can be in the form of fish oils, or, if vegan, in the form of algae oil. A dietitian or doctor can help you determine the right dose based on your medical history.

The Bottom Line

Triathletes need a nutritious diet to fuel their performance and recovery, but some supplements may help support your health and performance too. Consider your own individual diet and where some nutrients may fall short, like Vitamin D and omega-3s. You can also consider performance enhancers, like beta alanine or beet juice shots. Always consult your doctor or dietitian first before starting any supplement regimen.

Good luck, and I hope to see you at a race! 🙂

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