Performance Supplements for Endurance Athletes: Worth the Hype?

In episode 117 of The Eat for Endurance Podcast, I’m joined by sports dietitian and fellow endurance nutrition expert Vic Johnson (MPH, RDN) of Mountain Sports Nutrition.

Vic lives and works in Utah, but joined me from New Zealand on the tail end of a year-long family adventure traveling around the world (jealous, anyone?). Between hopping continents, parenting a toddler, and training for his own 100K race, he's also been helping some of the top trail and ultra runners fuel smarter and optimize their performance.

In this episode, we dig into a topic that’s both fascinating and frequently misunderstood: endurance athlete supplements and ergogenic aids. From widely used caffeine and trendy ketone esters, to potentially risky sodium bicarbonate, Vic and I break down the latest research, practical strategies, and what actually works (or not) for our endurance athletes.

If you’ve been curious about performance supplements as an endurance athlete, or tempted to try one without really knowing what it does, this episode is for you.

Spoiler alert: Supplementation is the cherry on top of your nutrition strategy. If you haven't yet dialed in your day-to-day eating, or your intraworkout fueling and hydration strategy, that’s where you should start.

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Supplements for Endurance Athletes: What Works (and What Doesn’t)

Have you ever browsed a supplement company website or scrolled through Instagram and wondered, “should I be taking that product?” We are constantly inundated with information and marketing tactics when it comes to performance supplements, especially for endurance athletes. 

So how do you know which ones are legit, which are overhyped, and which ones you should try? Where do you even begin to sift through the loads of information and ads to find what works best for you?

On the podcast, Vic and I mostly focus on three of the most buzzed-about supplements in the endurance space:

• Caffeine

• Sodium bicarbonate

• Ketone esters

Caffeine: The MVP of Performance Supplements

Caffeine is the most well-researched and widely used supplement among endurance athletes, and for good reason. It can enhance alertness, reduce perceived exertion, and improve performance across a variety of sports, especially when used strategically.

While the science supports dosing in the range of 3–6 mg of caffeine per kg of body weight, how you get there depends on the duration of your event and your personal tolerance.

Here’s how Vic approaches caffeine with his endurance athletes:

• Elite athletes may use up to 75–100 mg/hour during key races, as long as they’ve trained with that amount and don't have GI issues

• Recreational athletes typically do better with lower doses (i.e. 0.8 to 1.5 mg/kg/hour), especially if they’re out there for 12+ hours or struggle with gut issues

• Timing matters, so some athletes save caffeine for the second half of a race (or overnight segments in ultras) to avoid early GI distress and maximize the alertness benefit when fatigue really sets in

• Practice in training is essential. Caffeine supplements are not something you want to test for the first time on race day

Many athletes think they’re using a lot of caffeine during races, but Vic often finds that they’re only taking small doses, like a gel with 20mg here and there. That usually won’t cut it, unless you're benefiting from a placebo effect. 

“If you want a real performance effect, it often requires more than you’d expect,” Vic shared. 

That doesn’t mean more is always better, though. GI tolerance, sleep disruption, and individual sensitivity all matter. If you’re taking 100mg an hour for 24 hours straight, it can backfire big time.

Sodium Bicarbonate: Promising, But Risky

Sodium bicarbonate (aka baking soda) acts as a buffer in the body, helping to neutralize lactic acid and delay the onset of muscular fatigue during high-intensity efforts. 

Sounds great, right? Maybe… but consider this first. 

While some studies have shown benefits in short-duration, high-intensity efforts, like sprints or 10K time trials, there’s much less data supporting its use in long-distance endurance events. That hasn’t stopped a growing number of trail and ultra athletes from trying it, especially since it's been widely promoted by high-profile coaches and elite runners.

The biggest issue? GI distress. In its basic form, sodium bicarb can cause nausea, vomiting, and diarrhea, basically a trail runner’s nightmare.

To get around these tricky symptoms, some athletes are using Maurten's bicarb system, which encapsulates the supplement in small hydrogel “pellets” to reduce GI symptoms. But even with these improvements, the results are mixed.

“I've had athletes swear by it and others who never want to touch it again,” Vic says. “It’s not a silver bullet, and it definitely comes with risks.”

Bottom line: It might help if you’re racing a hard, short course, and you’ve trained with it. But don’t take this one lightly, or spontaneously.

Ketone Esters: A Controversial Trend

Ketone esters are another supplement generating buzz in the endurance world. They provide an alternative fuel source (ketones) that the body typically produces during starvation or low-carb states. The idea is that by consuming ketones exogenously (i.e., in a supplement), athletes may improve endurance, focus, and even post-workout recovery.

It sounds promising, but here’s the reality: 

• They taste awful, according to many who’ve tried them

• They’re expensive and a few doses can run you $80+

• They may cause nausea or other GI symptoms, especially when consumed pre-race

• The evidence is limited, especially in real-world endurance scenarios

Vic rarely recommends using ketone esters before or during a race, but some of his athletes do use them after training for recovery, which is another possible benefit. He still advises athletes to remain cautious.

If you’re curious about ketone esters, it’s best to try them during training, not racing.

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Honorable Mention Supplements for Endurance Athletes

Caffeine, sodium bicarbonate, and ketone esters are three of the most popular endurance athlete supplements on the market, but there are some other popular ones that we touched on during our conversation, some more promising than others. 

Dietary Nitrates

There’s decent research behind dietary nitrates like beetroot juice, especially for amateur athletes. Elite athletes may be less responsive, and some find it causes increased urination or GI discomfort.

The good news? You can just drink beet juice or eat nitrate-rich greens like spinach, arugula, and kale to achieve the same effect. I’m always a proponent of reaching for real food sources over a supplement whenever possible.

Polyphenols

Polyphenols like tart cherry, pomegranate, and blackcurrant may help reduce inflammation and support recovery, but excessive doses might blunt training adaptations if consumed post exercise. If you'd like to experiment with this one, start with whole foods first.

Creatine, Collagen, and Beta-alanine

These supplements have potential benefits, but mostly for specific populations.

• Creatine may support strength and recovery in older or vegetarian athletes

• Collagen might be helpful for joint or tendon support, if dosed and timed correctly

• Beta-alanine is better suited for short, intense efforts, not 100-milers

Context Is Key When Choosing Supplements for Endurance Athletes

When it comes to choosing supplements for endurance athletes, context is key. Not every supplement is meant to work for every athlete or every type of race.

The basics like nutrition, hydration, and rest matter more than anything. If you’re not eating enough, sleeping enough, or getting enough carbs and fluids during your workouts, no supplement is going to save your performance. 

Instead of spending all of your time and money on supplements, it’s best to channel that energy into establishing a strong nutrition foundation. Once your nutrition is dialed in, then you can consider experimenting with select supplements that are well-researched, appropriately dosed, and tested in training.

Quick Safety Reminder: The supplement industry is not well regulated. If you choose to try a supplement, make sure it’s third-party tested (look for NSF Certified for Sport, Informed Sport, or USP Verified).

Key Takeaways From This Episode

• Caffeine is the most consistently effective ergogenic aid

• Sodium bicarbonate and ketone esters have potential, but carry risk (and are expensive)

• Personal experimentation is critical, so try everything in training

• Focus on the basics first, like food, hydration, carb intake, recovery, and sleep

Ready to Dial In Your Fueling Strategy?

If you're wondering whether a supplement might help you with your performance, or if you just want to start feeling stronger in your daily life, I can help! 

As a Registered Dietitian and endurance athlete myself, I’ve worked with runners, triathletes, cyclists, and active people of all levels to fine-tune their everyday and performance nutrition for over ten years. I have a wide variety of services available to fit every budget. 

• Join my membership service, Fuel for Life Crew, for $30/month (cancel anytime)

• Check out my free nutrition downloads

• Fill out a new client inquiry form if you’re interested in 1:1 nutrition coaching

Let’s take the guesswork out of fueling and help you feel strong, confident, and supported in every workout.

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Disclaimer: All information provided is for educational and entertainment purposes only and is in no way meant to replace individual medical and nutrition recommendations.