Marathon Swimming Nutrition: A product comparison

I hope you’ve enjoyed “Nutrition Week” here at Freshwater Swimmer. As you may have noticed, I’ve been vague about recommending specific products. There’s a reason for that: I don’t believe there’s any single best nutrition plan for all people, in all situations. However, I’ve personally tried a number of sports drink products, and will share my thoughts on them.

Beginning with the low-end market… These products include, but are not limited to: Gatorade, Powerade, and Vitamin Water. Some signs you might be buying one of these products:

  • You can buy it in supermarkets and gas stations
  • It is brightly colored
  • Produced by a subsidiary of a Fortune 500 company, such as Coca-Cola or PepsiCo
  • Advertised on national television and/or billboards
  • Has a flashy, Javascript-heavy website that contains very little actual information.
  • Ingredients lists may be difficult to find. When you do find one, it’s often extensive and includes strange additives like “xanthan gum” and “brominated vegetable oil.”
  • Most relevant to endurance athletes: The primary carbohydrate source is a simple sugar such as sucrose, dextrose, or high-fructose corn syrup (or a combination).


Vitamin Water

Please note: This isn’t an argument about the “morality” of simple sugars. From an exercise perspective, it all ends up as glucose anyway. The issue is osmolality. Because maltodextrin is a larger molecule, it’s easier to consume more carbs without your stomach treating it like food, flooding with water, and causing gastric distress. This might not matter in an everyday workout, but in an 8+ hour swim, it matters.

It’s also easier to control the flavor of a maltodextrin-based drink. By itself, it’s almost tasteless. If you like a sweet, strong-flavored drink, you can always add fructose, fruit juice, or even Gatorade. With simple sugars, the only way to control the flavor is by watering it down – and thus consuming fewer calories.

Now to the higher-end, designer “endurance fuels,” which typically use maltodextrin as their primary carb source.

Unlike Gatorade and Powerade, the nutrition facts and ingredients lists are usually easy to find. I’ve included an image of each product label, which you can click to enlarge.

I also included a cost estimate for each product. It’s not obvious how to do this, given they’re sold in different-sized containers, and often recommend different serving sizes. So, I decided to calculate a cost-per-carb. The standard serving of maltodextrin is 20g carbs in 250ml (8.45 oz) water – an 8% solution. This is approximately what I drink every 20 minutes during a marathon swim. So, the costs listed below are for each 250ml serving of 20g carbs.

The “numerator” of the cost calculation is the largest-sized container available, purchased from with free shipping and no sales tax. If the product is not available from Amazon, I use the price listed on the product website.

Note: The following is written from the perspective of a marathon swimmer, and may be less relevant to runners, triathletes, etc. As always, YMMV.

Hammer HEED

Hammer HEED

  • carb source: maltodextrin only
  • extras: electrolytes, amino acids
  • cost per 250ml: $0.45
  • NOTES: Very mild flavor – some might feel, too mild. The fewest electrolytes among the listed products, so a viable option for a channel swim. Amino acid content is probably too negligible to matter.

Hammer Perpetuem

Hammer Perpetuem

  • carb source: maltodextrin only
  • extras: protein, fat, electrolytes
  • cost per 250ml: $0.52
  • NOTES: Heavier mouthfeel due to the protein & fat content. Detractors might say “chalky.” Caffe Latte flavor good for warm feeds. Low electrolyte content, so also a reasonable option for channel swims. Some people have trouble digesting protein while swimming.



  • carb sources: maltodextrin, fructose, dextrose, alpha-L-polylactate
  • extras: electrolytes, chromium, amino acids
  • cost per 250ml: $0.25
  • NOTES: In my opinion, the best-flavored of the listed products. Amino acid content unknown, and therefore probably negligible. No idea whether their patented carbohydrate alpha-L-polylactate has any measurable benefit.

GU Electrolyte Brew

GU electrolyte brew
GU ingredients

  • carb sources: maltodextrin, fructose
  • extras: electrolytes
  • cost per 250ml: $0.42
  • NOTES: High sodium content, so beware of using in a channel swim. Pretty good flavor.

GU Roctane

GU roctane drink
GU roctane drink ingredients

  • carb sources: maltodextrin, fructose
  • extras: electrolytes, amino acids
  • cost per 250ml: $0.64
  • NOTES: A brand-new product from GU. They market the amino acid content heavily, but unfortunately the quantity of that content is not revealed.

First Endurance EFS

1st Endurance EFS

  • carb sources: maltodextrin, sucrose, dextrose
  • extras: electrolytes, amino acids
  • cost per 250ml: $0.83
  • NOTES: Tart, salty flavor due to the very high electrolyte content. Not recommended for channel swims. Somewhat expensive.

Amino Vital Endurance

Amino Vital Endurance

  • carb sources: maltodextrin, sucrose, fructose
  • extras: electrolytes, amino acids
  • cost per 250ml: $1.21
  • NOTES: Should probably be considered more of an “amino acid supplement” than a primary endurance fuel. Strong flavored. Fairly high electrolyte content. Very expensive.

Generation UCAN

Generation UCAN
Generation UCAN ingredients

  • carb source: hydrothermally modified corn starch (a.k.a. Superstarch ™)
  • extras: electrolytes
  • cost per 250ml: $1.41
  • NOTES: This is the product recommended by Peter Attia. Apparently, it provides a slower-release glucose, which minimizes insulin spikes. I haven’t tried it, so I have no idea how it tastes. Somewhat high sodium content. Extremely expensive.

Here are some nutritional data on each of these products, on a per 250ml, per 20g carbohydrate basis.

[table id=2 /]

Summary and Recommendations

None of these products is perfect.

  • Hammer HEED and Perpetuem are probably the best options for a channel swim, because of the lower electrolyte content. However, some people find HEED too mild-flavored, and others have trouble with the soy protein in Perpetuem.
  • I like the flavor and high amino acid content of EFS, but the electrolyte content is awfully high for long-distance swimming – especially ocean swimming.
  • Generation UCAN is an intriguing idea, but prohibitively expensive to use on an everyday basis.

And that is why… with the occasional exception of Perpetuem, I don’t use any of these products. In the next (and final) post in this series, I’ll review what I consider to be the two best options for marathon swimmers:

  1. Purchase a plain (unflavored) complex carbohydrate, such as Carbo-ProMaxim, or Generation UCAN-plain, and flavor it yourself.
  2. Infinit Nutrition.

15 thoughts on “Marathon Swimming Nutrition: A product comparison”

  1. Man this post is one of the best I’ve ever seen. Thanks for the research and compiling all your information here. I’m gonna add a permanent link to this entry.

    1. Thanks Gords, I’m happy you liked it! Despite the coincidental timing with your post earlier today, I had been working on this for a while…

  2. Definitely bookmarking this particular post and your next one. I’ve had little to no experience with supplements while swimming. I’ve “practiced” with half-apple juice/half-water with a pinch of salt for my long 2-3 hour pool swims. However, I’m waiting till I return to the states to try these bad-boys. Trying to find then afford these guys in Moscow would be VERY expensive!

  3. Thanks for sorting through the hype. So far, Maxim mixed with water and a little bit of Gatorade has worked well for me. The Hammer Perpeteum doesn’t sit well in my stomach. I can’t wait to read your two best options.

  4. Interesting blog Evan, thanks.

    My five cents’ worth:

    I swam the English Channel in the Summer of 2011 and stuck to the Channel favourite: Maxim. Double dosage, mixed with half water and half apple juice (easy on the stomach), 250 mls every 20 minutes. Plus half a banana every hour. Worked very well.

    1. I recently swam my furthest 21k, just over 6hrs, I eat half a banana every 4k or so
      and drank water and getorade, my last 4k or so was tiring and tidous, this is my
      second year swimming and am fairly new to it, would any on recommend some ”during the swim nutrietion”.

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