New Research Spurs Change In EFS Formula

  • By Bethany Mavis
  • Published May 20, 2014

First Endurance has removed vitamins C and E from its drink mix.

Based on the newest research in sports nutrition, First Endurance chose to change its EFS (Electrolyte Fuel System) sport drink mix formula to not include vitamins C and E, which were shown to possibly have a negative effect on endurance when consumed before and/or during exercise.

The study was performed by researchers at the Norwegian School of Sport Sciences and was published in The Journal of Physiology in February. The results suggest that vitamins C and E may blunt muscles’ natural response to endurance training.

In the 11-week trial, 54 young, healthy participants either took 1000 milligrams of vitamin C and 235 milligrams of vitamin E, or a placebo. The participants all completed an endurance training program, which consisted of three to four workouts per week, primarily running. Fitness tests, blood samples and muscle biopsies were taken at the beginning and end of the trial to see how the participants’ bodies adapted to the training.

The researchers found that the vitamin supplements didn’t affect maximal oxygen uptake or the results of a 20-meter shuttle test—the supplements did not appear to negatively affect participants’ overall performance. However, the muscles of the participants in the placebo group had produced more mitochondria (“powerhouses” of the cells), which is a natural response to training, while those in the supplement group did not see an increase. Also, the four participants with the biggest improvements in running performance seen in the study were all in the placebo group.

“Our results indicate that high dosages of vitamin C and E—as commonly found in supplements—should be used with caution, especially if you are undertaking endurance training,” said Dr. Gøran Paulsen, lead author of the study. Figuring out exactly how vitamin supplements may interfere with improvements in muscle endurance requires further research, the researchers said.

First Endurance, which had previously included vitamins C and E in its EFS sports drink, immediately changed its formula to remove the vitamins as soon as the new research came out. “While the research is relatively new, the team doctors from the HTC-Highroad team [the pro cycling team First Endurance sponsors] told us they were concerned about the riders using vitamin C and E during exercise three years ago,” says First Endurance’s Mike Fogarty. “Because there wasn’t a significant amount of research on it then, we didn’t reformulate the EFS drink at that time. When the additional new research came out late last year, we modified the EFS drinks immediately.”

First Endurance places an emphasis on staying up to date on relative research. “We take great pride in developing and upgrading products that are based on the most current research and are proven to enhance endurance,” Fogarty says. “The research has to be done on endurance athletes, not mice or people coming ‘off the couch.’”

All four flavors (Fruit Punch, Mild Grape, Orange Splash and Tart Lemon Lime) of the newly reformulated EFS drink mix are currently available for purchase ($24.95 for 25 servings,, and the taste has not been affected by the change in formula.

RELATED: First Endurance Sets New Fuel Rules For Athletes

FILED UNDER: News / Nutrition / Performance Nutrition TAGS:

Bethany Mavis

Bethany Mavis

Bethany Mavis is the managing editor of Triathlete magazine. She's a mom, rec soccer player, multiple half-marathon finisher and is learning daily how to become a better triathlete.

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