A blog by runners. For runners.

Study: Think twice before you take Vitamins C and E

vitamins C and E in supplement form may reduce runners’ fitness gains from workouts

Experts have long said it’s best to meet your nutritional needs through diet alone. Still, the supplement market is hot.

Many of us turn to supplements thinking they’ll help our health. But more research keeps coming out that says some supplements don’t have any value. And, worse, some research has found that certain supplements interfere with the natural processes our bodies go through to get healthier and fitter.

Runners who take vitamins C and E should take note of a recent study published in the Journal of Physiology.

The study
Researchers found taking vitamins C and E in supplement form may reduce runners’ fitness gains from workouts.

For the study, 54 participants followed an intense 11-week training plan. Some subjects took 1000mg of vitamin C and 235mg of vitamin E daily, while other participants took placebo pills. The scientists took biopsies of the participants’ quadriceps muscles before and after the 11-week period.

The muscle tissue from the group who took the supplements showed increased oxidative stress and reduced cell signaling. Basically, this means the supplements may interfere with fitness gains made through endurance training. It’s also important to note the four runners whose performance improved the most over the study period were all in the placebo group.

The study authors cautioned endurance athletes to think twice before taking supplements high in vitamins C and E. However, keep in mind that this research is preliminary. More studies are needed before experts can say if vitamin C and E supplements are truly harmful to fitness or not.

Where to get your C and E
If you’re in good health and eat a variety of foods – including vegetables, fruit, whole grains, lean sources of protein, and dairy products – you most likely don’t need to take supplements (some populations, including women who plan to become pregnant, pregnant women, and adults over age 50, need supplements or fortified foods).

In fact, you may already be taking in plenty of vitamins C and E through diet alone.

Adult men need about 90mg of vitamin C each day, and adult women should aim for 75mg. These foods are high in vitamin C:

  • Citrus fruits. A medium orange contains about 70mg.
  • Chili peppers. A half cup of diced chili peppers offers 108mg.
  • Red bell peppers. A half cup of the chopped variety contains 95mg.
  • Green bell peppers. A half cup contains 60mg.
  • Kale. One cup of kale packs 80mg.
  • Broccoli. One serving of broccoli comes in at 130mg.
  • Strawberries. 1 cup of strawberries contains 85mg.
  • Kiwi. One kiwi comes in at 67mg.

Adults need about 15mg of vitamin E each day. Try these foods high in vitamin E:

  • Sunflower seeds. One-fourth cup contains 8mg.
  • Almonds. 1 ounce (about 24 almonds) comes in at 7mg.
  • Spinach. 1 cup of cooked spinach contains 7mg.
  • Safflower oil. 1 tablespoon contains nearly 5mg.
  • Peanut butter. A 2 tablespoon serving comes in at nearly 3mg.
  • Avocado. One-fourth of an avocado contains 2mg.

 Written by Jen Matz.

Additional sources: 1 | 2 | 3 | 4 | 5