Also known as ascorbic acid or ascorbate, vitamin C is a water-soluble vitamin that is not synthesized or stored in the body in high amounts. Its main role is to provide potent antioxidant protection to cells and systems in the body. As such, vitamin C is involved in immune-system protection, wound healing and synthesizing collagen, amino acids, hormones and neurotransmitters.
It’s essential to get adequate amounts of vitamin C in the diet because, unlike many other mammals, humans cannot synthesize this valuable micronutrient. Although vitamin C is found in abundance in most citrus fruits and in many vegetables (like peppers, broccoli and cabbage), a study published in the International Journal of Sport Nutrition and Exercise Metabolism illustrates that athletes undergoing regular strenuous exercise encounter greater levels of oxidative stress — suggesting a need for supplemental antioxidant support. Furthermore, dieting strength athletes with heavy training schedules (like bodybuilders) who follow low-carbohydrate diets (with little variety) tend to have lower vitamin C intake.
Although recent research has suggested that long-term “megadosing” of vitamin C can negatively impact muscular gains and performance, there’s an abundance of data illustrating that modest dosing (500 milligrams to 1 gram per day) can produce significant ergogenic effects. Below we have summarized the most recent data in support of modest vitamin C supplementation.
Go With the Flow
It has been known for years that vitamin C’s antioxidant effects protect blood vessels from oxidative stress. During exercise, the endothelial cells that line blood vessels produce vasodilators that increase blood flow to working muscle, which serves to more quickly and efficiently deliver oxygen and nutrients and take away metabolic byproducts. One such vasodilator is nitric oxide. Research from human and animal studies suggests that vitamin C supplementation plays a dual role in supporting increased NO-mediated vasodilation during exercise. First, vitamin C helps with NO production by shielding the enzyme that helps form NO from the free radicals that build up during exercise. Second, vitamin C increases NO bioavailability. A study from Athens University Medical School in Greece showed that vitamin C taken with arginine boosts NO levels better than taking arginine alone. The scientists concluded that vitamin C’s antioxidant effects increase NO bioavailability by preventing its breakdown by free radicals. Because of its effects on NO (and muscle blood flow), vitamin C makes an appearance in many of today’s preworkout formulas.
Beyond helping to increase blood flow, vitamin C supplementation can increase exercise performance by altering feelings of fatigue. In a recent study published in Nutrition, it was reported that overweight subjects undergoing a four-week calorie-restricted diet who took 500 milligrams of vitamin C daily had decreased signs of fatigue, heart rate and perceived exertion during treadmill exercise.
Drop the Fat
In 2007, a study published in The Journal of Nutrition reported that blood levels of vitamin C were inversely related to body mass index, body-fat percentage and waist circumferences in men and women — suggesting that low vitamin C levels may contribute to weight gain. This may be (at least partly) true because vitamin C is used by the body to synthesize carnitine — a substance required for fat burning.
Support for vitamin C as a fat-burning catalyst comes from a study published in Nutrition & Metabolism in 2006, which showed that levels of vitamin C in the body correlated with fat oxidation during fat-burning cardio exercise on a treadmill. In this investigation, fat burning was measured in subjects with marginal and adequate vitamin C levels during 60 minutes of low-intensity cardio. Subsequently, subjects with marginal vitamin C levels completed an eight-week double-blind, placebo-controlled study in which they were asked to do a low-intensity treadmill walk while depleted of vitamin C and again after taking a vitamin C supplement. In the end, it was found that individuals with marginal vitamin C levels burned 25 percent less fat during exercise compared to subjects with adequate vitamin C levels. Furthermore, taking 500 milligrams of vitamin C per day was found to increase fat burning fourfold compared to depleted control subjects.
Vitamin C is frequently taken as a home remedy for preventing and treating the common cold. Unfortunately, the body of research on vitamin C doesn’t support it as a cure — at least for the general population. A recent meta-analysis published in The Cochrane Database of Systematic Reviews reported that although routine vitamin C dosing does not reduce the incidence of colds in the general population, it might reduce their severity and duration. Most important, the authors highlighted that vitamin C supplements seem to be most useful to those who are exposed to regular intense exercise. All in all, the data suggest that regular vitamin C supplementation will keep you out of the doctor’s office and in the gym.
A Dose of C
We hope that we have convinced you that vitamin C is an essential component of the diet that can help you achieve your workout goals while keeping you healthy and free from sniffles. However, it must be stressed that recent evidence has shown that reactive oxygen species (the “oxidants” that antioxidants combat) may be involved in producing beneficial training adaptations and that doses of vitamin C above 1 gram per day have been shown to impair sport/exercise performance.
According to the research, the beneficial effects of vitamin C come from doses ranging from 500 milligrams to 1 gram per day. Based on this, on regular and non-training days, we recommend taking 500 milligrams of vitamin C per day, split into two doses and taken with food. During high-intensity training periods, you can bump your dose up to 1 gram per day, split into three doses and taken with food. This dosing regimen will ensure you maintain adequate vitamin C levels and avoid the downfalls of megadosing.