The potential benefits were particularly noticeable for men with low to average vitamin C levels at the start of the study, report researchers from Arizona State University, Isagenix International LLC, and the Cancer Treatment Centers of America.
The study was conducted with 28 healthy non-smoking men aged between 18 and 35 using a vitamin C dose of 1,000 mg per day for eight weeks.
Results for the final two weeks of the trial showed a 40% increase in the physical activity score increase for the vitamin C group, compared with placebo.
“The role of vitamin C in promoting physical activity may relate to its antioxidant properties since oxidative stress is related to fatigue,” they wrote in the journal Nutrients. “Vitamin C also possesses neuroprotective properties and influences the brain’s oxidative fuel supply, processes that may influence a sense of wellbeing.”
Commenting on the potential reduction in the incidence and the duration of colds, the authors noted that the body of literature is “large and controversial”. Indeed, a recent Cochrane review of 29 trials concluded that vitamin C may reduce the risk of developing common cold for marathon runners by 50%, but there is little evidence that it helps the rest of us.
“Based on the evidence to date, it may be that only populations with low vitamin C status, or those experiencing extreme physical exertion or cold stress, may experience anti-cold benefits of supplemental vitamin C,” wrote the authors of the new study.
Carol Johnston from Arizona State University, Gillean Barkyoumb from Isagenix International, and Sara Schumacher from the Cancer Treatment Centers of America recruited 28 young men to participate in their randomized, double-blind, eight-week trial.
Results from the Wisconsin Upper Respiratory Symptom Survey-21 daily and the Godin Leisure-Time Exercise Questionnaire weekly indicated a ‘modest’ increase in physical activity score rose modestly for the vitamin C group.
Furthermore, fewer people in the vitamin C group reported cold episodes, and duration of the colds was reduced by an average of 59% in the vitamin C, compared with the placebo group.
“These data suggest that measurable health advantages are associated with vitamin C supplementation in men with adequate-to-low vitamin C status,” wrote the researchers. “This simple dietary strategy to promote physical activity and physical health merits further research and the consideration of health practitioners.”
2014, Volume 6, Number 7, Pages 2572-2583, doi:10.3390/nu6072572
“Vitamin C Supplementation Slightly Improves Physical Activity Levels and Reduces Cold Incidence in Men with Marginal Vitamin C Status: A Randomized Controlled Trial”
Authors: C.S. Johnston, G.M. Barkyoumb, S.S. Schumacher