According to a new study published in the American Journal of Clinical Nutrition, a daily vitamin C intake equivalent to eating two kiwifruits a day is required to ensure our muscles maintain optimal levels.

The study, conducted by Prof Margreet Vissers and colleagues from the University of Otago in Christchurch, New Zealand, has shown that skeletal muscle is very sensitive to changes in vitamin C intake, and that the vitamin C content in muscle will fall if intake decreases below optimal levels. This is likely to affect muscle function.

The scientists gave 54 males aged between 18 and 35 either half a kiwifruit or two kiwifruit a day over a six week period. They then measured the vitamin C content in muscle and elsewhere in the body.

They found that general energy levels were increased with the ‘two per day’ kiwifruit dose, and this is likely to reflect the optimal muscle function under these conditions.

“Eating high-value vitamin C foods, like kiwifruit, is the ideal way to maintain healthy levels,” Prof Vissers said.

“Many people think that all fruit and vegetables are equally able to supply vitamin C, but this is not the case. The levels in food vary hugely across the spectrum. We should eat a good range daily, but because many fruit contain only one tenth of a healthy daily vitamin C requirement, we would recommend at least one serve per day of a high-value food like kiwifruit.”

“This will help you easily reach an optimal vitamin C intake, as well as delivering other vital nutrients,’’ Prof Vissers concluded.

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Bibliographic information: Anitra C Carr et al. 2013. Human skeletal muscle ascorbate is highly responsive to changes in vitamin C intake and plasma concentrations. Am J Clin Nutr, vol. 97, no. 4, pp. 800-807; doi: 10.3945/ajcn.112.053207