Vitamin C: Effects of Exercise and Requirements with Training

Abstract

Ascorbic acid or vitamin C is involved in a number of biochemical pathways that are important to exercise metabolism and the health of exercising individuals. This review reports the results of studies investigating the requirement for vitamin C with exercise on the basis of dietary vitamin C intakes, the response to supplementation and alterations in plasma, serum, and leukocyte ascorbic acid concentration following both acute exercise and regular training. The possible physiological significance of changes in ascorbic acid with exercise is also addressed. Exercise generally causes a transient increase in circulating ascorbic acid in the hours following exercise, but a decline below pre-exercise levels occurs in the days after prolonged exercise. These changes could be associated with increased exercise-induced oxidative stress. On the basis of alterations in the concentration of ascorbic acid within the blood, it remains unclear if regular exercise increases the metabolism of vitamin C. However, the similar dietary intakes and responses to supplementation between athletes and nonathletes suggest that regular exercise does not increase the requirement for vitamin C in athletes. Two novel hypotheses are put forward to explain recent findings of attenuated levels of cortisol postexercise following supplementation with high doses of vitamin C.

Antioxidant Supplementation and Immunoendocrine Responses to Prolonged Exercise

“…The findings from the present study are in line with the suggestion of Peake (2003) that adrenal cortisol and VC release do not occur together (co-release) in response to oxidative stress. Given the significantly blunted cortisol response with antioxidant supplementation it is possible that there are some direct effects upon the HP A axis, and it has been suggested that this occurs at the level of the adrenal glands (Peake, 2003;Peters et aI., 200Ia, b).…”

“…The findings from the present study are in line with the suggestion of Peake (2003) that adrenal cortisol and VC release do not occur together (co-release) in response to oxidative stress. Given the significantly blunted cortisol response with antioxidant supplementation it is possible that there are some direct effects upon the HP A axis, and it has been suggested that this occurs at the level of the adrenal glands (Peake, 2003;Peters et aI., 200Ia, b). However, the observation of a trend for a blunted ACTH response in the AO compared with PLA group in the present study suggests that there may also be some effects elsewhere upon the HP A axis, possibly at the level of the hypo thalamus or the anterior pituitary gland.…”

“…Acute VC supplementation account for this difference but in general it would seem that attenuation of the cortisol response is not caused simply by increased plasma VC concentration and reduced general oxidative stress which agrees with Peake (2003) Peters et al (200Ia,b).…”

“…The present findings support the contention that cortisol is not co-released from the adrenal glands with VC in response to oxidative stress (Peake, 2003). For example, in study 2 (Chapter 4) acute VC supplementation resulted in a significant increase of plasma antioxidant capacity before and following prolonged exercise and seemed to reduce exercise-induced oxidative stress.…”

Antioxidant Supplementation and Immunoendocrine Responses to Prolonged Exercise

“…The findings from the present study are in line with the suggestion of Peake (2003) that adrenal cortisol and VC release do not occur together (co-release) in response to oxidative stress. Given the significantly blunted cortisol response with antioxidant supplementation it is possible that there are some direct effects upon the HP A axis, and it has been suggested that this occurs at the level of the adrenal glands (Peake, 2003;Peters et aI., 200Ia, b).…”

“…The findings from the present study are in line with the suggestion of Peake (2003) that adrenal cortisol and VC release do not occur together (co-release) in response to oxidative stress. Given the significantly blunted cortisol response with antioxidant supplementation it is possible that there are some direct effects upon the HP A axis, and it has been suggested that this occurs at the level of the adrenal glands (Peake, 2003;Peters et aI., 200Ia, b). However, the observation of a trend for a blunted ACTH response in the AO compared with PLA group in the present study suggests that there may also be some effects elsewhere upon the HP A axis, possibly at the level of the hypo thalamus or the anterior pituitary gland.…”

“…Acute VC supplementation account for this difference but in general it would seem that attenuation of the cortisol response is not caused simply by increased plasma VC concentration and reduced general oxidative stress which agrees with Peake (2003) Peters et al (200Ia,b).…”

“…The present findings support the contention that cortisol is not co-released from the adrenal glands with VC in response to oxidative stress (Peake, 2003). For example, in study 2 (Chapter 4) acute VC supplementation resulted in a significant increase of plasma antioxidant capacity before and following prolonged exercise and seemed to reduce exercise-induced oxidative stress.…”

The effects of acute vitamin C supplementation on cortisol, interleukin‐6, and neutrophil responses to prolonged cycling exercise

“…This is in contrast to the trend for lower cortisol concentrations observed by Davison and Gleeson (2005) with acute vitamin C supplementation, and is in opposition to our original hypothesis. It would appear, therefore, that attenuation of the cortisol response is not caused simply by increased plasma vitamin C concentration and reduced general oxidative stress, which is in line with the findings of Peake (2003) and Nieman et al ( , 2002. In the present study, there was only a trend for plasma vitamin C concentration to increase during exercise on the placebo trial.…”

Antioxidant Supplementation and Immunoendocrine Responses to Prolonged Exercise

“…The findings from the present study are in line with the suggestion of Peake (2003) that adrenal cortisol and VC release do not occur together (co-release) in response to oxidative stress. Given the significantly blunted cortisol response with antioxidant supplementation it is possible that there are some direct effects upon the HP A axis, and it has been suggested that this occurs at the level of the adrenal glands (Peake, 2003;Peters et aI., 200Ia, b).…”

“…The findings from the present study are in line with the suggestion of Peake (2003) that adrenal cortisol and VC release do not occur together (co-release) in response to oxidative stress. Given the significantly blunted cortisol response with antioxidant supplementation it is possible that there are some direct effects upon the HP A axis, and it has been suggested that this occurs at the level of the adrenal glands (Peake, 2003;Peters et aI., 200Ia, b). However, the observation of a trend for a blunted ACTH response in the AO compared with PLA group in the present study suggests that there may also be some effects elsewhere upon the HP A axis, possibly at the level of the hypo thalamus or the anterior pituitary gland.…”

“…Acute VC supplementation account for this difference but in general it would seem that attenuation of the cortisol response is not caused simply by increased plasma VC concentration and reduced general oxidative stress which agrees with Peake (2003) Peters et al (200Ia,b).…”

“…The present findings support the contention that cortisol is not co-released from the adrenal glands with VC in response to oxidative stress (Peake, 2003). For example, in study 2 (Chapter 4) acute VC supplementation resulted in a significant increase of plasma antioxidant capacity before and following prolonged exercise and seemed to reduce exercise-induced oxidative stress.…”

The effects of acute vitamin C supplementation on cortisol, interleukin‐6, and neutrophil responses to prolonged cycling exercise

“…This is in contrast to the trend for lower cortisol concentrations observed by Davison and Gleeson (2005) with acute vitamin C supplementation, and is in opposition to our original hypothesis. It would appear, therefore, that attenuation of the cortisol response is not caused simply by increased plasma vitamin C concentration and reduced general oxidative stress, which is in line with the findings of Peake (2003) and Nieman et al ( , 2002. In the present study, there was only a trend for plasma vitamin C concentration to increase during exercise on the placebo trial.…”

Antioxidant Supplementation and Immunoendocrine Responses to Prolonged Exercise

“…The findings from the present study are in line with the suggestion of Peake (2003) that adrenal cortisol and VC release do not occur together (co-release) in response to oxidative stress. Given the significantly blunted cortisol response with antioxidant supplementation it is possible that there are some direct effects upon the HP A axis, and it has been suggested that this occurs at the level of the adrenal glands (Peake, 2003;Peters et aI., 200Ia, b).…”

“…The findings from the present study are in line with the suggestion of Peake (2003) that adrenal cortisol and VC release do not occur together (co-release) in response to oxidative stress. Given the significantly blunted cortisol response with antioxidant supplementation it is possible that there are some direct effects upon the HP A axis, and it has been suggested that this occurs at the level of the adrenal glands (Peake, 2003;Peters et aI., 200Ia, b). However, the observation of a trend for a blunted ACTH response in the AO compared with PLA group in the present study suggests that there may also be some effects elsewhere upon the HP A axis, possibly at the level of the hypo thalamus or the anterior pituitary gland.…”

“…Acute VC supplementation account for this difference but in general it would seem that attenuation of the cortisol response is not caused simply by increased plasma VC concentration and reduced general oxidative stress which agrees with Peake (2003) Peters et al (200Ia,b).…”

“…The present findings support the contention that cortisol is not co-released from the adrenal glands with VC in response to oxidative stress (Peake, 2003). For example, in study 2 (Chapter 4) acute VC supplementation resulted in a significant increase of plasma antioxidant capacity before and following prolonged exercise and seemed to reduce exercise-induced oxidative stress.…”

The effects of acute vitamin C supplementation on cortisol, interleukin‐6, and neutrophil responses to prolonged cycling exercise

“…This is in contrast to the trend for lower cortisol concentrations observed by Davison and Gleeson (2005) with acute vitamin C supplementation, and is in opposition to our original hypothesis. It would appear, therefore, that attenuation of the cortisol response is not caused simply by increased plasma vitamin C concentration and reduced general oxidative stress, which is in line with the findings of Peake (2003) and Nieman et al ( , 2002. In the present study, there was only a trend for plasma vitamin C concentration to increase during exercise on the placebo trial.…”