Vitamin C

https://www.tandfonline.com/doi/abs/10.1080/10408398.2011.649149

 

Vitamin C supplementation may be even more beneficial for people who perform heavy physical activity. In five trials with 598 total participants, who were exposed to short periods of extreme physical stress, vitamin C reduced common cold risk by nearly 50%

https://www.ncbi.nlm.nih.gov/labs/pmc/articles/PMC8078152/pdf/CD000980.pdf

 

Vitamin C, or ascorbic acid, is a water-soluble vitamin known for its ability to support a strong immune system. In addition to promoting various cellular functions of the immune system, vitamin C helps the body grow and repair tissue, heal wounds, and absorb iron.

 

Most animals and plants can synthesize ascorbic acid, but humans are unable to synthesize it due to non-functional enzyme L-gulono-1,4,-lactone oxi- dase, which catalyzes the final step in the ascorbic acid biosynthesis in animals (Naidu 2003). Therefore, humans require it as an essential supplement in their diet.

 

Many animals can synthesize ascorbic acid in vivo; however, others such as humans and guinea pigs have lost the ability to make ascorbic acid be- cause of mutations in the L-gulono-g-lactone oxidase gene, which is essential for ascorbic acid synthesis in vivo.11) Therefore, animals without the enzyme activity of L-gulono- g-lactone oxidase must obtain ascorbic acid from dietary sources.

Vitamin C is readily absorbed when the intake is up to 100 mg/day; and at elevated levels of intake (500 mg/day), the efficiency of absorption of ascorbic acid swiftly declines (Naidu 2003).

 

Toward a new recommended dietary allowance for vitamin C based on antioxidant and health effects in humans.

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Discrepancies in global vitamin C recommendations: a review of RDA criteria and underlying health perspectives.
Carr AC, Lykkesfeldt J.Crit Rev Food Sci Nutr. 2021;61(5):742-755. doi: 10.1080/10408398.2020.1744513. Epub 2020 Mar 30.
Global Vitamin C Status and Prevalence of Deficiency: A Cause for Concern?
Rowe S, Carr AC.Nutrients. 2020 Jul 6;12(7):2008. doi: 10.3390/nu12072008.
Factors Affecting Vitamin C Status and Prevalence of Deficiency: A Global Health Perspective.
Carr AC, Rowe S.Nutrients. 2020 Jul 1;12(7):1963. doi: 10.3390/nu12071963.
Symposium on Vitamin C, 15th September 2017; Part of the Linus Pauling Institute's 9th International Conference on Diet and Optimum Health.
Carr AC.Antioxidants (Basel). 2017 Nov 21;6(4):94. doi: 10.3390/antiox6040094.
Synthetic or food-derived vitamin C--are they equally bioavailable?
Carr AC, Vissers MC.Nutrients. 2013 Oct 28;5(11):4284-304. doi: 10.3390/nu5114284.

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