Vitamin C

Vitamin C is the predominant plasma antioxidant. This water-soluble vitamin scavenges plasma free radicals and prevents their entry into low-density lipoprotein (LDL) particles [44]. Vitamin C regenerates active vitamin E and increases cholesterol excretion and improves endothelium-dependent vasodilation and reduces monocyte adhesion. Supplementation with vitamin C (1,000 mg) and vitamin E (800 IU) before the ingestion of a high-fat meal has been found to reverse endothelial dysfunction and vasoconstriction following the meal.

On the skin, the function of vitamin C is the production of collagen, which forms the basis for connective tissue in bones, teeth, and cartilage. It also plays an important role in wound healing,immunity, and the nervous system,and acts as a water-soluble antioxidant. Because vitamin C is water soluble, its antioxidant functions take place in aqueous body compartments. It also helps protect low-density lipoprotein cholesterol (LDL-C) against free radical damage. As an antioxidant, it helps protect against cancer [43], CVD [45, 46], and certain effects of aging [47].

Severe deficiency of vitamin C leads to scurvy, which includes symptoms of bleeding gums, joint pain, easy bruising, dry skin, fluid retention, and depression. Marginal deficiencies may play a role in the development of cancer [48, 49], CVD [50], hypertension [51], decreased immunity, diabetes [52], and cataracts [53]. The RDA for vitamin C is 75 mg/day for women and 90 mg/day for men. Smokers require an additional 35 mg/day due to increased oxidative stress and other metabolic differences. The UL for vitamin C is 2,000 mg/day [43]. It remains possible that higher vitamin C intake may be beneficial in the treatment or prevention of certain diseases, particularly cancer and respiratory disorders.