Vitamin C

What is Vitamin C?

Vitamin C is a water-soluble vitamin and a powerful antioxidant that is found in many fruits and vegetables. Most people think of it as the vitamin that makes oranges and orange juice so good for you.

Vitamin C in the Diet

Vitamin C is available in many fruits and vegetables–many of which have more vitamin C than an orange. Besides other citrus fruits, vitamin C can also be found in strawberries, peppers, papaya, pineapple, Brussels sprouts and broccoli.

In the US, the Estimated Average Intake (EAR) is 90 mg/day for men,               60 mg/day for women, 70 mg/day for pregnant women and 90 mg/day for lactating women. The Average Requirement (AR) for vitamin C, according to the European Food Safety Authority (EFSA), is 110 mg/day for men, 95 mg/day for women and an additional 10 mg/day for pregnant women and an additional 60 mg/day for lactating women.

Vitamin C and Your Eyes

Vitamin C acts in three different ways within the eyes to protect them:

  • As an antioxidant
  • As a stimulus for regenerating vitamin E
  • To maintain collagen synthesis

Antioxidant: While we all enjoy a sunny day, it produces high energy blue light (also known as UV light) that can damage our eyes. That blue light can interact with oxygen to create something called “free radicals.” Those free radicals can cause a series of reactions in the eye that ultimately result in the formation of the same kind of age spots that older adults get on their skin.

Vitamin E regeneration: Although vitamin E is itself an antioxidant, it can also get oxidized through various processes in the body. Vitamin C helps regenerate vitamin E when that occurs.

Collagen synthesis: Vitamin C helps the body to make and maintain this connective tissue throughout our bodies, including the collagen that is found in the cornea of the eye.

Vitamin C and Skin Health

Like lutein, vitamin C is a normal component of the skin, primarily in the epidermis (outer layer) and the dermis. Like lutein, vitamin C functions as an antioxidant, but rather than absorbing UV light, it protects the skin from the oxidation that occurs after exposure to UV rays. Vitamin C also differs from other nutrients in one important function: building collagen, the elastic tissue found throughout the body. Collagen is an important component of the skin and connective tissue.

The importance of vitamin C to maintaining skin health was seen in the days when scurvy, the condition caused by vitamin C deficiency, was prevalent. With scurvy, collagen is unable to form, connective tissue is damaged and blood vessels weaken. As a result, the outermost layer of the epidermis thickens, there are small spots of bleeding underneath the skin, wounds take longer to heal and lesions appear on the skin.1

Luckily, scurvy is a rare condition in developed countries and the focus has been on the roll vitamin C plays in skin aging. Research has shown that skin of people with higher intakes of vitamin C from the diet had a better appearance, with fewer issues with dry skin and fewer wrinkles.2,3 But if you’re going to take vitamin C to improve your skin condition, keep in mind that it may be most effective when taken in partnership with vitamin E.4,5

Vitamin C and Brain Health

Collagen isn’t just important for keeping skin supple, it also keeps arteries flexible, ensuring adequate blood flow to the brain – hence a significant role for vitamin C in the brain. Vitamin C is also important for the production of neurotransmitters, the cells that allow nerve cells in the brain to talk to one another. Vitamin C’s all-important role as an antioxidant also plays out in the brain, where it protects it from damage that could lead to impaired cognitive function.

Studies examining differences in cognitive function among those with different levels of vitamin C intake have had mixed results. In one study that followed elderly individuals over several years, the use of either vitamin E or C supplements alone was associated with better cognitive performance after three and five years. Vitamins E and C taken together still had an effect but the difference was less significant.In another study, consumption of vitamin C supplements was associated with a lower prevalence of more severe cognitive impairment but was not associated with better scores on tests of verbal and category fluency.

 


1 Linus Pauling Institute at Oregon State University
2 Am J Clin Nutr. 2007 Oct;86(4):1225-31
3 J Am Coll Nutr. 2001 Feb;20(1):71-80
4 J Am Acad Dermatol. 1998 Jan;38(1):45-8
5 J Invest Dermatol. 2005 Feb;124(2):304-7
6 Neurology. 2000. 54(6):1265-72
7 Am J Epidemiol. 1998 Jul 1;148(1):45-50