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The Multiple Benefits of Vitamin C

by Shari Barbanel | April 1, 2012

Vitamin C (ascorbic acid) is a water-soluble vitamin that is essential for the growth and repair of the body’s tissues. In addition, vitamin C is an antioxidant that can block damage caused by free radicals. The human body does not have the ability to produce or store vitamin C, as a result, it must be obtained through the diet. According to the Linus Pauling Institute, the recommended dietary allowance (RDA) for an adult male is 90 mg/day, the RDA for an adult female is 75 mg/day and smokers should add an additional 35 mg/day. Many fruits and vegetables including citrus fruits, strawberries, broccoli and tomatoes are rich sources of vitamin C.

Protective Aspects

While vitamin C benefits a number of the body’s systems, it is best known for promoting immune health and has been shown to promote both the production and function of white blood cells. In a study published August 2011 in the Journal of the American College of Nutrition, researchers examined the effects of vitamins C and E (from food and supplementation) on the risk of upper respiratory tract infections (URTIs) in approximately 1,500 Swedish men and women, aged 20 to 60 years.

Researchers found that an intake of vitamin C helped lower the risk of URTIs in women. “In addition, it appears that supplement use of vitamin E and vitamin C may reduce the risk of URTIs among men, who overall had a lower intake of vitamin C from food than women,” said the researchers.

According to another study published in the journal Clinical and Translational Allergy, vitamin C can have a varying beneficial effect on asthmatic children, depending on the age, exposure to mold or dampness in their bedroom and the severity of their asthma. In the study, Dr. Mohammed Al-Biltagi (Tanta University, Egypt) and Dr. Harri Hemila (University of Helsinki, Finland) analyzed the effect of 0.2 g/day of vitamin C on 60 asthmatic children aged 7 to 10 years. The effect of vitamin C on the forced expiratory volume per one second (FEV1) was modified by age and exposure to molds or dampness. In the younger children aged 7 to 8.2 years with no exposure to molds or dampness, vitamin C administration increased the FEV1 level by 37 percent. In the older children aged 8.3 to 10 years with exposure to mold or dampness in their bedroom more than one year before the study, vitamin C increased the FEV1 level by only 21 percent.

According to the researchers, the effect of vitamin C on the asthma symptoms was modified by age and the severity of asthma symptoms. In the younger children with mild asthma symptoms, the benefit of vitamin C was greatest. In the older children aged 8.3 to 10 years who had severe asthma symptoms, the benefit of vitamin C was smallest.

Ocular Expression

According to the Linus Pauling Institute, cataracts are a leading cause of vision impairment throughout the world, and become more frequent and severe as people age. In the U.S., more than $3 billion is spent on cataract-related costs annually. The good news is that studies have also shown vitamin C to be effective in promoting vision health.

Low levels of vitamin C in the lens of the eye have been linked to a risk of developing cataracts. In an Indian study published in the journal Ophthalmology, researchers studied 5,638 people aged 60 years and older. Study participants provided blood samples, took part in a clinical exam and were questioned about their diet and lifestyle habits, as well as their history with cataracts.

Researchers found that nearly 73 percent of the participants had cataracts, but the risk began to significantly fall as vitamin C blood levels and vitamin C intake rose. Researchers also found that in the approximately 25 percent of older adults with the highest levels of vitamin C, the risk of cataracts was 39 percent lower than in people with the lowest levels of the nutrient.

In another study published in the Journal of Neuroscience, scientists at Oregon Health & Science University (OHSU) recently discovered the cells in the eye are bathed in vitamin C. The researchers discovered that high doses of vitamin C are necessary to keep the retina of the eye, and likely the brain, functioning properly. “Because the retina is part of the central nervous system, this suggests there’s likely an important role for vitamin C throughout our brains, to a degree we had not realized before,” explained Henrique von Gersdorff, PhD, a senior scientist at OHSU’s Vollum Institute and a co-author of the study.

Heart Attribute

Cardiovascular health is another area studies have shown the benefits that vitamin C can provide. One such study was conducted by Japanese researchers investigating the effects of vitamin C on the life expectancy and morbidity rates from cardiovascular disease in Asian men and women over a 16. 5-year period. Participants included 35,611 women and 23,119 men aged 40 to 79 years without a history of cardiovascular disease or cancer. Researchers found that the highest intakes of vitamin C resulted in lower numbers of total stroke, coronary heart disease and cardiovascular disease in women, but significant differences for men were inconclusive.

Resources:

• http://lpi.oregonstate.edu

References:

Fondell E, Bälter O, Rothman KJ, Bälter K. “Dietary intake and supplement use of vitamins C and e and upper respiratory tract infection.” Journal of the American College of Nutrition. 2011 Aug;30(4):248-58.

Al-Biltagi, Mohammed, Baset, Ahmed, Hemila, Harri. “Vitamin C and asthma in children: modification of the effect by age, exposure to dampness and the severity of asthma.” Clinical and Translational Allergy, 2011; 1 (1).

Ravindran RD, Vashist P, Gupta SK, Young IS, Maraini G, Camparini M, Jayanthi R, John N, Fitzpatrick KE, Chakravarthy U, Ravilla TD, Fletcher AE. “Inverse Association of Vitamin C with Cataract in Older People in India.” Ophthalmology. 2011 Oct;118(10):1958-1965.

Calero CI, Vickers E, Moraga Cid G, Aguayo LG, von Gersdorff H, Calvo DJ. “Allosteric modulation of retinal GABA receptors by ascorbic acid.” Journal of Neuroscience, 2011; 31 (26) :9672-9682.

Kubota Y, Iso H, Date C, Kikuchi S, Watanabe Y, Wada Y, Inaba Y, Tamakoshi A; the JACC Study Group. “Dietary Intakes of Antioxidant Vitamins and Mortality From Cardiovascular Disease: The Japan Collaborative Cohort Study (JACC) Study.” Stroke. 2011 Jun;42(6):1665-72.

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