Vitamin C Deficiency Not Uncommon in the US
Many Americans may not be getting enough vitamin C, potentially leading to a deficiency of this important nutrient, according to the Third National Health and Nutrition Examination Survey (NHANES III) reported in the American Journal of Public Health (2004;94:870–5).
Vitamin C is a water-soluble nutrient found in many fruits and vegetables. Rich food sources of vitamin C are strawberries, potatoes, broccoli, red peppers, citrus fruits, and kale. Vitamin C functions as an antioxidant, protecting against heart disease and neutralizing toxins such as those found in cigarette smoke. It also plays a central role in wound healing, and may protect against the development of certain cancers such as stomach and breast cancer. An overt deficiency of vitamin C causes scurvy: a condition characterized by weakness, anemia, gum disease, easy bruising and bleeding, and defects in tooth and bone development. Scurvy was once considered a disease of the past; however, new questions are arising concerning the possibility of vitamin C deficiency among Americans. Recent studies have reported that while the average intake of vitamin C by Americans is well above the United States recommended daily allowance (USRDA), many people actually consume far too little of this vitamin.
The new study investigated vitamin C status among Americans. Information from 15,769 people aged 12 to 74 years was collected during in-home and clinic interviews. Participants answered questions regarding dietary intake and health history, type, and frequency of supplement use. Blood levels of vitamin C were measured and participants were categorized as deficient (low blood levels of vitamin C), depleted (marginally low levels), or normal.
The average vitamin C intake among the participants was 177 mg per day, well above the USRDA of 75 and 90 mg per day for women and men, respectively. However, 14% of all men and 10% of all women were deficient in vitamin C. Men aged 25 to 64 years were more likely than other groups to be deficient. Smokers had the highest risk of vitamin C deficiency, and people who hadn’t taken vitamin C–containing supplements in the past month had a greatly increased risk. Non-Hispanic black men had a higher risk of deficiency than white males. Mexican-American men and women had the lowest risk, perhaps owing to the influence of the traditional Mexican diet, which is rich in vitamin C. The rate of vitamin C depletion ranged from 15 to 23% among men and 13 to 20% among women.
Many of the fruits and vegetables commonly eaten by Americans have a relatively low vitamin C content, such as iceberg lettuce and french fries. Heating and storage both decrease the vitamin C content in foods. The results of this study suggest that Americans, especially cigarette smokers and poor eaters, should increase their consumption of vitamin C–rich foods and consider taking a vitamin C supplement.
Kimberly Beauchamp, ND, received her bachelor’s degree from the University of Rhode Island and her Doctorate of Naturopathic Medicine from Bastyr University in Kenmore, WA. She is a co-founder and practicing physician at South County Naturopaths, Inc., in Wakefield, RI. Dr. Beauchamp teaches holistic medicine classes and provides consultations focusing on detoxification and whole-foods nutrition.
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