Vitamin C deficiency in low‐income persons in the United States: 2003–2006 National Health and Nutrition Examination Survey (NHANES)

Low‐income adults are at increased risk for vitamin C deficiency. NHANES 2003–2006 data were used to assess risk factors such as obesity, smoking, and/or low vitamin C intake. Income status was defined using the poverty‐income ratio (PIR), which was calculated by dividing family income by a poverty threshold that is specific for family size. Low, medium and high incomes were defined as PIR <1, 1 to <3, and ≥3, respectively. Trend analysis was used to test for significance. Low‐income adults were more likely to be vitamin C deficient than medium‐ or high‐income adults (OR: 1.4, 2.1; p<0.001) and equally likely to be obese as those with medium or high incomes (35%, 35%, 32%; p=0.11). Percent of adult smokers (serum cotinine >10 ng/mL) decreased linearly (41%, 31%, 25%; p<0.001) with increasing income category. Percent of adults with one‐day dietary intake of vitamin C < estimated average requirement (EAR) decreased linearly (61%, 58%, 55%; p<0.05) with increasing income category. Only 26% of low‐income adults used any vitamin C‐containing supplements in the previous 30 days compared with 39% of medium‐ and 53% of high‐income adults (p<0.001). Race/ethnicity, gender and age were also considered in a multiple logistic regression model. Poor diet, non‐use of vitamin C‐containing supplements, smoking and being non‐Hispanic white were major factors associated with vitamin C deficiency among low‐income persons (p<0.01).