“…Potential confounders were identified according to previous studies ( 20 , 21 ): age, gender (male and female), race (Mexican American, other Hispanic, non-Hispanic white, non-Hispanic black, and other race), the ratio of family income to poverty (PIR) (<1.3, 1.3 to 3.5, and >3.5) ( 22 ), an education level (less than high school, high school and above high school), marital status (married or living with a partner and living alone), body mass index (BMI), smoking status (non-smoker, former smoker and current smoker), physical activity status (active and inactive), diabetes (Yes and no), serum uric acid, sugar intake, water intake, and Vitamin B6 intake. Individuals were regarded as current smokers if they responded “Yes” to the question “Have you smoked at least 100 cigarettes in your entire life?” and “Yes” to “Do you now smoke cigarettes?” Former smokers were those who responded “Yes” to the first question and “No” to the second question; Participants who answered “No” to the first question were considered non-smokers.…”