OBJECTIVES: Anemia is known to be a health problem with major health consequence worldwide. The causes of anemia vary. The major cause is the nutritional deficiencies, particularly iron deficiency. In Japan, prevalence of anemia is reportedly higher than in other developed countries. To investigate the reason for the higher prevalence, we analyzed National Health and Nutrition Examination Survey (NHANES) database in the United States, consisting of demographic data including ethnicity, dietary data, examination data, laboratory data, and questionnaire data.

METHODS: NHANES database (2017-March 2020) including data from 15,560 individuals were used. We analyzed individuals aged ≥18 years and had all information used for the analysis. Factors associated with anemia (hemoglobin values of ≤13 or ≤12 g/dl for men and women, respectively) were examined using a logistic regression with age, sex, ethnicity (white [reference group], Hispanic, black, Asian, or other race), income level, BMI, and dietary iron intake as explanatory variables.

RESULTS: In total 5,836 individuals were identified for the analysis. Prevalence of anemia was 3.6% in men and 9.5% in women. An association of anemia was indicated in races of Hispanic (odds ratio [OR]: 1.376), black (OR: 4.472), or Asian (OR: 1.602) relative to white, higher age (OR: 1.020), female (OR: 2.612), lower income (OR: 0.872 for income), lower BMI (OR: 0.997 for BMI), or lower dietary iron intake (OR: 0.995 for dietary iron) with statistically significant (p < 0.01).

CONCLUSIONS: Asian race is suggested to be associated with higher anemia prevalence than white among Americans after adjusted by the other factors. This may be contributed to higher prevalence of amenia in Japan than other developed countries mainly Western countries.