Objective: Young women being underweight is a public health problem in Japan. The aim of this study was to investigate this problem by measuring lymphocyte count as an indicator of nutritional status.
Methods: The subjects were 114 women aged 20-39 who participated in an annual health checkup for residents in a city in Aichi, Japan. Data from a questionnaire, physical examination, and blood tests were analyzed in relation to women who were severely underweight [body mass index (BMI) </= 17.5 kg/m(2)], slightly underweight (17.5 < BMI < 18.5 kg/m(2)), of normal weight (18.5 </= BMI < 25 kg/m(2)), and obese (BMI >/= 25 kg/m(2)).
Results: Lymphocyte count tended to be lower with a decrease in BMI. The prevalence of low lymphocyte count of <1,500/mm(3) increased in underweight women. In women who had restricted food intake for weight loss, leukocyte count, and total serum protein, and lymphocyte count were lower. A multivariate logistic regression analysis showed the association of low lymphocyte count to being severely underweight [odds ratio (OR): 1.95; 95% confidence interval (CI): 1.07-3.56] and to restricted food intake for weight loss (OR: 3.73; 95% CI: 0.91-15.30).
Conclusion: This study suggests that being severely underweight and on restricted food intake for weight loss in adult women can be risk factors for low lymphocyte count, an indicator of malnutrition. It is important for young women to maintain BMI >17.5 kg/m(2) and not to restrict food intake when of normal weight or underweight in order to prevent malnutrition.