The objective of this study was to examine whether high serum 25-hydroxyvitamin D (25(OH)D) concentration was associated with high skeletal muscle mass, taking into account the effects of sex and age among the participants of the Korea National Health and Nutrition Examination Survey (KNHANES) aged 40 years or older. This was a cross-sectional study using data from the 2009 to 2010 KNHANES; a total of 8406 subjects (3671 men and 4735 women) were included. The appendicular skeletal muscle mass index (ASMMI, kg/m2) was estimated to measure the skeletal muscle mass. Hypovitaminosis was classified when the level of serum 25(OH)D was <20 ng/ml. The general linear model adjusted for confounding factors was used to determine differences in means of ASMMI by 25(OH)D status. The mean values of ASMMI were higher for men when compared with women. Women had a greater proportion of hypovitaminosis (71·1 %) compared with men (53·2 %). After adjusting for multiple factors, men were seen to have significant differences in ASMMI based on 25(OH)D status regardless of age, showing a lower mean value of ASSMI in those with hypovitaminosis. However, there was no difference in ASMMI by 25(OH)D status among women in both younger and older age groups. In conclusion, we found that there might be a positive relationship between 25(OH)D and skeletal muscle mass in men, indicating that interventions to improve 25(OH)D levels that are aimed at increasing muscle mass could be beneficial for men with more rapid decreased rate of skeletal muscle mass.

Thyroid cancer is the most common cancer among Korean women. However, there are few data on dietary factors related to thyroid cancer risk. The objective of the present study was to evaluate the association between raw vegetables and fruits intake and thyroid cancer in a case–control study. We included 111 histologically confirmed malignant thyroid cancer cases and 115 benign cases. Controls who did not have nodules in thyroid ultrasonography were matched to cases by age ( ± 2 years). Food and nutrient intakes were estimated using a quantitative FFQ with 121 items. Conditional logistic regression analysis was used to obtain OR and corresponding 95 % CI. The intake of total vegetables was not associated with malignant thyroid cancer, but inversely associated with benign cases. High raw vegetable intake was inversely associated with thyroid cancer risk both in malignant and benign cases (P for trend = 0·01 in both malignant and benign cases). Among fruits, persimmon intake had an inverse association with thyroid cancer risk in both malignant and benign cases (P for trend = 0·06 in malignant cases; P for trend = 0·01 in benign cases) and tangerine intake had an inverse association in malignant cases (P for trend = 0·03). The frequency of consumption of raw vegetables and persimmon also had a consistent inverse association in both malignant and benign cases. These results suggest that high consumption of raw vegetables, persimmons and tangerines may decrease thyroid cancer risk and help prevent early-stage thyroid cancer.

Little is known about the effect of dietary carbohydrate, glycaemic index (GI) and glycaemic load (GL) on the risk of the metabolic syndrome, especially in populations with white rice as the staple food. The study examined the cross-sectional relationship between carbohydrate, GI, GL and risk of the metabolic syndrome. There were a total of 910 middle-aged Korean adults. Dietary carbohydrate, GI and GL were determined by an interview-administered FFQ. The metabolic syndrome was defined using the modified criteria published in the Third Report of the National Cholesterol Education Program Adult Treatment Panel III. The risk of developing the metabolic syndrome was positively related to dietary carbohydrate (P for trend = 0·03), GI (P for trend = 0·03) and GL intakes (P for trend = 0·02) in women after adjusting for potential confounding variables. Among the components of developing the metabolic syndrome, the risk of high TAG and low HDL-cholesterol were positively related to high GI and GL intakes in women. The risk of developing the metabolic syndrome was considerably higher in the highest quintiles of carbohydrate (OR 6·44; 95 % CI 2·16, 19·2), GI (OR 10·4; 95 % CI 3·24, 33·3) and GL intakes (OR 6·68; 95 % CI 2·30, 19·4) than in the lowest quintiles among women with a BMI ≥ 25 kg/m2. However, there was no difference in risk across quintiles of carbohydrate, GI and GL among women with a BMI < 25 kg/m2. In conclusion, both the quantity and quality of carbohydrate intake has a positive relationship with the risk of the metabolic syndrome in women but this relationship was dependent on the BMI level.