Eui-Hyun Yoon, et al: BMD and Food-frequency health problems.1,2) It is estimated that 10 million Americans are currently affected with this disorder and another 18 million have low bone mass, placing them at future risk.3) The lifetime risk of fracture is about 40% for women and 13% for men.1) In the elderly, hip fractures are associated with mortality in up to 20% of cases, and most survivors need costly long-term nursing home care.4) It is well known that genetic factors are a major cause with an influence on peak bone mass, but many environmental factors also play a role in altering genetic effects.5,6) Previous studies reported risk factors for osteoporosis, including low physical activity,7) smoking,8,9) alcoholism,10) and lack of estrogen in postmenopausal women.11) Nutritional factors are particularly important to bone health because they are modifiable. Proper nutrition plays a role in the prevention and treatment of osteoporosis. One of the most important nutritional factors in prevention of osteoporosis is calcium and vitamin D.12) In addition to calcium and vitamin D, inadequate intake of phosphorus, magnesium, fluoride, boron, vitamins (K, C, and B6), potassium, and protein have been reported as having a connection to osteoporosis.13) Several studies suggest that dietary habits and nutrition influence bone mineral density (BMD). They involve many nutrients and food components like milk, fruits, vegetables, meat, sea food, and shellfish.14) Also included are nutrients like minerals, vitamins, and macronutrients.15) It was not until recently that foods and food components, such as dairy products, fruits and vegetables, dietary fibers, mineral water, soy products, carbonated beverages, caffeine, and alcohol have been investigated.16) But results from many studies evaluating the dietary impact on bone health15) are still inconclusive or even contradictory. What is certain, however, is that nutrients and food components interact to influence bone status. The majority of research on the association between diet and BMD was performed in western countries. However, in Korea, dietary habits are different from western countries. Previous studies performed in Korea had a small sample size and were not focused on the association between food frequencies and BMD, but rather, the amount of dietary nutrient intake and BMD. In this study, we examined the food-frequency of each food group and the relationship between the food-frequency and 288 | Vol. 33, No. 5 Sep 2012 the BMD in Korean adults using data from the 2008 and 2009 Korea National Health and Nutrition Examination Survey (KNHANES). This study, with its large population size, intends to evaluate dietary factors that may affect BMD. METHODS 1. Study Population The study population was derived from the data of the KNHANES during 2008 to 2009. These surveys gathered data about the health and nutritional status of subjects in various regions of Korea. At baseline, 20,277 subjects made BMD measurements. Of these, 14,560 completed a dietary questionnaire, and 1,755 subjects who were younger than 20 years old were excluded. Therefore, a total of 12,895 (5,246 males and 7,649 females) individuals were included in this study. This study was approved by the ethics committee of Hanyang University Hospital in Seoul. 2. Bone Mineral Density Measurements BMDs were measured in the femoral neck and lumbar spine by dual-energy X-ray absorptiometry. BMD is an important predictor of fracture. A patient with BMD that is reduced by ≥ 2.5 standard deviations below peak bone mass is considered to have osteoporosis.17) 3. Dietary Intake Usual dietary intake was assessed with the use of the food- frequency questionnaire which consists of 11 food groups, including 58 food items, such as staple carbohydrates (rice and grains other than rice), other carbohydrates (ramen, noodles, breads, rice cakes, and confectionery), legumes (bean curd, legumes, and soybean milk), potatoes (potato and sweat potato), meat and eggs (beef, chicken, pork, ham/bacon/sausage, and egg), fish (mackerel, tuna, croaker, and pollack), vegetables (Chinese cabbage, radish, radish leaves, bean sprouts, spinach, cucumber, red pepper, carrot, pumpkin, cabbage, tomato, and mushrooms), seaweeds (sea mustard and laver), fruits (tangerine, persimmon/dried persimmon, pear, watermelon, oriental melon, strawberry, grape, peach, apple, banana, and orange), milk and dairy products (milk, yogurt, and ice cream), and instant foods Korean J Fam Med