The increasing proportion of underweight young women may lead to an increase in those with low bone mass. The present study investigated whether bone mass level is associated with lifestyle factors among young Japanese women. A total of 103 Japanese female college students aged 20-21 majoring in food science participated in this cross-sectional study. We measured bone area ratio at the os calcis using quantitative ultrasound (QUS) and assessed lifestyle factors including diet and physical activity using a self-reported questionnaire. Bone area ratio was defined as a proportion of bone substance in a cross section of os trabeculare. Ninety-one subjects who completed the questionnaire were categorized into two groups according to the average bone area ratio of the 103 subjects (30.9%), calculated based on the screening method for osteoporosis prevention: 69 subjects with normal bone mass (bone area ratio: 36.2 +/- 3.8%) and 22 subjects with low bone mass (bone area ratio: 28.1 +/- 1.6%). In normal group, 12 subjects (17.4%) had a dietary habit of not daily intake of green and yellow vegetables, such as carrot and spinach, while this occurred in 10 subjects (45.5%) in low group (P = 0.007). Adjusted logistic regression analyses showed that the subjects without daily intake of green and yellow vegetables had almost 5-fold risk of low bone mass, compared to the subjects having daily intake of the vegetables [Odds ratio: 4.96 (95%CI 1.36-18.18)]. In conclusion, daily intake of green and yellow vegetables is effective for maintaining bone mass in young women.