Seeking volunteers for calcium retention study The Grand Forks Human Nutrition Research Center is seeking healthy women who are under the age of 75 and have gone under menopause for at least three years. The loss of bone that occurs with aging constitutes a major public health threat. Among dietary factors known to affect bone metabolism, high protein intake has been considered as a risk factor for osteoporosis because it may increase urinary acid and calcium excretion. You are invited to join this study to see if acid production, calcium retention, and bone metabolism are greater with a high-meat diet than with a low-meat diet. Participants will live at home and eat breakfast at the Nutrition Center every weekday for 14 weeks. They will take lunch, dinner, and weekend meals home with them. They could earn up to $2,500 for this 16-week study. The study starts January 2008. During the course of the study, they will eat meals provided by the Nutrition Center for 14 weeks (seven weeks of food high in meat protein, followed by one week of break, where they eat their own meals, and then followed by seven weeks of food low in meat protein). For two days during each of the food periods (for a total of four days), they will consume radioactive calcium, which will allow us to measure calcium absorption from each diet. They will have your calcium absorption tested 20 times. There will be seven blood draws, urine collection, a three-day food diary, and questionnaires. Participants must be non-smokers. They have gone under menopause for at least three years, have no chronic disorder, and not taking medications regularly. However, some stable conditions may be individually approved. The women must have no history of non-traumatic bone fractures, have an average body mass index, and be willing to eat only the food the Nutrition Center provides for 14 weeks. They must agree to not take vitamins/minerals/nutritional supplements, other than those provided by the Nutrition Center. They cannot donate blood or plasma, nor use a tanning bed during the study. You can go online to apply to be in this study by going to http://ars.usda.gov/npa/gfhnrc If you have questions, please call Dorothy Olson at (701) 795-8396 or (800) 562-4032. -- Brenda Ling, Information Officer, USDA-ARS Grand Forks Human Nutrition Research Center, brenda.ling@ars.usda.gov, 795-8300