A 65-year-old asymptomatic man is concerned about his risk of osteoporosis. His mother died after a hip fracture at 74 years of age. The patient has no history of fractures but has lost 7.6 cm (3 in.) in height; he does not smoke and has never taken corticosteroids. He drinks two glasses of beer (16 oz, or about 0.5 liter, each) per day. His body-mass index (the weight in kilograms divided by the square of the height in meters) is 25. Measurements of bone mineral density with the use of dual-energy x-ray absorptiometry show T scores of -2.6 at the spine and -2.2 at the femoral neck, findings that are consistent with osteoporosis. What should you recommend?