Introduction: Reduced bone mineral density and increased risk of falls are related with Alzheimer disease, and these increase likelihood of bone osteoporotic fractures causing serious complications such as disability, fear of falling, loss autonomy, decreased quality of life, and anticipated mortality in elderly patients. Gait and balance disturb are 2 factors to favor falls in elderly, and in patients with cognitive impairment, the risk of falls increases to double. Exercise and Mediterranean diet produce beneficial effects for aging, cognitive decline, and are widely recommended to reduce the effects of osteoporosis, fall risk, and related fragility fractures. The primary objective of this study is to evaluate the short and medium-term effects during 6 months, of a multicomponent physical exercise program with a Mediterranean diet on bone mineral density, fall risk, balance, and gait by a controlled clinical trial in patients with Alzheimer disease. Methods: The study is a 6-month, randomized controlled parallel-group, single-blinded clinical trial. Institutionalized patients with Alzheimer disease will be included. The intervention group will perform a multicomponent physical exercise program in reduced groups, with a frequency of 3 sessions per week, associated with a Mediterranean diet. This program includes strength, balance, and aerobic resistance exercises, and in the main part of the session, also ludic exercises to improve agility, coordination, and balance. The control group will receive usual care. The outcomes to assess are the change of physical functions, such as gait and balance, and the change of bone mineral density by calcaneal quantitative ultrasound, during the study follow-up at 1, 3, and 6 months. This clinical trial will generate more and new evidence on the effects of a multicomponent physical exercise program and Mediterranean diet in patients with Alzheimer disease on risk of falls and osteoporotic fractures, the relation of these with bone mineral density, gait and balance, and the correlations between them. Ethics and dissemination: This study protocol has been approved by the Ethics Committee of the University of Salamanca. The results will be published in peer-reviewed journals and disseminated in national and international conferences, to the participants and their families, and the general public through the associations of people with AD. Trial registration ID: ClínicalTrials.gov ID: NCT04439097.