The statement follows a European-wide review of the balance of risks and benefits of HRT in response to growing concerns about the safety of HRT in long-term use.
The MHRA has not advised on alternatives to HRT, currently estimated to be taken by some 350,000 women in Britain. However many supplement makers currently market products designed to help prevent osteoporosis.
The World Health Organisation has defined osteoporosis as the second leading health care problem after cardiovascular disease. High calcium and vitamin D levels are thought to help prevent osteoporosis-related fractures, while research also suggests that soy isoflavones may help women with low bone mineral content prevent fractures in postmenopause years. There is also evidence from animal studies that antioxidant supplements, such as vitamin C, could reverse osteoporosis.
The review said that short-term use of HRT could help treat menopausal symptoms but that the risks when used in the long-term for preventing osteoporosis, outweigh its benefits.
The chairman of the UK's Committee on Safety of Medicines (CSM), Professor Gordon Duff, said: "While this new advice does not require any urgent change in treatment, women who are currently receiving HRT as long-term prophylaxis should have their treatment reviewed at the next routine appointment. The CSM is keeping the safety of osteoporosis treatments, including HRT, under continual review, and will issue further advice as necessary."
Findings from previous studies indicate that HRT is associated with a duration-dependent increase in the risk of breast cancer, endometrial cancer and ovarian cancer. In addition, HRT is no longer thought to have a beneficial effect on cardiovascular disease and has been shown to increase the risk of heart attacks and venous thromboembolism (VTE or blood clots), especially in the first year, and to increase the risk of stroke.
A European funded project called Osteodiet is aiming to investigate dietary strategies for the prevention of osteoporosis.