Growth factors may affect older women’s bone density more than does vitamin D

The dissertation was written by general practitioner Helena Salminen, who also works at the Center for Family and Community Medicine (CeFAM) in Stockholm. It is based on clinical studies that included approximately 400 randomly selected Swedish women between the ages of 70 and 80 years.

Osteoporosis is so common that approximately every third woman over age 70 is affected —and most of them don’t realize it. Although being older and a woman are important risk factors, Dr. Salminen shows that that few Swedish women are examined for osteoporosis or receive the correct diagnosis and treatment. Approximately thirty percent of the women in the study had osteoporosis, but only seven percent had been diagnosed with the disease and treated with calcium and vitamin D supplementation. Only two percent had received more active treatment with bisphosphonates, a group of drugs that hinder the loss of bone mass.

“The results are discouraging, but it is never too late to start treatment of osteoporosis”, says Dr. Salminen. “This is where the Primary Health Care plays an important role, in identifying warning signs and previous fractures, diagnosing and treating the disease, as well as preventing the disease by promoting opportunities for strength and balance training.”

NUTRITIOUS FOOD IMPORTANT FOR BONE MASS

For a long period of time scientists have connected Osteoporosis with low levels of vitamin D. However, in the presented results few women with osteoporosis actually had low levels of vitamin D. Instead it was the levels of the growth factor and binding protein that seemed to have a stronger connection with bone density.

“IGF-1 level drops with increasing age”, says Dr Salminen. “If you also suffer a hip fracture for instance, it drops even more dramatically and the level of the binding protein IGFBP-1 shoots sky-high. Protein supplementation can increase the level of IGF-1, have a positive effect on muscle strength and healing after a fracture, and reduce loss of bone mass.”

The dissertation research also demonstrated that a small change for the worse in nutritional status doubles the risk of osteoporosis. To have good nutritional status, a person must fulfill criteria that include consuming enough protein and minerals and maintaining a healthy BMI (Body Mass Index). Dr Salminen therefore recommends elderly women to eat at least three steady meals a day, to prevent them from becoming underweight. It was also shown that a very low dose of estrogen can have a protective effect on the bones of the hip and lumbar spine. The result is interesting as many older women need local estrogen treatment for fragile mucous membranes.

Finally, Dr Salminen compared the reliability of two methods of diagnosing osteoporosis: the more traditional method of measuring the hip and lumbar spine, and the newer method of measuring the heel bone. She then could see that diagnostic reliability is as good for heel measurement as for hip and lumbar spine measurement, but that more women were classified as positive for osteoporosis when the heel bone method was used.

“This is promising news, because measuring the heel bone is often both cheaper and easier”, she says. “But the method cannot be recommended as a replacement for hip and lumbar spinal measurement. We need to know more about how much a reduction of bone mass in the heel raises the risk of fractures.”

Dissertation: Osteoporosis in Elderly Women in Primary Health Care by Dr Helena Salminen. Primary doctoral dissertation advisor was Professor Lars-Erik Strender, Karolinska Institutet, CeFAM. Her co-advisor was Dr. Maria Sääf, Karolinska Institutet, Department of Molecular Medicine and Surgery.