Relationship Between Diet and Bone Mineral Density in Postmenopausal Breast Cancer Survivors

Breast cancer is the most prevalent form of cancer in women and accounts for 28% of all new cancer cases. Osteoporosis is another debilitating disease that affects approximately 10 million Americans. Postmenopausal breast cancer survivors are subject to many side effects physically and emotionally due to various forms of treatment and symptoms of the disease. Decreased bone mineral density (BMD) is one major effect that can lead to osteoporosis and fracture. Studies have investigated diet in relation to breast cancer as well osteoporosis. The time at cancer diagnosis has been noted to be a "teachable moment" in a patient's life and therefore more susceptible to lifestyle and dietary changes. Diet composition has been shown to help with prognosis and decrease risk of recurrence and risk of contracting secondary diseases. Dietary intake of calcium, vitamin D, and protein has also been noted to bring beneficial effects to those with low BMD. Twenty-seven postmenopausal breast cancer survivors (stages 0-III) were assessed from a convenience sample from a larger ongoing study. Change in dietary intake diagnosis after breast cancer diagnosis was examined along with the effect of dietary composition on BMD. Skeletal BMD was assessed with the dual-energy X-ray absorptiometry (DXA). Participants were asked to fill out two nutrition history questionnaires to assess dietary change after diagnosis and a twenty-four hour dietary recall to assess diet composition in relation to BMD. Fifteen participants (60%) reported making a dietary change after cancer diagnosis with a decrease in fat (24%) being the most common change. The average percent of energy intake of the participants was 17% protein, 49% carbohydrate, and 34% fat. Percent protein intake was positively correlated to total BMD, body weight, and left total femur BMD (p ≤ 0.05). ANOVA was used to analyze percent protein of those consuming ≤ 20% with those consuming ≤ 20% on measurements of BMD. Based on this cut point, those that consumed ≤ 20% protein had significantly higher total BMD (p =0.028). Dietary calcium was positively correlated to lumbar spine BMD, body weight, and lean mass (LM). Supplemental calcium was negatively correlated to total BMD, possibly due to the fact most women had low BMD and were supplementing calcium. The DXA results showed that 27 women 22 were osteopenic and 3 were osteoporotic. Dietary intake is more likely to change at diagnosis of cancer and the quality of diet composition can lead to a decreased risk of recurrence and a decreased risk of contracting secondary diseases that are more susceptible in breast cancer survivors. Having the recommended amounts of protein and calcium in the diet can also aid in maintaining or increasing BMD. Dietary composition as a non-pharmaceutical approach in postmenopausal breast cancer survivors is a viable option to help reduce problematic long-term effects of cancer and its secondary diseases such as osteoporosis. Focusing on dietary changes and diet composition would be highly beneficial to improve the physical conditions as well as the quality of life in this population.