The effect of prolonged breast-feeding on the development of postmenopausal osteoporosis in population with insufficient calcium intake and vitamin D level

Abstract

Breast-feeding affects bone metabolism and calcium homeostasis, and prolonged breast-feeding may influence the development of postmenopausal osteoporosis, particularly in highly susceptible populations. The study determined that breast-feeding may be a risk factor for postmenopausal osteoporosis, especially in people with low calcium intakes and vitamin D deficiencies.

INTRODUCTION: The purpose of this study was to determine whether breast-feeding is a risk factor in the development of postmenopausal osteoporosis, especially in highly susceptible population.

METHODS: The study was performed using data from the 2010 to 2011 Korea National Health and Nutrition Examination Survey, and it included 1231 postmenopausal women who were aged between 45 and 70 years. Osteoporosis was defined using the World Health Organization's T-score criteria, namely, a T-score of ≤-2.5 at the femoral neck or the lumbar spine. The patients' ages, body mass indexes, daily calcium intakes, serum vitamin D levels, exercise levels, smoking histories, and reproductive factors relating to menarche, menopause, delivery, breast-feeding, hormone treatment, and oral contraceptive use were evaluated. Comparisons between the osteoporosis and non-osteoporosis groups were undertaken using Student's t test and the chi-square test, and logistic regression models were built.

RESULTS: A significant increase in the risk of osteoporosis was apparent in postmenopausal women with prolonged breast-feeding histories (≥24 months) (model 1: odds ratio [OR]?=?2.489; 95 % confidence interval [CI]?=?1.111 to 5.578, p?=?0.027; model 2: OR?=?2.503; 95 % CI?=?1.118 to 5.602, p?=?0.026; model 3: OR?=?2.825; 95 % CI?=?1.056 to 7.56, p?=?0.039), particularly in those with inadequate serum vitamin D levels and calcium intakes (<800 mg/day).

CONCLUSIONS: Breast-feeding seems to increase the risk of postmenopausal osteoporosis; however, its impact may not be definitive in women with sufficient vitamin D levels and calcium intakes. Therefore, sufficient calcium intakes and adequate vitamin D levels may be important to prevent osteoporosis in postmenopausal women that is derived from breast-feeding.