The role of nutrition for bone health in cystic fibrosis

Abstract

Cystic fibrosis (CF) is a common autosomal recessive genetic disorder that causes abnormal sodium and chloride transport due to mutations in the CF transmembrane conductance regulator (CFTR). Individuals with CF have altered osmolarity of body secretions, resulting in lung and gastrointestinal (GI) complications, lung infections, pancreatic insufficiency, maldigestion, and malabsorption. With improvements in medical care, life expectancy has increased and osteoporosis and osteopenia are increasingly recognized in those with CF. CF-related low bone mass is multifactorial and is influenced by nutritional status, disease severity, glucocorticoid use, hormonal status, inflammation, GI function, mechanical loading, and physical activity patterns. Nutritional intakes sufficient to acquire and maintain bone mass are essential to promote bone health, particularly among children with this disease as many long-term sequelae of CF accelerate bone loss in later life. Optimal calcium and vitamin D status can be impacted by alterations in gut integrity and fat malabsorption. The high-sodium intakes needed to maintain sodium balance may further limit calcium retention. Emphasis should be placed on maximizing bone acquisition early in life and on maintenance of appropriate body mass given the growth deficits that are often evident in those with CF. Additional data are needed on optimal intake of magnesium, zinc, phosphorus, copper, and vitamin K in support of bone health. Treatment regimens and identification of those at greatest risk for low bone mass will continue to evolve as more information is obtained on the genetics of bone acquisition and on the function of CFTR in bone physiology.