Nutrition for Bone Health

References

Bones are the body’s structure and support system. Made mostly of collagen and minerals, bone is living, growing tissue, according to the National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS).

Collagen, a protein that provides framework, and calcium phosphate, a mineral that adds strength and hardens, make bone strong and flexible. Throughout life, bones are constantly renewed through a two-part process, resorption and formation. In resorption, old bone tissue is broken down and removed by cells known as osteoclasts. During bone formation, new bone tissue is laid down to replace the old by osteoblasts. These two opposite functions are regulated by hormones, including calcitonin, estrogen (in women) and testosterone (in men). Osteoporosis develops when bone removal occurs too quickly or replacement occurs too slowly or both. People are more likely to develop osteoporosis, a condition in which the bone weakens and deteriorates, creating an increased risk of fractures, if they do not reach their maximum peak bone mass during the crucial bone building years. NIAMS added that women are more likely than men to develop osteoporosis, since women have smaller, thinner bones, and can lose bone tissue rapidly in the first four to eight years after menopause, due to the sharp decline in production of estrogen.

Public awareness on the importance of bone health is rising, as television ads tout drugs for preventing osteoporosis and magazines encourage readers to drink more milk for strong bones. There is also a wide range of bone supplements that have appeared on the market, allowing consumers to select one that best fits their age, condition and ailments.

Classic Calcium

Calcium is the healthy bone standby. An essential mineral for the growth and maintenance of bones and teeth, consistent calcium intake is required throughout life; calcium deficiency can lead to osteoporosis, a condition in which the bone weakens and deteriorates, creating an increased risk of fractures.

Interventions with calcium have supported its bone-building claims. In an 18-month study, researchers found a daily calcium supplement (555 mg/d) boosted bone mineral content (BMC) in teenage girls with low habitual calcium intake (n=96).¹ Compared with the control group, the supplemented group showed significantly greater gains in BMC over the 18-month intervention; in addition, bone mineral density (BMD) was significantly greater for all skeletal sites, and concentrations of bone resorption markers and parathyroid hormone were significantly lower in the supplemented group than in the control group. However, after 42 months, gains in BMC and BMD and differences in bone resorption were no longer evident, suggesting calcium acts by suppressing bone turnover, which is reversed upon supplement withdrawal. A similar study evaluated the effects of calcium supplement and milk intake on BMD and growth in children.² Researchers concluded both milk and calcium intakes could significantly improve children’s BMD; however, compared with the control group, increasing milk intake also significantly promoted growth and development compared to the calcium supplement group.

Another study on BMD and the effects of low habitual calcium intake was conducted by researchers at Changhai General Hospital, Singapore, using a group of elderly subjects (n=77) with hip fractures.³ Mean daily calcium intake was 650 mg, and only six patients had a daily calcium intake above 1,000 mg/d. Further, patients with BMD in the osteoporotic and osteopenic ranges had no significant difference in dietary calcium intake.

Calcium supplementation is obviously important, but it’s also crucial to balance calcium intake with magnesium supplementation. Magnesium deficiency has been shown to be a key factor in bone loss and osteoporosis.⁴ One study from the University of Tennessee concluded that greater magnesium intake was significantly related to higher BMD.⁵ In the trial, 2,038 older and white men and women aged 70 to 79 had their dietary intake of magnesium assessed using a semi-quantitative food frequency questionnaire, and supplement data was collected based on a medication inventory. Researchers found magnesium intake was positively associated with BMD. A similar study from the University Graduate School of Medical and Dental Sciences, Japan, investigated a possible association between magnesium intake and bone mass in young adult women.⁶ Subjects consisted of 106 female university students aged 19 to 25 years. Calcium and magnesium intakes were evaluated using the duplicate sampling method; spinal and femoral BMD were measured. Researchers did not find an association between magnesium intake and bone mass in young women, concluding calcium intake needs to be included as an important, potential confounding factor when exploring such an association.