Bone Health: Calcium and Vitamin D

There is an enormous amount of research supporting calciums benefits for bone health. The daily recommended intake of calcium in the United States is 1,200 mg and one study found bone mass density (BMD) in older men and women could be improved by increasing protein intake provided that subjects meet the currently recommended intakes of calcium and vitamin D.²Friesland Coberco Dairy Foods, The Netherlands, conducted a study in 2002 with indications that healthy, late postmenopausal women with an adequate calcium intake may increase hip bone mineral density (BMD) within 12 months after supplementing with a chicken eggshell powder-enriched supplement.³

Researchers designed a randomized, double blind, placebo-controlled study where 85 healthy Caucasian women, selected by age and at least five years post-menopausal with a lumbar spine T-score greater than -2.5 were assigned to eggshell powder-enriched (group A), purified CaCO3-enriched (group B) or a placebo (group C; n 27) for 12 months. At baseline, subjects had an adequate intake of mean, habitual daily calcium. After 12 months of supplementation, only mean BMD of the femoral neck in group A was significantly increased (P=0.014) by 1.75 percent compared with a decrease of -0.60 percent in group C. This increase coincided with significant decreases in markers of bone resorption and formation. There were no significant changes in BMD at other sites, including lumbar spine, nor in groups B and C; and no differences were found between groups A and B, or B and C. In parallel, a paper published in the International Journal of Clinical Pharmacology Research concluded, Clinical and experimental studies showed that eggshell powder has positive effects on bone and cartilage and that it is suitable in the prevention and treatment of osteoporosis.⁴

The National Osteoporosis Foundation describes osteoporosis, meaning porous bone, as a disease in which bones become fragile and more likely to break. If not prevented or if left untreated, osteoporosis can progress painlessly until a bone breaks. These broken bones, also known as fractures, occur typically in the hip, spine and wrist. Currently, osteoporosis afflicts 28 million Americans.

A double blind, placebo-controlled study out of Australia examined calciums ability to decrease the risk of clinical fractures.⁵ For five years, 1,460 women, older than 70 years, were randomized to receive 600 mg of calcium carbonate twice per day or an identical placebo. In the women selected, 16.1 percent sustained one or more clinical osteoporotic fractures. In the intention-to-treat analysis, calcium supplementation did not significantly reduce fracture risk; however, 830 patients who took 80 percent or more of their tablets (calcium or placebo) per year had a reduced fracture incidence in the calcium compared with the placebo groups. Calcium-treated patients had improved quantitative ultrasonography findings of the heel, femoral neck and whole-body dual x-ray absorptiometry data and bone strength compared with the placebo-treated patients. Of the 92,000 adverse events recorded, constipation was the only event increased by the treatment. Researchers found 1,200 mg/d of calcium carbonate ineffective as a public health intervention in preventing clinical fractures in the ambulatory elderly population as a result of poor long-term compliance; but, they did find it effective in patients who were compliant.

There are some products that assist the uptake of calcium and increase its bioavailability in the body, Friesland Foods Domo USA Inc. has supported studies on its Vivinal GOS, which have its ability to increase calcium absorption, likely due to its transgalactooligosaccharides.⁶ In Wister rats, Vivinal GOS produced a significant hypocholesterolemic effect and enhanced volatile fatty acid production, prevented bone loss and lowered serum total cholesterol concentration.⁷

In contrast with popular research, data from a study published in the American Journal of Public Health did not support the hypothesis that milk or other food sources of calcium by adult women protects against hip or forearm fractures.⁸ The study was a 12-year prospective study among 77,761 women, aged 34 through 59 years, who had never used calcium supplements in which researchers found no evidence that higher intakes of milk or calcium from food sources reduce fracture incidence. Women who drank two or more glasses of milk per day had relative risks of 1.45 for hip fracture and 1.05 for forearm fracture when compared with women consuming one glass or fewer per week. Likewise, higher intakes of total dietary calcium or calcium from dairy foods were not associated with decreased risk of hip or forearm fracture.

Vitamin D is another popular vitamin for bone health as it enhances intestinal absorption of calcium and phosphorous.⁹ It has recently received a lot of attention for its prevalent deficiency in the U.S. population, which may lead to osteopenia, osteoporosis and osteomalacia, increasing the risk of fracture. Research has shown the need for vitamin D in patients with osteoporosis. A systematic review of double blind, randomized control trials of oral vitamin D supplementation with or without calcium supplementation versus calcium supplementation or a placebo in older persons examining hip or non-vertebral fractures was conducted.¹⁰ A vitamin D dose of 700 to 800 IU/d reduced the relative risk (RR) of hip fracture by 26 percent and any non-vertebral fracture by 23 percent versus calcium or a placebo. No significant benefit was observed in 400 IU/d vitamin D.

For a 12-month period, a separate Swiss study investigated 222 consecutive hip fracture patients with a mean age of 86 (77 percent women).¹¹ Mean serum 25-hydroxyvitamin D levels (25(OH)D) levels were low among hip fracture patients admitted from home (34.6 nmol/l), from assisted living (27.7 nmol/l) and from nursing homes (24 nmol/l). Severe vitamin D deficiency below 30 nmol/l was present in 60 percent, 80 percent were below 50 nmol/l, and less than 4 percent reached desirable levels of at least 75 nmol/l. Consistently, only 10 percent of hip fracture patients had any vitamin D supplementation on admission to acute care with significantly higher 25(OH)D levels among individuals supplemented with 800 to 880 IU/day (63.5 nmol/l). The study concluded, Controlling for age and gender, vitamin D supplementation, type of dwelling and season were independently and significantly associated with 25(OH)D levels.

This article is part of a larger feature: Naturally Battling for Better Bone Health

Click here for complete references .