July 9, 2007

Vitamin D, calcium boost bone health after fractures - study

By Stephen Daniells

09/07/2007 - Supplementation with vitamin and calcium could cut reduce bone loss in patients with recent osteoporotic fractures, suggests a new study from Denmark.

Writing in the American Journal of Clinical Nutrition, researchers from Copenhagen University Hospital and Roskilde University Hospital report that supplementation with the vitamin and mineral approximately halved levels of a hormone associated with bone turnover.

"Supplementation with calcium and vitamin D is important for patients with low-energy fractures because it decreases bone loss," wrote lead author Mette Hitz. "The effect of intervention was positively related to physical performance, which emphasizes the importance of mobilisation."

The combination of vitamin D and calcium has long been recommended to reduce the risk of bone fracture for older people, particularly those at risk of or suffering from osteoporosis, which is estimated to affect about 75m people in Europe, USA and Japan.

Use of these supplements is widely accepted by the general public, with calcium reported to be the biggest seller in the US supplements industry. Annual sales were about $993m (€836m) in 2004, according to the Nutrition Business Journal.

The researchers looked at the effect of joint vitamin D, calcium supplementation on elderly subjects with history of fractures due to osteoporosis. The researchers note that such a population are marked by poor bone status, vitamin D deficiency, and low physical performance, and are susceptible to low-energy fractures of the hip, forearm, shoulder, and spine.

In a double-blinded design, 122 patients (average age 70) with hip fracture (lower-extremity fracture, or LEF) or upper extremity fracture (UEF) were randomly assigned to receive 3000 mg calcium carbonate plus1400 IU cholocalciferol, or placebo (200 IU cholecalciferol) for one year. Sixty-eight per cent of participants (79 subjects) completed the study. The regimens were taken in combination with a multivitamin tablet (Pharma Vinci A/S, Denmark).

Hitz and co-workers report that vitamin D status, measured using concentrations of 25-hydroxyvitamin D2, increased as a result of supplementation but not placebo, with the greatest improvements observed in the hip fracture patients. The group say vitamin D levels increase from 33 to 82 nmol/L.

Bone turnover also decreased as a result of intervention, measured using parathyroid hormone (PTH) levels, although bone resorption (weakening of the bone) remained high in hip fracture patients who received the intervention, with the researchers suggesting this could be due their low mobility.

"A one-year intervention with calcium and vitamin D reduced bone turnover, significantly increased BMD in patients younger than 70 years, and decreased bone loss in older patients," concluded the researchers.

Vitamin D refers to two biologically inactive precursors - D3, also known as cholecalciferol, and D2, also known as ergocalciferol. The former, produced in the skin on exposure to UVB radiation (290 to 320 nm), is said to be more bioactive. The latter is derived from plants and only enters the body via the diet, from consumption of foods such as oily fish, egg yolk and liver.

Both D3 and D2 precursors are hydroxylated in the liver and kidneys to form 25- hydroxyvitamin D (25(OH)D), the non-active 'storage' form, and 1,25-dihydroxyvitamin D (1,25(OH)2D), the biologically active form that is tightly controlled by the body.

Source: American Journal of Clinical Nutrition
2007, Volume 86, Pages 251-259
"Bone mineral density and bone markers in patients with a recent low-energy fracture: effect of 1 y of treatment with calcium and vitamin D"
Authors: M.F. Hitz, J.-EB. Jensen, P.C. Eskildsen

Source: www.nutraingredients.com