Studies that link diet and bone mass have focused primarily on calcium and vitamin D intake. However, other nutrients such as magnesium, fluoride, phosphorus, zinc, vitamin K and vitamin C, are also important for their specific role in bone composition.

Recent randomized placebo controlled clinical trials investigating the influence of supplements like DHEA, phytoestrogens and vitamin K on bone density and incidences of bone fracture have pointed to the potential of these supplements being used to prevent osteoporosis.

Calcium with Vitamin D Supplementation

Data obtained from the WHI (Women’s Health Initiatives) calcium and vitamin D Trial of 36,282 postmenopausal women aged from 50 to 79 found only a modest benefit in preserving bone mass and prevent hip fractures in certain groups including older women but do not prevent other types of fractures. These supplements were associated with a 17% increase in kidney stones formation.

Women who consistently took the full supplement dose experienced a significant 29% decrease in hip fracture. Those who were older than 60 had a significant 21% reduction in hip fracture. The supplements had no effect on spine or total fractures. Since hip fractures are considered to be more serious than kidney stones, it is thought that the public health benefit of the supplements outweighs the risks.

Dehydroepiandrosterone (DHEA)

DHEA is produced naturally in the adrenal glands in humans; levels in the body peak during mid-twenties. Evidence from randomized controlled trials suggests that intake of DHEA at 50mg/day for at least 12 months may help in preventing osteoporosis in healthy women over 60 years of age. However, larger trials of longer duration are warranted to confirm this preliminary result.

Phytoestrogens

Results from randomized controlled trials show that it is difficult to compare outcomes from these trials because the products being evaluated were not equivalent in composition and formulation. In one trial, 54mg of genistein produced an increase in lumbar spine bone mass density (BMD) by 3.0 +/- 2%(p<0.04),while hormone (17-beta-estradiol 1mg and norethisterone acetate 0.5mg) increased lumbar spine BMD by 3.8 +/- 2.7%(p<0.04) and placebo failed to increase lumbar spine BMD indicates potential benefit in the use of genistein to increase BMD.

Out of a sample of 11 trials, only 4 reported a positive effect of phytoestrogens on BMD. Hence it is not clear whether isoflavones have a beneficial effect on BMD. Further investigation using well designed trials and fully characterized products is warranted.

Vitamin K2 (menaquinone)

A Randomized controlled trials reported a lower incidence of vertebral fracture rates with vitamin K2. This supplement has few adverse effects. It interacts with coenzyme Q10 and warfarin. 45mg/day of vitamin K2 may maintain spinal BMD in osteoporotic women with preliminary data suggesting a decreased incidence of vertebral fractures.

Chang Yok Ying
Senior Pharmacist
Specialist Outpatient Clinic Pharmacy

References:
1.	NEJM Feb 16 2006 p669-p683 Calcium plus Vitamin D Supplementation and the risk of fractures
2.	The annals of pharmacotherapy 2006 May Vol 40 Natural health products in the prevention and treatment of osteoporosis:Systematic review of randomized controlled trials
3.	CMAJ Nov 27 2001 165(11) The role of nutrition in the prevention and treatment of adult osteoporosis