By David Liu, Ph.D.

Sunday Sept 3, 2011 (foodconsumer.org) -- Vitamin d is important for bone health and vitamin D deficiency, which is common among old women, has been associated with a myriad of  diseases including diabetes, heart disease and cancer.  But vitamin d in extremely high doses may do more harm than good at least in some cases, a new trial study suggests.

The trial presented in March 2011 at European Congress on Osteoporosis & Osteoarthritis found old women who received an extremely high dose of vitamin d3 once a year were more likely to fall and suffer fractures, compared with those who received a placebo.

The study was meant to examine whether a high dose of cholecalciferol orally administered in fall or winter would have an effect on the fall and fracture risk.

For the trial, Kerrie Sanders and colleagues gave 2,256 community-dwelling women at an average age of 76 either a single oral dose of vitamin d3 or placebo each fall or winter for three to five years.  Falls and fractures were recorded for four to six years.

Those who received vitamin d3 were 15 percent more likely to have falls and 26 percent more likely to have fractures than those in the control group.

The median baseline vitamin d in the blood measured as 25-hydroxyvitamin d or simply 25D was 49 nmol/L at baseline.  Fewer than 3 percent of participants had less than 25 nmol/L.  

Those who had oral vitamin D had 120 nmol/L, 90 nmol/L and 70 nmol/L at one month, three months and 12 months respectively.

It was observed that in the first three months, the fall rate was particularly higher in the vitamin D group.

Vitamin D is produced when the skin is exposed to UV rays. Only a few foods naturally carry this vitamin and they are oily fish like salmon, egg yolk and mushrooms (vitamin D2).