Large monthly doses of vitamin D do not reduce all-cause mortality among older people who are not deficient in the vitamin, and may even up the risk of death from cancer, an Australian study has found.

Queensland researchers randomly assigned more than 21,000 Australians aged between 60 and 79 to receive one oral gel capsule of either 60,000 IU vitamin D3 or placebo once a month for five years.

Blood samples taken from nearly 4000 randomly sampled participants during follow-up revealed a mean serum 25-hydroxy vitamin D concentration of 77 in the placebo group and 115nmol/L in the intervention group.

After five years, some 1100 participants had died, reported the QIMR (Queensland Institute of Medical Research) Berghofer Medical Research Institute study.