One of the most serious side effects of long-term corticosteroid use is accelerated osteoporosis. Although we don't fully understand how this works, corticosteroid interference with calcium and vitamin D is known to play a major role.
Calcium and vitamin D supplements are definitely beneficial for fighting ordinary
; in addition, there is good evidence that they also protect against osteoporosis brought on by corticosteroids.
A review of 5 trials enrolling a total of 274 participants found that calcium and vitamin D supplementation significantly prevented bone loss at the lumbar spine and forearm in corticosteroid-treated individuals.
For example, in a 2-year double-blind placebo-controlled study of 130 individuals, supplementation with 1,000 mg of calcium and 500 IU of vitamin D daily actually reversed steroid-induced bone loss, causing a net bone gain.