At age 75 we only produce 25% of the vitamin D from sunlight as we do at age 20. This puts us at higher risk of vitamin D deficiency as we age which can lead to falls fractures and muscle weakness.

I discuss the effects of vitamin D on various tissues including the immune system and some data on cancer prevention. Diagnosis of deficiency with lab values is explained and why different levels are used. Toxicity risk is addressed but low in community living older adults exposed to occasional sunshine.

Treatment options for vitamin D_2, D₃ and calcium are discussed and reasons explained for various formulations to be used in different settings.