Do Elderly benefit from Vitamin D supplements?

Question

For elderly, whose sceletal strength weakens, can Vitamin D supplements slow down the degeneration of bones?

I have found this source discussing which supplement works best, but it never established if Vitamin D supplements actually help.

Answer 1

According to some studies, adequate vitamin D intake from foods and supplements may prevent bone weakness (osteporosis) in elderly, but according to others it may not.

Efficacy of optimization of vitamin D in preventing osteoporosis and osteoporotic fractures: A systematic review (PubMed, 2006):

...vitamin D intake of 10-17.5 μg/day (400-700 IU/day) or more is effective in preventing bone loss in late postmenopausal women and an intake of 17.5-20 μg/day (700-800 IU/day) or more together with a calcium supplement reduces the risk of osteoporotic fractures.

Vitamin D (Linus Pauling Institute, updated 2017):

The results of a meta-analysis of 23 randomized controlled trials with more than 4,000 participants (mean age, 59 years) showed little evidence for an effect of vitamin D supplementation on bone mineral density at any of the five skeletal sites examined...

A prospective cohort study that followed more than 72,000 postmenopausal women in the US for 18 years found that those who consumed at least 600 IU/day of vitamin D from diet and supplements had a 37% lower risk of osteoporotic hip fracture than women who consumed less than 140 IU/day of vitamin D (73). However, daily supplementation with 400 IU of vitamin D3, in combination with 1,000 mg calcium, did not significantly reduce risk of hip fracture compared to a placebo in 36,282 postmenopausal women from the Women's Health Initiative trial...

According to Mayo Clinic:

• Uncontrollable risk factors for osteoporosis include age over fifty, female sex, Asian heritage, small body frame and osteoporosis in family members.
• Controllable risk factors include insufficient intake of calcium and vitamin D, excessive intake of protein, sodium, caffeine or alcohol, physical inactivity, smoking and chronic diseases (hyperthyroidism, rheumatoid arthritis, cancer, etc).

Logically, vitamin D supplements could help to prevent osteoporosis in people with insufficient vitamin D intake or sun exposure, but since this can be corrected by adequate vitamin D intake from foods and by sun exposure, the supplements may not be necessary.

In people without vitamin D deficiency but with other risk factors for osteoporosis, vitamin D supplements would be much less likely effective, as suggested by the above studies.