Research

Hormonal

Daily supplementation of 400 IU of vitamin D prevents nutritional rickets in children, whereas 800 IU of vitamin D combined with appropriate calcium intake reduces osteoporotic fracture risk in vitamin D-deficient or institutionalized elderly subjects.

If you are an older adult living in care or have low vitamin D levels, take 800 IU of Vitamin D3 daily along with adequate calcium to help protect your bones from fractures. For children, 400 IU daily is the standard to prevent rickets. Do not assume mega-doses work better; very high single doses may actually increase fracture risk.

GoodSupportsHIGH confidence
Rickets and osteomalacia can be prevented by daily supplements of 400 IU of vitamin D. These risks can be reduced by 800 IU of vitamin D together with an appropriate calcium intake, given to institutionalized or vitamin D–deficient elderly subjects.
Roger Bouillon et al. · Endocrine Reviews · 2018

Why this rating

Supported by multiple RCTs and observational studies cited in the review, though the paper notes mixed results for extraskeletal effects.

Source

Skeletal and Extraskeletal Actions of Vitamin D: Current Evidence and Outstanding Questions

Roger Bouillon et al. · Endocrine Reviews · 2018

DOI 10.1210/er.2018-00126

narrative_reviewCited 1,098×
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DOI resolved against Crossref · corpus check 2026-06-10

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