Cholecalciferol for bone, heart, immune and other health effects
What it found
High-dose cholecalciferol improved bone density, blood sugar control and immune markers in some groups, but large trials in cancer, heart disease and thinking skills gave mixed results.
The evidence comes from people, animals and lab studies.
What they found
Studies in people
Bone density
In people, weekly doses of 20,000 IU of cholecalciferol slowed the decline in hip bone mineral density compared with placebo. Higher vitamin D levels were linked to stronger, harder bone.
Blood sugar and diabetes
A trial of 1,774 people with prediabetes found no improvement in pancreatic beta-cell function after 4,000 IU daily for 24 months. But a review of 28 trials with 3,848 people found vitamin D lowered HbA1c, fasting glucose and insulin resistance, especially with calcium and in women over 50.
Heart and blood vessels
The VITAL trial found no big drop in major heart events with 2,000 IU daily in the general population. Some subgroups, like people with low vitamin D at the start, seemed to benefit.
Gut conditions
In people with inflammatory bowel disease, daily doses of at least 2,000 IU improved disease scores and quality of life. In children with IBD, vitamin D levels were lower during active disease than in remission.
Cystic fibrosis
A review found that adults with cystic fibrosis taking high-dose cholecalciferol reached an average vitamin D level of 40.19 ng/mL, compared with 28.50 ng/mL in controls. No cases of high calcium or vitamin D toxicity were reported.
Immune system and infections
Daily or weekly vitamin D reduced acute respiratory infections, especially in people who started with low vitamin D. In hospitalized COVID-19 patients, supplementation was linked to fewer ICU admissions and lower death rates.
What the authors conclude
- They say vitamin D3 is a promising but complex therapeutic agent that needs more rigorously designed clinical trials.
- They advise that food fortification and targeted screening are underused but cost-effective public health measures.
- They emphasize the need for personalized strategies because excessive intake may cause high calcium or kidney stones.
How it was done
Vitamin D is known for bone health, but scientists are exploring whether it also helps with blood sugar, heart health, immunity and other conditions. The authors wanted to pull together the evidence on high-dose cholecalciferol for these wider uses.
The authors searched scientific databases for studies on high-dose cholecalciferol and human health, with no limits on language or publication date. They included clinical trials, observational studies and lab work covering bone, heart, gut, kidney, immune and neurological conditions.
What it can’t tell you
- Many of the studies used different doses, different groups of people and different ways of measuring results, so the authors could not draw firm conclusions for all conditions.
- Some findings come from animals or cells, which cannot show what happens in people.
- Observational studies can show links but cannot prove that vitamin D causes the health effects seen.
Who paid
- Conflicts
- The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.
- Authors work at
- Faculty of Health Science, Ecuador
The paper
- Title
- Cholecalciferol (vitamin D3): efficacy, safety, and implications in public health
- Type
- ReviewThe authors read earlier studies and describe what they found. It isn’t a new study.
- Evidence
- Studies in people
- Summarised from
- Full text
- Cite
- Ortiz-Prado E, Vasconez-Gonzalez J, Izquierdo-Condoy JS, et al (2025). Cholecalciferol (vitamin D3): efficacy, safety, and implications in public health. Frontiers in nutrition. doi:10.3389/fnut.2025.1579957Free full textPubMed 40551736DOI
Summary written 26 Sep 2026. Check it against the paper before it changes what you eat. How we summarise papers · Report an error