Vitamin D supplements and target blood levels
What it found
Vitamin D supplements raise blood levels of 25(OH)D, and different guidelines set different target levels and daily doses.
The paper compares these guidelines and the evidence behind them.
What they found
Studies in people
Childhood levels and heart risk
In a Finnish study of 2,148 people, those with the lowest childhood 25(OH)D levels had higher odds of a high-risk carotid artery measurement later in life.
Cancer and vitamin D levels
Women with 25(OH)D levels of at least 40 ng/mL had a lower risk of invasive cancer than women with levels below 20 ng/mL. In a trial, postmenopausal women taking calcium plus 1,100 IU of vitamin D a day had a significant reduction in all-cancer risk.
Memory and dementia
In older people, very low 25(OH)D levels below 10 ng/mL were linked to faster cognitive decline over 6 years and to the onset of non-Alzheimer's dementia over 7 years.
Death rates
An analysis of 73 groups with 849,412 participants found that people with 25(OH)D below 10 ng/mL had a higher risk of death than those with at least 30 ng/mL.
Other findings
Bone-focused guidelines
Bone-focused guidelines recommend a target 25(OH)D level of 20 ng/mL (50 nmol/L) and daily vitamin D doses of 400 to 800 IU, depending on age.
Broader guidelines
Guidelines that consider vitamin D's wider effects recommend a target of 30 ng/mL (75 nmol/L) and daily doses of 400 to 2,000 IU, depending on age, body weight, disease status and ethnicity.
Natural sources
Natural sources of vitamin D can raise 25(OH)D levels, but the paper says they are regarded as ineffective for keeping levels in the 30 to 50 ng/mL range all year round in the general population.
Side effects are rare
Adverse effects from taking vitamin D yourself, such as high calcium in the blood or urine, are rare and usually result from taking extremely high doses for a long time.
What the authors conclude
“The wise and balanced choice of the recommendations to follow depends on one's individual health outcome concerns, age, body weight, latitude of residence, dietary and cultural habits, making the regional or nationwide guidelines more applicable in clinical practice.”
Also in their conclusions
- They say the wise and balanced choice of which recommendation to follow depends on a person's health concerns, age, body weight, latitude of residence, diet and cultural habits.
- They advise that regional or nationwide guidelines are more applicable in clinical practice.
- They say that self-administering vitamin D is not a panacea for treating diseases or reducing the risk of death, and caution is advised for doses higher than those recommended for the general population.
How it was done
Vitamin D is known to affect bone and many other body systems, and studies link higher blood levels of 25(OH)D with better outcomes for several diseases. Many agencies have issued different supplement recommendations, which can confuse doctors and shoppers.
The authors reviewed published vitamin D supplementation guidelines and the studies behind them, including trials and observational studies in people. They compared target blood levels of 25(OH)D and daily vitamin D doses recommended by different groups.
What it can’t tell you
- The paper is a review of guidelines and studies, not a single new trial, so it cannot prove that vitamin D causes the health outcomes linked to it.
- Many of the links come from observational studies, which can show an association but not cause and effect.
Who paid
- Authors work at
- The Children's Memorial Health Institute, Poland; Boston University Medical Center, USA; and Health Research Center, USA
The paper
- Title
- Vitamin D supplementation guidelines
- Type
- Study
- Evidence
- Studies in people
- Summarised from
- Full text
- Cite
- Pludowski P, Holick MF, Grant WB, et al (2018). Vitamin D supplementation guidelines. The Journal of steroid biochemistry and molecular biology. doi:10.1016/j.jsbmb.2017.01.021Free full textPubMed 28216084DOI
Summary written 26 Sep 2026. Check it against the paper before it changes what you eat. How we summarise papers · Report an error