Don't take vitamin D to live longer if you aren't deficient in it

Cost

About 0.2 to 0.5 CNY a day, 100 to 200 CNY a year. The money is not large; the real cost is thinking you have already done something to prevent disease.

What you get

The VITAL trial enrolled 25,871 people who took 2000 IU a day and followed them for 5.3 years (median). No difference was seen in cancer, heart and blood vessel problems, or death. For cancers that spread, HR 0.96 (HR is the hazard ratio; 1 means the two sides are the same; 95% CI 0.88–1.06 is the plausible range). Major cardiovascular events HR 0.97 (0.85–1.12). All-cause death HR 0.99 (0.87–1.12). The D-Health trial enrolled 21,315 Australians aged 60 and older. They took 60,000 IU a month and were followed for 5 years. This one also showed no difference, with all-cause death HR 1.04 (0.93–1.18). The share who died was 5.3% versus 5.1%. It looks like a good deal because some studies only tracked people without intervening, found that people with low vitamin D levels died more often, and that was misread as “taking it will work”. People who rarely go outside have a separate set of advice. The UK Department of Health recommends that adults who rarely go outdoors, live in nursing homes, or cover most of their skin when outside take 10 micrograms of vitamin D a day all year. The NHS states that 1 microgram equals 40 IU, so 10 micrograms is 400 IU. China's health industry standard gives a recommended amount of 10 micrograms a day for adults 18 to 64 and 15 micrograms for those 65 and older. The same standard gives a tolerable upper intake of 50 micrograms a day (2000 IU), because too much makes blood calcium too high. The NHS's upper limit for adults is looser, at 100 micrograms (4000 IU). Tiredness has many causes; the NHS lists not enough sleep, stress and depression, iron-deficiency anemia, diabetes, an overactive thyroid and sleep apnea. It advises seeing a doctor if you have been tired for weeks with no clear reason, or so tired it affects daily life. Taking more is not better. VITAL also analyzed fractures: people taking 2000 IU a day were the same as those not taking it (HR 0.98, 0.89–1.08). VITAL also looked at depression, among 18353 of its participants aged 50 and older who had no depression at the time. Those who took it had 12.9 cases of depression or recurrence per 1000 people per year, versus 13.3 for those who did not, no difference (HR 0.97, 0.87–1.09). Mood scores did not differ either. The authors write that the results do not support taking vitamin D to prevent depression in adults. A Canadian trial enrolled 311 healthy people aged 55 to 70 without osteoporosis, in three groups taking 400, 4000 and 10000 IU a day for 3 years. The larger the dose, the more bone density fell at the radius in the wrist, by 1.2%, 2.4% and 3.5% in the three groups. No difference was seen in the bone's compressive strength. The authors concluded that this does not support a benefit to bones from high-dose vitamin D. A Swiss trial enrolled 200 people aged 70 and older who had fallen, taking 24,000 (2.4万) IU or 60,000 (6万) IU a month for a year. In the 60,000 IU group leg function did not improve, and more people fell within the year (66.9% versus 47.9%). An Australian trial enrolled 2256 women aged 70 and older, each taking 500,000 (50万) IU once a year in autumn and winter. They fell about 15% more often (RR 1.15, 1.02–1.30) and had about 26% more fractures (RR 1.26, 1.00–1.59)

Notes

Dispute: neither VITAL nor D-Health specifically recruited people who were truly deficient in vitamin D, so the conclusion covers only people who were “not deficient to begin with.” People found to be truly deficient, people with osteoporosis, and infants and young children should still take it as their doctor says. Even severe deficiency does not always require an injection. The 2016 global consensus on rickets recommends oral dosing, because oral supplementation works faster than intramuscular injection. One trial enrolled 61 children with rickets and compared a single injection of 600,000 (60万) IU with 60,000 (6万) IU taken by mouth weekly for 10 weeks; at 12 weeks lab tests and X-rays showed no difference. After finishing the dose your doctor prescribes, get rechecked; if it still can't be brought up, have the doctor check whether there is an absorption problem. Taking 400 IU a day for people who get no sun is to prevent deficiency. The health industry standard states that vitamin D deficiency causes rickets, osteomalacia and osteoporosis. That does not show it prevents cancer or heart disease, nor that it treats tiredness. If your doctor has prescribed a different dose, follow the doctor. Whether supplements help people who already have depression is mixed. A 2023 analysis pooling 41 trials saw a small drop in depression scores, but the results differed widely across studies, and the authors rated the quality of the evidence at the lowest level. A 2024 analysis split by duration found that trials followed for a year or more showed no effect. If you have depression, see psychiatry or psychology first; don't use vitamin D in place of treatment. This section looked at total death, cancer, heart and blood vessels, bones, falls and depression, and nothing else. For how to supplement infants, see §20.16 (give 400 IU of vitamin D a day).

Evidence grade

A : Specific numbers from meta-analyses, large cohorts or randomized trials; for law and policy, the statute or official text.

Sources

1. Manson JE et al. (2019). Vitamin D Supplements and Prevention of Cancer and Cardiovascular Disease. NEJM. https://doi.org/10.1056/NEJMoa1809944
2. Neale RE et al. (2022). The D-Health Trial: a randomised controlled trial of the effect of vitamin D on mortality. Lancet Diabetes Endocrinol. https://doi.org/10.1016/S2213-8587(21)00345-4
3. NHS. Vitamin D. https://www.nhs.uk/conditions/vitamins-and-minerals/vitamin-d/
4. NHS. Tiredness and fatigue. https://www.nhs.uk/symptoms/tiredness-and-fatigue/
5. National Health Commission of China. WS/T 578.4-2018 Dietary Reference Intakes for Chinese Residents, Part 4: Fat-Soluble Vitamins [in Chinese], Table 1. https://www.nhc.gov.cn/wjw/yingyang/201805/3dcd74635d8e40bcb5d834d3b2f66964/files/1739783549670_23371.pdf
6. LeBoff MS et al. (2022). Supplemental Vitamin D and Incident Fractures in Midlife and Older Adults. NEJM. https://doi.org/10.1056/NEJMoa2202106
7. Burt LA et al. (2019). Effect of High-Dose Vitamin D Supplementation on Volumetric Bone Density and Bone Strength: A Randomized Clinical Trial. JAMA. https://doi.org/10.1001/jama.2019.11889
8. Bischoff-Ferrari HA et al. (2016). Monthly High-Dose Vitamin D Treatment for the Prevention of Functional Decline: A Randomized Clinical Trial. JAMA Intern Med. https://doi.org/10.1001/jamainternmed.2015.7148
9. Sanders KM et al. (2010). Annual high-dose oral vitamin D and falls and fractures in older women: a randomized controlled trial. JAMA. https://doi.org/10.1001/jama.2010.594
10. Munns CF et al. (2016). Global Consensus Recommendations on Prevention and Management of Nutritional Rickets. J Clin Endocrinol Metab. https://doi.org/10.1210/jc.2015-2175
11. Mondal K et al. (2014). A Randomized controlled trial on safety and efficacy of single intramuscular versus staggered oral dose of 600 000IU Vitamin D in treatment of nutritional rickets. J Trop Pediatr. https://doi.org/10.1093/tropej/fmt105
12. Okereke OI et al. (2020). Effect of Long-term Vitamin D3 Supplementation vs Placebo on Risk of Depression or Clinically Relevant Depressive Symptoms and on Change in Mood Scores: A Randomized Clinical Trial. JAMA. https://doi.org/10.1001/jama.2020.10224
13. Mikola T et al. (2023). The effect of vitamin D supplementation on depressive symptoms in adults: A systematic review and meta-analysis of randomized controlled trials. Crit Rev Food Sci Nutr. https://doi.org/10.1080/10408398.2022.2096560
14. Ghaemi S et al. (2024). The effect of vitamin D supplementation on depression: a systematic review and dose-response meta-analysis of randomized controlled trials. Psychol Med. https://doi.org/10.1017/s0033291724001697

Translated from the Chinese original. Original book, section 6, tip 3. Content may be out of date and rules differ by place. When you actually deal with an agency, a doctor or a court, follow what local officials, doctors and lawyers tell you. Disclaimer