06-003 · EVIDENCE A · LOW-RISK READING
Don’t give vitamin D supplements to people who already have enough
不要为了长寿给不缺维生素 D 的人补维生素 D
Roughly 0.2 to 0.5 yuan per day, or 100 to 200 yuan per year. That’s not much money, but the real cost is the false sense of security it gives — the belief that you’ve already taken preventive steps.
Two large trials looked at this issue across multiple cohorts taking supplements over five years. For people who already had adequate vitamin D levels, there was no change in cancer rates, cardiovascular problems, or overall mortality — the death rates were 5.3% versus 5.1% respectively. This does not apply to people who truly lack vitamin D, those with osteoporosis, or anyone who rarely gets sunlight; they should follow their doctor’s advice.
A
Move “Don’t give vitamin D supplements to people who already have enough” to Future Me's calendar
The excuse
One more exception feels free because the bill arrives outside the current scene.
What feels good now
Today I keep a few minutes and avoid interrupting my default routine.
What the source says
The source summarizes the return this way: “Two large trials looked at this issue across multiple cohorts taking supplements over five years. For people who already had adequate vitamin D levels, there was no change in cancer rates, cardiovascular problems, or overall mortality — the death rates were 5.3% versus 5.1% respectively. This does not apply to people who truly lack vitamin D, those with osteoporosis, or anyone who rarely gets sunlight; they should follow their doctor’s advice.” Evidence grade A. The original states the population, caveats, and sources; this is not a personal forecast.
Open the original entry, check who the evidence applies to, then pick one small step that fits.
THE ENGLISH EDITION
Original recommendation and evidence
3. Don’t give vitamin D supplements to people who already have enough
Cost: Roughly 0.2 to 0.5 yuan per day, or 100 to 200 yuan per year. That’s not much money, but the real cost is the false sense of security it gives — the belief that you’ve already taken preventive steps.
In plain terms: Two large trials looked at this issue across multiple cohorts taking supplements over five years. For people who already had adequate vitamin D levels, there was no change in cancer rates, cardiovascular problems, or overall mortality — the death rates were 5.3% versus 5.1% respectively. This does not apply to people who truly lack vitamin D, those with osteoporosis, or anyone who rarely gets sunlight; they should follow their doctor’s advice.
Benefit: The VITAL trial followed 25871 participants who took 2000 IU of vitamin D daily for 5.3 years on average. No difference emerged in cancer rates, cardiovascular issues, or overall mortality. For cancers likely to spread, the hazard ratio was 0.96 (a range of 0.88–1.06), meaning no real effect. Similar results appeared for major cardiovascular events and overall death rates. The absolute value of this effect is 0.93. The D-Health trial involved 21315 Australians over 60; they received 60000 IU monthly for five years, yet saw no meaningful change in mortality or other outcomes. The apparent benefit often stems from studies that only observe low vitamin D levels without intervention, mistakenly concluding that supplementation helps.
Evidence grade: A
Sources: Manson JE et al. (2019). Vitamin D Supplements and Prevention of Cancer and Cardiovascular Disease. NEJM. <https://doi.org/10.1056/NEJMoa1809944>; 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>
Notes: These trials specifically excluded people with proven vitamin D deficiency, so their findings apply only to those already getting enough. Individuals who truly lack vitamin D, have osteoporosis, rarely get sunlight, or are infants still need proper medical guidance. This analysis focused solely on overall mortality, cancer, and cardiovascular health; other effects were not examined.
Read the complete Chinese source and notes
3. 不要为了长寿给不缺维生素 D 的人补维生素 D
成本: 一天约 0.2 到 0.5 元，一年 100 到 200 元。钱不算多，真正的代价是以为自己已经做了预防。
说人话: 本来就不缺维 D 的人补上 5 年，得癌症、得心血管病和死亡的人数，都和不补的人一样。查出来确实缺的人、有骨质疏松的人、长期晒不到太阳的人不在这条里面，他们按医生说的补。
收益: VITAL 试验找了 25,871 人，每天吃 2000 IU，跟踪了 5.3 年（中位数）。癌症、心脏血管的毛病和死亡都没看出差别。会扩散的那类癌 HR 0.96（HR 是风险比，1 就是两边一个样；95% CI 0.88–1.06 是可信范围）。主要心血管事件 HR 0.97（0.85–1.12）。全因死亡 HR 0.99（0.87–1.12）。D-Health 试验找了 21,315 名 60 岁以上的澳大利亚人。他们每月吃 60,000 IU，跟踪 5 年。这一项也没看出差别，全因死亡 HR 1.04（0.93–1.18）。死亡的比例是 5.3% 对 5.1%。它看起来划算，是因为有些研究只跟踪记录、不做任何干预，发现维 D 水平低的人死得多，这被误读成了「补上就管用」
证据等级: A
来源: Manson JE et al. (2019). Vitamin D Supplements and Prevention of Cancer and Cardiovascular Disease. NEJM. <https://doi.org/10.1056/NEJMoa1809944>；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>
备注: 争议：这两项试验都没有特意去招真正缺维生素 D 的人，所以结论只管「本来就不缺的人」。查出确实缺的人、有骨质疏松的人、长期晒不到太阳的人、婴幼儿，还是按医生说的补。这里只看了总死亡和癌症、心脏血管这几件事，别的没看
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