Vitamin EAlpha-tocopherol · 4 claims

The 2005 analysis pooled 19 trials and 135,967 participants at doses from 16.5 to 2000 IU/day. Overall there was no mortality effect — but in 9 of the 11 high-dose trials (≥400 IU/day) risk was significantly raised, with a pooled risk difference of 39 additional deaths per 10,000 people. The authors concluded high-dosage supplementation was “clearly unjustified.”

A later analysis pooled 57 trials, 246,371 participants and 29,295 deaths, and found a risk ratio of 1.00 (95% CI 0.98–1.02) with no dose-response relationship at all — concluding no effect up to 5,500 IU/day.

Both are large. Both are published in serious venues. A third paper exists specifically to examine why different meta-analytic approaches to the same literature produce inconsistent answers. This claim does not have a settled answer, and any source that gives you one is overstating.

• MetaMiller ER 3rd, Pastor-Barriuso R, Dalal D, et al. High-dosage vitamin E supplementation may increase all-cause mortality Ann Intern Med 2005;142(1):37-46 · 19 trials, 135,967 participants
• MetaAbner EL, et al. Vitamin E and all-cause mortality: a meta-analysis 57 trials, 246,371 subjects, 29,295 deaths · RR 1.00 (0.98–1.02) · PMID 21235492
• MetaThe questionable association of vitamin E supplementation and mortality — inconsistent results of different meta-analytic approaches PMID 19267994 · on why the two disagree

This was the original reason people took vitamin E, and it has been tested properly. The HOPE and HOPE-TOO trials followed participants on long-term vitamin E and reported on cardiovascular events and cancer. Systematic reviews of antioxidant supplements for cardiovascular prevention have consistently found no benefit.

The observational data that motivated the hypothesis did not survive randomisation — a pattern that recurs across most antioxidant supplements.

• RCTLonn E, et al. Effects of long-term vitamin E supplementation on cardiovascular events and cancer (HOPE / HOPE-TOO) JAMA 2005;293:1338-47
• MetaEfficacy of vitamin and antioxidant supplements in prevention of cardiovascular disease: systematic review and meta-analysis BMJ 2013;346:f10

The Selenium and Vitamin E Cancer Prevention Trial (SELECT) was designed specifically to test this. It did not find protection. Follow-up reporting associated vitamin E with increased prostate cancer risk in the supplemented group.

Broader systematic reviews of antioxidant supplements for cancer prevention, including gastrointestinal cancers, reach the same null-or-worse conclusion.

• RCTLippman SM, Klein EA, Goodman PJ, et al. Effect of selenium and vitamin E on risk of prostate cancer and other cancers (SELECT) JAMA 2009;301(1):39-51
• MetaBjelakovic G, et al. Mortality in randomized trials of antioxidant supplements for primary and secondary prevention JAMA 2007;297:842-57

A 1997 trial in the New England Journal of Medicine tested alpha-tocopherol, selegiline, or both in Alzheimer's disease and reported delayed progression on functional endpoints. Practice guidelines at the time began recommending vitamin E on that basis.

The 2005 mortality meta-analysis explicitly flagged this as premature, noting the recommendation rested on evidence too thin to justify the dose involved — 2000 IU/day, five times the level at which its own mortality signal appeared. Later reviews of vitamin E in Alzheimer's remain equivocal.

Note the dose collision. The Alzheimer's trials used 2000 IU/day. That is the same territory the mortality debate is about. Whatever you conclude about claim one applies directly here.

• RCTSano M, Ernesto C, Thomas RG, et al. A controlled trial of selegiline, alpha-tocopherol, or both as treatment for Alzheimer's disease N Engl J Med 1997;336:1216-22
• RevBrowne D, McGuinness B, Woodside JV, McKay GJ. Vitamin E and Alzheimer's disease: what do we know so far? Clin Interv Aging 2019;14:1303-1317 · PMID 31409980