Vitamin E and Alzheimer's: The Trials, the Dose and the Safety Limit
Vitamin E has one of the more interesting records in Alzheimer's research. In two trials it slowed the loss of everyday abilities in people who already had Alzheimer's. In a third it did nothing to stop mild memory problems turning into Alzheimer's. And the dose used in those trials is twice the safe upper limit for unsupervised use.
Why vitamin E was tested at all
Vitamin E is an antioxidant. Brain cells in Alzheimer's show signs of oxidative damage, the same kind of chemical wear that antioxidants are supposed to soak up, so in the 1990s researchers tried a high dose to see whether it would slow the disease. It was cheap, widely available and seemed safe. Three large trials later, the picture is mixed in a way that's worth understanding before anyone buys a bottle.
The three trials that matter
| Trial | Who took part | Daily dose | What happened |
|---|---|---|---|
| Sano, New England Journal of Medicine, 1997 | 341 people with moderately severe Alzheimer's, for two years | 2,000 IU of alpha-tocopherol | After adjusting for differences at the start, vitamin E delayed the combined outcome of death, nursing home placement, loss of basic daily abilities or severe dementia |
| Petersen, New England Journal of Medicine, 2005 | 769 people with mild cognitive impairment, for three years | 2,000 IU | No difference from placebo in how many developed Alzheimer's |
| TEAM-AD, JAMA, 2014 | 613 veterans with mild to moderate Alzheimer's, about two years on average | 2,000 IU | Daily abilities declined more slowly than on placebo, roughly a 19% slower decline per year |
The 1997 trial
The Alzheimer's Disease Cooperative Study trial gave people with moderately severe Alzheimer's either selegiline, vitamin E, both, or a placebo. The placebo group happened to start out with better memory scores, which made the raw results hard to read. Once the researchers adjusted for that, people on vitamin E took longer to reach the trial's end point.
Median days until death, nursing home, loss of daily abilities or severe dementia
Adjusted for baseline memory scores. Longer is better.
Show the data as a table
| Group | Median days |
|---|---|
| Placebo | 440 days |
| Vitamin E 2,000 IU | 670 days |
The 2014 TEAM-AD trial
This was a larger test in the VA system. In the TEAM-AD trial, people with mild to moderate Alzheimer's who took 2,000 IU of vitamin E lost their everyday abilities more slowly than those on placebo, about 3 points less on a standard daily-living scale. The authors put it as a delay in progression of about 19% a year, or roughly six months over the follow-up. Memory test scores themselves didn't change much, and memantine, an Alzheimer's drug tested alongside it, didn't beat placebo on the same measure.
Six months may not sound like much. For a family, six more months of someone dressing and eating on their own is a lot.
The 2005 trial in mild memory problems
This is the trial that should cool any excitement about vitamin E as prevention. The NIH-funded study of people with mild cognitive impairment found no benefit at all from vitamin E over three years. About 16% of participants progressed to Alzheimer's each year, with no difference between the vitamin E and placebo groups at any point.
What the Cochrane review concluded
Cochrane reviewers pulled this evidence together in 2017. Their review of vitamin E for Alzheimer's and mild cognitive impairment found no clear effect on memory and thinking in people with Alzheimer's, some evidence of slower functional decline from the one trial that measured it the right way, and no effect on progression from MCI to Alzheimer's. They found no difference in serious side effects or deaths in those trials.
So the fair summary is narrow. Vitamin E might help people who already have Alzheimer's keep their daily abilities a little longer. It doesn't seem to prevent Alzheimer's, and it doesn't improve memory scores.
The safety problem with 2,000 IU
Every one of those trials used 2,000 IU a day, under medical supervision. That's well above what's considered safe to take on your own. MedlinePlus gives the upper limit for adults as 1,000 mg a day, which is 1,500 IU of natural vitamin E or 1,100 IU of the synthetic form, and warns that high-dose supplements might raise the risk of bleeding in the brain.
There's also a broader warning. A 2005 meta-analysis of 19 trials with nearly 136,000 participants found that in 9 of the 11 trials using 400 IU a day or more, death rates ran higher in the vitamin E group, and concluded that high-dose vitamin E may increase overall mortality. That analysis had its critics, but it's why doctors don't hand out high-dose vitamin E casually.
Source: Trials above; MedlinePlus vitamin E fact sheet
If you take a blood thinner, or have had a bleeding stroke, high-dose vitamin E is a firm no unless your doctor says otherwise.
Getting vitamin E from food
For most people, food covers it. MedlinePlus lists these as good sources:
| Food group | Examples |
|---|---|
| Vegetable oils | Wheat germ, sunflower, safflower, corn and soybean oils |
| Nuts | Almonds, peanuts, hazelnuts |
| Seeds | Sunflower seeds |
| Green vegetables | Spinach, broccoli |
| Fortified foods | Breakfast cereals, fruit juices, margarine and spreads with added vitamin E |
A handful of almonds and a salad dressed with sunflower oil goes a long way. None of that will reach trial doses, and it doesn't need to: the evidence for food-level vitamin E is about general health, not treating Alzheimer's.
Where this leaves supplements
If someone in your family has Alzheimer's and you're wondering about vitamin E, take the question to their doctor, together with the TEAM-AD paper. It's a reasonable conversation to have, and the answer depends on their other medicines and health.
For memory supplements sold online, check whether vitamin E is even in them and at what dose. Many have none. Phytomem One, for example, takes a different route, built around saffron and blood sugar herbs; our Phytomem One review goes through each of its ten ingredients and the research behind them.
Questions readers ask
Does vitamin E prevent Alzheimer's?
The trial evidence says no. In people with mild cognitive impairment, 2,000 IU a day for three years did not lower the rate of progression to Alzheimer's.
Should someone with Alzheimer's take vitamin E?
Possibly, but only with their doctor's approval. Two trials found slower functional decline at 2,000 IU a day, which is above the safe upper limit for unsupervised use and can interact with blood thinners.
Is vitamin E from food enough?
For general health, yes. Adults need about 15 mg a day, which a normal diet with nuts, seeds and vegetable oils provides. Food won't reach the doses used in the Alzheimer's trials.