Vitamins and Dietary Supplements

Rigorous studies of vitamin supplements that showed some promise of preventing or delaying dementia have produced decidedly mixed results. No vitamin, dietary supplements, or complementary treatment can prevent, reverse, or cure symptoms of Alzheimer's disease.

Alternative treatments for Alzheimer's symptoms — gingko biloba, folate, vitamin B, and vitamin E — have yet to prove effective and safe in large, rigorous scientific studies. Manufacturers of those supplements continue to market them as antidotes to Alzheimer's, but be aware that they may not have any scientific evidence to back up their claims. Unlike prescription and over-the-counter drugs, the herbal remedies, vitamins, and other dietary supplements are not required to prove their effectiveness or safety before they are marketed and sold in the United States.

Vitamin E

Antioxidants such as vitamins E and C can neutralize free radicals that circulate in your bloodstream, and they may protect nerve cells in the brain. Many theorize that antioxidants may protect against dementia, and in fact one large federally funded study during the 1990s showed that taking large doses of vitamin E slightly delayed loss of cognitive ability in Alzheimer's patients.


Though vitamin E may have other health benefits, few doctors recommend the supplements as a treatment for dementia, and Alzheimer's experts warn against taking the supplement unless you are under a physician's supervision. High doses of vitamin E can interact with other medications and may also prevent blood clotting in older adults.

However, scientific studies since that time haven't really indicated that vitamins E or C provide brain protection, even at high doses. A large five-year study published in the Journal of the American Geriatrics Society in February 2008 showed no reduced risk for dementia or AD among older adults who use over-the-counter vitamin E or C supplements. That was true even among subjects who took both vitamins, hoping the combination might offer greater protection, and among older adults who took E at higher than normally recommended doses.

Ginkgo Biloba

A staple of traditional Chinese medicine for centuries, gingko biloba is a plant extract thought to have both antioxidant and anti-inflammatory effects. It is used in Europe to treat cognitive symptoms of neurological disorders, and preliminary studies in the United States indicated that it might enhance brain health.

But the Gingko Evaluation of Memory (GEM) study, the largest, longest independent clinical trial of ginkgo biloba's effectiveness in preventing memory loss, surprised and disappointed those who had high hopes for the supplements' effectiveness and safety.

Researchers from five academic medical centers followed 3,069 volunteers ages 75 and older for approximately six years, and found that gingko supplements neither prevented nor delayed dementia or Alzheimer's disease. The researchers reported in the Journal of the American Medical Association (JAMA) in 2008 that most participants were cognitively healthy at the outset of the trial, though some had mild cognitive impairment, and that half took two doses of 120 milligrams of ginkgo biloba extract daily and half were given placebo pills. The study was double-blind, meaning that neither the participants nor the study staff knew who was receiving gingko supplements and who was taking a placebo.


Americans spent about $107 million on ginkgo biloba supplements in the United States in 2007, according to Consumer Reports. A year's supply of the supplement can cost about $200 per person.

During the course of the study, 523 participants were diagnosed with dementia. Of those, 246, or 16.1 percent, were taking placebos; 277, or 17.9 percent, were taking ginkgo biloba.

Gingko is generally well tolerated, which means that most people can take it without experiencing side effects. It has, however, been associated with slight increases in strokes and mini-strokes, and with irregular bleeding. Ginkgo inhibits the action of platelets in the blood and can interfere with blood coagulation, or clotting, according to federal health officials, who warn against taking ginkgo if you are taking the blood thinner warfarin (Coumadin) or antiplatelet drugs such as clopidogrel (Plavix). Ginkgo may lower blood sugar, so people taking drugs for diabetes should avoid gingko as well.

In the GEM study, researchers reported no difference in heart attack or ischemic strokes between the ginkgo and placebo-treated patients. There were more hemorrhagic (bleeding) strokes among the ginkgo group, though the number of cases was not significant, they noted. According to the study's authors, the possible adverse effects of gingko bolstered the case against recommending the supplement.

Coenzyme Q10

Coenzyme Q10 (CoQ10), or ubiquinone, is an antioxidant that occurs naturally in the body and is needed for normal cell reactions. CoQ10 levels, which decrease with age, appear to be low in people with certain chronic diseases.


An estimated 73 percent of Americans ages 65 and older are overweight, according to the Centers for Disease Control and Prevention. Simply being overweight can double your chances of developing dementia.

You can increase levels of CoQ10 in your body by taking CoQ10 supplements, medical experts say, but it is not clear that replacing low CoQ10 is beneficial or that it will counteract disease. CoQ10 has been used, recommended, or studied for numerous conditions, but it remains controversial as a treatment in many areas.

Some preliminary evidence suggests that CoQ10 supplements may slow some symptoms of dementia in people with Alzheimer's.


Studies of the omega-3 fatty acid docosahexaenoic acid (DHA), which is found in fatty fish and fish oil, suggest it shows some promise as a brain booster. The most abundant fatty acid in your brain, DHA is crucial to normal vision and brain function. It is also a natural anti-inflammatory and antioxidant agent. Clinical trials are investigating indications that people with high levels of DHA in their bloodstreams may be at reduced risk for Alzheimer's and that omega-3 fatty acid supplements may slow decline in very early AD.

Do any supplements show promise?

Several dietary supplements that may help stave off or slow cognitive decline are under investigation. Researchers are testing the combined effects of antioxidants (vitamin E, vitamin C, alpha-lipoic acid, and coenzyme Q10), omega-3 fatty acids, curcumin, and huperzine as possible therapies for AD.

Folate and B Vitamins

Claims that large doses of B vitamins might minimize brain deterioration in people with AD were undercut in 2008, when clinical trials of high-dose supplements of folate and vitamins B6 and B12 showed no effect on the symptoms of people with mild and moderate Alzheimer's.

B vitamins were thought to reduce homocysteine, an amino acid suspected of playing a role in Alzheimer's. In the trial, homocysteine levels did indeed drop in the subjects who took the supplements, but it didn't change their symptoms. The study also found some evidence that the B vitamin supplements were harmful at high doses.

  1. Home
  2. Alzheimer's Disease
  3. Can Alzheimer's Be Prevented?
  4. Vitamins and Dietary Supplements
Visit other sites: