Can Supplements Reduce Your Risk of Alzheimer’s Disease?
Alzheimer’s disease (AD), the most common form of dementia, is a progressive, degenerative disorder of the brain that destroys a patient’s personality and impairs the ability to carry out daily activities. More than four million adults in the US suffer from Alzheimer’s disease today, and as the population ages, as many as 16 million Americans will have the disease by 2050, unless a cure is found.
Although the cause of Alzheimer’s disease is unknown, physicians can treat patients in the early to middle stages of the disease. For example, we know that certain brain cells manufacture acetylcholine. We also know that as we age, these cells begin to die off. Fortunately, the FDA has approved a group of medications called “acetylcholinesterase inhibitors,” which increase the amount of acetylcholine in the brain by decreasing its natural breakdown and consequently help alleviate confusion and language difficulty and may help control behavioral symptoms such as insomnia , anxiety , and depression . However, these medications do not address the underlying cause of the disease, and as symptoms worsen, they eventually lose their effect.
As a result (and playing on the fears of many older Americans) many companies are promoting the use of certain supplements to prevent and treat memory problems. Scientists are actively investigating the effects of these supplements, but for the most part, there is little to no evidence to support their claims. There is no supplement that has survived rigorous scientific evaluation to prove that it is helpful in fighting Alzheimer’s disease.
Supplements Believed to Stop or Slow the Progression of Alzheimer’s Disease
There are several different types of supplements thought to improve mental function and reduce the risk of Alzheimer’s disease.
An excess of free radicals (also known as oxidants) may contribute to the development of Alzheimer’s disease. Antioxidants may protect against Alzheimer’s disease by limiting the buildup of toxic amyloid protein. So far, the evidence suggests that diets rich in foods containing antioxidant vitamins such as E , C , and beta-carotene may reduce the risk of Alzheimer’s, but that the supplement forms of these vitamins have essentially no benefit. One recent meta-analysis noted an increase risk of death (due to all causes) in patients taking high doses of vitamin E. More randomized controlled trials are needed in this area.
Gingko biloba , thought to help deliver oxygen to the brain by improving blood flow to capillaries, is the most widely used herb to improve cognitive function. But the data thus far are inconclusive. Researchers who conducted a systematic review of previous studies found that Alzheimer’s patients who received gingko performed better on various cognitive tests than patients who did not. However, in two other trials, comparing the effects of gingko to placebo, no measurable benefit was seen.
Huperzine A , an extract from a club moss, may hold promise for people with Alzheimer’s disease by inhibiting the enzyme that breaks down the neurotransmitter acetylcholine (which carries information in the brain). There is some evidence in animal studies that it may have benefit. But there’s no indication that it can stave off memory loss in healthy people.
Evidence is also mixed for vinpocetine , a chemical derived from vincamine (found in the leaves of the periwinkle plant). Vinpocetine is thought to enhance memory and mental function by improving circulation in the brain and helping the brain to utilize oxygen more efficiently. More research is needed in this area.
Other Essential Nutrients
There are a number of other essential nutrients that are also purported to improve cognitive function. These include:
- Phosphatidyl serine
- Coenzyme Q10 (ubinquinone)
- Omega-3 and omega-6 (essential) fatty acids
Carnitine, a derivative of the amino acid lysine , plays an important role in energy production. Several small trials have suggested that it can modestly slow cognitive decline in patients with AD. Nevertheless, a large multi-center randomized control trial involving patients diagnosed with Alzheimer's disease did not find carnitine treatment to be different than placebo.
Phosphatidyl serine and choline are both involved in the structure and maintenance of cell membranes. Phosphatidyl serine has been shown to be mildly effective in the early stages of Alzheimer’s disease. Clinical trials of choline have not.
Because of its antioxidant properties, coenzyme Q10 (ubinquinone), which is involved in energy production, may play a role in reducing AD risk. However, research in this area is preliminary. There are no published clinical trials of coenzyme Q10 in Alzheimer’s disease.
It has been suggested that a dietary deficiency of omega-3 and omega-6 (essential) fatty acids could be a risk factor for Alzheimer's disease. Again, research in this area is preliminary.
Are Supplements Safe?
Buyers should beware that products that are natural are not necessarily safe or good for you. If you do choose to take supplements, use the following chart as a guide. Remember that a healthy diet will provide you with adequate vitamins and minerals.
Recommended Adult Dose
|Vitamin E||22 IU/d (15 mg/d); 1,500 IU (1,000 mg) per day is the Tolerable Upper Intake Level (UL)*|
|Vitamin C||90 mg/d for men, 75 mg/d for women; the UL is 2,000 mg/d *|
|Beta-carotene||None (Supplements are not advisable at any level)*|
|Gingko||40 to 80 mg 3 times daily**|
|Huperzine A||100 to 200 micrograms (µg) twice a day**|
|Vinpocetine||10 mg 3 times per day**|
Other essential nutrients
|Carnitine||500 to 1,000 mg 3 times daily**|
|Phosphatidyl serine||Up to 100 mg two or three times a day**|
|Choline||The Adequate Intake (AI) level is 550 mg/d for men and 425 mg/d for women; the UL is 3.5 g/d*|
|Coenzyme Q10||30 to 300 mg/d**|
|Omega-3 fatty acids||The AI is 1.6 g/d for men and 1.1 g/d for women*|
|Omega-6 fatty acids||The AI is 17 g/d for men and 12 g/d for women*|
|Folate (folic acid)||400 µg/d; the UL is 1,000 µg/d*|
|Vitamin B12||2.4 µg/d; no UL as been set*|
*Set by the Institute of Medicine
**Suggested intake levels only—based on “typical” dosages used in studies
Are Supplements Worth it?
Clearly, the market for memory enhancers is huge. And, as the population ages, interest in ways to slow or stop the progression of Alzheimer’s disease will only continue to grow. Unfortunately, since further research is needed, it may be years before the benefits and risks of supplements are fully established. Moreover, supplements are expensive. Some brands could cost you $100 a month or more.
Furthermore, patients and families of AD patients should be sure to talk with their doctors before taking any supplements or over-the-counter medications.
In the meantime, consider that by exercising, eating right, and using your mind—reading books, playing games, learning a new language—you will greatly improve your chances of preserving mental acuity. It may not be as simple as popping a pill, but the gains are worth it.
Alzheimer’s Disease Education and Referral Center
Food and Drug Administration (FDA)
National Alzheimer’s Association
Office of Dietary Supplements, National Institutes of Health (NIH)
Alternative Treatments: Buy? Or beware? Alzheimer's Association website. Available at: http://www.alz.org/ResourceCenter/Advances/Winter2000.pdf. Accessed July 30, 2003.
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Last reviewed October 2007 by Rimas Lukas, MD
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