Can Supplements Reduce Your Risk of Alzheimer Disease?
Alzheimer disease (AD), the most common form of dementia, is a progressive, degenerative disorder of the brain that slowly impairs the ability to carry out daily activities.Since there are only a few medicines available to slow the progress of Alzheimer disease, many companies are promoting the use of certain supplements to prevent and treat memory problems. Scientists are 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 consistently helpful in fighting Alzheimer’s disease.
Supplements Studied to Stop or Slow the Progression of Alzheimer Disease
There are several different types of supplements that have been studied to see if they improve function in adults with Alzheimer disease or prevent the risk of Alzheimer disease in adults who do not yet have impaired function.
An excess of free radicals (also known as oxidants) may contribute to the development of Alzheimer disease. Antioxidants theoretically may protect against Alzheimer’s disease by limiting the buildup of toxic amyloid protein. Diets rich in foods containing antioxidant vitamins, such as E
, have been associated with a reduced risk of Alzheimer disease. However, the supplement forms of these vitamins have not shown the same association. Also one randomized trial failed to show that vitamin E supplementation prevented Alzeimer's disease. A meta-analysis noted an increase risk of death (due to all causes) in patients taking high doses of vitamin E. But, based on the evidence so far, it does not appear that supplements are useful for the prevention of Alzeimer disease.
, thought to help deliver oxygen to the brain by improving blood flow to capillaries, is the most widely used herb to improve cognitive function. However, overall the data thus far is inconclusive. Some studies have found some benefit as a treatment in improving cognitive function in patients with dementia while others have not.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. It also may have some benefit as a treatment for patients who already have Alzeimer's disease. However, there is 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 use 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:
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. Overall, literature reviews suggested that it may only be mildly helpful at best for Alzheimer disease.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 alfoscerate have also shown some promise.It has been suggested that a dietary deficiency of omega-3 and omega-6 (essential) fatty acids could be a risk factor for Alzheimer disease. Evidence appears to be mixed. One review of 3 studies found that omega-3 fish oil supplements did not improve cognitive function in healthy adults over 60 years old. In contrast, 3 observational studies found that eating fish 2 or more times a week reduced risk of dementia and Alzheimer disease compared to those who did not eat fish. From these studies, it appears that evidence supports eating fish, but not taking pills with these fatty acids in them.