Resveratrol: potential impact on Alzheimer’s

photo by ThinkStock via Tri County Health Dept

photo by ThinkStock via Tri County Health Dept

As the population ages, research into Alzheimer’s disease treatment and prevention has increased. A recent study examined the potential impact of resveratrol, a naturally occurring plant compound, on people with mild to moderate Alzheimer’s disease.

What is it?

Resveratrol is a phenolic, antioxidant compound found naturally in foods such as red wine, grapes, peanuts, seeds, flowers and the bark of various plants. Primarily due to this compound’s antioxidant properties, many believe there are potential health benefits from consumption of resveratrol. A few of the current perceived health benefits are below.

Perceived health benefits of resveratrol:

  • Cholesterol lowering
  • Reduction of blood clot formation (reducing risk of heart attack and stroke)
  • Decrease in blood sugar levels
  • Reduction of risk for various cancers
  • Reduction of brain plaque levels in those with Alzheimer’s disease

Human studies on the perceived health benefits of resveratrol are currently lacking. Long-term studies identifying the efficacy, safety and effectiveness of resveratrol are needed before definitive recommendations can be responsibly put forth.

Bioavailability- or lack thereof:

One study looked specifically at the absorption, bioavailability and metabolism of resveratrol. This study, which reviewed current research, found gaps when it came to studies in humans. Most studies on resveratrol to date have used cell/tissue or animal models to evaluate effects, which does not always mimic absorption and bioavailability in humans. Current research indicates that resveratrol has an oral absorption rate of approximately 75% (which is a high absorption rate for a dietary polyphenol) although the bioavailability of the polyphenol is close to zero. Bioavailability is different from oral absorption in that it refers to the availability of the absorbed compound for use in the body, which in this case is much lower than the oral absorption. Additional research to enhance understanding of the mechanisms of absorption and bioavailability is essential.

Resveratrol supplementation:

It is important to note that like other supplements on the market, the U.S. Food and Drug Administration (FDA) does not regulate resveratrol supplements. Without FDA regulation, there is no way for consumers to be sure they are getting what the bottle says that it contains. Supplements also lack specific dosage recommendations that have been properly studied for safety and efficacy.

Currently, there is no recommended daily dose or intake level for resveratrol. Use of supplements at this time due to gaps in research- specifically regarding the long-term effects of use. While resveratrol is found in various foods, total content in these is not well documented. One source references a few content studies. These studies found resveratrol content for 1 cup of raw peanuts to be 0.01-0.26 mg and 1 cup of red grapes to be 0.24-1.25 mg. These numbers are significantly lower than any resveratrol supplement dosage used in research up to this point.

Dosage:

Studies using resveratrol have routinely used high dosage supplementation as opposed to intake from dietary sources. Some studies have used dosages equivalent to the amount found in over 1000 glasses of red wine (red wine contains approximately 1-2 mg of resveratrol per 8oz.) The most recent study on resveratrol related to Alzheimer’s disease (discussed below) used a max resveratrol dosage of 2000 mg per day.

Resveratrol and Alzheimer’s:

Most recently, results of a yearlong human clinical trial focusing on the safety, efficacy and potential impact of resveratrol on Alzheimer’s disease have surfaced.

Study Details:

  • Who? Individuals with mild to moderate Alzheimer’s at start of study
  • Number of participants: 119 (104 at end of 52 weeks)
  • Length: 52 weeks
  • Treatment groups: Resveratrol (see dosage below) versus placebo (no resveratrol supplementation)

Oral Dosage for resveratrol supplementation:

Start- 500mg once daily

Every 13 weeks- increase in dosage by 500mg

End dose- 1000mg twice a day- 2000mg daily total (similar to amount of resveratrol found in 2000 glasses of red wine)

 Results of the study:

  • Resveratrol was considered safe and well-tolerated for the duration of the study
  • Resveratrol was able to be absorbed into the brain (passed through the blood-brain barrier) to affect the central nervous system- larger studies are needed to determine if this is beneficial

Conclusions:

  • Resveratrol is a polyphenol found in various dietary sources including red wine, dark chocolate and peanuts.
  • Resveratrol supplementation is not regulated by the FDA and is not currently recommended for use.
  • Studies using resveratrol supplementation have used very high doses.
  • This study did not find any clear benefits to resveratrol supplementation in those with Alzheimer’s Disease- more research is needed.
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