People who were already showing early signs of the disease discovered their symptoms-such as memory loss or cognitive abilities-didn't progress while they were taking resveratrol supplements.
Supplements deliver far higher levels of resveratrol than is realistically achieved from food or wine. One 500 mg supplement-which the volunteers started out with-is equivalent to around one thousand bottles of red wine.
In the experiment by researchers at the Georgetown University Medical Centre in Washington, 119 people with mild to moderate Alzheimer's were given the supplements for a year, or instead given a placebo, or sugar pill. Those given the supplements started out on 500 mg a day, but this was increased to 1000 mg twice a day after around six months.
Their blood bio-markers and brains were regularly scanned during the year, and those taking the supplements saw a slowing of the markers for the disease, although they did suffer a few minor side effects, such as nausea, diarrhea and weight loss.
Resveratrol was also able to cross the blood-brain barrier to slow brain loss, the researchers said.
(Source: Neurology, 2015; 10.1212/WNL.00000000000002035)