Fisetin is a flavonol found in strawberries, nuts, wine, onions, cucumbers, apples, and persimmons. By far the highest concentration is found in strawberries, which contain 160 mcg/gram. That’s five to 10 times higher than the next highest fruit or vegetable.

One study found that among all fruits and vegetables, strawberries, blueberries, and spinach were the only plants that could not only stop brain aging, but also could reverse it. (This study used a strawberry concentrate, not whole strawberries.)

There are three animal models of Alzheimer’s disease, and fisetin has consistently prevented loss of cognitive function in all three models. In these studies, fisetin reduced brain inflammation, oxidative stress, and lipid peroxidation, and stimulated brain cell pathways that enhance memory and brain cell growth. In another study, fisetin significantly improved mental function and memory in an animal model of vascular dementia.

Studies using animal models of Parkinson’s disease showed that fisetin could reverse many of the pathological effects of the disease. Fisetin increased dopamine levels in the striatum (a structure in the forebrain), protected neurons in the substantia nigra, improved movement, and improved energy production by these neurons. Higher doses were more effective.

Fisetin has also resulted in significant benefits in animal models of other neurological disorders, including ALS, Huntington’s disease, ischemic and hemorrhagic strokes, subarachnoid hemorrhage, and traumatic brain injury.

Fisetin has also been shown to significantly reduce age-related brain pathology, lower measures of oxidative stress, and increase levels of antioxidant enzymes in the brain. It significantly increases both health span and life span.

One of the more dramatic ways fisetin improves resistance to disease and aging is by elevating the level of glutathione in cells. Glutathione is one of the cell’s most important antioxidant molecules. But glutathione is depleted by aging. This depletion is associated with impaired learning and memory, can trigger high levels of free radical generation and lipid peroxidation, eventually leading to cell death.

The most important way fisetin improves general health, as well as brain health, is by removing senescent cells. One of the more rigorous tests of fisetin’s ability to protect the brain against neurodegeneration used a type of mice (SAMP8) specifically bred to develop rapid aging and extensive senescent cell accumulations with most of the features of human Alzheimer’s diseases. Mice fed fisetin for seven months experienced no loss of motor function or cognition. Brain inflammation and other markers of free radical attack were partially reduced.