By Dr. Mercola
Ask several people what their favorite fruit is, and a good number of them will say strawberries. But aside from being luscious and one of the most fragrant, colorful essences of summer, this fruit contains a powerful compound that can make a remarkable difference in treating, improving and protecting against many disorders and diseases in your body.
This somewhat obscure compound, fisetin, has been shown to decrease pain, prevent toxicity, maintain energy and improve your energy levels on a macro level, translating to more specific benefits in your overall health. Forbes noted:
"Never heard of fisetin? That's because it was only identified a little more than a decade ago when scientists isolated plant flavonols with the ability to protect brain cells from degeneration. Like the similar flavonol quercetin, it's a sirtuin-activating compound that mimics many of the natural effects of calorie restriction, a well-studied anti-aging strategy."1
Also the coloring agent, fisetin is also a flavanol, also found in persimmons, apples, mangoes, grapes, cucumbers and onions, but strawberries contain the most by far, according to a 2013 study.2 A Japanese study reported that the highest concentration of fisetin was found in strawberries (160 μg/g, or microgram/gram) followed by apple (26.9 μg/g) and persimmon (10.5 μg/g).3
While fisetin has antioxidant properties, which can help curb cell damage caused by free radicals, one of the most dramatic ways it impacts your health is targeted toward your brain, as studies indicate it can help prevent Alzheimer's and other age-related neurodegenerative diseases.
According to Forbes, Pamela Maher, senior staff scientist at the Cellular Neurobiology Laboratory at the Salk Cellular Neurobiology Laboratory, called fisetin a "novel neuroprotective and cognitione-enhancing molecule."4 She and her colleagues spent 10 years conducting studies on fisetin to find additional brain benefits as well as benefits for other areas of the body.
According to the study,5 some of the ways fisetin impacts your brain health is that it helps protect against damage due to injury and degeneration from aging and also improves your memory while working with other compounds, activating nerve cells and increasing the defense systems throughout your brain and body.
Fisetin Studies Related to Brain Aging
One of Maher's studies in 2014 focused on memory loss in mice due to familial Alzheimer's, which is a type that accounts for only 3 percent of cases. The newest study examined possible fisetin advantages on sporadic Alzheimer's disease, the most common type associated with age.6 Scientists used mice that had been "genetically engineered to age prematurely, resulting in a mouse model of sporadic Alzheimer's disease," Medical News Today said:
"When the prematurely aging mice were 3 months old, they were divided into two groups. One group was fed a dose of fisetin with their food every day for 7 months, until they reached the age of 10 months. The other group did not receive the compound.
The team explains that at 10 months of age, the physical and cognitive states of the mice were the equivalent to those of 2-year-old mice. All rodents were subject to cognitive and behavioral tests throughout the study, and the researchers also assessed the mice for levels of markers linked to stress and inflammation."7
Assessment then revealed that the 10-month-old mice not given fisetin had more markers linked to stress and inflammation, and performed "significantly worse" in cognitive testing than those given fisetin. Maher termed the differences "striking." More specifically, two neurons, astrocytes and microglia, usually considered anti-inflammatory, were actually promoting inflammation in the brains of the no-fisetin mice.
Those dosed with the compound were reported as having the behavior and cognitive function of 3-month-old mice — their actual age. Alzheimer's Prevention noted fisetin halted memory loss in mice typically prone to Alzheimer's within a year of their birth.8 Maher and company noted that while mice aren't people, there were enough similarities indicating fisetin's potential as a preventative, not just for Alzheimer's, but many age-related cognitive diseases, that they encouraged further rigorous studies.
Fisetin Decreases Brain Damage From Stroke, Minimizes Damage From Injury
Fisetin is not a new compound. Other clinical studies and examinations have revealed its incredible potential for several years, but its strength was usually attributed to its free radical-scavenging antioxidant properties (which are, of course, extremely important). However, SelfHacked notes several highly significant studies on how fisetin protects your brain:
- Mice treated with fisetin showed fewer behavioral abnormalities after a stroke than mice that weren't.9 Another study showed how the compound helps protect the parts of the brain starved of blood flow during a stroke.10
- It was one of 10 flavonoids tested for protective effects against glutamate toxicity and found to be one of four that increased neuroprotective and anti-inflammatory effects. (Sulfuretin, butein, butin and eriodictyol were the other four.)11
- In the case against brain injury induced by a head injury causing repeated seizures characterized by traumatic epilepsy, a study indicated that animal models experienced fewer episodes when they were treated with fisetin.12
- Indicating its effectiveness in inhibiting inflammatory pathways, rats given high doses of fisetin showed far superior neurological function and less brain swelling after brain injury.13
Fisetin also increases SIRTI, an enzyme that can "'turn off' certain genes that promote aging, such as those involved in inflammation, fat synthesis and storage, and managing blood sugar levels.
Fisetin's Protection Against Brain Degeneration
• A 2004 study of Maher's revealed that as a flavonoid, fisetin protects nerve cells from oxidative stress by "multiple mechanisms."14 The upshot was that, among several flavonoids, fisetin was most effective at causing new brain growth.
• Another involving scientists from Salk as well as from Australia, Germany and Austria showed one reason the compound had so many brain-boosting effects was due to its ability to cross the blood-brain barrier.15 (BrainFacts explains that "the brain is the only organ known to have its own security system, a network of blood vessels that allows the entry of essential nutrients while blocking other substances."16)
• Supplementation with fisetin increases the strength of long-term memory pathways, which may influence memory disorders like Alzheimer's.17 It regulates several pathways, such as mitochondrial and antioxidant function, connected with age-related brain decay.18 Glutathione, a key cellular antioxidant with the ability to protect nerve cells, is increased by a mechanism that activates transcription factors, such as Nrf2.
• Fisetin limits the buildup of harmful compounds in your brain like phosphorylated tau, which are implicated in Alzheimer's.19 It's also useful for decreasing inflammation in microglia, immune cells that can exert neurotoxic effects and which are often activated in neurogenerative disorders.20
• Fisetin also was found to slow progression of Huntington's disease, an ultimately fatal neurodegenerative disorder characterized by psychiatric, cognitive and motor symptoms in animal studies by activating the Ras-extracellular signal-regulated kinase (ERK) cascade.21
Neuroprotective Aspects of Fisetin
Aluminum chloride, a neurotoxin, is a common ingredient in one of the products many Americans say they would never go without: antiperspirants. But fisetin has been shown to protect against the damaging effects of this common household ingredient.22 Fisetin was shown to lower elevated levels of ammonia in blood (hyperammonemia) with the potential to damage vital brain functions in hyperammonemic rats.23
Another brain protective aspect of fisetin, shown in mice, is its power to increase serotonin, which helps elevate your mood and energy, and noradrenaline, a hormone produced naturally by the body that functions as a neurotransmitter. One study explains the importance of noradrenaline "to maintain the cognitive processes such as attention, perception, and particularly the memory consolidation and retrieval. Disruption of these processes may result in symptoms of neuropsychiatric diseases and neurodegeneration."24
Mice given fisetin in another study revealed fewer symptoms of anxiety and depression brought on by pain.25 Further, the antidepressant effects of fisetin are shown to be enhanced by 5-Hydroxytryptophan (5-HTP), an amino acid precursor of serotonin, with additional benefits for anti-anxiety, sleep and weight loss, SelfHacked explains.26
More Ways Fisetin Supports and Protects Your Body
It's easy to see how many vital roles fisetin plays in your body, for brain health and several aspects under a similar umbrella, such as mental health and inflammation, which translate in your body to more optimal health and well-being, including:
- The treatment of inflammatory bowel disease (IBD) and inflammatory responses caused by high blood sugar
- Suppression of mast cells, found in tissues, especially in your skin, respiratory and GI tracts
- Allergic reactions due to inhibiting inflammatory cytokine production
- Treatment for eczema in animals, reducing inflammatory cytokines, eosinophils (disease-fighting white blood cells), mast cells and T-cells (white blood cells involved in immunity) found in skin lesions27
- Inhibits pathways needed for overactive cancer cells to grow and survive,28 inhibits their ability to invade healthy tissues, discourages proliferation and induces apoptosis of certain leukemias, including chronic myeloid leukemia (white blood cell cancer)29
Strawberries: One of the Most Popular Fruits in the US — And the Dirtiest
Strawberries are one of the top fruit picks for many Americans, as stats show that combined with other berries such as raspberries, blueberries and cranberries, they come in fifth, according to the U.S. Department of Agriculture.30 California is the largest strawberry-growing state in the U.S., producing 1.5 million tons in 2015. Bananas come in first, followed by citrus fruits, apples and watermelon.
Strawberries contain the highest concentrations of fisetin, but it would require eating 37 of them to get the optimal amount for actual benefits (or nine servings of other fisetin-containing fruits), so supplementation has been an ongoing endeavor for more than one company. Besides the above fruits, there are other fisetin-producing plants, including acacia trees, honey locust and the Japanese wax shrub.
But according to the Environmental Working Group (EWG), strawberries are again the No. 1 fruit on the Dirty Dozen List of the most pesticide-laden crops, which means that as American eat their 8 pounds of this fruit per year, they're also ingesting dozens of varieties of pesticides, including chemicals known to cause cancer and reproductive damage, many of them banned in Europe. EWG notes:
"What's worse, strawberry growers use jaw-dropping volumes of poisonous gases, some developed for chemical warfare but now banned by the Geneva Conventions, to sterilize their fields before planting, killing every pest, weed and other living thing in the soil … USDA (U.S. Department of Agriculture) tests found that strawberries were the fresh produce items most likely to be contaminated with pesticide residues, even after they are picked, rinsed in the field and washed before eating."31
How Can You Keep From Ingesting Toxins on Strawberries? Grow Your Own
The only way to avoid ingesting the chemical concoctions doused on strawberries, EWG asserts, is to grow your own, organically, or buy organically grown strawberries, as the list of hazardous chemicals on conventionally grown varieties is long and harrowing, including such toxins as:
- Carbendazim, a hormone-disrupting fungicide
- Bifenthrin, an insecticide California regulators call a possible human carcinogen
- Malathion, toxic to the nervous system and a probable human carcinogen
Unfortunately, as good as fisetin is for you, if you don't grow your own clean crop of strawberries or buy them from a source you know is organic, without any of the potentially neurologically system-poisoning sprays they're typically grown with, I would recommend passing them up until you can find a good source.
Research shows that organic produce has about 180 times fewer pesticides on them than conventional produce. In lieu of that, if you know you're suffering because of a lifetime of eating tainted fruits and vegetables, you can eat fermented foods such as cauliflower and cabbage, and even make your own kimchi, as studies show it can actually break down the toxins and negate some of the damage to your system.