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This blog is part of an ongoing blog series, where we cover different causes, testing methods, and treatment protocols for Cognitive Decline. Learn more here.
5.7 million Americans are living with Alzheimer’s Disease (AD). Alzheimer’s disease and other related dementias are on pace to double by 2060 in the United States. While these statistics are pretty draining to see, the good news, thanks to the work of Dr. Dale Bredesen, is that we have the tools and research to use nutrition and lifestyle modifications to significantly reduce the risk of cognitive decline and modify the trajectory of early-stage cognitive impairment.
When working with patients who want to prevent or reverse symptoms, we look at many different potentially-contributing factors across their history, physiology, metabolism, diet and lifestyle. Among that, nutrition is one of the most powerful tools we have to effect change. What we eat can either significantly improve or worsen cognitive conditions.
A plant-rich diet has been correlated with reduced risk of AD and dementia. Scientists believe that is in large part because many plants are rich sources of phytonutrients, and especially polyphenols.
What are phytonutrients and polyphenols?
Phytonutrients, also known as phytochemicals, is the term for naturally occurring chemical compounds found in plant-based foods that often contribute to the color of fruits, vegetables, herbs, teas, legumes, and grains. Apart from macronutrients (carbs, protein, fat), and micronutrients (vitamins and minerals), phytonutrients have a wide range of benefits to our health.
There are thousands of phytonutrients, and we’re only beginning to scratch the surface of our understanding of them in scientific studies. However, the preliminary science is overwhelmingly optimistic! The benefits associated with these compounds include antioxidant, anti-inflammatory, antiviral, and antibacterial effects, positive epigenetic contributions (turning on “good” genes”), repairing cell damage, and boosting the immune function.
Polyphenols represent a large category of phytonutrients that are powerful antioxidants with free radical scavenging capabilities as well as anti-inflammatory activity. They have been shown, in general, to reduce oxidative stress and the risk for many diseases, including neurodegenerative diseases such as Alzheimer’s disease, as well as Parkinson’s and Huntington’s disease.
The consumption of certain polyphenols has been shown to enhance learning and memory as well as general improvement of cognition.
What is oxidative stress and how does it relate to cognitive health?
Oxidative stress is a process that involves the excessive production of free radicals (agents that cause damage to cells and DNA). In a heightened state of oxidative stress, we are at risk of developing disease. When it comes to cognitive decline, excessive amounts of free radicals are produced leading to cell damage associated with neurodegeneration (damage to brain cells and neurons).
Antioxidants, including vitamins like C and E, as well as some phytonutrients, serve to neutralize the oxidative species and protect our DNA and cells from damage. We talk about some of these pathways in our food guide for preventing Alzheimer’s Disease. It’s thought that many polyphenols exert their effect on cognitive function by improving neuron generation and survival by reducing oxidative stress and damage.
Different categories of polyphenols and their effects on brain function
Flavonols such as quercetin, kaempferol, and myricetin are the most abundant flavonoids in plant foods. Higher dietary intake of the flavonoid flavonol may be associated with reducing the risk of developing Alzheimer’s. A just-published (Jan 2020) prospective cohort study of older adults infers that people who consumed the highest dietary intake of flavonols were 48% less likely to develop Alzheimer’s dementia than people with the lowest intake of these foods.
The flavonol quercetin may possess a protective effect against the neurotoxicity of amyloid β-peptide associated with AD. Quercetin has also been found to regulate NF-κB, a key compound in the modulation of biological inflammatory pathways, which could lead to an improvement in inflammation involved in neurodegenerative diseases.
Foods high in flavonols include:
- leafy vegetables
Anthocyanins are flavonoid pigments that give plants deep red, purple and blue colors. They are powerful phytonutrients with significant cardioprotective, neuroprotective and antitumor properties.
Foods high in anthocyanins include:
- Deep red, purple berries and blueberries
- Red wine
- Leafy and root vegetables (eggplant, cabbage, beans, onions, radishes)
Blueberries, in particular, have been shown to possess powerful neurocognitive benefits. Studies show enhanced neural response during working memory challenges in the at-risk population. Blueberry concentrate improved brain perfusion and activation in brain areas associated with cognitive function in healthy older adults.
Catechins and epicatechins are flavonoids found mostly in green tea and cocoa.
Research investigating the relations between cocoa and cognition show improvements in general cognition, attention, processing speed, and working memory. Cocoa flavonoids could also enhance normal cognitive functioning and exert a protective role on cognitive performance. When choosing chocolate, it’s important to consume sources of cacao that are in the form of plain, dairy-free, low sugar dark chocolate. This is the form that has been shown to increase a person’s total antioxidant capacity and ultimately protect the brain from cognitive decline.
Epigallocatechin gallate (EGCG)
The flavonoid Epigallocatechin gallate, also known as EGCG, can be found in high amounts in green and white tea. EGCG has been reported to be an even more effective free radical scavenger (antioxidant) than the already-powerful vitamins E and C.
Green tea has been shown to improve working memory, which is the capacity to hold information briefly in memory while performing other mental operations on the information. Both green and white tea extracts have been shown to inhibit an enzyme called acetylcholinesterase, a mechanism that has been identified as a potential treatment of AD and dementia.
Green tea has been extensively studied due to the significant health benefits associated with the antioxidant activity from the phytochemicals it contains. Studies have identified that consumption of 2 or more cups of tea per day may reduce the prevalence of cognitive impairment.
Olive polyphenols – Oleuropein/Hydroxytyrosol/Tyrosol
Olive oil contains over 30 phenolic compounds that are potent antioxidants and free radical scavengers, however the major phenolic compounds in olive oil are oleuropein, hydroxytyrosol and tyrosol.
Many reports demonstrate that the phenols from olives and olive oil exert strong antioxidant properties and are able to counteract oxidative stiff in brain tissue. Besides the antioxidant activity of these polyphenols, there is a great potential for these compounds to counteract amyloid aggregation and toxicity on the pathways involved in the onset and progression of Alzheimer’s disease.
To source these beneficial polyphenols, choose first cold-pressed, extra virgin olive oil, in a dark glass bottle. Keep it out of direct sunlight and use before the best by date. Since polyphenols tend to have a more pungent, sometimes peppery, flavor, you can also get a rough gauge of polyphenol content from the taste.
Resveratrol, a stilbene polyphenol, has been known to possess cardiovascular benefits but has also been found to enhance brain health. Benefits involve multiple mechanisms including anti-oxidative, anti-inflammatory, anti-apoptotic processes. Furthermore, because of its effects on vascular function, we should not be surprised that resveratrol increases cerebral blood flow and improvements synaptic plasticity (building new neuronal connections).
Regular consumption of foods rich in resveratrol has been shown to enhance brain function, memory, and brain connectivity in older adults. Resveratrol is found in the greatest amounts in grapes and red wine. Polyphenols in red wines, including resveratrol, may help slow dementia by inhibiting β-amyloid generation as well as the promotion of β-amyloid clearance. Another suggested pathway involves modulating tau neuropathology.
A note on wine consumption and brain health. Consumption of alcohol might have a negative effect on brain health, not outweighed by the relatively small resveratrol concentration. It can also be commonly found in concentrated amounts in supplements, which might be a more effective way to counter cognitive decline for some individuals, particularly where consumption of wine might be counterproductive.
Carnosic acid is a phenolic diterpene found in herbs such as rosemary, sage and oregano. Carnosic acid possesses antioxidant and antimicrobial properties.
Due to the antioxidant and antiapoptotic (prevention of cell death) potential of carnosic acid, it could play a protective role in the prevention of neurodegeneration. These can be consumed as whole herbs or extracts, as well as essential oils. One study found that inhaling rosemary oil helps prevent the breakdown of acetylcholine, a brain chemical that plays an important role in concentration and memory.
The bioactive polyphenol curcumin, found in the turmeric plant, is said to be one of the most extensively studied compounds due to its potent antioxidant and anti-inflammatory properties. Curcumin protects the brain from free radicals lipid oxidation to ultimately prevent cognitive decline. Another suggested mechanism in cognitive decline prevention and treatment is associated with its ability to bind to amyloid plaques and modulate inflammation through NF-κβ.
Curcumin has been associated with general improvements in cognitive function, better mood, and protective effects against various brain diseases. It’s been suggested that high consumption of curcumin in India might, at least in part, contribute to the relatively low prevalence of Alzheimer’s disease in that country.
The following table summarizes the phytonutrients discussed and the foods rich in those brain-boosting benefits. You might also want to download our free guide for preventing Alzheimer’s disease here.
Leafy and root vegetables (eggplant, cabbage, beans, onions, radishes)
Looking for more support?
Phytonutrients are one aspect of our Functional Memory Rx approach for the protection of brain health and the prevention of cognitive decline. Along with diet, we focus on incorporating other important lifestyle modifications. However, if you’re feeling overwhelmed or simply need added guidance, leaning on Functional Medicine clinicians trained in the implementation of the Bredesen ReCODE protocol might be your next best step.
Dr. Bredesen’s Protocol + Functional Medicine = Best Outcomes
In our clinic, we see the best outcomes when combining Dr. Bredesen’s protocol with our full Functional Medicine approach.
The entire process leads to comprehensive diagnostic and treatment programs for our patients. Our advanced lab assessments go far beyond what is available in a conventional medical or neurology clinic, enabling us to identify underlying brain-impacting imbalances that standard medicine evaluations usually ignore such as:
- Hormone imbalances
- Blood sugar control
- Environmental toxins and infectious triggers
- Nutrient deficiencies
- Food-related allergies and sensitivities
- Gastrointestinal inflammation
- Digestive function
- Microbiome imbalances in the gut
Why is our combined approach effective?
- We use specific tests to measure underlying factors driving the formation and removal of amyloid plaque, which is felt to be the main final disease mechanism in Alzheimer’s
- We lean on Dr. Bredesen’s system to accurately classify the disease by 6 subtypes based on specific testing, informing individual treatment based on the root cause
- A comprehensive plan addresses accompanying lifestyle factors, especially diet, sleep, stress management, and exercise.
- Personalized protocols address the root causes of the disease for each individual patient, including gut health, hormonal balance, environmental exposures, and infectious triggers.
- We establish a systematic and full systems approach to the prevention and treatment of Alzheimer’s and cognitive decline.
Contributing Author: Mary Ellen Valverde MS CNS LDN
Mary Ellen is a Certified Nutrition Specialist and a graduate of the clinic’s Functional Nutrition Residency Program (FNRP). She holds a Master of Science in Nutrition from the University of Bridgeport as well as an MLIS in Library and Information Science from Rutgers University. Mary Ellen is a plant-based educator focusing on fighting inflammation, find her at https://maryellenvalverde.com/