By Leslie Taylor ©2025

The previous article in this series has explained that if your diet is the common low-polyphenol Western diet, then you are probably already dealing with some level of chronic low-grade inflammation and oxidative stress. Tens of thousands of studies agree that this increases your risks of getting one or more chronic diseases. And it's literally just a matter of time.

Diseases Caused by Oxidative Stress and Chronic Inflammation

We now know that inflammation and oxidative stress can be a cause or a contributing factor to a wide range of diseases, including almost every chronic disease. From heart diseases (clogged arteries, high cholesterol, high blood pressure, and heart failure) to diabetes and metabolic syndrome, Alzheimer’s disease and dementia, and cancer to autoimmune diseases, and even obesity—chronic inflammation and oxidative stress are playing significant roles. Many of these studies reveal that when you reduce oxidative stress and chronic inflammation, it has a beneficial impact on these conditions. Better yet, if you manage your levels of oxidative stress and chronic inflammation with polyphenol antioxidants, you can avoid developing these many conditions. Polyphenol compounds with antioxidant and anti-inflammatory actions have surfaced in all this research as the most important natural plant compounds available to us that have the ability to help prevent these diseases.

Obesity

New research indicates that obesity is actually a chronic inflammatory disease, and the fatty tissues of overweight individuals are inflamed and suffering from oxidative stress and immune cell damage. When fat cells and fatty tissues are damaged by inflammation and oxidative stress, they do not produce enough of certain natural metabolic chemicals that are required to reduce inflammation, store and burn fats, maintain insulin sensitivity, and to maintain a healthy weight.

Scientists have now discovered more than 80 adipokines that are secreted by fat cells, many of which have known metabolic actions. Research has increased significantly on these natural fat-produced substances and their roles in obesity, diabetes, heart diseases, and other disorders since 2010. New knowledge about these substances and their roles have encouraged the development of new drugs targeting this metabolic system in the treatment of obesity, metabolic diseases, and heart conditions.

Since our fatty tissues and fat cells expand as we gain weight, all these fat-secreted deregulations and resulting inflammation and oxidative stress increases as our fat increases. You don’t have to be obese either; just gaining some extra weight can start the process and head you down the road to deregulations. These deregulations make it much harder to lose weight, and some can make it virtually impossible to lose weight. Adipokines also help regulate functions in the heart and how we process sugar and insulin. Obesity-caused adipokine deregulations are now the main link of why obesity significantly increases our risks of developing type 2 diabetes and cardiovascular disease.

A significant amount of research has been conducted in humans and animals on many different polyphenols that report weight-loss benefits and actions. The main mechanisms of actions reported is the reduction of oxidative stress, AGEs, and chronic inflammation, in addition to some polyphenols’ ability to lower the calories in foods by blocking digestive enzymes that break down fats, sugars, and starches before they can be absorbed.

Cardiovascular Diseases

Adipokines produced in our fat cells control how we regulate our blood pressure and fluid balance, create new blood vessels, and how well our hearts contract to regulate blood flow. The direct deregulations of adipokines in fat cells created by obesity is now considered a main reason that, when we gain too much weight, we are at greater risk for developing heart problems.

In addition to fat deregulations, free radicals are particularly damaging to the cells in the heart and cardiovascular system because they are actually circulating in our bloodstream and are in constant contact with our veins and arteries. Thousands of studies report the mechanisms by which free radicals and the oxidative damage and the inflammation they cause can contribute to the development of clogged arteries, high blood pressure, peripheral vascular disease, coronary artery disease, heart failure, cardiomyopathy, and cardiac arrhythmias.

Free radical damage is also the main reason people who smoke cigarettes have much higher risks for developing cardiovascular diseases. Cigarette smoke actually contains free radicals, and the chemical reactions smoke creates in the lungs generates significantly more free radicals. Chemicals used in e-cigarettes and vaping solutions are poorly studied for possible free radicals they might produce in the lungs. The recent reports of lung inflammation and lung cell death (the hallmark of free radical damage) don’t bode well for the safety of these poorly studied vaping chemicals going into your lungs. If you stop smoking, free radical production in your body will drop dramatically and you’ll reduce the risk of free radical damage to your heart and cardiovascular system to prevent heart diseases in addition to curbing the damage to your lungs.

Polyphenol antioxidants, especially those found in rainforest plants, are the subject of a substantial body of research documenting their actions and benefits to the cardiovascular system and their ability to prevent heart diseases. Many human, animal, and in vitro studies report that polyphenols exert beneficial effects on the vascular system via the increase of antioxidant defenses and reduction of oxidative stress. These beneficial effects include lowering blood pressure, improving endothelial function, inhibiting platelet aggregation (which reduces blot clots), reducing low-density lipoprotein (LDL) cholesterol oxidation, and relieving chronic inflammation by reducing inflammatory responses. The link between polyphenol consumption and the reduction of heart disease risk is well established and widely accepted.

Diabetes and Metabolic Diseases

Type 2 diabetes is also categorized as a chronic inflammatory disease that is associated with oxidative stress and insulin resistance. The increased production of reactive oxygen species (ROS) or a reduced capacity of the ROS-scavenging antioxidants can lead to abnormal changes in intracellular signaling and result in chronic inflammation and insulin resistance. Prevention of ROS-induced oxidative stress and inflammation can be an important therapeutic strategy to prevent the onset of type 2 diabetes and well as diabetic complications and co-occurring diseases.

New research also reveals that fat cell–produced adipokines play important roles in glucose metabolism and insulin resistance. It is established through human research that adipokines are deregulated in people with diabetes, and these deregulations are one of the underlying reasons obesity or just being overweight increases the risk of developing type 2 diabetes. Since many of these adipokine deregulations can be remediated with substances that reduce inflammation and oxidative stress, polyphenols have evolved as natural substances that can treat or prevent diabetes.

The initiation and progression of diabetes can also be linked to higher AGE levels in the body and the cellular damage, generation of additional free radicals, and inflammation these AGEs cause. A significant body of research represents important advances related to influence of polyphenols and polyphenol-rich diets on preventing and managing type 2 diabetes. This research reveals that the main methods of actions polyphenols utilize to prevent diabetes include protection of pancreatic beta cells against glucose toxicity; anti-inflammatory and antioxidant effects; inhibition of digestive enzymes, which decrease starch conversion and sugar absorption; and inhibition of AGE production. Anthocyanin-type polyphenols have also been reported to exhibit antidiabetic properties by reducing blood glucose and HbA1c levels as well as improve insulin secretion and resistance in human and animal studies.

Cancer

It is well established that free radicals can damage DNA in various cells in our bodies. This DNA damage can result in a healthy cell mutating into a cancerous cell. For that reason, one of the main roles our natural built-in antioxidant system plays are to protect us from cancer by preventing the DNA damage free radicals can cause. This aspect is certainly a good reason to keep our antioxidant systems in good working order! Many plant polyphenol antioxidants have been clinically verified to protect cells from mutating into cancerous cells, and some have even been documented with the ability to repair the DNA damage already caused by free radicals. This has resulted in many studies around the world reporting that polyphenol-rich diets, as well as supplements rich in polyphenols, provide highly effective cancer-preventative actions.

Plant polyphenols (including novel ones only found in rainforest plants) also have the ability to bind to other chemical substances (mostly enzymes and proteins) in the body that are found in well-known signaling pathways that cancer uses to promote its development, encourage its growth, invasiveness, and metastasis, and escape detection from the immune system. When many of these signaling pathways are changed by plant polyphenols, it has a direct effect of killing the cancer cells, or restoring natural processes that allows the immune system to start killing the cancer cells again.

It is well established, however, that people who are battling cancer have a decreased antioxidant capacity, higher levels of damaging free radicals, and can be vitamin C deficient since their body’s natural processes are trying to battle the cancer and are depleting these natural resources. These issues can be much worse while taking chemotherapy drugs. Taking rainforest plant antioxidants as nutritional support while battling cancer can be a good strategy.

Neurodegenerative Diseases and Brain Disorders

Neurodegenerative disorders—including dementia, Parkinson’s disease, and Alzheimer’s disease—are becoming an increasingly significant concern in aging populations, largely due to their rising prevalence with age. Although these conditions are driven by a complex interplay of factors, oxidative stress and inflammation in the brain are common underlying mechanisms across most neurodegenerative diseases. Neurons are particularly vulnerable to oxidative stress, and the resulting damage can disrupt chemical processes in the brain and ultimately lead to neuronal death. During the electron transfer in the respiratory chain (how we metabolize the oxygen we breathe), free radicals are produced, which may damage the mitochondrial respiratory chain if our built-in antioxidant system is faltering. The brain is particularly vulnerable to the production of ROS because it metabolizes 20 percent of the total body oxygen and has a limited antioxidant capacity. Brain cells just don’t store as much or as many of the natural antioxidants we produce in other cells in our bodies to reduce ROS naturally. That makes plant polyphenols and plant antioxidants important to support healthy brain function to pick up the slack.

There are countless studies published about polyphenols preventing or treating dementia, Alzheimer’s disease, Parkinson’s disease, and other brain disorders by reducing ROS and oxidative stress, repairing cellular damage, preventing cell death, and reducing chronic inflammation caused by excess ROS in the brain. Many other studies report these natural antioxidants can also increase memory and reduce anxiety through the same mechanisms of actions.

Studies looking at dietary factors and brain disorders report that regular dietary intake of polyphenol-rich foods and/or beverages has been associated with 50 percent reduction in the risk of dementia, a preservation of cognitive performance with aging, a delay in the onset of Alzheimer’s disease, and a reduction in the risk of developing Parkinson’s disease. Some polyphenols have been reported to reduce the neurodegeneration associated with the accumulation AGEs during normal and abnormal brain aging.

Research also suggests that some polyphenols (particularly anthocyanins found in red and purple fruits) are able to cross the blood-brain barrier; thus, these polyphenol compounds are likely to be candidates for direct neuroprotective and neuromodulatory actions. Polyphenols are considered to be neuroprotective because they provide a defense against many underlying causes of neurodegenerative diseases, namely oxidative stress, neuroinflammation, protein aggregation, metal toxicity, and mitochondrial dysfunction. A handful of polyphenols have been reported to bind with and disable a substance called amyloid plaque (implicated in Alzheimer’s) as well as a protein called tau implicated in Parkinson’s and other degenerative brain diseases.

There is also a growing interest in the potential of polyphenols to improve memory, learning, and general cognitive ability. Human studies suggest that polyphenols may have a positive impact on memory, anxiety and depression, and there is a large body of animal behavioral research to suggest that polyphenols are effective at reversing age-related deficits in spatial working memory, in improving object recognition memory, and in modulating inhibitory fear conditioning.

Liver Disease

The most leading causes of liver diseases are oxidative stress, lipid peroxidation (the oxidation of fats by free radicals), chronic inflammation, and immune response deregulations. Natural polyphenols have attracted increasing attention as potential agents for the prevention and treatment of liver diseases. Their striking capacities in relieving oxidative stress, lipid metabolism, insulin resistance, and inflammation put polyphenols in the spotlight for the therapies of liver diseases as well as for the prevention of liver diseases. Numerous studies on polyphenols and polyphenol-rich medicinal plants report the liver-protecting ability of these substances. Thousands of animal studies report that cellular-protective polyphenols can protect the liver from just about anything scientists give the animals—liver-toxic drugs, toxic doses of aspirin and alcohol, high fat diets which lead to fatty liver disease and other substances or diseases like diabetes, which are known to cause liver damage.

Eye Diseases

Oxidative stress and inflammation play a critical role in the initiation and progression of age-related eye abnormalities such as cataracts, glaucoma, diabetic retinopathy, macular degeneration, and even the autoimmune eye disease Sjögren’s syndrome. Therefore, natural plant chemicals with proven antioxidant and anti-inflammatory activities, such as carotenoids and polyphenols, could be of benefit in preventing and treating these diseases.

Fatigue

One of the easiest ways to maintain good energy levels (besides getting enough sleep) is to keep free radicals in check with a healthy and high-functioning natural antioxidant system. Oxidative stress can impact energy levels on a cellular level in numerous ways. Oxidative stress in the mitochondria of many cell types can lower the cellular energy these cells need to do their jobs, and this alone can contribute to both mental and physical fatigue. For example, when muscle cells don’t have enough cellular energy, it causes weak muscles that tire out more easily. When mitochondrial dysfunction from free radicals is affecting the cardiovascular system, then less oxygen is carried through the bloodstream to all our cells, including the lungs, and we get winded and tire out more easily when we’re physically active.

Many studies have been published on the anti-fatigue action of polyphenols in general, especially as it relates to exercise. When muscles are worked out strenuously, free radicals are generated as muscles are called on to metabolize more oxygen and glucose into cellular energy to perform harder or longer. Over 1,000 studies report that antioxidant supplementation of some sort benefits athletes and others performing strenuous exercise by more efficiently reducing these free radicals as they are formed, with an end result of more stamina and endurance and less pain and fatigue.

Premature Aging

A significant body of research indicates that polyphenols may help slow down aging by affecting the different ways our bodies change as we get older. These compounds can work on the main causes of aging, like damage to our DNA, proteins, and how our genes are controlled—problems that build up over time as we get older. Polyphenols might also help with other aging-related processes that, when out of balance, can harm the body. Finally, they may support the body’s ability to stay stable and keep tissues and organs healthy by reducing the effects of damage that builds up over time. Just relieving chronic inflammation and oxidative stress will significantly change how we age, as well as our overall health in old age in highly positive ways.

Chronic Bowel Disorders

Some polyphenols are harder than others to digest. These types of polyphenols have shown to act as prebiotics by feeding and promoting the growth of beneficial gut bacteria. In turn, this supports a healthy gut microbiome and contributes to overall gut health. In the colon, certain good bacteria can break down polyphenols into smaller compounds. These breakdown products are often more bioavailable (easier for the body to use) and can have anti-inflammatory and antioxidant effects. Many have shown real benefits in effectively treating (or preventing) inflammatory bowel diseases since these chemicals are produced where the oxidative damage and inflammation is actually occurring.

Other break-down products include important neurotransmitters the brain needs to function normally or the building blocks to make even more neurotransmitters that gut bacteria make. A lack of these important bacteria-produced substances has been linked to mood disorders of younger generations (anxiety, depression, poor stress responses, etc.) as well as memory loss, dementia, and cognition issues older generations are often faced with. Quite a few polyphenols have shown to helpful for memory preservation or enhancement, and the treatment of mood disorders for this reason.

Summary

When you understand the importance of polyphenols and how they can prevent many diseases, it’s not all that difficult to understand why we’re in such a health crisis with the significant rise in chronic diseases we’re experiencing today. Our diets no longer contain the natural polyphenols that are necessary to support our antioxidant defenses to keep our oxidative stress and inflammation levels within the healthy levels, and illness ensues. More than 50 percent of the American population is overweight with rising levels of chronic inflammation and oxidative stress, 48 percent have some type of cardiovascular disease led by the increasing number of people with hypertension, and more than 100 million American adults are now living with diabetes or prediabetes. Metabolic syndrome, a prediabetes condition that usually leads to diabetes, now affects 30 percent of the U.S. population.

What to Do?

If your diet is much like the standard Western diet, you should consider making a change, to overcome the deficiencies that are increasing your risks for ill health and disease. Choosing whole-food sources of polyphenol-rich foods to add to your diet is the best strategy, and, second to that, adding whole-food supplements like freeze dried or dehydrated fruit and vegetable supplements is the next best thing to do. The best sources of dietary polyphenols are colorful fruits (especially berries, grapes, and pomegranates), green and black tea, coffee, red wine, dark chocolate, extra virgin olive oil, flax seed oil, nuts like walnuts and pecans, and spices like cloves and turmeric. These foods are particularly concentrated in polyphenols and have been the most studied for health benefits.

Fruits rich in polyphenols include blueberries, blackberries, raspberries, strawberries, cranberries, grapes (especially red and purple), apples with skin, and pomegranates. These fruits provide anthocyanins, resveratrol, quercetin, and other antioxidants that support healthy aging, hormones, metabolism, brain and liver function, glucose metabolism, and disease prevention.

Rainforest fruits, and fruits grown in the tropics will provide even more polyphenols than American conventionally grown fruits. These include the rainforest fruits acerola, camu-camu, acai, aguaje, jabuticaba, aguaymanto, maqui berry, mango, passion fruit, guava, and as well as other tropical fruits such as dragon fruit, lucuma, lychee, and others to choose from.

Common vegetables high in polyphenols include red onions, spinach, broccoli, kale, and artichokes. These vegetables are excellent sources of flavonoids and phenolic acids that reduce inflammation and support immune function. Rainforest plants with very high polyphenols to choose from include chanca piedra, embauba, Brazilian peppertree (leaves), sarsaparilla, guacatonga, yerba mate, mutamba, boldo, pata de vaca, erva tostao, and/or artichoke.

Articles in this Series:

What are Free Radicals and Antioxidants?
The Power of Polyphenols
Low Polyphenol Diets: The Hallmark of the New Western Diet
How Polyphenols Can Prevent and Treat Disease