Maximizing Polyphenols Benefits

The Symbiotic Relationship Between Gut Bacteria And Polyphenols

Author: Dr. Stephen Chaney

How to maximize polyphenols benefits?

Polyphenols are ubiquitous in the plant world. There are many kinds of polyphenols, and they are found in a wide variety of fruits, vegetables, whole grains, and legumes. You probably already know that polyphenols are also found in tea, coffee, chocolate, and many herbs and spices.

Polyphenols are thought to have a wide array of health benefits. For example, the polyphenols in grapes are thought to:

Reduce inflammation.
Reduce the risk of heart disease, cancer, and diabetes.
Prevent or delay the onset of neurodegenerative diseases like Alzheimer’s.

The amazing thing is that polyphenols are effective at all. They are poorly absorbed and rapidly eliminated from the circulation. For example, resveratrol, a polyphenol found in red grapes, only stays in the circulation for a few hours.

In the case of resveratrol, we know that, during its brief time in our bodies, it turns on “anti-aging” genes that control things like inflammation, protection against free radical damage, cholesterol metabolism, blood sugar control, and blood pressure. We are less certain how other polyphenols exert their beneficial effects during the short time they are in our bodies.

When we scientists are facing a problem like this, it stimulates our creative thinking. We start asking questions like:

Can we improve the absorption of beneficial polyphenols into the bloodstream?
Would that improve their effectiveness and health benefits?

A recent review (D Zhao et al, Critical Reviews In Food Science and Nutrition: Jan 7, 1-29, 2019) looked at the first question. It summarized the most promising strategies for improving the absorption of grape polyphenols. We don’t yet know the answer to the second question.

Before I discuss the most promising strategies, the professor in me wants to cover Polyphenols 101, something I call “The Symbiotic Relationship Between Gut Bacteria and Polyphenols”.

The Symbiotic Relationship Between Gut Bacteria and Polyphenols

The world of polyphenols is complex. For example:

Resveratrol is the best-known and best-studied polyphenol in grapes, but there are dozens of other beneficial polyphenols in grapes.
Each of these polyphenols have unique metabolic pathways and unique health benefits.
Each variety of grapes has a unique blend of polyphenols.
Each polyphenol is metabolized differently by our gut bacteria and by enzymes in our body.
You start with dozens of polyphenols in the grape and end up with hundreds of metabolites in the body.
Some of these metabolites are better absorbed. Some are not absorbed at all. Some of these metabolites are highly active. Others are inactive. The possibilities are endless.

As if that weren’t enough, there are two more complexities to factor into the equation.

There is a symbiotic relationship between gut bacteria and polyphenols.
Our gut bacteria influence the metabolism and absorption of the polyphenols in our diet.
The polyphenols we consume influence the population of bacteria in our gut.
The kinds of fiber we consume influence which bacteria populate our gut, and that, in turn, influences how we metabolize the polyphenols we consume.

Faced with this level of complexity, there have been two types of approaches to improving the absorption of polyphenols.

The pharmaceutical approach, which tries to bypass the complexities of polyphenol absorption.
The natural approach, which tries to optimize the complexities of polyphenol absorption.

The review (D Zhao et al, Critical Reviews In Food Science and Nutrition: Jan 7, 1-29, 2019) gives examples of each type of approach, which I will discuss below.

Pharmaceutical Approaches: These are approaches designed to bypass the complexities of polyphenol absorption. The authors considered the following two strategies to have the most probability of success:

Chemical alteration of polyphenol structure. This is a classical pharmaceutical strategy. You start with naturally occurring compound that has medicinal benefit. Then you chemically modify it in multiple ways until you find a chemical modification that is efficiently absorbed and is stable in the circulation. There are two drawbacks to this approach:
You have created a new compound with its own properties. You have created a drug that needs to be tested for safety and efficacy. Resveratrol, for example, offers a cautionary tale. A drug company modified it. The modified form was efficiently absorbed and was stable in the bloodstream. They thought they had created the perfect drug. Unfortunately, when they tested it, they found out it was toxic.
Even if you did optimize safety and efficacy of the polyphenol, you have only optimized one polyphenol out of the dozens found in the real food.
Incorporate the polyphenol into nanoparticles that are absorbed so efficiently by the intestine that they effectively bypass metabolism by gut bacteria. This is a strategy currently being explored by drug companies to improve the efficacy of poorly absorbed drugs. Even if successful, this approach has the same type of drawbacks.
This is a relatively new technology. There are some concerns it may not be safe.
Foods have dozens of polyphenols. A nanoparticle strategy may improve the absorption of one or two polyphenols, but it is unlikely to replace the real food.

Natural Approaches: These approaches are designed to optimize the complexities of polyphenol absorption.

Develop a probiotic supplement containing bacteria that improve polyphenol uptake. There is some promising research in this area.
However, when we talk about gut bacteria, the phrase “It takes a village” takes on a whole new meaning. There may be dozens of bacteria involved in improving polyphenol uptake, not just one or two. The probiotic supplement may need to be a horse pill
Add fiber to the diet to support the growth of the gut bacteria that enhance the absorption of polyphenols. This may be the most promising strategy.
Studies have already shown that pectin and similar non-digestible polysaccharides improve the absorption of polyphenols found in grapes and many other foods.
While grapes are low in pectin, other fruits (most notably apples, peaches, citrus fruit, apricots, and plums) are high in pectin. Legumes and some vegetables are also high in pectin. The only reason you don’t find them on most lists of high pectin foods is these lists are for foods that have enough pectin to make good jams without any added pectin. Legumes and vegetables are also high in insoluble fibers, which interfere with the gelling required for a good jam. Besides, kale or pea jam are probably not high on anyone’s list of favorite jams.
The best thing about this approach is that it is completely natural. It involves eating a plant-based diet with fruits, vegetables whole grains, and legumes, something humans have been doing for thousands of years. This a diet chock full of beneficial polyphenols and the fiber needed to support the gut bacteria that help us utilize those polyphenols. There are no side effects. There is no danger associated with this approach.

Once again, Mother Nature knows best.

Addendum

While writing this article I happened to read “The People’s Pharmacy” column by Joe & Terry Graedon in our local paper (Yes, I still read a physical newspaper). They were talking about combining pectin with grape juice to relieve arthritis pain. Some of the polyphenols in grape juice have anti-inflammatory effects. But, grape juice alone is not very effective at relieving arthritis pain. However, it turns out that pectin plus grape juice, something called “purple pectin remedy,” is a home remedy for arthritis pain relief that has been around since the 1940s. They did not discuss a mechanism, but now we know how it works.

Note: I suppose if you are getting your grape polyphenols from grape juice, wine, or some other liquid source, you could stir in some pectin to improve their absorption. However, my recommendation would be to consume a primarily plant-based diet with a variety of fruits, vegetables, whole grains, and legumes along with your liquid polyphenol source.

The Bottom Line

Resveratrol and other polyphenols found in grapes have many health benefits. However, these polyphenols are poorly absorbed. A recent review described ongoing research into approaches for improving the absorption of grape polyphenols

I discuss the various approaches that are being studied in my article above. Some are pharmaceutical approaches that involve structural alterations to the polyphenol or nanoparticle delivery systems to improve absorption. Others involve probiotics that contain bacterial strains that enhance polyphenol absorption. Each of these approaches have limitations, or dangers, or both.

The most promising approach was to simply add fiber to the diet to support the growth of the gut bacteria that enhance the absorption of polyphenols.

Studies have already shown that pectin and similar non-digestible polysaccharides improve the absorption of polyphenols found in grapes and many other foods.
While grapes are low in pectin, other fruits (most notably Apples, peaches, citrus fruit (especially the skin), apricots, and plums) are high in pectin. Legumes and some vegetables are also high in pectin. The only reason you don’t find them on most lists of high pectin foods is these lists are for foods that have enough pectin to make good jams without any added pectin. Legumes and vegetables are also high in insoluble fibers, which interfere with the gelling required for a good jam. Besides, kale or pea jam are probably not high on anyone’s list of favorite jams.
The best thing about this approach is that it is completely natural. It involves eating a plant-based diet with fruits, vegetables whole grains, and legumes, something humans have been doing for thousands of years. This a diet chock full of beneficial polyphenols and the fiber needed to support the gut bacteria that help us utilize those polyphenols. There are no side effects. There is no danger associated with this approach.

Once again, Mother Nature knows best.

Note: If you are getting your grape polyphenols from grape juice, wine, or some other liquid source, you could stir in some pectin to improve their absorption. However, my recommendation would be to consume a primarily plant-based diet with a variety of fruits, vegetables, whole grains, and legumes along with your liquid polyphenol source.

For more details read the article above. You will also find an interesting story about the “purple pectin remedy”.

These statements have not been evaluated by the Food and Drug Administration. This information is not intended to diagnose, treat, cure or prevent any disease.