Polyphenols can be found in many fresh foods

  • Stock PhotoMany healthful foods are rich in polyphenols, including blueberries.

    Stock PhotoMany healthful foods are rich in polyphenols, including blueberries.

By Dr. Eve Glazier and Dr. Elizabeth Ko
Posted8/14/2022 6:00 AM

Q: My dad is 76, and he's getting interested in nutrition. Lately, he's been reading news stories about something called "polyphenols," and that they're really good for your health. Can you talk a little bit about what they are and what foods to eat to get enough? What do they do?

A: As is often the case with health-based news, findings from a recent study have propelled polyphenols into the headlines. Or to be more accurate, put them into the headlines once again. This isn't the first -- nor likely the last -- time these micronutrients have had their moment in the news cycle.


The word "polyphenols" refers to a broad category of chemical compounds that occur naturally in plants. They help protect the plant from damage caused by ultraviolet radiation from the sun, and make it more resistant to viruses, bacteria, fungi and other pathogens that can cause disease.

More than 8,000 of these small molecules have been identified. Based on variations in their chemical structure, polyphenols can be divided into subcategories. Among these are flavonoids, which are often mentioned when discussing the beneficial properties of polyphenols.

One of the things that makes polyphenols useful to humans is their antioxidant and anti-inflammatory properties. Studies that look at lifestyle behaviors and health outcomes have found evidence that a diet rich in polyphenols may offer protection against Type 2 diabetes, cardiovascular diseases, osteoporosis, neurodegenerative diseases, obesity and developing certain cancers.

The most recent study into the health benefits of polyphenols, which comes from researchers in Spain, focused on older adults. They began with the fact that polyphenols were poorly absorbed in the small intestine. That means these micronutrients pass through the upper reaches of the digestive tract and accumulate in the large intestine. Once there, the researchers found that polyphenols catalyzed changes in the makeup and function of the gut microbiome that led to significantly lower levels of inflammation. This is important because even low levels of ongoing inflammation can damage healthy cells and leave the body more vulnerable to disease.

by signing up you agree to our terms of service

The anti-inflammatory effect was seen in study participants who ate a diet rich in polyphenols. The control group, who were on a different diet, did not have the same results.

Fortunately for anyone who wants to harness the benefits of polyphenols, these micronutrients are abundantly available in a wide variety of fresh and healthful foods. These include blueberries, plums, cherries, apples, strawberries, black currants, black olives, dark chocolate, black tea, coffee, hazelnuts and pecans. Some spices, including turmeric, cloves, cinnamon, ginger and cumin are also high in polyphenols.

There is no official guidance on the amounts of polyphenols someone should consume. Study participants typically took in 500 milligrams or more per day. Blueberries, for example, contain 560 mg of polyphenols per 100 grams, which is just 3.5 ounces.

All of the research into these micronutrients focuses on fresh foods and not on supplements. In fact, the safety of polyphenol supplements has not yet been established. Because these micronutrients are so easily obtained in fresh foods, which have so many other health benefits, it's best to get them through your diet.


Q: I run a lot and developed a growth on the knuckle of my second toe. It's hard, with a sharp point in the middle, and it hurts. I thought it was a callus, but my running coach says it's a corn. I thought only older people got those. Will it go away on its own?

A: A corn is a small, round area of thickened and hardened skin. Those that form on the top of the foot, typically in the bony regions of the toes, are known as hard corns. Soft corns, which have a pliable surface and a springy, almost rubbery, texture, form between the toes.

Corns can also occur on the bottoms of the feet. These are typically quite small, with a seedlike appearance that gives them their name. This type of corn often appears in clusters. When seed corns develop on the weight-bearing portion of the foot, they can be quite painful.

As with a callus, corns form because the skin has sustained repeated damage from pressure, friction or both. This often results from footwear that is too tight or fits poorly. To protect itself from further injury, the skin develops a physical barrier made up of tougher cells. Corns are different from calluses in that they are smaller and deeper. Calluses can develop anywhere, but corns occur in areas where a bone exerts pressure on the skin.

Unlike calluses, corns are often tender or painful. This is due to their central core, which is the sharp point you described. It forms around the area of damage the skin is trying to protect.

It is true that corns become more common as we get older. This is often due to the age-related physical changes that take place in the foot and in the gait, which can then affect the fit of someone's existing shoes or socks. Osteoarthritis can also affect the bones of the foot and lead to corn formation.

Corns don't go away on their own, so it's important to take steps to mitigate them. Untreated, they can get infected and have an adverse effect on posture, gait and alignment. Begin by assessing your footwear. Shoes that are too loose or too tight can cause the pressure and friction that cause corns. So can long toenails. As a runner, you might also consider if something in your stride or foot placement has changed.

To treat a corn, soften the area daily in warm water, then gently rub with a pumice stone. Only remove the topmost layers of dead cells each time, as taking too much can damage healthy skin. Use moisturizer to keep the area soft, and protect it from further damage with doughnut-shaped corn pads. These are available at drugstores. Corn-removal products, which use salicylic acid to thin the skin, can be effective. However, they are not recommended for anyone with poor circulation.

If a corn doesn't respond to treatment, see your health care provider. Never try to cut or shave a corn, as this can lead to a serious infection.

• Dr. Eve Glazier is an internist and associate professor of medicine at UCLA Health. Dr. Elizabeth Ko is an internist and assistant professor of medicine at UCLA Health. Send your questions to askthedoctors@mednet.ucla.edu.

Article Comments
Guidelines: Keep it civil and on topic; no profanity, vulgarity, slurs or personal attacks. People who harass others or joke about tragedies will be blocked. If a comment violates these standards or our terms of service, click the X in the upper right corner of the comment box. To find our more, read our FAQ.