Dear Doctors: 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?
Dear Reader: 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 that 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.
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. Since 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.
Eve Glazier, M.D., MBA, is an internist and associate professor of medicine at UCLA Health. Elizabeth Ko, M.D., is an internist and assistant professor of medicine at UCLA Health. Send your questions to firstname.lastname@example.org, or write: Ask the Doctors, c/o UCLA Health Sciences Media Relations, 10960 Wilshire Blvd., Suite 1955, Los Angeles, CA, 90024. Owing to the volume of mail, personal replies cannot be provided.
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