What are polyphenols and how to add them to your diet to improve your health

What are polyphenols

Polyphenols are chemical compounds that producedC. Manach, A. Scalebert, C. Morand. Polyphenols: food sources and bioavailability / The American Journal of Clinical Nutrition plants to protect against solar radiation and various pathogens.

Some of them, such as anthocyanins, color flowers and fruits pink, red, blue or purple. Others - tannins - are responsible for the tart, astringent taste of grapes, berries, and drinks like wine or tea.

About 8,000 polyphenols of various chemical structures have been identified so far, and several hundred of them are found in foods. The most common classes includeC. Manach, A. Scalebert, C. Morand. Polyphenols: food sources and bioavailability / The American Journal of Clinical Nutrition:

• Phenolic acids - coffee, ferulic, gallic, protocatechuic, synapic. Most of them are in blueberries, kiwi, cherries, plums and coffee. There are also a lot of phenolic acids in blueberries, raspberries, black currants, apples and pears.
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• Stilbens - resveratrol, piceatannol. PresentM. Reinisalo, A. Karlund, A. Koskela. Polyphenol Stilbenes: Molecular Mechanisms of Defense against Oxidative Stress and Aging‑Related Diseases / Oxidative medicine and cellular longevity in cocoa, grapes, peanuts, blueberries, blueberries, strawberries, cranberries, white and red wine.
• Lignans - lariciresinol, matairesinol, secoisolariciresinol. A large number of these polyphenols containedC. Rodriguez‑Garcia, C. Sanchez-Quesada, E. Toledo. Naturally Lignan‑Rich Foods: A Dietary Tool for Health Promotion? / Molecules in sesame and flax seeds. There are also many lignans in cashew nuts and peanuts, some in other nuts and legumes.
• Flavonoids - flavanols quartzetin and kaempferol, flavanones, flavones, isoflavones, catechins and epicatechins. This is an extensive class of polyphenols found in many vegetables, fruits, and berries. For example, a lot of flavanols containedC. Manach, A. Scalebert, C. Morand. Polyphenols: food sources and bioavailability / The American Journal of Clinical Nutrition in onions and cabbage. Parsley is especially rich in flavones, while chocolate, green and black tea, beans, and red wine are rich in catechins.

At the same time, the amount and class of these substances can vary greatly depending on the type of product, the way it is processed, the region of cultivation, the time of collection, and many other factors.

What are the benefits of polyphenols

Scientists suggestH. Cory, S. Passarelli, J. Szeto. The Role of Polyphenols in Human Health and Food Systems: A Mini‑Review / Frontiers in nutritionthat polyphenols are beneficial to health due to their antioxidant activity.

In the human body, reactive oxygen species, or, in other words, free radicals, are constantly formed. Their accumulation can lead to oxidative stress, cell breakdown and death, inflammatory response and various diseases.

There is a theory that polyphenols are able to neutralize free radicals, forming stable chemical complexes with them, and thus save a person from oxidative stress.

Scientific studies confirm that substances are useful:

• To reduce inflammation. Phenolic components mayH. Zhang, R. Tsao. Dietary polyphenols, oxidative stress and antioxidant and anti‑inflammatory effects / Current Opinion in Food Science reduce oxidative stress and affect the production of cytokines - proteins of the immune system.
• Maintaining the health of the intestinal microflora. It is believed that polyphenols ableMarín L, Miguélez EM, Villar CJ, Lombó F. Bioavailability of dietary polyphenols and gut microbiota metabolism: antimicrobial properties / BioMed research international suppress the reproduction of harmful microorganisms in the intestines and supportVendrame S, Guglielmetti S, Riso P, Arioli S, Klimis‑Zacas D, Porrini M. Six-week consumption of a wild blueberry powder drink increases bifidobacteria in the human gut / Journal of agricultural and food chemistry growth of beneficial bifidobacteria.
• Protection against neurodegenerative diseases. Curcumin, resveratol and catechins reduceRossi L, Mazzitelli S, Arciello M, Capo CR, Rotilio G. Benefits from dietary polyphenols for brain aging and Alzheimer's disease / Neurochemical research oxidative stress and regulate immunity by protecting nerve cells from the toxic effects of beta-amyloid proteins, the accumulation of which can lead to the development Alzheimer's diseasea.
• Reducing the risk of cancer. Some types of flavonoids ableWang S, Moustaid‑Moussa N, Chen L, Mo H, Shastri A, Su R. Novel insights of dietary polyphenols and obesity / The Journal of Nutritional Biochemistry neutralize free radicals and inhibit the growth of tumor cells. Polyphenols can reduce1. Zhou Y, Zheng J, Li Y. Natural polyphenols for prevention and treatment of cancer / Nutrients
  2. Fujiki H, Sueoka E, Watanabe T, Suganuma M. Primary cancer prevention by green tea, and tertiary cancer prevention by the combination of green tea catechins and anticancer compounds / Journal of cancer prevention risk of colon, prostate, skin, endometrial and breast cancer.
• Reducing the risk of type 2 diabetes. Some polyphenols protectJ. b. Xiao, P. Hogger. Dietary polyphenols and type 2 diabetes: current insights and future perspectives / Current medicinal chemistry pancreatic beta cells from inflammation and oxidative stress, slow down starch digestion and regulate glucose transport, improving glycemic control.
• Normalization of weight and protection against obesity. Catechins, resveratol and curcumin contributeWang S, Moustaid‑Moussa N, Chen L, Mo H, Shastri A, Su R. Novel insights of dietary polyphenols and obesity / The Journal of Nutritional Biochemistry[ oxidation of adipocytes - fat cells. They inhibit lipogenesis, reduce inflammation and increase energy release. In the long run, this may lead to normalization of weight. In addition, some polyphenols ableA. H. Baretta, N. F. Farhadia, T. J. Smith. Slowing starch digestion and inhibiting digestive enzyme activity using plant flavanols/tannins— A review of efficacy and mechanisms / LWT suppress digestive enzymes, disrupting the absorption of starches, fats and proteins.
• Protection against other diseases. Those who get enough polyphenols from their diet on a consistent basis also are decliningH. Cory, S. Passarelli, J. Szeto. The Role of Polyphenols in Human Health and Food Systems: A Mini‑Review / Frontiers in nutrition risks osteoporosis - loss of bone mass, problems with the digestive tract and lungs.

How polyphenols can harm

There are several conditions in which a high amount of polyphenols in the diet can be detrimental to health.

Impair the absorption of vitamin B1

During digestion, certain polyphenols, such as caffeic, chlorogenic and tannic acids, mayThiamine deficiency and its prevention and control in major emergencies / World Health Organization bind to vitamin B1 (thiamine), disrupting its absorption. Also, the metabolism of the latter can be affected by the flavonoids quercetin and rutin.

Vitamin B1 is essential for the health of the nervous and cardiovascular systems, and its deficiency can cause congestion. heart failure, polyneuritis - damage to the peripheral nervous system, weight loss and loss of muscle masses.

At risk are pregnant and lactating mothers, people with serious liver disease and thyroid gland, infections and oncology. Heavy physical exertion, chronic high doses of alcohol and diseases of the digestive system can also disrupt the absorption of thiamine and provoke its deficiency.

But since vitamin B1 is found in sufficient quantities in common foods - wheat flour, cereals, legumes, nuts and pork, then a varied diet virtually eliminates the possibility of deficit.

Adults need about 1-1.2 mg of thiamine per day, and this amount can be obtained by eating, for example, a serving of buckwheat with pork.

However, people at risk of deficiency still recommendThiamine deficiency and its prevention and control in major emergencies / World Health Organization Consume foods rich in thiamine, separate from foods with polyphenols. For example, drink tea after a meal, and not with it. Also add more foods to your diet. vitamin C, which promotes the absorption of B1.

Increase the risk of iron deficiency anemia

Two research1. N. Petry, I. Egli, C. Zeder. Polyphenols and phytic acids contribute to the low iron bioavailability from common beans in young women / The Journal of nutrition
2. Fuzi S.F.A., Koller D., Bruggraber S., Pereira D.I., Dainty J.R., Mushtaq S. A 1‑h time interval between a meal containing iron and consumption of tea attenuates the inhibitory effects on iron absorption: A controlled trial in a cohort of healthy UK women using a stable iron isotope / The American Journal of Clinical Nutrition have shown that taking polyphenols in supplements or tea reduces iron absorption by 37–45%. In the long run, this could harm people from at-risk groupsIron Deficiency Anemia / Cleveland Clinic for iron deficiency anemia:

• women with heavy bleeding during menstruation;
• those who have experienced blood loss due to trauma, surgery, frequent donation or a large number of tests;
• pregnant and lactating mothers;
• suffering from diseases of the digestive system - autoimmune gastritis, celiac disease, irritable bowel syndrome, ulcerative colitis, Crohn's disease, as well as those infected with the bacterium Helicobacter pylori and who underwent surgery on the digestive tract.

At the same time, in one study notedFuzi S.F.A., Koller D., Bruggraber S., Pereira D.I., Dainty J.R., Mushtaq S. A 1‑h time interval between a meal containing iron and consumption of tea attenuates the inhibitory effects on iron absorption: A controlled trial in a cohort of healthy UK women using a stable iron isotope / The American Journal of Clinical Nutritionthat if you drink tea rich in polyphenols, separately from meals, plant antioxidants will not interfere with the absorption of the trace element.

How to get enough polyphenols from your diet

Unlike vitamins and trace elements, there is no recommended norm for polyphenols. This is a difficult topic to research because there are too many varieties of these natural antioxidants.

Two fruits from the same tree can have different amounts of polyphenols, simply because one grows in the sun and the other in the shade. Moreover, even in the same fruit, the skin and pulp can vary greatly in antioxidant content.

Thus, it is impossible to determine exactly how much and what foods you need to eat in order to get a full set of polyphenols for a long and healthy life.

In the meantime, there are some good strategies to safely increase your dietary intake:

• ConsumeHealthy Diet / World Health Organization at least 400 g of fruits and vegetables per day. Add them to every meal, including snacks.
• Turn onC. Rodriguez‑Garcia, C. Sanchez-Quesada, E. Toledo. Naturally Lignan‑Rich Foods: A Dietary Tool for Health Promotion? / Molecules in the diet legumes, nuts, seeds, whole grains and cereals.
• Try to go by color - add red, green, blue and yellow plant foods to your diet. So you will surely get a diverse set of polyphenols.
• If possible, eat unprocessed foods. Some polyphenols are rapidly disappearM. Shengul. The Effect of Cooking on Total Polyphenolic Content and Antioxidant Activity of Selected Vegetables / International Journal of Food Properties during the cooking process. For example, cooking destroys 80% of the quartzetin in tomatoes and onions. This does not mean that you need to switch to a raw food diet, just add to your diet not only fried and canned, but also fresh fruits and vegetables.
• Eat fruits and berries with skin - in it containedY. Sadef, T. Javed, R. Javed. Nutritional status, antioxidant activity and total phenolic content of different fruits and vegetables’ peels / PLOS One more polyphenols than pulp.

In any case, remember about the sense of proportion and do not go to extremes. Food should be not only varied, but also tasty. So if you can't stand raw onions, frown grapes and experience nausea from green tea, do not torture yourself.

Should You Take Polyphenol Supplements?

Since polyphenols have been recognized as beneficial to health, a huge number of dietary supplements, drinks and cosmetics have appeared with the addition of these antioxidants.

How notedH. Cory, S. Passarelli, J. Szeto. The Role of Polyphenols in Human Health and Food Systems: A Mini‑Review / Frontiers in nutrition in one scientific review, their production is not regulated in any way, and the amount and composition of polyphenols, like other dietary supplement components, can vary greatly. So it is not possible to explore all this diversity and come to any conclusion.

Moreover, high doses of polyphenols from herbal supplements, such as green tea extract, may1. v. J. Navarro, H. Barnhart, H. L. Bonkovsky. Liver injury from Herbals and Dietary Supplements in the US Drug Induced Liver Injury Network / Hepatology
2. G. Mazzanti, F. Menniti-Ippolito, P. A. Moro. Hepatotoxicity from green tea: a review of the literature and two unpublished cases / European journal of clinical pharmacology harm the liver, although such cases meetT. Isomura, S. Suzuki, H. Origasa. Liver‑related safety assessment of green tea extracts in humans: a systematic review of randomized controlled trials / European Journal of Clinical Nutrition extremely rare.

In addition, unlike powders and tablets, food with polyphenols is also rich in vitamins, trace elements and fiber. Therefore, it would be much more rational and useful to spend money on fresh vegetables and fruits, berries, seeds and nuts.