Polyphenols are natural chemicals that are abundantly found in many plants including fruits and vegetables, green tea, black tea, coffee, chocolate, olives, red wine, and extra virgin olive oil. (Not all of those foods are good for dogs and cats BTW!)
These super-phytochemicals are jam-packed with antioxidants and a big reason we focus so much on whole foods in our Bestie Kitchen supplements.
There are more than 8,000 different types of polyphenols that have been identified so far. Some polyphenols that have gained popularity are epigallocatechin gallate (EGCG) in green tea and resveratrol in grapes and wine.1
Polyphenols are categorized into four groups -- Flavonoids, phenolic acids, stilbenes, and lignans.
- Flavonoids are the most studied group of polyphenols. More than 4,000 types of flavonoids have been identified.
- Phenolic acids are abundant in fruits, vegetables, legumes, cereals, herbs, and oilseeds. Aside from their potent antioxidant activity, phenolic acids also promote anti-inflammatory properties.
- Stillbenes are abundant in grapes. These non-flavonoid phytochemicals are known for their extraordinary potential for the prevention and treatment of various diseases because of their antioxidant, anti-inflammatory, and cell death activation properties.
- Lignans are at their highest levels in flaxseed and virgin olive oil. They are also called ‘phytoestrogens’ that exert beneficial effects on the prevention of chronic illnesses, such as cardiovascular disease and certain types of cancer.
What’s so healthy about polyphenols?
Animal, human and epidemiologic studies show that various polyphenols have powerful antioxidant and anti-inflammatory properties that could have preventive and/or therapeutic effects for cardiovascular disease, neurodegenerative disorders, cancer, obesity, and many types of non-communicable diseases.2
Table 1. Potential Health Benefits Of Polyphenols
Health Issue/Medical Condition
Specific types of cancers with evidence of beneficial effects from polyphenols include colon, prostate, epithelial, endometrial, and breast cancer
Flavanoids such as anthocyanins, catechins, flavanols, flavones, flavanones, and isoflavones, may neutralize free radicals and decrease cancer risk by arresting cellular growth in tumors
Flavonoid-rich foods have been associated with improved ventricular health, reduced platelet activity, enzymatic modulation, anti-inflammatory effects, and lower blood pressure, to increase overall vascular health
Flavonoids and resveratrol may block cholesterol oxidation to reduce LDL and lower risk of cardiovascular disease
Type 2 diabetes
Several polyphenolic compounds, anthocyanins being the most substantiated, are associated with both the prevention and management of type 2 diabetes through protection of beta cells from glucose toxicity, anti-inflammatory and antioxidant effects, slowing of starch digestion, and regulation and altered transport of glucose, leading to better glycemic control
Polyphenols like catechins, resveratrol, and curcumin are associated with anti-obesogenic effects, potentially through adipocyte oxidation, inhibition of lipogenesis, reduction in inflammation, and increases in energy expenditure, leading to improved weight loss and maintenance.
A number of polyphenols have been shown to have protein-binding properties that can inhibit starch, lipid, and protein digestion in the gastrointestinal tract by interacting with and inhibiting digestive enzymes.
Polyphenols are powerful antioxidants
Polyphenols are primarily known for their antioxidant properties. Antioxidants help the body combat oxidative cell damage and prevent the development of various medical conditions associated with oxidative stress.
Polyphenols protect the body against oxidative stress in several ways.
- Biochemical Scavenger Theory -- This theory assumes that polyphenols act against free radicals by forming stabilized chemical complexes which can eventually prevent further reactions.3
- Production of hydrogen peroxide (H2O2) which can help regulate the actions of the immune response. 3
- Polyphenols inhibit pro-inflammatory factors leading to protective effects against many inflammation-mediated chronic diseases.4
- The anti-carcinogenic effects of polyphenols are thought to arrest cell growth by inducing cell death or cell ageing.
- Resveratrol prevents platelet aggregation, relaxes the arterial blood vessels, and disrupts the oxidation of low-density lipoprotein (LDL) or “bad fats”.
One of the most popular theories that explain the mechanism of ageing is the free radical/oxidative stress theory. Under normal conditions, the body undergoes a certain amount of oxidative damage; however, as the body ages, the rate of this damage increases as the body’s efficiency of anti-oxidative and repair mechanisms decrease.11
The antioxidant capacity of the body is related to the consumption of antioxidants from the diet. An antioxidant-rich diet can help reduce or counteract the harmful effects of ageing.
Polyphenols can cross the blood-brain barrier (BBB) making it possible for these super chemicals to exert their beneficial effects on the adverse effects of ageing on the brain, spinal cord, and other parts of the nervous system.
The harmful effects of oxidative stress on the brain are a vital component in the development of neurodegenerative diseases. Being highly anti-oxidative in nature, polyphenols may provide protection in neurological diseases. In humans, polyphenols can help reduce the risk of developing Alzheimer’s disease, Parkinson’s disease, and Huntington’s disease.
The free radical scavenging activity of polyphenols is primarily responsible for their anti-cancer property. The effect of polyphenols on human cancer cell lines is most often protective and reduction of the number of tumours or of their growth.11
Type 2 Diabetes
Polyphenols boost insulin sensitivity and slow down the rate at which the body digests and absorbs sugar. Anthocyanins have been demonstrated to prevent and manage type 2 diabetes in animals and humans. Specific phytochemicals may affect glycemia through different mechanisms, including the inhibition of glucose absorption in the gut or of its uptake by peripheral tissues.5
Polyphenols significantly lower the levels of inflammation markers in the body. Long-term inflammation has been linked with certain medical conditions, such as cancer and heart disease.
Consuming foods rich in polyphenols can lead to a significant decrease in blood pressure, bad cholesterol (LDL), and an increase in good cholesterol (HDL).6
The “French Paradox”
Have you heard about how despite a high-fat diet and smoking, there is a low incidence of cardiovascular disease among the French? This is attributed to the consumption of a polyphenol-rich diet and their fondness for red wine which is rich in resveratrol.
Polyphenols play an important role in body weight regulation. A higher flavonoid intake has been shown to lower BMI and waist circumference.7Foods that are rich in polyphenols are nutrient-dense which can result in an overall lower calorie intake.
Also, certain polyphenols promote a reduction in the creation, differentiation, and proliferation of adipocytes (fat cells), coupled with the prevention of inflammation and promotion of lipolysis. 8Catechins prevent weight gain by promoting greater energy expenditure and fat oxidation.9
Curcumin in the diet has been shown in animal studies to reduce adipose tissue development, synthesis of fatty acids in the liver, and higher oxidation levels of fatty acids.10
Polyphenols influence gut bacteria
Polyphenols promote beneficial gut bacteria and boost their beneficial actions while inhibiting the growth and proliferation of invasive species. Blueberry extract helps modulate beneficial bacteria such as Clostridium difficile, Escherichia coli,and Salmonella typhimurium.12.
Other beneficial effects of polyphenols
Polyphenols also exert their benefits in the following conditions:
- Asthma - Polyphenols promote better lung function.
- Osteoporosis - Prevents the loss of bone mineral density
- Skin damage induced from exposure to sunlight (UV exposure)
- Promote absorption of minerals in the intestine
- Antiviral activity - Theaflavins in black tea have been demonstrated to have anti-HIV-1 activity. Studies have shown that polyphenols inhibited the entry of HIV-1 cells into the target cells. Theaflavins were also round to inhibit the activity of Severe Acute Respiratory Syndrome (SARS) coronavirus.11
Polyphenols for dogs and cats
Polyphenols, whether they’re incorporated in the diet or as a supplement, have been shown to prevent damage caused by oxidative stress and improved the general health status of dogs.
The addition of polyphenols to pet food can also increase the palatability, antioxidant capacity, and antibacterial activity of dry dog food.11
The health benefits of various types of polyphenols make these super-phytonutrients a valuable addition to your pet’s diet. They are considered relatively safe supplements for dogs and cats with minimal adverse effects. However, pets may differ in their response, thus you should monitor your cat or dog for any side effects. It’s highly recommended to check with your veterinarian first if your pet is on any medications or has special dietary requirements.
List of References:
- Emily Nock. What are Polyphenols? Another Great Reason to Eat Fruits and Veggies. June 2021. Kendall Reagan Nutrition Center. Colorado State University. Accessed: February 2022.
- Pérez-Jiménez J, Neveu V, Vos F, Scalber A. Identification of the 100 richest dietary sources of polyphenols: an application of the Phenol-Explorer database. Eur J Clin Nutr.(2010) 64:S112–20. 10.1038/ejcn.2010.221
- Fraga CG, Galleano M, Verstraeten SV, Oteiza I. Basic biochemical mechanisms behind the health benefits of polyphenols. Mol Aspects Med.(2010) 31:435–45. 10.1016/j.mam.2010.09.006
- EFSA Panel on Food Additives and Nutrient Sources Added to Food. Risk assessment for peri- and postmenopausal women taking food supplements containing isolated isoflavones. EFSA J.(2015) 13:4246 10.2903/j.efsa.2015.4246
- Xiao JB, Hogger P. Dietary polyphenols and type 2 diabetes: current insights and future perspectives. Curr Med Chem. (2015) 22:23–38. 10.2174/0929867321666140706130807
- Mark G. Shrime, Scott R. Bauer, Anna C. McDonald, Nubaha H. Chowdhury, Cordelia E. M. Coltart, Eric L. Ding. Flavonoid-Rich Cocoa Consumption Affects Multiple Cardiovascular Risk Factors in a Meta-Analysis of Short-Term Studies. The Journal of Nutrition, Volume 141, Issue 11, November 2011, Pages 1982–1988, https://doi.org/10.3945/jn.111.145482
- Vernarelli, J A and J D Lambert. Flavonoid intake is inversely associated with obesity and C-reactive protein, a marker for inflammation, in US adults. Nutr Diabetes. 2017 May; 7(5): e276. Published online 2017 May 15. doi: 10.1038/nutd.2017.22
- Wang S, Moustaid-Moussa N, Chen L, Mo H, Shastri A, Su R. Novel insights of dietary polyphenols and obesity. J Nutr Biochem.(2014) 25:1–18. 10.1016/j.jnutbio.2013.09.001
- Hursel R, Viechtbauer W, Dulloo AG, Tremblay A, Tappy L, Rumpler W, et al. . The effects of catechin rich teas and caffeine on energy expenditure and fat oxidation: a meta-analysis. Obes Rev.(2011) 12:e573–81. 10.1111/j.1467-789X.2011.00862.x
- Shao W, Yu Z, Chiang Y, Yang Y, Chai T, Foltz W, et al. . Curcumin prevents high fat diet induced insulin resistance and obesity via attenuating lipogenesis in liver and inflammatory pathway in adipocytes. PLoS ONE(2012) 7:e28784. 10.1371/journal.pone.0028784
- Kanti Bhooshan Pandey and Syed Ibrahim Rizvi. Plant polyphenols as dietary antioxidants in human health and disease. Oxid Med Cell Longev. 2009 Nov-Dec; 2(5): 270–278. doi: 10.4161/oxim.2.5.9498
- Lee HC, Jenner AM, Lowand CS, Lee YK. Effect of tea phenolics and their aromatic fecal bacterial metabolites on intestinal microbiota. Res Microbiol.(2006) 157:876–84. 10.1016/j.resmic.2006.07.004