Polyphenols form a family of major antioxidants, which protect the cell membranes and DNA, preventing some mutations that cause cancer.
Some epidemiological studies in humans have shown a positive correlation between the regular moderate consumption of red wine - a concentrated source of polyphenols – and a lower incidence of cardiovascular disease (e.g. atherosclerosis). This is currently known as the French paradox. Dogs and cats on the other hand are rarely affected by atherosclerosis, as they possess less LDL cholesterol (“low-density lipoprotein cholesterol”) than humans.
The major positive of polyphenols is their impact on free radicals, limiting the harmful effects of oxidative stress. The incorporation of green tea polyphenols in the diet can improve oral hygiene. Some compounds inhibit the growth of dental plaque bacteria, which cause periodontal disease, a common complaint among aging animals. The positive effect of flavanols, a special category of polyphenols, has also been observed in kidney and heart disease. They stimulate nitric oxide production, relaxing the smooth muscle fibres of the blood vessels. Daily administration of flavanols is associated with a fall in blood pressure.
There are more than 8000 known types of polyphenols and they are found in all vegetable sources. They are involved in pigmentation (tanins), growth, reproduction and plant resistance to disease. Grapes, green tea and cacao are the plants with the highest flavanol content.