Polyphenols

What are antioxidants and why are they important?

Antioxidants are substances that can render free radicals harmless. Free radicals are molecules that have one or more unpaired electrons and are therefore very reactive. They are constantly produced in the body through metabolic processes, but also through environmental influences such as UV radiation, smoke or pollutants. Free radicals can damage cell membranes, proteins or DNA and thus contribute to ageing, inflammation or cancer. Antioxidants can prevent or repair this damage by donating their electrons to the free radicals and thus stabilizing them.

What polyphenols are there and where do they occur?

There are more than 8000 different polyphenols, which can be divided into different classes. The most important are

• Flavonoids: They are found in many types of fruit and vegetables, for example in apples, berries, citrus fruits, broccoli or onions. They have a yellow or red color and protect the plant from UV radiation or insects. They have an anti-inflammatory, anti-allergic and antihypertensive effect.
• Phenolic acids: They are found in coffee, tea, wine, nuts and cereals. They have a bitter taste and protect the plant from fungi or bacteria. They have an antioxidant, antimicrobial and cholesterol-lowering effect.
• Lignans: They are found in linseed, sesame and soy. They have a hormone-like effect and protect the plant from stress or drought. They have a hormone-regulating, anti-cancer and bone-strengthening effect.
• Tannins: They are found in tea, wine, cocoa and pomegranate. They have an astringent effect and protect the plant from predators or injuries. They have an antioxidant, antiviral and hemostatic effect.

How do polyphenols affect dogs?

Polyphenols can also benefit dogs, as they have similar effects to humans. For example, they can

• strengthen the immune system and prevent infections
• reduce inflammation and relieve pain
• regulate blood sugar and prevent diabetes
• lower blood pressure and prevent cardiovascular disease
• detoxify the liver and promote digestion
• keep the coat shiny and the skin healthy
• improve memory and prevent dementia
• Increase well-being and reduce stress

How can you feed your dog polyphenols?

Polyphenols are contained in many plant-based foods that can be offered to dogs as a supplement to their meat diet. Care should be taken to ensure that the food is well tolerated by dogs and does not contain any toxic or allergenic substances. In addition, the food should be prepared as fresh, raw or gently as possible in order to preserve the polyphenols. Too much heat, light or oxygen can destroy or inactivate the polyphenols. Here are some examples of polyphenol-rich foods that you can feed your dog:

• Apples: they contain quercetin, a flavonoid that has anti-inflammatory, anti-allergic and anti-cancer properties. You can give your dog a piece of apple as a snack or mix it grated into their food. The core should be removed, as it contains small amounts of hydrocyanic acid, which can be poisonous in large quantities.
• Berries: They contain anthocyanins, flavonoids that are responsible for the red or blue color. They have an antioxidant, immune-boosting and blood sugar-lowering effect. You can give your dog fresh or dried berries such as blueberries, strawberries or raspberries as a treat or mix them pureed into their food. Grapes should not be used, as they can lead to kidney failure in dogs.
• Broccoli: It contains sulforaphane, a phenolic acid derivative that has anti-inflammatory, antimicrobial and anti-cancer properties. You can give your dog boiled or steamed broccoli as a vegetable side dish or mix it finely chopped into their food. You should not feed your dog too much broccoli, as it also contains mustard oil glycosides, which can lead to gastrointestinal problems in large quantities.
• Green tea: It contains catechins and flavonoids, which have antioxidant, antiviral and cholesterol-lowering effects. You can offer your dog lukewarm green tea as drinking water or pour it diluted over the food. You should not use black tea, as it contains more caffeine, which can be harmful to dogs.
• Pomegranate: It contains ellagic acid, a tannin that has antioxidant, antiviral and hemostatic effects. Pomegranate juice can be offered to dogs as drinking water or diluted and poured over their food. Pomegranate seeds should not be fed as they can lead to intestinal obstruction.

Are there any disadvantages or risks associated with feeding polyphenols?

Polyphenols are generally well tolerated and have few side effects in dogs. However, there are a few points to bear in mind to avoid potential problems:

• Not all foods containing polyphenols are suitable for dogs. You should always make sure that the food does not contain any toxic or allergenic substances and that it is easily digestible. For example, chocolate, grapes or onions are taboo for dogs because they contain theobromine, oxalic acid or thiosulphate, which are toxic to dogs.
• Not all dogs tolerate foods containing polyphenols equally well. You should always start slowly with small amounts and observe your dog's reaction. If the dog shows signs of diarrhea, vomiting or itching, you should stop feeding and consult a vet if necessary.
• Not all polyphenols have the same effect on dogs. You should always pay attention to the dosage and combination of polyphenols and follow the recommendations of your vet or nutritionist. Too many polyphenols can lead to an overdose and have undesirable effects. For example, too many tannins can lead to iron deficiency anemia or too many flavonoids can lead to blood thinning.