Antioxidants, free radicals, health and disease

The term “antioxidants” is becoming more commonly used in relation to health and disease, and they are now beginning to appear as ingredients in some pet foods – but what are they, and why are they important?

Free radicals:

To understand why antioxidants (AO) are so important, we need to first understand what free radicals are. Free radicals are a cellular by-product from normal metabolism, and are most commonly formed during the utilisation of oxygen in normal metabolism. When oxygen is used as fuel source, the by-product can be an unstable oxygen molecule which has an unbound free electron (called reactive oxygen species) and these “free radicals” can cause significant damage to other molecular structures.

The production of free radicals occurs all the time, and the body has many mechanisms designed to cope with them – both internal enzyme pathways and utilising external dietary sources of antioxidants. The production of free radicals does vary, and is increased during strenuous exercise, during inflammatory disease, and with poor circulation. External factors like pollutants, pesticides, food additives and certain drugs, anaesthetics and chemicals can also cause free radical formation at higher levels.

It is now widely accepted that the process of ageing, and the onset of many chronic diseases like heart disease and cancer, can be linked to the accumulation of free radical damage. It is also evident that pets with chronic allergies and skin disease have a much higher level of free radical formation which contributes to the ongoing skin irritations. The breakdown of excess fats in the diet also contribute to free radical formation, and is linked to the many diseases associated with obesity.

Managing free radicals:

As mentioned, the body has several mechanisms for dealing with free radicals. Internal enzyme pathways (eg glutathione peroxidase) function to decrease the level of the most harmful reactive oxygen species. These enzyme pathways require several essential dietary minerals like selenium, copper, manganese and zinc to function correctly, so any dietary deficiency in these will lead to excessive and ongoing tissue damage from free radicals.

Equally important is the utilisation of dietary antioxidants – molecules stable enough to donate an electron to the free radicals and thus neutralise them. The most well-known dietary AO’s are vitamins C and E, as well as carotenoids, but there are over 4000 recognised dietary AO’s. If a diet is deficient in naturally occurring AO’s, then accumulation of free radicals will result in chronic oxidative stress, which in turn leads to chronic degenerative diseases – skin disease, arthritis, cataracts, heart disease, and cancer….


AO’s are widely available in nature, and are most potent in fresh raw vegetables and fruits. The highest concentrations are usually found in coloured foods, like berries, grapes, tomatoes, carrots, and also in cruciferous greens, garlic, and many other sources.

Some of the highest sources can be found in goji berries, blue berries, bilberry, grape seeds, pine bark extract, milk thistle, phytoestrogens (eg soybean).

Additional sources are vitamin C, E, A, quercetin, coenzyme Q10, green tea, caffeine, dark chocolate (not for pets though). Mineral supplements like selenium and zinc are also vital to support the body’s own enzyme pathways.

Many of the naturally occurring AO’s are heat sensitive, and will be destroyed by cooking and processing, which is one of the reasons that we see such improved health, and longevity, in pets that are fed on raw food diets.

Antioxidant therapy:

Given many chronic diseases can be linked to AO deficiency, it makes sense that many of these diseases will respond to AO supplementation, particularly in relation to any age related illness and dementia.
Some vets have noted AO’s to be highly beneficial in treating allergic skin disease, and they can significantly reduce itching and the need for more potent drugs.

AO’s can be used in all senior pets, but in particular they can be of benefit for – diabetes, cataracts, arthritis, auto-immune disease, pre and post anaesthesia, senility and dementia, heart failure, long term drug therapy, chemotherapy and cancer management.

We endeavour to deliver the best information possible on natural health and diets for dogs and cats. Our articles involve contributions from senior veterinarians and are researched thoroughly. They remain the opinion of Vets All Natural however and we would always recommend seeking professional advice specific to your pet from a veterinarian. © Copyright 2015 Vets All Natural. All Rights Reserved

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