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Free Radicals & Antioxidants

During normal cell & tissue functions, including inflammatory processes, substances called "Free Radicals" (FR)  are produced as a natural byproduct of cell metabolism. In normal cell metabolism, FR are generated within the cell and the cell has defense mechanisms to help protect itself from the damage FR can cause to the cell itself.


However in some conditions there can be too many FR or as in the ageing body, too many FR are not desirable as they can cause unwanted damage to cells & tissues. FR attack other cells, damage the cell membranes, damage proteins & damage cell DNA.

FR and immune dysfunction are the major causes of age related diseases so the maintenance of antioxidants and immune fitness is vital in the ageing animal.


When pets are sick, elderly, exposed to toxins, or suffer from poor nutrition or chronic diseases, excess FR can be produced. Chronic Dermatitis (skin conditions) & Arthritis are common diseases where ongoing inflammation can result in excess FR production. Our pets can be easily exposed to environmental toxins e.g. lawn fertilizers, licking floors, and even chemicals in bedding. Damage to cell DNA may result in cancer,

"Antioxidants" (AO) are molecules that attack these destructive FR and safely remove them from the body. Our pets' own body has their own supply of AO but in pets with chronic disease & geriatric pets, these supplies can be depleted. Therefore it is important these animals have a diet rich in AO.

Antioxidants are supplied by vitamins, minerals & naturally occurring organic compounds. These include Vitamins E & C; polyphenols, beta-carotene, and selenium.

Benefits of Antioxidants

Antioxidants break the cycle of FR damage to cells & and tissues in the animal's body. Studies have shown that a diet rich in AO can improve the function of the immune system, and improve cognitive decline in geriatric animals where FR damage is attributed to brain aging. Decreased anxiety, decreased stress-related or obsessive behaviors & and improved interactions with family members were also research results.

Medical conditions with chronic inflammation such as Chronic Skin Disease and Arthritis will also benefit by tackling the inflammatory response & improving immune system function. The geriatric animal's immune system is less able to efficiently fight disease and less able to mount a proper response to vaccinations. Therefore with a diet rich in antioxidants, the animal's immune system is better equipped to fight disease and illness.

Traditional Chinese Medicine has used Yin & Yang tonifying herbs for centuries to maintain homeostasis in the body. We can use this knowledge to assist in rebalancing the immune system in the animal's body.


Cotman CW, Head E, Muggenburg BA, et al. Brain aging in the canine: A diet enriched in antioxidants reduces cognitive dysfunction. Neurobiol Aging 2002;23:809–818.

Milgram NW, Head E, Muggenburg B, et al. Landmark discrimination learning in the dog: effects of age, an antioxidant fortified food, and cognitive strategy. Neurosci Biobehav Rev 2002;26:679–695.

Antioxidant Supplements for Animals

Humans can supplement themselves with fruit & vegetables rich in AO such as blueberries and dark chocolate but we need to be careful how we supplement our pets. Dogs can have blueberries but not chocolate! While many fruits and vegetables are safe for pets, whether they eat them or not is another matter!

While we are familiar with the above foods, studies have shown that many herbs, spices, Omega 3 sources, and seaweed actually supply a much higher percentage of AO. Herbs and spices and composite herbal medicines are among the categories that contain the most antioxidants. Once again we need to be careful about which herbs and spices we choose. For example, spices such as cinnamon and cloves are very high in AO, but not suitable for animals.

The good news is we have readily available sources of AO-rich herbs & spices that whilst contributing little weight to the dinner plate, are important and convenient contributors to antioxidant intake. We can also access excellent supplies of AO in particular seaweeds (kelp) and oils rich in Omega 3. 

Research has shown that Omega-3 fatty acids (ALA) have significant roles in decreasing tissue inflammation in the body, in the immune system, and in the reproductive system. They are, however,  "essential fatty acids" which means they must be fed in the diet. Benefits of Omega 3 FA's include:

-  reduction in body inflammation
- minimise tissue damage
- reproductive system support
- improve & support horses with chronic airway disease

The most important Omega-3 FA's  are eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). The horse’s body can convert ALA to EPA and DHA. Fish oil is the best direct source of EPA and DHA. Linseed oil, on the other hand, yields ALA, which then must be converted to EPA and DHA.


Omega-6 FA have their own roles however are shown to be pro-inflammatory and therefore NOT as desirable. They are found in grain oils such as corn and sunflower oil. The ratio of Omega-3 to Omega -6 FA is very important with Omega-3 needing to be much higher.

Herbs & Spices:    Cordyceps Rosehips   Meadowsweet   Oregano  Marjoram  Thyme  Sage  

Flax seed:  Flaxseed oil has been shown to enhance the function of the antioxidant system due to its antioxidant compounds such as phenols and vitamin E.

Kelp: Seaweeds also contain a wide array of vitamins, including vitamin E, vitamin C, A, B1, B2, B3, B5, B6, and B8. The main groups of antioxidants in seaweeds are phenolics, polysaccharides, and pigments.


Kam M, Leung H Enhancement of ATP generation capacity, antioxidant activity and immunomodulatory activities by Chinese Yang and Yin modifying herbs. 
Chinese Medicine 2007, 2:3



Paur I, Carlsen MH, Halvorsen BL, et al. Antioxidants in Herbs and Spices: Roles in Oxidative Stress and Redox Signaling. In: Benzie IFF, Wachtel-Galor S, editors. Herbal Medicine: Biomolecular and Clinical Aspects. 2nd edition. Boca Raton (FL): CRC Press/Taylor & Francis; 2011. Chapter 2. Available from:

Musazadeh V, Jafarzadeh J, Keramati M, Zarezadeh M, Ahmadi M, Farrokhian Z, Ostadrahimi A. Flaxseed Oil Supplementation Augments Antioxidant Capacity and Alleviates Oxidative Stress: A Systematic Review and Meta-Analysis of Randomized Controlled Trials. Evid Based Complement Alternat Med. 2021 Sep 3;2021:4438613. doi: 10.1155/2021/4438613. PMID: 34527059; PMCID: PMC8437595.

Hess TM, Rexford JK, Hansen DK, Harris M, Schauermann N, Ross T, Engle TE, Allen KG, Mulligan CM. Effects of two different dietary sources of long chain omega-3, highly unsaturated fatty acids on incorporation into the plasma, red blood cell, and skeletal muscle in horses. J Anim Sci. 2012 Sep;90(9):3023-31. doi: 10.2527/jas.2011-4412. PMID: 22966078.

Nogradi N, Couetil LL, Messick J, Stochelski MA, Burgess JR. Omega-3 fatty acid supplementation provides an additional benefit to a low-dust diet in the management of horses with chronic lower airway inflammatory disease. J Vet Intern Med. 2015 Jan;29(1):299-306. doi: 10.1111/jvim.12488. Epub 2014 Oct 10. PMID: 25307169; PMCID: PMC4858086.

Portier K, de Moffarts B, Fellman N, Kirschvink N, Motta C, Letellierw C, Ruelland A, van Erck E, Lekeux P, Couder J. The effects of dietary N-3 and antioxidant supplementation on erythrocyte membrane fatty acid composition and fluidity in exercising horses. Equine Vet J Suppl. 2006 Aug;(36):279-84. doi: 10.1111/j.2042-3306.2006.tb05553.x. PMID: 17402432.

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