Dietary Antioxidants Are Important for Your Pet
Free Radicals Do the Damage
Oxygen gives your pet life but it may also behave aggressively to try to shorten it. Without sufficient oxygen your pet's tissues are in immediate jeopardy. Ironically, excess oxygen can poison the cells of Fido's body via free-radical formation – what a dichotomy.
Normal compounds are composed of atoms bonded together by sharing electrons, one from each atom. Free radicals are molecules with an unpaired electron. The unpaired electrons are highly energetic and seek out other electrons with which to pair, often stealing them in the process from normal compounds (typically oxygen). In the process, this produces a stable compound by pairing their unpaired electron; but it also alters the stable compound and creates another free radical – again short one electron – and continues the chain. This chain reaction creates havoc in the cell.
Free radicals are commonly produced as part of normal cell metabolism, but also can become excessive following injury or disease or can be caused by environmental pollutants such as UV radiation, cigarette smoke or smog. Excessive free-radical production (oxidative stress) results when the formation of free radicals overwhelms the body's defense system against them. Oxidative stress can overpower the ability to fight back and may result in cell and tissue damage, just like oxygen can brown an apple or banana, thus shortening your pet's life.
Uncontrolled free-radicals may run amuck throughout your pet's body, doing considerable damage to cells. They alter the structure of cell membranes and create havoc to poly-unsaturated fats, cell proteins and cell DNA. The more active the cell, the greater the potential risk of tissue damage. In people, this damage has recently been linked to degenerative diseases such as rheumatoid arthritis, cancer, cardiovascular disease, inflammatory bowel disease, kidney disease, Parkinson's disease and cataracts; it may also have a deleterious affect on aging. It is thought that free-radical damage may play a similar role in certain diseases of pets and wreak havoc on the aging process.
Antioxidants to the Rescue
Antioxidants are your pet's major defense system against the scourge of free-radicals and oxidative stress, and help keep their damage to a minimum. Antioxidants, like vitamin E, scavenge and convert free radicals to relatively stable compounds and stop or prevent the chain reaction of free radical damage. Antioxidants are therefore important to protect pets from tissue damage and disease and may in the process enhance immunity.
Dietary antioxidants include vitamin E, vitamin C, taurine and the carotenoids – beta carotene, lutein, and lycopene and certain trace minerals. These antioxidants gobble up free-radicals, stopping them in their tracks. Antioxidants keep your pet's cells healthy, including lungs, heart, blood cells, muscles, nerves, GI tract and reproductive organs. It was recently demonstrated that a cocktail of such antioxidants limited cell damage in dogs and cats. Work is currently being done to show the benefits of antioxidants to older pets' ability to learn, to modify certain behavioral problems and function better in their geriatric years.
Vitamin C. Vitamin C is a powerful water-soluble antioxidant. High activity dogs – those competing in fly-ball, agility, racing and high-demand rescue work – are thought to require increased amounts of vitamin C due to the increased demand of oxidative stress. Although the dog can synthesize vitamin C, racing and other forms of high-energy exercise are thought to increase the demand for all antioxidants to combat increased oxidative stress with increased body use of oxygen. Unlike requirements for humans and guinea pigs, the dietary vitamin C requirement of cats is negligible because they can synthesize it, though their need for vitamin C as an antioxidant is unexplored. Surely the benefit of vitamin C as an antioxidant is feasible.
Carotenoids. Carotenoids are red, yellow, and orange fat-soluble pigments found in plant foods such as carrots and tomatoes. Though the dog and cat are predominantly carnivores, the value of these powerful antioxidants could be important. We don't yet know all the benefits of these compounds to dogs and cats to prevent degenerative diseases, cancer, and combat conditions of aging. Dogs and cats are living longer today, and carotenoids may benefit pets in ways yet undiscovered.
Taurine. Taurine, an amino acid, is a critically important nutrient for cats. Its benefit is successful reproduction, healthy eyesight and heart function. Though important to cats, taurine is not similarly essential to dogs. For dogs and cats taurine is beneficial as an antioxidant in protecting cell membranes from damage.
Minerals. Certain minerals, especially zinc, manganese, copper and selenium assist several enzymes that act as antioxidants. These minerals are integral parts of various antioxidant enzymes in your pet's body.
Vitamin E. Vitamin E is unique among vitamins. As alpha-tocopherol, vitamin E is notably essential for the proper function of the reproductive, muscular, nervous, circulatory and the immune systems. Its antioxidant property is its prime function. Vitamin E, which can't be synthesized in your pet's body, is possibly the most important and essential antioxidant for protecting cell membranes from free-radical damage. Vitamin E works in concert with other antioxidants, protecting and reinforcing the effect of vitamin C and beta-carotene, and working together with selenium. Vitamin E may also work synergistically with taurine.
Seed oils such as soy and sunflower seed and organ meats such as liver and spleen are higher in vitamin E. In the wild, cats and dogs may naturally obtain vitamin E from organ meats. Today's pet foods are supplemented with vitamin E. Most critical for pet diets is the increase in vitamin E requirement with an increase in dietary poly-unsaturated fats. Fish oils in cat foods and other fat sources of unsaturated fats, requires an increased need for vitamin E.
Synthetic vitamins are, for the most part, equal in efficacy to natural source vitamins. Not so for vitamin E. The best vitamin E is isolated from seed oils, as opposed to synthetic vitamin E made from petrochemicals. The body preferentially transports and incorporates natural-source vitamin E. Synthetic vitamin E is not as biologically potent in comparison. The difference between the two is the difference in the chemical structure of the two, just like apples and oranges.
For your pet, natural vitamin E is better than synthetic. It functions better to provide their enhanced antioxidant need. From mice to elephants it has been shown that natural vitamin E has more punch, more 'bounce per ounce' than synthetic. There are physiological differences in its absorption, transport, utilization and tissue retention. Though past research has shown that natural vitamin E is 36 percent better than synthetic, current research in several species, including humans, shows a 200 to 300 percent potency of natural versus synthetic vitamin E.
For dogs and cats, vitamin E is essential for health. Healthy muscles, retinal (eye) health and reproductive success all are linked to sufficient vitamin E. Vitamin E is especially necessary to newborn kittens and puppies; since placental transfer is poor, first milk, colostrum, is important to provide adequate vitamin E. A sufficient amount of vitamin E is important to prevent oxidation of body fats. As polyunsaturated fats (PUFAs) are increased in dog and cats diets, the requirement for vitamin E increases. Years ago, without this knowledge, diets high in PUFAs (fish, fish meal, fish oils), and not supplemented with sufficient vitamin E, led to 'yellow-fat' disease – rancidity and destruction of body fat, leading to death in puppies and kittens.
According to the National Research Council (NRC), the need for vitamin E in the diet of cats is markedly influenced by dietary composition. Though 30 IU per kilogram of diet is considered the minimum requirement for cats, 50 IU per kilogram of diet is probably better, considering the high PUFA-containing diets many pet cats eat. Actually a high PUFA diet of tuna or other fish probably requires three to four times the minimum.
Similar to cats, the dietary requirement of dogs for vitamin E is closely associated to the dietary concentration of PUFAs. It has been reported that a smaller amount of vitamin E would not sustain reproduction in fox terriers fed unsweetened, irradiated evaporated milk, while a slightly larger amount would. However, one pup in four from a bitch receiving the higher level of vitamin E showed slight muscular dystrophy. In beagle puppies, 30 IU vitamin E per kilogram of diet prevented deficiency both clinically and histopathologically. According to the NRC, the recommended allowance for maintenance, reproduction and growth of dogs, should be satisfied by 20 IU vitamin E/kg diet, a little more for pregnancy and a little more for growth.
Pet Foods Needs Antioxidants, Too
Today's pet foods are supplemented with other antioxidants for the stability of the food. Dry pet foods are especially susceptible to fat rancidity and deterioration. Since dry dog and cat foods need to be stable, with sufficient shelf-life, antioxidants are included to keep them from spoiling. Today in premium pet foods, 'natural' antioxidants including mixed tocopherols, and rosemary extract, along with vitamin C and citric acid are often blended to stabilize fat sources, instead of chemically synthesized antioxidants such as BHA, BHT, and/or ethoxyquin.
Mixed tocopherols are different from vitamin E supplementation for your pet's health. Mixed tocopherols are composed of alpha, beta, delta, and gamma tocopherol, while vitamin E activity for your pet's health and nutrition is solely alpha-tocopherol. Although your pet foods may be stabilized with mixed tocopherols, vitamin E is usually provided by synthetic vitamin E.
Look For Natural Vitamin E in Your Pet's Food
For your own personal vitamin E needs, you search out natural-source vitamin E, d-alpha-tocopheryl acetate, that says "natural vitamin E" right on the bottle. You prefer natural vitamin E. Expect no less for your pet. Therefore, look for natural vitamin E in your pet's food. Look for d-alpha-tocopheryl acetate, natural vitamin E in the ingredient list of his dry dog or cat food. Similarly, when you look for shelf-life protection in your pet's food, look for mixed tocopherols, not BHA or ethyoxyquin.
Dietary antioxidants are important for your pets. Make sure your pet's food contains the necessary antioxidants, so that Fido will be able to run free, not the free-radicals.