Beta-carotene – provitamin A
Beta-carotene belongs to the carotenoids. Carotenoids are natural pigments; they are dark red pigments that give vegetables and various plants their orange (yellow) color. However, this does not mean that green vegetables do not contain carotenoids (in these vegetables, the color is masked by the deep green color of chlorophyll).
Beta-carotene is a provitamin A for dogs; this means that a dog’s body is able to convert beta-carotene into vitamin A. The beta-carotene present in food is absorbed in a dog’s intestines and then transported to the liver. In the liver, beta-carotene is subsequently converted into vitamin A. The liver serves as a “storage facility” for vitamin A until the body needs it; when needed, vitamin A is released into the blood and transported to where it is required.
Unlike dogs, cats’ bodies are unable to convert beta-carotene into vitamin A; this is because cats lack a certain enzyme (β-carotene 15,15’-monooxygenase) needed to convert beta-carotene into vitamin A. For cats, it is extremely important that their food contains sufficient vitamin A.
Although extensive attention is paid to vitamin A in dog and cat food, the same cannot be said for beta-carotene. Beta-carotene has an important function: it acts as an antioxidant against oxidative stress. This means that beta-carotene reduces the likelihood of damage to healthy body cells. However, this is not beta-carotene’s only important function; beta-carotene has several important functions:
- It acts as an antioxidant. Beta-carotene is able to neutralize free radicals. As a result, beta-carotene reduces the likelihood of oxidative stress—which occurs when there are excessive amounts of free radicals in the body. Free radicals are released during metabolic processes in the body, such as the repair of body tissues, digestive processes, blood circulation, etc.
- It contributes to healthy skin. This is partly because antioxidants, including beta-carotene, are thought to protect the body against UV radiation (Sies & Stahl, 2004) & (Sandmann, 2019). Because beta-carotene is a provitamin A, it also contributes to healthy skin because vitamin A has a positive effect on the growth and repair of body tissue; in this way, vitamin A protects the skin against damage.
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It supports the immune system. Research shows that beta-carotene supports the immune system. This is because it boosts both the primary and secondary immune defenses.
- The primary defense (the body’s first line of defense) is positively influenced by beta-carotene because it is a provitamin A. An enzyme (beta-carotene 15,15’ dioxygenase) is present in dogs’ intestines that can convert part of the beta-carotene into an active form of vitamin A. Vitamin A is needed for the formation and maintenance of healthy skin; the skin is one of the first barriers protecting the body against harmful microorganisms from outside. Vitamin A is also needed for the membranes lining the airways and intestinal tract. Both the skin and the mucous membranes in the airways and intestinal tract are extremely important for the immune system’s first line of defense.
- The secondary defense is supported by beta-carotene because beta-carotene improves the function and capacity of B and T cells; B cells produce antibodies that protect the body against harmful microorganisms, while T cells protect the body against viruses. Research has shown that dogs receiving beta-carotene through their diet have a significantly higher number of antibodies than dogs that do not receive beta-carotene through their food.
- The immune system of older dogs generally functions less effectively than that of younger dogs. Research has shown that beta-carotene supplementation has a positive effect on the functioning of the immune system in older dogs. In this study, older dogs received beta-carotene through their food. Compared with older dogs in the control group (which did not receive beta-carotene) and with younger dogs, beta-carotene supplementation improved immune system function.
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It contributes to good eye health. The retina is needed for normal vision. The retina is located at the back of the eyeball. It consists of cells called rods and cones. These cells are sensitive to light and use vitamin A to tell the brain what the eyes see. Rods in particular are sensitive to low levels of vitamin A, which is why it is important for dogs’ food to contain sufficient vitamin A and beta-carotene.
Beta-carotene not only provides sufficient vitamin A for good vision; it also protects the retina against oxidative stress (damage to healthy body cells). As a result, beta-carotene contributes to a reduced likelihood of developing cataracts and other eye conditions.
