Beta-carotene - provitamin A
Beta-carotene belongs to the carotenoids. Carotenoids are natural pigments; they are dark red pigments found in vegetables and various plants that provide the 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 can convert beta-carotene into vitamin A. The beta-carotene present in the diet is absorbed in the dog's intestines and then transported to the liver. In the liver, beta-carotene is converted into vitamin A. The liver serves as a 'storage place' for vitamin A until the body needs it; when needed, vitamin A is released into the blood and transported to the place where it is required.
Unlike dogs, cats' bodies cannot convert beta-carotene into vitamin A; this is because cats lack a certain enzyme (β-carotene 15,15’-monooxygenase) necessary for the conversion of beta-carotene into vitamin A. For cats, it is extremely important that their diet contains sufficient vitamin A.
Although much attention is given to vitamin A in dog and cat food, the same cannot be said for beta-carotene. While beta-carotene has an important function: it acts as an antioxidant against oxidative stress. This means that beta-carotene reduces the chance of damage to healthy body cells. However, this is not the only important function of beta-carotene; it has several key roles:
- It acts as an antioxidant. Beta-carotene can neutralize free radicals. This reduces the risk of oxidative stress – which occurs when there is an excess of free radicals in the body. Free radicals are released during metabolic processes such as tissue repair, digestion, blood circulation, etc.
- It contributes to healthy skin. This is partly because antioxidants, including beta-carotene, are believed to protect the body against UV radiation (Sies & Stahl, 2004) & (Sandmann, 2019). Since beta-carotene is a provitamin A, it also supports healthy skin because vitamin A positively influences the growth and repair of body tissues; in this way, vitamin A protects the skin from damage.
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It supports the immune system. Research shows that beta-carotene supports the immune system by boosting both primary and secondary defenses.
- The primary defense (the body's first line of defense) is positively influenced by beta-carotene because it is a provitamin A. In dogs' intestines, an enzyme (beta-carotene 15,15’ dioxygenase) is present that can convert part of the beta-carotene into an active form of vitamin A. Vitamin A is necessary 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 respiratory and digestive tracts. Both the skin and the mucous membranes in the respiratory and digestive tracts are crucial for the immune system's first line of defense.
- The secondary defense is supported by beta-carotene because it improves the function and capacity of B and T cells; B cells produce antibodies that protect the body against harmful microorganisms, and T cells protect the body against viruses. Studies have shown that dogs receiving beta-carotene through their diet have significantly higher antibody levels than dogs not receiving beta-carotene through their food.
- The immune system of older dogs generally functions less effectively than that of younger dogs. Research has shown that supplementation with beta-carotene positively influences the immune system function in older dogs. In this study, older dogs receiving beta-carotene through their diet showed improved immune function compared to older dogs in the control group (who did not receive beta-carotene) and to younger dogs.
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Contributes to good eye health. The retina is necessary 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 are especially sensitive to low vitamin A levels, so it is important that dogs' diets contain sufficient vitamin A and beta-carotene.
Beta-carotene not only ensures enough vitamin A for good vision but also protects the retina against oxidative stress (damage to healthy body cells). This helps reduce the risk of cataracts and other eye diseases.
