Beta-carotene is a substance from the group of carotenoids. Carotenoids are natural pigments found in fruits and vegetables.
What is beta-carotene?
Beta-carotene is a natural pigment found in many plants. Especially colored fruits, leaves and roots contain a lot of beta-carotene. Carotenes belong to the secondary plant substances. Secondary plant substances are chemical compounds produced by plants. They are not vital for plants, but serve as protection against predators. The natural substances are of great importance to humans. Beta-carotene is the precursor of vitamin A. Therefore, the plant substance is also called provitamin A. Vitamin A is also known as retinol. However, the absorption of beta-carotene is significantly more difficult than the absorption of vitamin A. For this, beta-carotene can also not be overdosed, unlike vitamin A.
Function, effect and tasks
Beta-carotene is the best-known plant substance from the group of carotenoids. It ensures that fruits and vegetables are bright yellow or orange. Beta-carotene can lower cholesterol levels. Due to its cholesterol-lowering and antioxidant effects, beta-carotene protects against vascular diseases, heart attacks and strokes. In the vessels, beta-carotene prevents the oxidation of cholesterol and thus its accumulation in the vessels. In this way, the carotenoid prevents arteriosclerosis. In particular, the cells of the gastric mucosa benefit from vitamin A and thus also from beta-carotene. Beta-carotenes have an anti-cancer effect. This is due to the strong antioxidant effect. Antioxidants can render free radicals harmless. Free radicals are produced in the body during numerous metabolic processes. Chemically, radicals are molecules that are missing an electron. They try to steal this electron from other cells and thus damage the cell membrane and, under certain circumstances, the entire cell. Free radicals are suspected of promoting cardiovascular disease, cancer and premature aging. As an antioxidant, beta-carotene also has a positive effect on brain function. It improves communication between brain cells and, in the form of vitamin A, also influences the beta-amyloid processing process. In case of disturbances in this process, Alzheimer’s disease may develop. Studies have shown that elevated levels of interleukin-6 are associated with low levels of carotenoids in the blood. When caritinoid levels increase, interleukin-6 levels decrease at the same time. Interleukin-6 is released by white blood cells (leukocytes) during inflammatory processes. The higher the level of interleukin-6 in the blood, the greater the inflammation as a rule. Beta-carotene thus has an anti-inflammatory effect. Vitamin A and provitamin A play a special role for the eyes. Vitamin A is important for the visual process. A deficiency of vitamin A can lead to night blindness or poor vision.
Formation, occurrence, properties, and optimal levels
Beta-carotene is the precursor of retinol. Deep yellow to orange fruits and vegetables contain the most beta-carotene. However, dark green vegetables also contain the pigment. Rich in beta-carotene are thus carrots, pumpkins, sweet potatoes, sea buckthorn, apricots, mangoes, papayas, nectarines, peaches, broccoli, cress, sorrel, purslane, spinach, endive, beet leaves, dandelion, asparagus, cabbage, corn, plums, sour cherries and peas. Beta-carotene is absorbed through the intestines. Its absorption is worse than that of vitamin A. To provide the same amount of vitamin A to the body, six times as much beta-carotene must be absorbed. The conversion to vitamin A is limited. It is dependent on beta-carotene intake and protein intake, among other factors. Vitamin E supply and the number of fats consumed also play a role in absorption. Vitamin A status must also be considered. The better the supply of vitamin A, the lower the enzyme activity and the less provitamin A is converted to vitamin A. A large part of the ingested carotenoids is transported in unchanged form. The highest concentrations of beta-carotene in the human body are found in the liver, testes, corpus luteum and adrenal glands. The lungs, muscles, heart, brain and skin, on the other hand, show only a low beta-carotene content.
Diseases and disorders
Excess beta-carotene is noticeable by a yellowing of the skin. This yellowing is also known as carotenoderma or carroticterus. First, the area around the nasolabial fold turns yellow. This is followed by the undersides of the hands and the soles of the feet. As soon as the over-supply is discontinued, the yellowing also recedes. Unlike vitamin A, beta-carotene cannot be overdosed. Even high doses of supplemented beta-carotene are not toxic. However, there is a suspicion that taking supplements of beta-carotene for several years increases the risk of lung and colon cancer in smokers and drinkers. All medications containing beta-carotene must therefore carry a warning label. Medications containing more than 20 mg of beta-carotene should not be prescribed to smokers. A deficiency of beta-carotene can have numerous consequences. In particular, if only little vitamin A is taken in with food, an adequate supply of beta-carotene is essential. In the case of a deficiency, there is a restriction of the ability to see. Particularly at dusk, vision is reduced. Night blindness occurs. In addition, the conjunctivae of the eye dry out. Foam-like spots form, the so-called Bitot spots. The cornea may also dry out. Corneal ulcers form, which can lead to blindness if left untreated. Symptoms of deficiency also appear outside the eye. The gums are inflamed and the oral mucosa shows ulcerations. Other symptoms of deficiency include anemia, impaired growth, and a diminished sense of smell.
