Carotenoids: Function & Diseases

Carotenoids are found in various fruits and vegetables and have many health-promoting properties. Probably the best known carotenoid is beta-carotene.

What are carotenoids?

Carotenoids are secondary plant compounds. Since the body cannot produce them itself, they must be supplied through the daily diet. Scientists have identified about 600 carotenoids to date. The health-promoting substances are divided into two groups (carotenes and xanthophylls). They differ in terms of their molecular structure: carotenes consist only of carbon and hydrogen atoms, while xanthophylls have an additional hydroxyl group. The carotenes include alpha-carotene, beta-carotene and lycopene. These carotenoids are heat resistant. Lutein, beta-cryptoxanthin and zeaxanthin are known xanthophylls. Foods containing these carotenoids should never be heated, as high temperatures destroy their bioactive ingredients. Carotenoids are fat-soluble and colored (red, yellow, orange). One tenth of them can be used for vitamin A synthesis. In addition to beta-carotene, alpha-carotene and beta-cryptoxanthin are also capable of producing the important vitamin.

Function, effect and tasks

Carotenoids are important antioxidants. They give off electrons and can thereby render radicals harmless. This prevents the oxidation of LDL cholesterol in the vessel walls and thus the development of arteriosclerosis. The age of all cells is increased. This anti-aging effect is particularly evident in skin cells: Premature wrinkling is prevented. The more carotenoids are present in the blood, the better the body is protected against free radicals, which even cause cancer. To further increase their antioxidant and cell-protective effects, consumers should definitely consume carotenoid-containing foods together with vitamin E and glutathione. The anticarcinogenic properties of the group of active substances are shown by the fact that they inhibit both the growth of tumor cells and their proliferation (cytostatic effect). Various carotenoids, such as beta-carotene, are capable of synthesizing the antioxidant vitamin A (retinol). It builds up the gastric mucosa and protects against the aggressive gastric acid. Retinol also improves the transmission of information between cells. In the brains of elderly people, it inhibits the development and progression of the dreaded Alzheimer’s disease by promoting communication between nerve cells. To build the important vitamin A, beta-carotene requires oxygen and an iron ion. Carotenoids also have a strong anti-inflammatory effect. They promote the proliferation of B, T, and T helper cells of the immune system and increase the activity of killer cells. A high level of carotenoids in the blood serum automatically causes a low level of interleukin-6. Since carotenoids are also deposited in the top layer of the skin, they provide the skin with protection against harmful UV light. For the best effect on the body, consumers should combine carotenoids with unsaturated fatty acids, iron-rich foods, and foods that contain vitamins A, D, E, and K. Foods containing beta-carotene are most useful if they have been previously crushed or heated. The carotenoid lycopene is better broken down when it comes from processed foods (tomato juice instead of raw tomato).

Formation, occurrence, properties, and optimal levels

Carotenoids are formed in the chromoplasts of red and yellow vegetables and fruits (peppers, tomatoes, beet, apricots) and in the chloroplasts of green vegetables. There, however, their red or yellow pigment is masked by the green of the chlorophyll. Green vegetables have a content of 60 to 80% xanthophyll. In the human body, carotenoids are found in varying concentrations mainly in cell walls. In blood serum there are about 40 carotenoids. With 15 to 30%, beta-carotene is most strongly represented there. 65% of carotenoids are stored in human fatty tissue. Liver, adrenal gland, ovaries and testicles are the organs with the highest concentration of carotenoids. To provide the body with sufficient beta-carotene, the consumer should consume 2 to 5 mg daily. This value corresponds to a beta-carotene concentration of at least 0.5 u mol/l in the blood plasma. A beta-carotene deficiency exists when the value is below 0.3 u mol/l.Even better protection against carotenoid deficiency is provided by the “5-a-day” rule: 5 servings of red, yellow, green fruits and vegetables daily. In this way, the consumer gets an amount of 10 to 25 mg of mixed carotenoids. Users of dietary supplements should also be sure to include as many different carotenoids as possible.

Diseases and disorders

If a person does not consume enough carotenoids, carotenoid deficiency occurs. An undersupply of beta-carotene automatically causes a deficiency of vitamin A. Those who permanently consume too few carotenoids have an increased risk of cancer. In addition, the probability of getting a cardiovascular disease (heart attack, stroke, etc.) is very high. Other possible consequences of an undersupply of carotenoids are: Visual disturbances up to macular degeneration, cataract, growth disorders in children, increased susceptibility to infections, pigment disorders, skin cancer. The destruction of the blind spot on the eye retina (macular degeneration), which usually occurs in older people, can even lead to blindness. In addition, some patients with carotenoid deficiency develop sarcopenia (muscle atrophy) – a condition that is not only associated with muscle weakness and restricted movement, even immobility, but also greatly increases the risk of falls. The administration of carotenoids causes an improvement of vitiligo (white spot disease). The non-pigmented areas of skin darken slightly, so that the difference between diseased and healthy areas of skin is no longer so clearly visible.