Pharmacological group: provitamins
Beta-carotene is a highly colored red-orange pigment found abundantly in plants and fruits. It is an organic compound chemically classified as a hydrocarbon and a terpenoid (isoprenoid), that is, a derivative of isoprene. Beta-carotene is biosynthesized from geranylgeranyl pyrophosphate. It is a carotene, that is, a tetraterpene, biochemically synthesized from eight isoprene units and therefore has 40 carbon atoms. Beta-carotene differs from all carotenes by the presence of a beta ring at both ends of the molecule. The absorption of beta-carotene increases when combined with fats, since carotenes are fat-soluble compounds.
Beta-carotene is found in carrots, pumpkin and sweet potatoes and is responsible for their orange coloring. Beta-carotene is the most common form of carotene in plants. As a food coloring, beta-carotene has the E number E160a. The structure of beta-carotene was first described by Carrère et al in 1930. In nature, beta-carotene is a precursor (inactive form) of vitamin A, and is converted to vitamin A through the action of beta-carotene 15,15"-monooxygenase. Isolation of beta-carotene from fruits rich in carotenoids is usually carried out using capillary chromatography. Isolation of beta -carotene from a mixture of other carotenoids is based on the polarity of the compound. Beta-carotene is a non-polar compound, so it is isolated using a non-polar solvent such as hexane. Being a highly conjugated compound, beta-carotene has a bright color. In addition, since it is not a hydrocarbon. lacks functional groups, this compound is very lipophilic (hydrophobic, fat-soluble).
Description of action
Natural carotene dye, the most active isomer of vitamin A and at the same time a provitamin and the main source of this vitamin. Causes a change in skin color (without scleral pigmentation), and also protects the skin from exposure to sunlight. Bioavailability depends on the amount of fat in the diet and normal bile secretion. About 50% of β-carotene is converted to vitamin A directly in gastrointestinal tract; after absorption, the compound is again converted into a provitamin and in this form is stored in the body, mainly in adipose tissue and in the skin, where it exhibits protective activity against sunlight. Not large numberβ-carotene is converted into vitamin A in the liver, and excess is excreted in the feces.
Provitamin A activity
Plant carotenoids are the main provitamin A in food. Beta-carotene is the best known provitamin A carotenoid. Other carotenoids include alpha-carotene and beta-cryptoxanthin. The absorption of carotenoids is limited to the duodenum of the small intestine and depends on the membrane protein phagocytic receptor class B (SR-B1), which is also responsible for the absorption of vitamin E (alpha-tocopherol). One molecule of beta-carotene can be broken down by the intestinal beta enzyme, beta-carotene 15,15"-monooxygenase, into two molecules of vitamin A.
The absorption efficiency of beta-carotene, according to various estimates, ranges from 9 to 22%. The absorption and conversion of carotenoids may depend on the form of beta-carotene (which can be in cooked or raw vegetables or in dietary supplement form), the co-consumption of fats and oils with it, and the body's current stores of vitamin A and beta-carotene.
Symmetrical and asymmetrical cleavage
In the molecule, the chain between the two cyclohexyl rings of beta-carotene can be cleaved either symmetrically or asymmetrically. Symmetrical cleavage by the enzyme beta, beta-carotene-15, 15"-dioxygenase, requires the presence of the antioxidant alpha-tocopherol. As a result of this symmetrical cleavage, we obtain two equivalent molecules of retinal, each of which then produces retinol (vitamin A) and retinoic acid. Beta -carotene can also be asymmetrically cleaved into two asymmetric products. The product of asymmetric cleavage of beta-carotene is beta-apocarothenal (8", 10", 12"). Asymmetric cleavage significantly reduces the amount of retinoic acid.
Methods for measuring vitamin A activity
Until recently, vitamin A activity in food was expressed in international units (IU). This measurement method is still used on food and dietary supplement labels. However, it is difficult to calculate total dietary vitamin A activity in terms of IU, since the absorption and conversion of carotenoids compared to retinol is variable. In 1967, the Food and Agriculture Organization of the United Nations/World Health Organization developed the "retinol equivalent" (RE) unit. Later, in 2001, the US Institute of Medicine proposed introducing a unit of “retinol activity equivalent” (RAE) as an intake standard.
International units
1 RAE = 3.33 IU of vitamin A retinol activity
1 IU retinol = 0.3 mcg RAE
1 IU beta-carotene from dietary supplements = 0.15 mcg RAE
1 IU beta-carotene from food = 0.05 mcg RAE
1 IU alpha-carotene or beta-cryptoxanthin = 0.025 mcg RAE
(Source: Otten JJ, Hellwig JP, Meyers LD, eds. Dietary Values: An Essential Guide to Nutritional Requirements. Washington, DC:...National Academy Press; 2006).
Retinol equivalents (REs)
1 RE = 1 mcg retinol
1 RE = 6 mcg beta carotene
1 RE = 12 mcg other provitamin A carotenoids.
Retinol activity equivalents (RAEs)
1 RAE = 1 mcg retinol
1 RAE = 2 mcg all-trans beta-carotene as a supplement
1 RAE = 12 mcg all-trans beta-carotene in food matrix
1 RAE = 24 mcg of other provitamin A carotenes in the food matrix.
Sources of beta-carotene in the diet
Beta carotene is responsible for the orange color of many fruits and vegetables. Vietnamese gac oil and crude palm oil are particularly rich sources of beta-carotene, as are yellow and orange fruits such as melon, mango and papaya, and orange root vegetables such as carrots and yams. The color of beta-carotene is masked by chlorophyll in green leafy vegetables such as spinach, kale, sweet potato leaves and sweet pumpkin leaves. Vietnamese gac oils and raw palm oil contain large amounts of beta-carotene, more than any known fruit or vegetable, 10 times more than, for example, carrots. However, gak is quite rare and unknown outside of Southeast Asia, and crude palm oil is typically processed to remove the cartenoids to improve color and clarity before sale.
Based on a pooled analysis of 500,000 women living in the United States, Canada and some European countries, the average daily required intake of beta-carotene is 2-7 mg.
Indications for use
Treatment of erythropoietic protoporphyria, photodermatosis, allergic reactions to ultraviolet radiation and phototoxic reactions (exanthema multiforme, urticaria), pigmentation abnormalities (vitiligo).
Contraindications
Hypersensitivity to any of the components of the drug, severe liver or kidney failure.
Interaction with other drugs
There is no data on the interaction of β-carotene with other drugs. During treatment with β-carotene, you should not take medications containing vitamin A.
Side effects of beta carotene
In some cases, moderate diarrhea, petechiae on the skin and joint pain. If too large doses are used, the skin turns an intense yellow color; therapeutic doses may cause slight yellowing of the skin. The most common side effect of excessive consumption of beta-carotene is carotenoderma, a physically harmless condition manifested by an orange tint to the skin due to the deposition of carotenoids in the upper layers of the epidermis. Chronic use of high doses of synthetic beta-carotene supplements is associated with a higher risk of lung cancer in smokers. In addition, taking beta-carotene from dietary supplements may increase the risk of prostate cancer, intracerebral hemorrhage, cardiovascular disease mortality, and all-cause mortality in smokers or people with high levels of asbestos exposure. Beta-carotene has a strong tendency to oxidize, more so than most dietary fats, and thus may, to some extent, accelerate oxidation more than other food colorings such as annatto.
Pregnancy and lactation
Category C. There is no data confirming the safety of β-carotene during lactation.
Dosage
Orally, usually at a dose of 1 mg/kg body weight. Treatment begins in spring and continues until autumn. To treat vetiligo, use 25 mg per day for 6–10 weeks; then a prophylactic dose of 25 mg per day. For the treatment of porphyria, use initially 50-200 mg/day in divided doses; then the dose is determined individually.
Note
β-carotene cannot be used in sunscreens; during dermatological treatment, filters with a high absorption coefficient of solar radiation should be used. During treatment, liver function tests should be carefully monitored.
Beta carotene overdose
Beta-carotene, a precursor form of vitamin A, is found in plants such as carrots. It is selectively converted into retinoids and therefore does not cause hypervitaminosis A, but excessive consumption can cause carotenosis, a benign condition that causes the skin to turn orange.
The proportion of carotenoids absorbed decreases as dietary intake increases. In the intestinal wall (mucosa), beta-carotene is partially converted into vitamin A (retinol) by the enzyme dioxygenase. This mechanism depends on the amount of vitamin A in the body. If the body has enough vitamin A, the conversion of beta-carotene is reduced. Thus, beta-carotene is a very safe source of vitamin A and high intake cannot lead to hypervitaminosis A. Excess beta-carotene is mainly stored in the fatty tissues of the body. The fat stores of adults often take on a yellow tint due to accumulated carotene, while the fat stores of infants are white. Excessive consumption of beta-carotene causes yellowing of the skin, but this effect is easily reversible when consumption is stopped.
Beta-Carotene Drug Interactions
Beta carotene may interact with cholesterol-lowering medications. Taking them together may reduce the effectiveness of these drugs. Beta carotene should not be taken with Orlistat, a weight loss drug, as Orlistat can reduce the absorption of beta carotene by as much as 30%. Bile acid secretants and proton pump inhibitors may also reduce the absorption of beta-carotene. Drinking alcohol with beta-carotene may reduce its ability to be converted into retinol and may possibly lead to hepatotoxicity.
Beta-carotene and lung cancer in smokers
Chronic intake of high doses of beta-carotene increases the risk of lung cancer in smokers, according to one study. This effect is especially noticeable when taking dietary supplements. No lung damage was found in patients exposed to cigarette smoke who took moderate doses of beta-carotene (6 mg) as opposed to high pharmacological doses (30 mg). Thus, the risk of cancer from beta-carotene supplementation is based on the combination of cigarette smoke and high daily doses of beta-carotene. There are at least two proposals for the mechanism of the observed harmful effects of high doses of beta-carotene in this group of individuals, but neither of them is yet widely accepted.
The effects of high doses are explained by the fact that when retinoic acid binds to RAR-beta (retinoic acid receptor beta), the complex binds AP1 (activating protein-1). AP1 is a transcription factor that binds to DNA and subsequently promotes cell proliferation. Thus, in the presence of retinoic acid, the retinoic acid:RAR-beta complex binds to AP1 and inhibits AP-1 binding to DNA. In this case, AP1 expression ceases and cell proliferation is not observed. Cigarette smoke increases the asymmetric breakdown of beta-carotene, significantly reducing retinoic acid levels in the body. This may lead to higher cell proliferation in smokers, and therefore a higher likelihood of lung cancer.
Another breakdown product of beta-carotene is suspected of causing cancer at high doses, trans-beta-apo-8"-aldehyde carotenoid (apocarotenal), which was found in one study to be mutagenic and genotoxic in cell cultures.
Medical Uses of Beta Carotene
Beta-carotene is used to treat various disorders such as erythropoietic protoporphyria. It is also used to reduce the risk of breast cancer in women before menopause, as well as to reduce the risk of age-related macular degeneration (AMD).
Beta carotene and cancer treatment
There is still debate about whether beta-carotene is effective in treating various forms of cancer. Studies have shown that patients with cervical intraepithelial neoplasia have a positive response to beta-carotene; however, high levels of beta-carotene have been found to increase the risk of lung cancer in people who smoke regularly or have smoked in the past. Beta-carotene is used to help prevent breast cancer, although there is currently no evidence to show that foods high in beta-carotene can help reduce the risk of breast cancer.
,Beta carotene is classified as carotenoid, natural antioxidant. Antioxidants are a molecule capable bind and therefore inactivate free radicals (chemically active molecules that can cause irreparable damage to the cellular structures of the body).
Every day, the cells of our body produce a certain amount of free radicals in the process of breathing; their formation increases in a busy lifestyle (sports, stress) and under the influence of external factors (smoking, sun rays, pollution).
Beta-carotene, being an antioxidant, performs important functions in the body:
- together with other carotenes is precursor to vitamin A, also called retinol, which, in turn, is important for the growth and development of bones, for vision;
- contacts vitamin A and forms a connection protects skin from damage due to sun exposure such as dryness and aging skin.
Not just carrots - where to find beta-carotene
Beta-carotene is a pigment that gives foods their natural orange-red color.
Foods richest in beta-carotene:
- carrot, potatoes, peppers, zucchini, red peppers, apricots, peaches and grapefruits.
- some leafy vegetables such as chard, spinach, lettuce and kale, but the beta-carotene in them is hidden by green chlorophyll.
- beta-carotene is also present in some cereals(corn, barley) and algae.
The effect of beta-carotene on humans
Beneficial effect of beta carotene, How antioxidant and a precursor to vitamin A, appears mainly in several positions:
- Leather: As I said, beta-carotene is a pigment that protects the skin during sun exposure, preventing the appearance of erythema, i.e. redness accompanied by itching. The accumulation of beta-carotene in the skin of the face, together with melanin, gives the tan a natural tint. In the case of vitiligo, when melanocytes stop working in some areas of the skin, it helps to avoid sunburn.
- Eyes: Some of the beta-carotene that enters the body is sent to the retina, where it is converted into vitamin A. This vitamin, along with another pigment, rhodopsin, provides the ability to see in the dark. Beta-carotene deficiency can therefore lead to decreased ability to see in the dark (“night blindness”).
- Hair: Beta-carotene, being a provitamin A, is an important condition well-being of skin cells and scalp. Indeed, vitamin A is a component of the cell membrane and when it is lacking, excessive production of keratin can begin, and therefore dry scalp.
- Acne: Since vitamin A is a component of scars, beta-carotene, both internally and topically, may be helpful in healing acne marks on the face.
Drug assistance - beta-carotene supplements
Despite the fact that beta carotene is present in many foods, sometimes its deficiency can be associated, for example, with intestinal pathologies that limit the absorption of the vitamin and its precursors. Since vitamin A is part of many biological structures, symptoms of its deficiency may include: dry skin and hair, decreased vision, fatigue, poor appetite.
In these cases it will be useful to resort to using beta-carotene based nutritional supplements. They may contain beta-carotene of natural origin (extracts) or synthetic.
There are several benefits of taking beta-carotene supplements:
- prevents breast and ovarian cancer in women during menopause, due to its antioxidant effect;
- reduces the risk of sunburn, as beta-carotene is a pigment that protects the skin from damage caused by sun exposure.
A pinch a day, and nothing more - a dose of beta-carotene
Beta-carotene, obtained both from food and through food additives , absorbed in the intestines and accumulates in the liver. When the body requires vitamin A, it begins to extract beta-carotene from the liver.
But how much beta-carotene do we need daily? In fact, very little: only 2 mg per day– this is a medium carrot (30 g), 5-6 apricots (130 g), 50 g spinach or chard.
Regarding food additives based on beta-carotene, usually enough to take one capsule per day to receive your daily dose.
Stomach upsets and side effects of beta-carotene
In order to reap the benefits of beta-carotene, it is enough to take, as we have seen, 2 mg per day, but what happens if you take it in excessive doses?
- Beta-carotene poisoning: A possible “side effect” of taking beta-carotene is a pleasant skin color, but if consumed in large quantities, it can cause a jaundice effect. Which, however, will disappear after stopping taking the supplement.
- Increased incidence of cancer in smokers: Some studies have shown that in high doses, beta-carotene increases the risk of cancer in smokers. However, the mechanism by which beta-carotene promotes the occurrence of malignant tumors in smokers has not yet been elucidated.
- Liver and kidney fatigue: Thoughtless use of antioxidant supplements has been proven to be harmful to humans. An increased intake of various substances forces the liver and kidneys to work more actively, which can lead to their damage and premature aging.
Healthy and balanced diet, varied and without frills, provides the body with everything it needs. The use of nutritional supplements should only occur in cases where there is a real need.
Finally, beta-carotene does not cause weight gain, since it does not participate in the body's energy metabolism and has no effect on overall metabolism!
Experts say that it is especially important for every person to enrich their body daily with a substance such as beta-carotene. What is it? Read on.
Beta-carotene - what is it?
“Elixir of youth”, “source of longevity”, “natural protective weapon” - these names characterize a unique substance. It's called beta-carotene. What is it? Let's try to figure it out.
Scientists note: provitamin A or, in other words, beta-carotene, E160a, is a yellow-orange plant pigment that belongs to the carotenoids group. These substances are formed during the process of photosynthesis. Fungi, algae and bacteria also produce beta-carotene. This dye is capable of being converted into retinol (vitamin A) in the body.
Beta-carotene: properties
To slow down the aging process in the body, reduce the risk of developing infectious diseases, and strengthen the immune system, experts recommend consuming foods that contain beta-carotene. What is it and what are its functions?
First: provitamin A is necessary for cell growth.
Second: beta-carotene restores vision.
Third: E160a supports healthy nails, hair and skin.
Fourth: beta-carotene is needed for the full functioning of the sweat glands.
Fifth: provitamin A affects the development of the embryo during pregnancy.
Sixth: E160a strengthens the enamel of teeth and bones.
The benefits of beta-carotene compared to vitamin A
E160a is much healthier than regular retinol. It turns out that with an overdose of vitamin A, the following symptoms are observed: nausea, vomiting, joint pain, itching, abdominal cramps, digestive tract disorders.
Beta carotene does not cause these side effects. The fundamental advantage of E160a is that it is completely non-toxic and does not pose a threat to human health in large quantities.
Provitamin A has the ability to be deposited in the depot (subcutaneous fat). Beta-carotene is converted into vitamin A in the amount necessary for the human body at a specific stage of its functioning.
How is beta-carotene absorbed in the body?
The above vitamin is absorbed in the intestines. The absorption of beta-carotene depends on such factors as the completeness of the rupture of cell membranes. Scientists say: it is because of this that whole carrots are digested much worse than, for example,
In addition, experts note that heat treatment of products helps to destroy 30% of this vitamin.
Beta-carotene, like all carotenoids, belongs to this means that fats are necessary for its absorption. Therefore, doctors recommend eating carrots with sour cream or vegetable oil.
It should be noted that provitamin A is accompanied by extremely important antioxidants such as vitamin E and C. They enhance the effect of each other. Vitamin E also promotes better absorption of the above substance.
Provitamin A deficiency in the human body
If an insufficient amount of E160a enters the body, the following problems may occur:
- “night blindness” (when vision deterioration is observed in low light);
- redness of the eyelids, dry mucous membranes of the eyes, watery vision in the cold;
- dry skin;
- dandruff and split ends;
- brittle nails;
- frequent viral infections;
- increased sensitivity of tooth enamel.
The reasons that lead to the above symptoms are different. This is primarily an unbalanced diet. That is, foods with a limited amount of fats and complete proteins are consumed.
Secondly, the cause of deficiency of this vitamin is also metabolic disorders due to too intensive use of E160a.
In addition, various diseases of the liver, pancreas and biliary tract can provoke a lack of the above substance.
Daily requirement for provitamin A
It is known that the body of every person needs to receive beta-carotene daily. Vitamin E160a is essential, and its daily requirement is about 5 mg.
There are some groups of people for whom it is primarily important to provide their body with the above substance:
- if they live in environmentally unfavorable areas;
- exposed to x-rays;
- state of pregnancy and breastfeeding;
- if you are taking medications that interfere with fat absorption.
It is also interesting that people living in colder climates need less beta-carotene than those living in hotter climates.
Which foods contain the above provitamin A?
Interestingly, plants have the lowest E160a content yellow, medium - orange in color, high - bright red products.
Beta-carotene in products contains the following:
- in vegetables (carrots, pumpkin, spinach, cabbage, zucchini, broccoli, sweet potato, green peas);
- in fruits (melon, apricots, cherries, mangoes, plums, nectarines).
Carrots are the leader among all the above products. It contains about 6.6 mg of provitamin A.
Beta-carotene is also found in foods such as:
- mustard;
- green beet leaves.
The concentration of this substance in vegetables and fruits depends on the degree of ripeness and time of year.
Our body needs beta-carotene in very small quantities; moreover, excess beta-carotene can even have side effects.
What is beta-carotene - what is it for?
Beta carotene is classified as carotenoid, natural antioxidant, present in a variety of plants that perform important functions in our body.
An antioxidant is a molecule capable bind and therefore inactivate free radicals, are a type of chemically reactive molecules that can cause irreparable damage to cellular structure.
As an antioxidant, beta-carotene performs important functions in our body:
- together with other carotenes it is used for vitamin A synthesis, which is important for the growth and development of bones, for vision, for reproduction;
- along with protects skin from damage due to sun exposure such as dryness and aging skin.
Where to find beta-carotene - not just carrots
Beta-carotene is a pigment that gives food its orange-reddish color.
Most abundantly represented in the following products:
- carrot, from which it was first isolated, potatoes and peppers, as well as zucchini, apricots, peaches and grapefruits.
- some vegetables such as chard, spinach, lettuce and kale contain a lot of beta-carotene, but it is “hidden” behind the bright green chlorophyll.
- beta-carotene is also present in some grains (corn, barley) and algae.
Properties and Benefits of Beta Carotene
The beneficial effect of beta-carotene, as an antioxidant and precursor of vitamin A, is expressed in relation to various organs and systems:
- For skin: Beta-carotene protects the skin during sun exposure, preventing the appearance of erythema. The accumulation of beta-carotene in the skin gives it a yellow-orange color and enhances the action of melanin, which is responsible for natural tanning. Even in the case of vitiligo, beta-carotene helps avoid sunburn on the white areas of the skin and therefore more sensitive.
- For eyes: Some of the beta-carotene that enters the body is transferred to the retina, where it is converted into vitamin A. At this level, vitamin A is necessary in order, together with other pigments (for example, rhodopsin), to realize the ability to night vision. Consequently, beta-carotene deficiency can lead to decreased ability.
- For hair: Beta-carotene, like provitamin A, is important for the well-being of skin and scalp cells. Vitamin A is a component of the cell membrane and when deficient in it can lead to excessive production of keratin, and therefore dry scalp.
- Acne: Vitamin A is a component of scar tissue; beta-carotene, both internally and topically, may be helpful in restoring facial skin after acne.
Medicinal supplements with beta-carotene
Despite the fact that beta carotene is present in many foods, it can sometimes be deficient, especially in the presence of intestinal pathologies that limit the absorption of vitamin A and its precursors. Since vitamin A is part of many biological mechanisms, there may be several symptoms associated with its deficiency: dry skin and hair, frequent infections, decreased visual acuity, fatigue, poor appetite.
In these cases it is useful to resort to using beta-carotene based nutritional supplements. They may contain beta-carotene of natural origin, that is, extracts, or synthetic.
There are several benefits of additionally using beta-carotene:
- preventing breast and ovarian cancer in women during menopause, thanks to its antioxidant effect, which neutralizes free radicals responsible for damage to DNA and enzymes responsible for controlling cell replication;
- reducing the risk of sunburn, since beta-carotene is a pigment that can protect against damage caused by sun exposure, even in the case of pathologies such as protoporphyria, which predisposes to sunburn.
A pinch a day, and nothing more!
Beta-carotene enters the body through food, absorbed in the intestines and accumulates in the liver. When the body requires vitamin A, beta-carotene reserves from the liver are mobilized and converted into this vitamin.
How much beta-carotene do we need per day? In fact, very little: only 2 mg per day, which are contained in one carrot (30 g), 5-6 apricots (130 g) or 50 g of spinach or chard.
Regarding food additives based on beta-carotene, usually the dosage is one capsule per day.
Beta-carotene poisoning and side effects
In order to get all the benefits of beta carotene, it is enough to take, as we have seen, 2 mg per day, but what happens if you take it in excessive doses?
- Beta-carotene poisoning: In moderate doses, beta-carotene will give the skin a nice tan color, but if consumed in excess, the effect will be like jaundice. However, skin color will be restored if you avoid or reduce the dose of beta-carotene.
- Increased incidence of cancer in smokers: Some studies have shown that beta-carotene increases the likelihood of developing cancer in people who smoke. However, the mechanism by which beta-carotene promotes the occurrence of malignant tumors in smokers has not yet been elucidated.
- Liver and kidney fatigue: Excessive use of antioxidant supplements may be harmful to humans. Along with antioxidants, we have to ingest excipients - synthetic molecules that take away the resources of the liver and kidneys for their metabolism and excretion.
As we have seen, beta-carotene, being an antioxidant, can have side effects if taken in excess. A healthy and balanced diet, without excesses, will provide the body with everything it needs. You should only turn to nutritional supplements in cases of real need.
Finally, Beta-carotene does not make you fat: It is not used in our body to produce energy and has no effect on overall metabolism!
