Beta-carotene – Natural source of vitamin A for the organism

Beta-carotene – Natural source of vitamin A for the organism

Beta-carotene was the first carotenoid whose pure form was obtained in a laboratory. The scientist Wackenroder isolated it in 1831 with the structure of micro-crystals using a carrot sample as substrate.

What is a carotenoid?

Carotenoids are chemical substances which are mainly responsible for the variety of yellow, orange and red colors from vegetables. Although they can also be responsible for some of the organ colors of some animal products.

Chemically speaking, they are a group within flavonoids which belong to the terpene family. However, only a 10% has the biological potential like vitamin A. More than six hundred components belong to this group. The most outstanding elements are beta-carotene, along with alpha-carotene and beta-cryptoxanthin.

The reason why they have a biological activity like vitamin A is due to their chemical structure. In fact, terpenes have terminal rings and at least one of them has to be closed and reduced, in other words, non-oxidized. This allows us to discard more famous carotenoids such as lycopene, zeaxanthin and lutein. These ones, even if they are important antioxidant pigments, they lack any vitamin value.

Benefits due to their nutrient supply

All in all, this group has a interesting range of positive effects for our health, specially in terms of:

  • Ocular health: they produce a valuable therapeutic effect against degenerative diseases of the retina.
  • Cardiovascular health: by working together with active ingredients such as glutathione and vitamins C and E.
  • Blocking tumors: all carotenoids are made up by acetylenic compounds. These elements have the ability to combat the development of tumors and some organism that trigger infections due to a cytotoxic effect.
  • Male fertility: an effect that, according to recent studies, seems to come from its antioxidant properties.
  • Skin health: it protects it against the harmful effects of environmental toxins and other agents that trigger diseases.
  • Some of them have more specific tasks, such as lycopene, a carotenoid from tomato that supports the liver, prostate, mammary glands, color and lungs.

Retinol is a fat soluble vitamin that can be available in two different chemical forms: pre-formed vitamin A, usually from animal products; and provitamin A, which is quite abundant in the plant kingdom, mostly as beta-carotene.

Sources of Beta Carotene

Beta-carotene, the icon of carotenoids

Wackenroder discovered beta-carotene by isolating a carrot. He used the scientific name in Latin of this plant daucus carota to name this compound.

It is a fat soluble substance of a yellowish color. Actually, it is the most abundant and efficient element among the so called pro-vitamin A. These substances are meant to be metabolized in vitamin by the organism.

Function in the organism

The human body is capable of breaking down each beta-carotene molecule in two. Consequently, it obtains two molecules of vitamin A. This is a clear advantage over other species of vitamins, since they tend to give just one vitamin A molecule. Therefore, the biological efficiency of beta-carotene is higher. However, we have to mention that to ensure its proper absorption, it has to be taken with a certain amount of fat.

It is almost completely metabolized in the bowel and an important amount is stored in the fat deposits.

Once in the small bowel, the body transforms it in vitamin A. This is thanks to a specific enzyme, 15:15 monooxygenase, which is available in the bloodstream to perform its tasks in the target organs.

If there is a retinol excess, it is deposited in the liver, which works as a reserve organ. This will be useful when it needs to be released in demanding situations. On the other hand, the amount of beta-carotene that has not been transformed into vitamin A is stored in the adipose tissue inside some specialized cells. They will remain there until the body needs to use them, as well as in the adrenal glands and ovaries in the case of women.

Physical and chemical features of beta-carotene

At an industrial level, there are two ways of obtaining beta-carotene: one is chemical synthesis and the other is of a biological type that uses a Dunaliella salina seaweed culture. This plant is very common in waters with a high concentration of sodium chloride.

Like the rest of substances that belong to the carotenoid family, it is susceptible to isomerization. This is actually quite possible specially under critical processing conditions, like a lack of oxygen, high temperatures, etc.

The intensity of the transformation into isomers will depend on each food and the degree of aggressiveness of the environment where it is found. We should expect that a 30-40% of isomerization of beta-carotene in trans form, transforming into common isomers like 9-cis and 13-cis.

Juices rich in beta carotene

Protein denaturation

This chemical phenomenon is a double-edged sword. On the one hand, it is a problem because it reduces the value of vitamin A from beta-carotene. Not in vain, the isomer 13-cis barely reaches a 50% of the vitamin value from the trans form, even less (around 40%) if we talk about 9-cis. However, the other side of the coin is that said drop is compensated by an increase of the bioavailability of this molecule. This is mostly due to the denaturation of protein with which it frequently forms a binding complex, specially in vegetable foods.

On the other hand, let’s not forget that cooking softens the cell membranes. Consequently, the vitamins and the beta-carotene from these foods are easier to absorb by the organism.

Apart from its nutritional and quasi-therapeutic uses, its use as food color is quite frequent, specially in drinks. Nevertheless, its insolubility in water makes it quite complex. This issue is easily fixed by using an ultra-thin powder (particles with a diameter not longer than 0.4 micron), using the polysaccharide arabic gum as thickener.

Moreover, synthetic beta-carotene is commonly used in the food industry for: coloring and providing vitamin A. For example, it is used in the bread and milk industry in order to make ice cream, fruit juices, chewing gum, sauces…

Foods and beta-carotene

Generally speaking, we can say that we are usually surrounded by products in which beta-carotene is an important component. They can be classified in three big groups:

  • Orange and yellow fruit, such as peach, apricot, orange and khaki.
  • Green leaf vegetables, such as spinach, chard, lettuce, cress, broccoli, etc.
  • Vegetables such as carrots, tomatoes, pumpkins, red pepper, etc.

In order to give more detailed information, we will provide an approximate list of foods, from highest to lowest according to their of beta-carotene content in micro-grams per gram of product:

Broccoli is rich in beta-carotene

  • Purslane 4650
  • Spinach 690
  • Carrot 673
  • Cress 560
  • Beetroot 468
  • Pepper 460
  • Peanut 360
  • Kale 345
  • Parsley 267
  • Khaki 253
  • Green bean 245
  • Fennel 241
  • Endive 240
  • Cilantro 228
  • Radish 214
  • Cantaloupe 200
  • Lettuce 190
  • Bear berry or uva ursi 172
  • Celery 144
  • Papaya 123
  • Pumpkin 114
  • Tomato 113
  • Mango 96
  • Bean 66
  • Watermelon 48
  • Brussels sprouts 41
  • Orange 28

More amount

In green vegetables, beta-carotene and xanthophyls make up part of certain specialized organelles. These elements are located within the vegetable cell called chloroplasts, which are responsible for the photosynthesis process, since they also contain chlorophyll. Carotenoids are the most abundant element in this group of vegetables.

However, the abundance of carotenoids in fruit will depend on their species. For instance, in the case of mango or khaki they will be beta-carotene. This unequal distribution will have to be taken into account when it comes to the diet. In fact, we will need to provide a wide variety of the different groups in order to ensure a proper intake of beta-carotene.

Although, in quantitative terms, its beta-carotene supply does not surpass the one from retinol (metabolically efficient vitamin A) if we use vitamin A as a reference. However, it has become an important source of vitamin A because it is abundant both in the vegetable kingdom, as well as in some animal products such as milk or egg yolk (rich in carotenoids but not all of them are beta-carotene).

We could mention that even there are developed countries, like the USA, whose diet does not precisely stand out for having an excess of vegetables. So, they basically take around a third of the vitamin A from these products. On the contrary, it plays an important role in vegetarian diets, where it usually exceeds a 50%.

All these foods that are rich in beta-carotene share an important feature: they help to stop the aging process while reducing the risk of suffering several types of cancer. Moreover, it has even been proven that it partially inhibits the invasive growth of tumor cells in prostate cancer.

Carrots are sources of beta-carotene

Properties of beta-carotene

Without any doubt, beta-carotene is the most reliable source of vitamin A. It plays an essential role in body growth, the integrity of the immune system and sight.

Due to its intrinsic antioxidant properties, beta-carotene becomes an obstacle for the formation of free radicals. These elements are over-active oxygen molecules which are highly harmful to the cell membranes and to the DNA. Their effects can result in an endless list of cardiovascular diseases and cancer.

Even though we cannot deny the positive effects beta-carotene and other carotenoids, there are several effects that remain determined. They may be caused by their powerful antioxidant capacity or maybe they could be connected to other mechanisms.

Fatty acid inhibition

Carotenoids, and particularly beta-carotene, have the ability to inhibit the beta-oxidation of fatty acids according to in vitro studies. Said studies are connected to others whose purpose was to establish or discard a cause-effect relation between beta-carotene and the blocking of atheroma plates which are a sign of coronary disease. There is evidence that this relation exists, even though it may be affected by other factors that make it more complex.

Its presence can alter the expression of a gen that codifies the structure of a protein. Said gen organizes itself in the form of channels that go through the cell membranes, which allow the exchange of small molecules. This effect seems to be exclusive to beta-carotene, not even vitamin A nor the antioxidant activities of other carotenoids play any role in this aspect.

Disease prevention

Adding fruits and vegetables to our diet is a decision that will significantly lower the risk of suffering breast cancer. This could even help pre-menopausal women with a family history of this type of cancer and those who excessively drink alcohol. A study published in 2012 in the journal “Breast Cancer Research and Treatment” revealed that its consumption lowers the risk of developing breast cancer in a 6%. In fact, this number that is equally applicable to alpha-carotene, but not to other carotenoids.

There are also clinical trials conducted on AIDS patients that reveal that a beta-carotene supplementation can stimulate the formation of white cells (specifically lymphocytes) and the activity of NK cells (natural killers). These are one of the main defense mechanism against harmful agents. However, it must be pointed out that it is not known with certainty if this function comes from beta-carotene as vitamin A once it is transformed, or to other intrinsic features of its family.

Immune system and beta-carotenes

Immune system

In addition, it contributes to activating a gland called thymus, which is one of the main cores of immune machinery during the first years of life.

Apart from its evident results in well-known pathologies, it can be interesting to point out other less obvious functions carried out by beta-carotene:

  • There is a congenital disease of scarce causality known as erythropoietic protoporphyria, which causes sensitivity to sun rays. The intake of beta-carotene can produce a palliative effect.
  • Keeping a proper beta-carotene rate in the tissues reduces the susceptibility to glucose intolerance. Consequently, it can protect us against diabetes.
  • It is possible to buffer age-related macular degeneration, which deteriorates the central sight by taking around 15mg of beta-carotene.
  • Oral leukoplakia is a peculiar disease. The symptoms are white spots in the mouth and tongue, usually due to unhealthy habits like smoking or drinking alcohol. Fortunately, a constant beta-carotene consumption can help to keep it under control.
  • Scleroderma is quite similar. In fact, it is a connective tissue disease that thickens and hardens the skin. One of its causes can be a beta-carotene deficiency.
  • A diet that lacks beta-carotene and vitamin C increases the risk of suffering rheumatoid arthritis. This is one of the autoimmune diseases caused by an anomalous reaction of the organism against its own elements.

Beta-carotene for the skin

One of its most renowned properties is its benefits for the skin. There are many studies that have proven how taking natural beta-carotenes prevents skin problems or diseases:

  • Preventing sunburns in people with sensitive skins
  • Reducing the signs of premature aging of the skin
  • Supporting the treatment of dry skin , psoriasis and eczema
  • Repairing damaged and wounded tissues; as well as treating skin patches
  • Improving the aspect of a healthy skin

Sunbathing and beta-carotenes

Does beta-carotene increase the skin tanning?

This issue has been widely discussed in the last few years. Many people actually wonder if beta-carotene could enhance the tanning after sunbathing.

There are certain studies that have proven that beta-carotene has properties that improve the skin tone. Nevertheless, the experts do claim that it does not protect the skin in any case against the problems that sunbathing may trigger. That is why they still advise using creams, avoid the hottest hours of the day and direct exposure to the sun; otherwise, all these factors can trigger different diseases.

Beta-carotene supplements

First of all, we need to see what the main health authorities have to say. For instance, the American Heart Association, the World Cancer Research Institute and the WHO International Agency for Research on Cancer support improving the diet by adding the active ingredient before using dietary supplements. To support this argument, there is a very eloquent fact…

Five portions of fruit and a portion of mainly green vegetables, provide between 6 and 10mg of beta-carotene.

However, it is commonly used for different pathologies such as a bad fat absorption, bile pathway alterations (hepatic insufficiency, cirrhosis…), pancreatic dysfunction or cystic fibrosis.

Types of supplements

Beta-carotene supplements are available with aqueous and oily base. The latter are easier to absorb orally, adjusting the intake pattern to 25000 IU, which equals 15 milligrams daily. Nevertheless, it is common to see people who take even 100000 IU or 60mg. There is no evidence that an excess provides any benefit for the organism. But, for instance, some doses can even reach 180mg per day in case of dermatological disorders. These amounts have not triggered any side effects that should be worth considering. When it comes to children, the best doses would be around 1300 IU between 4 and 8 years and 2000 IU until the age of 14.

We should keep in mind that the amount of beta-carotene that the organism is capable of absorbing varies according to several factors. For example, the rhythm and intensity of the individual metabolism and the presence of fatty matter available in the digestive tube. These are determinant factors for a complete and efficient absorption of beta-carotene.

Vitamin E capsules

Special capsules

After the experience of using dietary supplementation with this substance, it seems to provide better results with special formulas. For example, there are some of these formulas available in the HSN online store, which combine natural carotenoid blends (beta-carotene, alpha-carotene, cryptoxanthin, lutein, and zeaxanthin), multi-vitamin/mineral complexes and other antioxidant substances. This goes against the common belief of taking just isolated synthetic beta-carotene. An extraordinary cocktail would be an alpha and beta-carotene complex from carrot with lutein from marigold flowers and lycopene from tomato.

Most of the synthetic beta-carotene supplementation is made up by the molecule called “all-trans-beta-carotene”. On the other hand, the one from food combines two molecules, the previous one and 9-cis isomer beta-carotene, whose proportion is not standard, it changes depending on the source.

When it comes to purchasing a supplement, if you wish to know its origin you have to pay attention to the information that can be found on the label; if it is natural beta-carotene there are several possibilities, such as: “from D.salina”, “from algae”, “from palm oil”, or simply “natural beta-carotene”.

When it comes to purchasing a supplement, if you want to find out its origin, you will have to check the label. If it is natural, there are several possibilities such as: “from D. salina”, “from seaweed”, “from palm oil” or simply “natural”.

You can purchase beta-carotene supplements in the HSN online store. The only thing you need to do is click on this link and browse all the products

Contraindications of beta-carotene

  • Reducing the efficacy of medications aimed at lowering the cholesterol.
  • Not advised for those who have been in touch with asbestos.
  • It can inhibit the efficacy of an angioplasty treatment due to its antioxidant properties.
  • Avoid its intake during lactation due to the lack of research about its excretion through breast milk.

Side effects

In reality, it is a substance that practically has no side effects as long as we take the recommended dose. Nevertheless, a sustained intake of 100000 IU or 60mg per day can produce a yellow-orange color of the skin. But this does not entail any risk for our health and it will disappear after eliminating that extra intake. Even though we can also number some negative reactions:

  • Local allergic reactions
  • Chest pressure
  • Dizziness
  • Spontaneous bleeding
  • Diarrhea
Moreover, there is a general consensus among specialists that, for smokers, taking synthetic beta-carotene increases the risk of developing lung or prostate cancer.

When we follow a sustained beta-carotene supplementation, it is recommended to combine it with an extra supply of vitamin E. This is due to the fact that its levels may drop due to its intake.

Dry skin beta-carotene

Beta-carotene and other supplements

With biotin

Biotin is a water soluble vitamin from the B complex. It is necessary for the body to metabolize carbohydrates, fats and amino acids, immediate principles from which we obtain energy. In this case, their interest lies in that both of them are frequently combined in dietary supplements due to their excellent synergy.

With caffeine

To conclude, we will talk about combining beta-carotene and caffeine, which has sometimes caused controversy. Nowadays, the experts agree that they are completely compatible, since caffeine produces a double effect: laxative and diuretic. Both of them stimulate the loss of fluids and mineral salts. Nevertheless, they do not hinder the intestinal absorption of beta-carotene. This means that consuming a beta-carotene supplement with coffee for breakfast does not entail any contraindication.


Related Entries:

  • Vegetarians, athletes and smokers need more vitamins
  • What are the most important vitamins for our body?
  • Foods rich in vitamins and minerals
Beta-carotene Review

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About Alberto Ricón
Alberto Ricón
Alberto Ricón is a specialist in nutrition and food hygiene with large experience in the sector as well as being a Food Health Technician.
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