Vitamin C – which foods contain it and why is it useful?

Foods Rich in Vitamin C

Vitamin C is found in plant foods - vegetables, fruits, berries. It has always been believed that the highest dosages of vitamin C are found in citrus fruits, and the more acidic the citrus, the more “ascorbic acid” it contains. This is completely wrong!

Firstly, a sour lemon contains one and a half times less vitamin than a sweet orange, and secondly, both fruits contain little of it - about the same amount as apples. There is much more vitamin in dill, walnuts, rose hips, and sea buckthorn. They should be used intensively for viral diseases, instead of endlessly drinking tea with lemon.

Signs of excess

Although there are few cases where vitamin A is absorbed in greater quantities than necessary, they still exist. Hypervitaminosis was previously observed in residents of the North who ate bear meat every day. The liver of these animals contains excessive amounts of vitamin A.

Important! With an excess of vitamin, problems are observed not only with the digestive system, but also with disorders of the nervous system.

Today, cases of consuming large amounts of vitamin A are possible when a person drinks carrot juice every day in excess of the required norm, wanting to saturate the body with useful substances. After this, carotene accumulates in the dermis, resulting in a yellowish color of the skin. The shade becomes especially noticeable on the palms and heels. If you follow the norms of consuming foods containing vitamin A in your diet, skin color will be restored within a few weeks.

Increased need for vitamin C

In pregnant women, the need for it increases by about 10 mg, and in nursing women - by almost half. Also, increased amounts of vitamin C are needed by smokers and those who are exposed to harmful occupational factors.

During acute illnesses, it is permissible to consume up to 10 daily norms at a time! When recovering from various diseases, under high loads, in the cold season, you also need more vitamin C than usual.

Although many situations require increased use of vitamin C and the use of high dosages, it is not recommended to increase doses indefinitely. When consuming more than 2 g of the substance per day, a toxic effect of ascorbic acid on kidney tissue is observed.

What it is

Vitamin C or ascorbic acid is water-soluble. This means that it easily dissolves in body fluids and, with a small excess, is excreted in the urine.

Vitamin C helps synthesize collagen, a protein that is responsible for the condition of skin, hair, cartilage and blood vessels. Ascorbic acid is also involved in the formation of serotonin, the hormone of happiness.

The daily requirement of vitamin C for men is 90 mg, and for women - 75 mg. Usually, in the absence of it in the diet, symptoms of hypovitaminosis may appear - bleeding gums, lethargy, dry skin and eyes. But in today's realities, it is almost impossible to get hypovitaminosis or even vitamin deficiency. Even if the diet is very limited, many foods contain ascorbic acid as an acidity regulator.

It is generally accepted that there is a lot of it in citrus fruits, but in fact there is even more in rose hips, currants and cabbage. By the way, vitamin C is needed only by humans, primates and some species of birds and guinea pigs - nature has approached its distribution selectively.

Biological role of vitamin C

The functions of vitamin C are numerous, and they make its use very important for maintaining and improving health. The meaning of ascorbic acid is as follows:

• Is an antioxidant. This means that the substance resists the destructive process of lipid peroxidation in tissues, protects the body from diseases and aging. • Strengthens the immune system, increases its “alertness” against harmful microorganisms, especially viruses. • Promotes the full formation of connective tissue, strengthens bones and joints. • “Helps” folic acid, vitamin A, and iron to be absorbed and exhibit their effects. • Improves skin condition. Thanks to its independent anti-inflammatory effect, it reduces the severity of inflammation in acne and acne. • Reduces bleeding, strengthens blood vessels. • Prevents the rapid development of atherosclerosis, inhibits the growth of cholesterol plaques in blood vessels. • Reduces the toxicity of alcohol, improves detoxification, neutralization of many toxic and harmful substances: components of tobacco smoke, substances that pollute water and air, drug metabolites, etc. • Reduces the negative impact of stress on health. • Accelerates the restoration of various tissues when they are damaged. • Has a brightening effect on the skin.

The benefits of vitamin A for the human body

By adhering to the daily intake of nutrients in the diet, a beneficial effect on the human body will be observed. Namely:

• helps improve vision, normalize the condition of the cornea and tear fluid;
• takes an active part in skin regeneration, slows down the aging process;
• normalizes the stable functioning of the liver, increases its efficiency;
• Boosts immunity and protects against infectious diseases.

Signs of vitamin C deficiency

Vitamin C deficiency is common and its symptoms are familiar to many people. Among the signs of hypovitaminosis C, there may be such phenomena as a tendency to bleeding gums, easy formation of bruises on the body, frequent incidence of colds, a predisposition to exacerbations of existing chronic diseases, slow healing of injuries and delayed recovery, discomfort in the joints, problematic skin, hair loss, nosebleeds etc.

With a critical deficiency of the vitamin, a disease known as scurvy develops. It is rare in the modern world, but used to be extremely common. Patients experienced frequent bleeding, teeth falling out, and serious damage to joints and bones.

Signs of Vitamin A Deficiency

If there is a lack of vitamin A in the body, so-called “night blindness” may occur. But, today, such a phenomenon is extremely rare, since a critical amount of retinol is needed. As a rule, this happens with completely unsatisfactory nutrition, almost hunger.

The first signs that the human body does not receive the required amount of vitamin (hypovitaminosis):

• the appearance of wrinkles at an early age, dry skin, partial peeling;
• decreased vision, drying out of the mucous membrane, deterioration in the quality of vision in the dark;
• frequent cases of infectious diseases;
• weakened immunity.

Factors influencing the vitamin C content of foods

Ascorbic acid is a “fragile” vitamin. Upon contact with air, it oxidizes, which leads to some loss of its properties. For this reason, food containing vitamin C is not recommended for long-term storage. Fruit and vegetable juices should be drunk freshly squeezed.

The vitamin is also destroyed when exposed to high temperatures; cooking leads to almost 100% loss of this substance. Therefore, vegetables and fruits should be consumed fresh.

Some of the ascorbic acid is retained in products when frozen; a minimal amount of it “survives” when dried. The destruction of the vitamin is also observed in light. This means that you need to use dark, cool places to store vegetables.

Important fact. The vitamin C content of different products depends greatly on their shelf life. The maximum amount of ascorbic acid is present in ripe, fresh fruits. Meanwhile, kiwis, oranges, and lemons that “come” to our country were collected long before they reached optimal ripeness, and more than 2 months can pass from their collection to consumption. Accordingly, they lose most of their beneficial properties and vitamin C.

As a result, in order to meet the daily requirement for ascorbic acid, a person needs to eat several kilograms of plant foods daily. This is impossible. And this is precisely what leads to the fact that most of us live in conditions of chronic hypovitaminosis and need to take additional dosages of vitamin C.

Which foods contain the most vitamin A?

foods high in vitamin A
In most foods, vitamin A is contained in the form of inactive compounds, which, after entering the body, begin to activate beneficial properties. Such provitamins include carotenoids, among which beta-carotene is the richest in vitamin. A distinctive feature of carotenoids is the red, orange or yellow color of plant foods. It is thanks to color that you can recognize products that contain the composition of substances required for the human body.

Typically, in the summer, getting enough of the vitamin into your diet comes from a balanced diet of plant sources. In winter, the required “dosage” is obtained thanks to animal products. It is during the cold period that hypovitaminosis of the human body is often observed.

Animal products with vitamin A

Table 1 – Vitamin content (mcg) per 100 g of product and % coverage of the daily value

Plant-based foods with vitamin A

Table 2 – Vitamin content (mcg) per 100 g of product and % coverage of the daily value

Important! Pregnancy is no exception for the daily intake of vitamin A. Therefore, there is no need to increase the amount of foods containing it. Pregnancy vitamins contain a sufficient amount of beneficial components required for normal fetal development.

What if it's not enough?

A severe deficiency of vitamin C causes scurvy
: fragility of blood vessels, the appearance of hemorrhages under the skin, bleeding gums and tooth loss.
But if there is simply not enough of it in the body, the symptoms of hypovitaminosis are not very clear, and people often attribute them to the consequences of stress or fatigue. With a lack of ascorbic acid, the skin becomes dull and dry due to insufficient collagen synthesis. Even minor injuries cause severe hemorrhages and bleeding due to increased permeability of the vascular walls. Hair becomes dull and begins to fall out, nails break. The person becomes lethargic and gets tired quickly
.

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Often these symptoms appear in those who follow strict diets - especially those in which the consumption of fresh vegetables and fruits is sharply limited.

Vitamin C. Hypovitaminosis

Vitamin C

There was a time, about fifty years ago, when they talked, argued, and wrote about vitamins;
they were mentioned in films, they were believed in. At the peak of popularity was Sergei Obraztsov’s “Extraordinary Concert,” where the first number was the majestic cantata “Everyone Take Your Vitamin.” Any elementary school student could quickly retell many heroic stories about polar explorers, sailors, and travelers who, without proper nutrition, fell ill with scurvy and recovered only thanks to vitamin C - or, in its absence, did not recover. The same schoolboy willingly accepted another “ascorbic acid” from his mother, and sometimes he himself bought these balls or tablets at the pharmacy (remember?) as a specific treat, fortunately it cost a penny. From those same times, a belief has survived to this day, which is discussed in the article on hypervitaminosis: they say that any “colds” and acute respiratory viral infections can be treated with a loading dose of vitamin C, and if you take this very dose in advance, you will not get sick. Vitamin C has always looked like the king of the vitamin kingdom; to a certain extent this is true. But the more we study this kingdom, the more strange it looks: each fact raises dozens of questions and, as it seems at times, only adds to the overall uncertainty.

Vitamins, by definition, are neither food nor a source of energy for humans, but life without them is impossible - at least, life is healthy and long. They are classified as essential nutrients . The word “essential” in this case is not a decorative figure of speech, but a dryly stating part of the term: these substances are absolutely necessary for the human body for normal life, but they are not synthesized in the body itself and come exclusively from food. Due to the last reservation, some of the previously discovered vitamins had to be deleted from the nomenclature and transferred to the so-called category. vitamin-like substances (group B has especially decreased in this regard: as it turned out, some of the “former” vitamins of this group are still produced by the body). Other vitamins can enter our internal metabolic cycle in different ways, incl. and from the inside, but only under certain conditions: vitamin D, for example, is partially produced by the skin under the influence of ultraviolet rays. In addition, new studies of the biological role of vitamins force us to reconsider the list of their “functional responsibilities” : these are catalysts, coenzymes, hormone-like regulators, antioxidants, transport compounds, tissue regeneration factors (and at the same time an anti-aging agent), as well as immune stimulants, and neuroprotectors, and almost targeted anti-cancer cytostatics. Depending on which particular vitamin is missing and how deep the deficiency is, various hypo- and avitaminosis syndromes develop - very severe, at some point irreversible and, ultimately, lethal (see, for example, materials on pellagra, syndrome Gaie-Wernicke or pernicious anemia). On the other hand, hypervitaminosis is no less, and sometimes even more dangerous, than hypovitaminosis.

Some vitamins can be deposited in the body, for example, in the liver or muscles, while others are consumed almost immediately and require daily replenishment . But if we talk about the minimum, optimal and maximum permissible daily doses, then for almost every vitamin you have to create a long table: a separate line for children, a separate line for men, a separate line for pregnant women and a separate line for non-pregnant women, a separate line (in a red frame) for vegetarians , and all this broken down by age category, taking into account the type of activity (athletes, secretarial assistants, divers, etc.), and depending on the number of cigarettes smoked per day, annual consumption of alcohol and coffee, altitude of the region of residence above sea ​​level, the characteristics of national cuisine, the state of individual health and many other factors, the abundance of which, if you think about it, blurs and casts doubt on the applicability of these tables.

Another characteristic feature is stable dyads, triads and, possibly, tetrads of vitamins, which seem to be in a secret conspiracy: they say, they are ready to work, but not individually, but only as part of their pair, or three, or team.

Finally, despite all the unambiguous (as it seemed at first) usefulness, irreplaceability, and effectiveness of synthetic vitamins, almost each of them comes with a list of contraindications and possible side effects , even if they are rare, but still.

One inevitably comes to mind with an analogy with another natural phenomenon that is just as difficult to understand and just as prone to throwing fog in the path of researchers: viruses. By the way, recently thoughts have been increasingly expressed that we may be a little mistaken in perceiving viruses as an unambiguous evil; Perhaps today we are cautiously examining under electron microscopes the most powerful tool of genetic engineering and genetic therapy, which tomorrow will completely change all our ideas about what medicine is and how, in general, it should be treated.

However, let's return to vitamin C. The above discussions about the vitamin kingdom apply, of course, to its king.

People guessed that food contained “something other than food” a long time ago, but they didn’t know what to call it cleverly, until the biochemist Kazimierz Funk proposed the conceptual name “vital amines” in 1912 And, as it later turned out, his proposal was not very successful, since the nitrogen-hydrogen (amine) group is not contained in all “amines of life.” Ascorbic acid, for example, does not contain it.

The discovery of vitamins involved many different people, starting with the ancient Egyptians, Aztecs and Chinese; It’s a shame that there aren’t enough Nobel Prizes for everyone, and indeed they aren’t awarded retrospectively. It is at least fair that history has preserved the names of N.I. Lunin and V.V. Pashutin, J. Goldberger and G. King. How many names have been forgotten? There is no doubt that many researchers came close and perhaps even took the last half step, but misinterpreted their own results, underestimated their significance, and did not publish on time...

in the middle of the 18th century actually found a cure for scurvy, proved it in practice, and even published a corresponding treatise, is widely known And still he was not heard, despite the fact that scurvy (vitaminosis C) was a real scourge for long-distance sailors; despite the fact that a little later the most authoritative British navigator J. Cook completely confirmed Lind's discovery.

It is believed that vitamins as a concept of specific substances - theoretically predicted, discovered in nature, then obtained artificially and comprehensively studied - appeared in the modern scientific paradigm only in the early 1910s . Vitamin C is designated by the third letter of the Latin alphabet because it was not the “firstborn”: only in the period 1928-1932, the Hungarian biochemist Albert Szent-Gyorgyi first extracted (from sweet peppers) an organic compound, which he called hexuronic acid. But even then it was not yet clear whether hexuronic acid was the very “cure for scurvy” that had been sought so intensely and purposefully - and strangely in vain - for at least a century and a half. This was finally proven by the works of the British Sir Walter Howorth, the Swiss Paul Karrer and many other researchers. In 1933, hexuronic acid was synthesized artificially with the formula C6H8O6. There are two isomers, left-handed and right-handed; Only the L-isomer has biological significance, which turned out to be the king of vitamins. L-hexuronic acid was renamed ascorbic acid (from the Latin “anti-scorbutus”, anti-scorbutic).

The Nobel Prize for the discovery of vitamin C in 1937 was shared by Szent-Györgyi, Karrer and Haworth (sometimes written “Gowart”, “Haworth”, etc., since the sound of the surname Haworth cannot be authentically conveyed in Cyrillic).

However, one cannot help but recall two more names in this context (they are not even mentioned in the Russian-language Wikipedia, but perhaps articles will appear later) - the names of outstanding Norwegians Axel Holst and Theodor Froelisch. The first was initially the scientific supervisor of the second, although both ended their lives in full glory, international recognition and professorship. Holst and Froelsch, back in 1907, conducted a series of experiments on guinea pigs and pigeons, actually identifying vitamin C as a cure for “sea beriberi” (as they called scurvy). And once again, key work on this problem was not picked up and developed by the scientific community! - apparently, again turned out to be premature... However, today it is generally accepted that the revolutionary discoveries of 1911-1933 , at least in terms of vitamin C, were based precisely on the model of Holst and Fröhlisch. These scientists were also nominated for the Nobel Prize - and did not receive it, just as Lunin, Funk, five-time nominee Goldberger and many other specialists, without whom the search for the mysterious “accessory food factors”, as the Nobel laureate called them, did not receive Sir Frederick Hopkins) would probably continue to this day. There's nothing you can do about it: that's the history of medicine. In the end, the overall result - and the memory of those who achieved it - is more important than any awards.

Causes of vitamin A deficiency in the body

If there is a deficiency of vitamin A in the body of a healthy person, several factors may affect this:

• Low quality of consumed products. This is often observed in the presence of nitrates in food products (tomatoes, carrots, herbs, etc.). Remember, the better, more natural and fresh the products, the more required nutrients they contain.
• Disruption of the digestive system. Such disorders include gastritis, pancreatitis, colitis and cholelithiasis. In this case, you will need to increase the dose of the vitamin, after consulting with your doctor, who will be able to create an individual diet.
• Improperly balanced diet. Frequent consumption of fast foods, semi-finished products, fried foods, not fresh foods, and weekly meals. Remember that foods and foods that are prepared immediately before consumption are better digested, and not those that sit in the refrigerator for several days and are reheated. All this will contribute to a decrease in the amount of vitamin A and its ineffectiveness for the body.