Vitamin deficiencies and excesses
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Vitamins and supplementation
Today we are talking about deficiencies and excesses of vitamins*, which must be obtained through the diet because our body is unable to synthesise them on its own. The amounts required are usually very small, in the order of milligrams or sometimes micrograms, under normal conditions.
Many vitamins have an antioxidantfunction, that is, they help counteract the free radicals that form normally through metabolism and can disrupt the normal functioning of the body.
Among the vitamins, for example, we find vitamin C, vitamin A and vitamin E.
These vitamins all have an antioxidant function, but they differ in their structure, which as a result makes them act in different areas of the body.
Vitamin E and vitamin A in fact have a fat-soluble structure, so they act mainly in fats, for example in membrane phospholipids.
Vitamin C on the other hand, having a water-soluble structure, acts mainly in watery structures such as blood and cytoplasm.
For a correct diet it is therefore advisable to take in all the vitamins.
The clinical conditions caused by vitamin deficiency are called avitaminosis. Conversely, excessive use of vitamins is called hypervitaminosis.
Excessive use of vitamins can have toxic effects on the body, particularly with the fat-soluble ones (A, D, K); water-soluble vitamins on the other hand (B, C, folic acid etc.) are eliminated more easily by our body, so toxic effects are rare. In that case, if anything, it is a waste of money, if these vitamins are taken in excessive doses, perhaps using expensive food supplements that contain high doses.
Let us take a quick, detailed look at the characteristics of the individual vitamins:
1) vitamin A: it is stored in the liver, so any disease states associated with a deficiency only become apparent after fairly long periods. It has an antioxidant function, and the symptoms linked to a deficiency are loss of appetite and a tendency to fall ill easily.
2) vitamin D: as well as being obtained from food, particularly egg yolk, sea fish and liver, it is synthesised in the skin following exposure to ultraviolet rays. For this reason the dietary intake of vitamin D is usually lower, especially in particularly sunny countries. Older people, on the other hand, because of their reduced exposure to sunlight, obtain vitamin D mainly from their diet. The function of vitamin D is mainly linked to calcium metabolism; a deficiency is therefore often linked to rickets (which makes bones less rigid and less strong) in children and osteomalacia (a predisposition to fractures) in adults.
3) vitamin E: it has an antioxidant function, and a deficiency (rare) can cause damage to nerves and muscles.
4) vitamin C: it is easily absorbed in the intestine, so any problems that may arise are caused mainly by an inadequate diet or by increased requirements. In particular, people who do physical activity need more vitamin C. It has an antioxidant effect, and a dietary deficiency can cause a feeling of tiredness, muscle weakness and loss of appetite. In its most severe forms it can cause scurvy as a result of the inability to form collagen.
5) thiamine (vitamin B1): it helps the metabolism of carbohydrates and amino acids. For this reason it should be taken in larger amounts by those who eat a lot of carbohydrates, in the case of fever, during pregnancy or by those who do intense physical activity. A dietary deficiency of this vitamin can cause weakness, reduced endurance, asthenia and weight loss. In the most serious cases it can lead to mental confusion, ophthalmoplegia (loss of eye-movement coordination) and ataxia (inability to control motor function), symptoms that are characteristic in particular of Wernicke-Korsakoff syndrome, which is very common in chronic alcoholics.
6) riboflavin (vitamin B2): it helps oxidative metabolism and the electron transport system. A deficiency (rare) can cause changes to the skin, mucous membranes and nervous system.
7) niacin: it plays a role in oxidative metabolism and in the electron transport system. A deficiency can cause irritability and, in its most severe forms, the disease pellagra, characterised by dermatitis, diarrhoea and dementia.
8) pyridoxine (vitamin B6): it is a vitamin found in many foods, so deficiency is rare. It is needed for gluconeogenesis, and a deficiency is linked to forms of dermatitis.
9) folic acid (vitamin B9): it helps the synthesis of haemoglobin and nucleic acids. A deficiency can cause anaemia and a feeling of tiredness that considerably reduces endurance in prolonged sporting activities. During pregnancy the requirement for folic acid increases, and for this reason pregnant women are usually prescribed folic acid supplementation. In this case a deficiency can increase the risk of neural tube defects in the foetus.
10) cobalamin (vitamin B12): it is abundant in meat, so a deficiency may be found in people who have followed a vegetarian diet for a long time. Vitamin B12 helps the synthesis of haemoglobin, and a deficiency can cause anaemia and neurological symptoms.
*source: "Alimentazione per lo sport e la salute" by Pierluigi Biagi, Antonio Di Giulio, Amelia Fiorilli, Antonello Lorenzini.
Today we are talking about deficiencies and excesses of vitamins*, which must be obtained through the diet because our body is unable to synthesise them on its own. The amounts required are usually very small, in the order of milligrams or sometimes micrograms, under normal conditions.
Many vitamins have an antioxidantfunction, that is, they help counteract the free radicals that form normally through metabolism and can disrupt the normal functioning of the body.
Among the vitamins, for example, we find vitamin C, vitamin A and vitamin E.
These vitamins all have an antioxidant function, but they differ in their structure, which as a result makes them act in different areas of the body.
Vitamin E and vitamin A in fact have a fat-soluble structure, so they act mainly in fats, for example in membrane phospholipids.
Vitamin C on the other hand, having a water-soluble structure, acts mainly in watery structures such as blood and cytoplasm.
For a correct diet it is therefore advisable to take in all the vitamins.
The clinical conditions caused by vitamin deficiency are called avitaminosis. Conversely, excessive use of vitamins is called hypervitaminosis.
Excessive use of vitamins can have toxic effects on the body, particularly with the fat-soluble ones (A, D, K); water-soluble vitamins on the other hand (B, C, folic acid etc.) are eliminated more easily by our body, so toxic effects are rare. In that case, if anything, it is a waste of money, if these vitamins are taken in excessive doses, perhaps using expensive food supplements that contain high doses.
Let us take a quick, detailed look at the characteristics of the individual vitamins:
1) vitamin A: it is stored in the liver, so any disease states associated with a deficiency only become apparent after fairly long periods. It has an antioxidant function, and the symptoms linked to a deficiency are loss of appetite and a tendency to fall ill easily.
2) vitamin D: as well as being obtained from food, particularly egg yolk, sea fish and liver, it is synthesised in the skin following exposure to ultraviolet rays. For this reason the dietary intake of vitamin D is usually lower, especially in particularly sunny countries. Older people, on the other hand, because of their reduced exposure to sunlight, obtain vitamin D mainly from their diet. The function of vitamin D is mainly linked to calcium metabolism; a deficiency is therefore often linked to rickets (which makes bones less rigid and less strong) in children and osteomalacia (a predisposition to fractures) in adults.
3) vitamin E: it has an antioxidant function, and a deficiency (rare) can cause damage to nerves and muscles.
4) vitamin C: it is easily absorbed in the intestine, so any problems that may arise are caused mainly by an inadequate diet or by increased requirements. In particular, people who do physical activity need more vitamin C. It has an antioxidant effect, and a dietary deficiency can cause a feeling of tiredness, muscle weakness and loss of appetite. In its most severe forms it can cause scurvy as a result of the inability to form collagen.
5) thiamine (vitamin B1): it helps the metabolism of carbohydrates and amino acids. For this reason it should be taken in larger amounts by those who eat a lot of carbohydrates, in the case of fever, during pregnancy or by those who do intense physical activity. A dietary deficiency of this vitamin can cause weakness, reduced endurance, asthenia and weight loss. In the most serious cases it can lead to mental confusion, ophthalmoplegia (loss of eye-movement coordination) and ataxia (inability to control motor function), symptoms that are characteristic in particular of Wernicke-Korsakoff syndrome, which is very common in chronic alcoholics.
6) riboflavin (vitamin B2): it helps oxidative metabolism and the electron transport system. A deficiency (rare) can cause changes to the skin, mucous membranes and nervous system.
7) niacin: it plays a role in oxidative metabolism and in the electron transport system. A deficiency can cause irritability and, in its most severe forms, the disease pellagra, characterised by dermatitis, diarrhoea and dementia.
8) pyridoxine (vitamin B6): it is a vitamin found in many foods, so deficiency is rare. It is needed for gluconeogenesis, and a deficiency is linked to forms of dermatitis.
9) folic acid (vitamin B9): it helps the synthesis of haemoglobin and nucleic acids. A deficiency can cause anaemia and a feeling of tiredness that considerably reduces endurance in prolonged sporting activities. During pregnancy the requirement for folic acid increases, and for this reason pregnant women are usually prescribed folic acid supplementation. In this case a deficiency can increase the risk of neural tube defects in the foetus.
10) cobalamin (vitamin B12): it is abundant in meat, so a deficiency may be found in people who have followed a vegetarian diet for a long time. Vitamin B12 helps the synthesis of haemoglobin, and a deficiency can cause anaemia and neurological symptoms.
*source: "Alimentazione per lo sport e la salute" by Pierluigi Biagi, Antonio Di Giulio, Amelia Fiorilli, Antonello Lorenzini.
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