Vitamins, the Complete Guide From A to Z

Vitamins are organic substances contained in foods in very small amounts are essential for the growth and maintenance of the organism. Their lack or insufficient presence in the diet determines specific morbid manifestations, called avitaminosis or hypovitaminosis.

Unlike other nutrients, such as proteins, carbohydrates, or fats that must be consumed in large quantities and which are processed and burned by our body, vitamins work as catalysts, promoting many fundamental reactions for your well-being.

History of vitamins

Experimental proof of the existence of accessory dietary factors dates back to 1897. To have an official name it will take 1912. When the Polish scientist Casimir Funk isolated and identified the organic compound essential to the life of the organism. Giving it the name of vitamin = amine of life. After 1920 some morbid manifestations began to be related to dietary and therefore vitamin deficiency. Such as scurvy which could be cured by administering doses of fruit juices. The content in fruits factor was called Vitamin C . Research and experimentation continued quickly and by the 1930s. The13 vitamins are known today and they began to be reproduced in the laboratory to create the synthetic version.

Vitamin classification

Their chemical constitution allows a classification by solubility. They are therefore arbitrarily grouped into two classes:

  • Water- soluble vitamins: (water-soluble): all B vitamins and vitamin C.

The solubility in lipids makes these vitamins storable by the liver and adipose tissues. Thus allowing the creation of reserves that the body can draw on in times of need. This is not possible for water-soluble vitamins which must therefore be taken constantly with food.

Vitamins with antioxidant function

Some vitamins have an antioxidant action. In other words, they can counteract the action of the free radicals responsible. If not counterbalanced, for causing cellular oxidation, responsible for the general aging of the organism and the onset of some pathologies, even serious ones.

The three vitamins that play this role are vitamin A, vitamin C, and vitamin E.

Vitamin deficiency and surplus: hypervitaminosis and hypovitaminosis

In a balanced and balanced diet, there is no risk of incurring hyper or hypovitaminosis. On the other hand, a surplus is possible by using multivitamin supplements that should be taken only in cases of deficiencies ascertained by your doctor. L ‘ Hypovitaminosis instead occurs in cases of malnutrition, in case of increased needs (eg pregnant or lactating ), or if you follow unbalanced diets and are deficient in certain micronutrients, such as in the vegan diet, where integration vitamin is almost always needed.

The various vitamins have different roles, so we propose a classification of all vitamins, with the details of their main functions, the list of foods through which you can take them, and some useful advice for their consumption.

Vitamin A

You can find pre-formed vitamin A in foods (retinol) or the form of provitamin A (carotenoids). Carotenoids (of which beta-carotene is the main one) are its precursors, that is, they are transformed into vitamin A by the body.

Why do you need it?
Vitamin A is essential for the formation and maintenance of the skin, hair, and mucous membranes. It is also useful for eyesight, bones, teeth, and blood circulation. It is anti-stress and anti-infectious. In addition, it seems to play a fundamental role in cancer prevention and support during cancer treatment. Helping to moderate the consequences generated by the disease and chemotherapy.
Its deficiency can cause dryness and ulceration of the cornea, decreased visual intensity, less resistance to infections, migraines, nervousness, anxiety, and increased fatigue.

The daily amount recommended by the European Union is 800µg.

Where do you find it?
The largest amounts of vitamin A are found in yellow or orange fruits and vegetables, green leafy vegetables, liver, and dairy products.

A tip: try to consume raw or steamed vegetables.

If you want to know more, we recommend that you read our in-depth analysis: Vitamin A: properties, benefits, and foods that contain it.

Vitamins of group B

Generally, we talk about vitamin B, but it is a vitamin complex comprising 8 vitamins, each with specific benefits.
Let’s find out in detail:

2 – Vitamin B1

Vitamin B1, also called thiamine, is rapidly absorbed in the small intestine and then carried via the circulatory system to the liver, kidneys, and heart. The body needs a daily supply of this substance.

Why do you need it?

This vitamin helps the body release energy from carbohydrates during metabolism. It also helps muscle tone and growth.

Its deficiency can cause heart problems, fatigue, nervous disorders, and mental confusion. The daily amount recommended by the European Union is 1.4 mg.

Where do you find it?

You can find vitamin B1 in brewer’s yeast, wheat germ oil, whole grains, wheat, and liver. Don’t forget that B1  is wiped out by alcohol, smoking, and the consumption of sweets and sugar.


3 – Vitamin B2

This vitamin, also called riboflavin, is included among the water-soluble vitamins. Which cannot be accumulated in the body but must be taken regularly through daily nutrition.

Why do you need it?
Vitamin B2 helps the body release energy from proteins. Fats and carbohydrates during metabolic processes.

Its deficiency can cause anemia, loss of appetite, muscle weakness, tachycardia problems, and visual disturbances. Including conjunctivitis. Other problems can affect the skin and mucous membranes, with cracks in the corners of the mouth, itching, especially in the nose, ears, and scalp.

The daily amount recommended by the European Union is 1.6mg.

Where do you find it?
Vitamin B2 is present in milk and its derivatives. Especially in cheeses and yogurt. It is also found in eggs, brewer’s yeast, liver and beef entrails, chicken, almonds, and green leafy vegetables.

A tip: always try to keep food away from light. This vitamin is photosensitive and exposed to sunlight will be destroyed.

4 – Vitamin B3

Water-soluble vitamin B3 is also known as niacin.

Why do you need it?

Vitamin B3 contributes to the correct energy metabolism of our body, carrying out an effective toning action that removes the sensations of fatigue and profound tiredness. It also participates in the normal performance of all the functions of the nervous system and psychological functions.

Its deficiency can cause muscle weakness, general fatigue, loss of appetite, indigestion, and various skin rashes.

The daily amount recommended by the European Union is  18mg.

Where do you find it?

It is found mainly in meat (beef, poultry, fish), fortified cereals, peanuts, potatoes, dairy products, and eggs.

Vitamin B5

Also called pantothenic acid or vitamin W, it is part of the water-soluble vitamins, which cannot be stored in the body.

Why do you need it?
Vitamin B5 also plays a fundamental role in the metabolism of fats, proteins, and carbohydrates and is involved in the synthesis of cholesterol and hormones. In particular, it is indicated for the protection of hair and skin, to prevent states of fatigue, and for the healing of wounds and burns.

Its deficiency can cause fatigue, vomiting, stomach pain, infections, and muscle cramps.

The daily amount recommended by the European Union is 6mg.

Where do you find it?
The foods richest in vitamin B5 are legumes and offal, but also lean meats, wheat flour, vegetables, and fruit.

A tip: to get the most vitamin B5 it is preferable to consume raw fruits and vegetables.

6 – Vitamin B6

Among all the vitamins, B6, also known as pyridoxine, is extremely important for the health of our body because it protects the central nervous system.

Why do you need it?
Pyridoxine can protect brain functions and prevent ailments such as depression, irritability, difficulty concentrating, insomnia, lack of appetite, pain, vision and heart problems, and chronic headaches. It is also useful for combating premenstrual pain and for this reason it has also been called ” the woman’s vitamin “.

Its deficiency can cause seizures, dermatitis, muscle weakness, skin lesions, and anemia.

The daily amount recommended by the European Union is 2mg.

Where do you find it?
Foods that contain the greatest amounts of vitamin B6 include fish, poultry, lean meats, bananas, plums, avocados, and legumes, such as dried beans and chickpeas: one cup of canned chickpeas contains 1.1 milligrams of B6, i.e. 55% of the recommended daily value.

7 – Vitamin B7

also known as biotin, it is often incorrectly referred to as B8. Among the eight vitamins of group B., It is the least known, even if it carries out the fundamental task of helping our body to produce energy. Intervening in the process of transforming carbohydrates into glucose, a real fuel for our body.

Why do you need it?
Vitamin B7 is considered a valid aid to stimulate memory because it counteracts the wasting of nerve cells. Furthermore, it can be an excellent ally in cases of abdominal swelling.

Its deficiency can cause nausea, vomiting, depression, hair loss, and dry, cracked skin.

The daily amount recommended by the European Union is 150μg.

Where do you find it?
Excellent sources of vitamin B7 are bran and whole grains, yeast, citrus fruits, meats in general, and, in particular, the liver.

8 – Vitamin B9

This vitamin, better known as folic acid, is essential in cell division and the formation of genetic material. It is also involved in the production of red blood cells.

Why do you need it?

Very important in pregnancy,  especially in the first 4-8 weeks of life, the period in which the first organs are formed. Furthermore, it is useful for treating anemia and determines a beneficial contribution in the treatment of many diseases, such as depression, gastritis, dyspepsia, arthritis, diarrhea, and spina bifida.

Its deficiency can cause anemia, depressive symptoms, apathy, anxiety, insomnia, and digestive disorders.

The daily amount recommended by the European Union is 200µg.

Where do you find it?

It is found in many different foods, such as milk, liver, green leafy vegetables, peas, beans, and dried lentils.

9 – Vitamin B12

Vitamin B12, or cobalamin, is essential in the formation of red blood cells, so much so that it is the best known anti-anemic factor. It is also essential for a healthy and well-functioning nervous system.

Why do you need it?
Vitamin B12 is indicated in anemia, neuralgia, rheumatic pain, allergies, colitis, and intellectual fatigue. It also increases physical energy. Promotes growth and strengthens the immune system.

Its deficiency can cause anemia, nervousness, fatigue, and, in many cases, neuritis and brain degeneration.

The daily amount recommended by the European Union is 1.0µg.

Where do you find it?
It is contained in all foods of animal origin, such as meat, fish, and dairy products. The clams, the mussels, mackerel, herring, and animal liver are the foods rich in this vitamin.

Tip: If you are on a vegetarian diet, you may need a supplement to get this vitamin.


C vitamin

Vitamin C, or ascorbic acid, is the most common and powerful anti-oxidant and delays cellular aging by keeping tissues young. In addition, it also protects against carcinogens, improves and often conditions the absorption of iron and that of almost all vitamins.

Why do you need it?
It is essential for the structure of bones, cartilage, muscles, and blood vessels. It helps maintain the integrity of capillaries and gums, protects against carcinogens, and also has a toning. Strengthening and anti-stress action. In addition, it prevents heart disease and ailments resulting from exposure to toxins (smoking, pollution, alcohol, drugs).

Its deficiency can cause swelling or bleeding of the gums, delayed healing, fatigue, scurvy, depression, and indigestion.

The daily amount recommended by the European Union is 60mg.

Where do you find it?
The main sources of vitamin C are almost all plants. Citrus fruits have always been considered the food that contains the greatest amount, but in reality, the vegetable that contains the most are red peppers (95mg per serving). Other foods rich in this vitamin are kiwis, broccoli, tomatoes, strawberries, melon, currants, and Brussels sprouts.

Tip: since our body has no reserves of vitamin C. It is necessary to take a significant amount of it every day through raw fruit and vegetables.

Vitamin D

This vitamin is produced directly by our body when the skin is exposed to sunlight.

Why do you need it?
Contributes to the formation of teeth and bones; helps heart function and the nervous system.

Its deficiency can cause rickets and other bone deformities in children. While in adults it can cause bone decalcification.

The daily amount recommended by the European Union is 5µg.

Where do you find it?
To get vitamin D, exposure to the sun is essential. Among the rare naturally occurring food sources that contain this vitamin, one of the best is cod liver oil. You can also find it in dairy products, fatty fish rich in omega 3 (salmon, sardines, tuna, herring), egg yolk, and green leafy vegetables.

Tip: Always try to spend more time outdoors to allow your body to synthesize vitamin D thanks to natural light.

Vitamin E

It is a powerful antioxidant that protects cells from free radicals: by preventing them from being attacked by toxic waste. It slows down their aging.

Why do you need it?
This vitamin is essential in energy production and many studies have shown that it increases muscle power and resistance to fatigue. In addition, it protects brain tissues, preventing cognitive decline.

Its deficiency can cause muscle weakness, nerve damage, reproductive problems, and anemia.

The daily amount recommended by the European Union is 10mg.

Where do you find it?
It is contained in mixed and fortified cereals, nuts, wheat germ, raw vegetable oils, and green leafy vegetables.

Tip: Try to keep food in vacuum containers and away from light.

Vitamin K

It’s a key ingredient in blood clotting – without vitamin K your body wouldn’t be able to stop bleeding when you cut or bruise yourself.

Why do you need it?
It is indicated for hemorrhages, liver disorders, colitis, urticaria, and antibiotic treatments that destroy the intestinal microbial flora.

Its deficiency can cause possible bleeding in infants and in people taking anticoagulant drugs to thin the blood.

A recommended daily amount for vitamin K has not been established by the European Union.

Where do you find it?
Vegetables, artichokes and green leafy vegetables in general, fruit, cereals, and dairy products.

Tip: Watch out for some medications that can reduce vitamin K levels, such as those that impair liver function or destroy intestinal flora (for example, antibiotics) as well as those that limit intestinal absorption.

To help you not forget all the information about vitamins. We offer you a handy summary table.


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