Avitaminosis or Vitamin Deficiency: Risks

Avitaminosis or Vitamin Deficiency: Risks
Photo source: Getty images

A rational diet with a balanced intake of essential nutrients, minerals and vitamins is key to maintaining and improving health. What is the function of vitamins and why is their daily dietary intake important? What causes a vitamin deficiency and how does it manifest?


Avitaminosis is a condition characterised by a severe deficiency or a complete absence of vitamins in the body.

Vitamin deficiency occurs at two levels: when vitamin levels fall below reference values, the condition is called hypovitaminosis. It is a precursor to severe vitamin deficiency.

If hypovitaminosis is not compensated for and vitamin levels continue to decline, a more serious and in some cases life-threatening condition develops: avitaminosis.

While hypovitaminosis is clinically manifested by a wide range of disorders of individual functions of the body, avitaminosis can cause serious diseases.

The severity, course and manifestations of avitaminosis always depend on the specific type of vitamin involved in the deficiency.

Today, avitaminosis is very rare, especially in developed countries. Various forms of hypovitaminosis are more common.

Vitamin deficiency affects all ages and usually coexists with mineral deficiencies (e.g. zinc, iodine, iron, etc.).

What are vitamins and what is their role?

Vitamins are organic compounds with a diverse, yet relatively simple chemical structure.

They are considered essential micronutrients that the human body is unable to make on its own (with some exceptions), which is why we depend on dietary intake of vitamins.

Vitamins occur naturally in food in very small amounts.

The physiological function of vitamins is quite diverse and at the same time unique for each vitamin.

In general, they are indispensable and necessary for the normal functioning of metabolic processes, the maintenance of health and also for the normal growth and development of the organism.

They interfere in a number of biochemical processes either directly or more often they function as coenzymes, i.e. they influence processes in the body secondarily.

As coenzymes, they are part of the body's enzymes and condition their action. The enzymes are then already capable of accelerating or slowing down the biochemical processes themselves.

In addition, some vitamins act as hormones.

The basic action of vitamins in the body can therefore be summarized as follows:

  • As hormonally active substances, they interfere with hormonal regulation.
  • They are involved in the formation of new cells.
  • They promote cell maturation.
  • They have antioxidant effects.
  • They serve as cofactors that strengthen metabolic pathways.

Vitamins show a biological effect even at very low concentrations.

A glimpse into the history...

Vitamins as chemical substances were only isolated at the turn of the 19th and 20th centuries. The development of analytical chemistry contributed to this.

Since the first chemical isolated from them was a molecule containing an amine group, as a group they were named from the Latin words "vital" and "amine", which translated means vital amines.

After the discovery of other molecules, many of which did not contain an amine group, their names were simplified to "vitamins".

The first vitamin isolated in crystalline form was vitamin B1 in 1926.

Vitamins have received increased attention in recent years. This is mainly due to their antioxidant action and positive influence on the body's defences against cancer, cardiovascular and degenerative diseases (also in the elderly).

Nomenclature and classification of vitamins

Initially, there were two groups of vitamins. The first one was a vitamin soluble in organic solvents called fat-soluble factor A (later to be called vitamin A).

The second group was the original "vital amine" called water-soluble factor B, or vitamin B.

In the following years, other vitamin molecules were discovered which were named with letters in alphabetical order (C, D, E, etc.)

The exception was vitamin K. Its name is based on its function in blood clotting (the letter K comes from the Danish word for "coagulation", the language of its discoverer).

Gradually, more B vitamins were discovered, so they began to be designated by the letter B with a number (B1, B2, B3, ..., B12).

Today, vitamins are classified by their ability to dissolve into two basic groups: fat-soluble vitamins and water-soluble vitamins.

Fat-soluble vitamins are found in the fatty component of foods. In general, when these vitamins are taken in large quantities, they are mainly stored in the body in fat tissue and in the liver.

Their reserves are quite large and are released gradually and slowly, depending on the needs of the organism. That is also why the symptoms of their deficiency occur only after a few months.

Water-soluble vitamins, on the other hand, are not stored in the body and their reserves are very small, which is why we need to get them from the diet on a daily basis.

The symptoms due to a deficiency of these vitamins become apparent within a few days or weeks.

When taking high doses of these vitamins, there is usually no risk of side effects, and excess amounts are simply excreted from the body in the urine.

The classification of vitamins on the basis of their solubility is also justified from a nutritional point of view. Vitamins of the same group are commonly found in foods at the same time.

Metabolism of the human body
Metabolism of the human body. Photo: Getty Images.

An overview of vitamins on the basis of their solubility:

1. Fat-soluble vitamins

  • Vitamin A – retinol, (provitamins - carotenoids)
  • Vitamin D – calciferol (D2 - ergocalciferol, D3 - cholecalciferol)
  • Vitamin E – tocopherol, tocotrienol
  • Vitamin K – (K1 – phylloquinone, K2 – menaquinone)

2. Water-soluble vitamins

  • Vitamin B1 – thiamine
  • Vitamin B2 – riboflavin
  • Vitamin B3 – niacin
  • Vitamin B5 – pantothenic acid
  • Vitamin B6 – pyridoxine
  • Vitamin B7 – biotin
  • Vitamin B9 – folic acid
  • Vitamin B12 – cyanocobalamin
  • Vitamin C – ascorbic acid

Table: overview of functions and food sources of vitamin A

Biological function of vitamin A Dietary sources of vitamin A
  • Essential for the formation of the visual pigment - rhodopsin.
  • Promotes the growth and maturation of epithelial cells - mucous membranes, skin, hematopoietic cells.
  • Involved in the development of the placenta and the formation of sperm.
  • Contributes to the function of the immune system.
  • Involved in the metabolism of bones and teeth.
  • Antioxidant properties.
  • Foods of animal origin - offal, milk, cheese, butter, eggs, fish oil.
  • Vegetables - carrots, peppers, tomatoes, parsley, spinach, squash, broccoli, peas, sweet potatoes.
  • Fruit - apricots, peaches.

Vitamin A is inactivated by UV radiation. It is lost from food during processing such as frying or baking.

The concentration of vitamin A in blood plasma is 30-95 µg/100 ml. 

Table: functions and food sources of B vitamins

Biological function of vitamin B1 Dietary sources of vitamin B1
  • Dignificantly involved in the process of energy generation.
  • Affects the nervous system.
  • Foods of animal origin - milk, egg yolk, liver, pork.
  • Vegetables - peas, beans, soybeans, asparagus.
  • Cereals, oatmeal, nuts.
  • Yeast.
Biological function of vitamin B2 Dietary sources of vitamin B2
  • Interferes with oxidation-reduction processes.
  • Involved in the metabolism of amino acids and carbohydrates.
  • Involved in the formation of blood cells.
  • Foods of animal origin - offal, especially liver, milk, cheese, egg yolk.
  • Cereals, yeast.
  • Vegetables - spinach, tomatoes, carrots, broccoli, asparagus.
Biological function of vitamin B3 Dietary sources of vitamin B3
  • An important coenzyme for a number of biochemical processes.
  • Involved in the metabolism of fats, amino acids, steroids.
  • Foods of animal origin - offal, especially liver, eggs.
  • Legumes.
  • Yeast, tea, coffee.
  • The human body can make a certain amount of vitamin B3 from the amino acid tryptophan.
Biological function of vitamin B5 Dietary sources of vitamin B5
  • Involved in the metabolism of fatty acids, sugars, fats and proteins (as a cofactor).
  • Foods of animal origin - offal, chicken, egg yolk.
  • Vegetables - peas, cabbage, sweet potatoes, broccoli.
  • Yeast, nuts.
  • A certain amount of vitamin B5 is produced by the intestinal microflora.
Biological function of vitamin B6 Dietary sources of vitamin B6
  • Involved in the metabolism of amino acids, fats, neurotransmitters.
  • Essential for the formation of haem (part of the red blood pigment - haemoglobin).
  • Food of animal origin - offal, pork, milk, eggs.
  • Yeast.
  • Vegetables - green salad, cabbage.
  • Legumes, nuts.
Biological function of vitamin B7 Dietary sources of vitamin B7
  • Essential for the formation of fatty acids and urea.
  • Supports the function of the immune system.
  • Foods of animal origin - liver, milk, egg yolk.
  • Vegetables.
  • Cereals, yeast, nuts.
  • A certain amount of vitamin B7 is produced by the intestinal microflora.
Biological function of vitamin B9 Dietary sources of vitamin B9
  • Essential for the formation of nucleic acids (DNA).
  • Affects the formation of amino acids, the maturation of blood cells.
  • Food of animal origin - offal, meat, eggs.
  • Vegetables - leafy greens, beans, asparagus, broccoli.
  • Fruit - strawberries, orange.
  • Mushrooms, yeast, nuts.
Biological function of vitamin B12 Dietary sources of vitamin B12
  • Essential for the formation of nucleic acids (DNA), amino acids, heme (as a coenzyme).
  • Affects the function of the peripheral nervous system.
  • Indirectly affects the production of red blood cells (via vitamin B9).
  • Foods of animal origin - offal, especially liver, heart, meat, milk, cheese, butter, egg yolk, seafood.

Table: overview of the functions and food sources of vitamin C

Biological function of vitamin C Dietary sources of vitamin C
  • Strong antioxidant effect, protecting cells from the action of free oxygen radicals.
  • Supports the immune system.
  • Involved in the formation of collagen, hormones, carnitine, neuromediators (as a cofactor of enzyme systems).
  • Participates in the conversion of cholesterol into bile acids.
  • Increases iron absorption.
  • Almost all living organisms.
  • Mostly fresh vegetables and fruits - lemon, orange, grapefruit, strawberries, kiwi, melon, tomatoes, spinach, broccoli, cabbage, cauliflower, asparagus, potatoes, peas, beans.
  • Foods of animal origin - liver, heart, milk.
  • Fortified foods (foods to which vitamin C is deliberately added to increase the amount of vitamin C).

During storage at room temperature, transport or during treatments such as cooking, vitamin C is degraded.

Table: functions and food sources of vitamin D

Biological function of vitamin D Dietary sources of vitamin D
  • Vitamin of hormonal nature.
  • Regulates calcium and phosphorus metabolism.
  • Responsible for the absorption of calcium and phosphate from the intestines.
  • Increases the absorption of calcium into the bones, which has a positive effect on their structure and mineralization.
  • Supports the immune system.
  • Foods of animal origin - offal, especially liver, fish oil, egg yolk, dairy products.
  • Fish - tuna, salmon, sardines, herring.
  • Fats enriched with vitamin D.

Vitamin D is also produced in our body - in the skin by the conversion of cholesterol in the presence of UV radiation.

Especially in summer, this route is the main source of vitamin D (up to 80% of the total), exceeding the dietary intake.

The concentration of vitamin D in blood plasma is 10 - 60 ng/dl.

Table: functions and food sources of vitamin E

Biological function of vitamin E Dietary sources of vitamin E 
  • Strong antioxidant effect, protecting cells from the action of free oxygen radicals.
  • Preventive effect against atherosclerosis.
  • Interferes with blood clotting processes.
  • Anticancer effect.
  • Promotes reproduction and growth.
  • Foods of animal origin - eggs, offal, especially liver.
  • Vegetable oils - soybean, cereal germ, poppy seed.
  • Cereals.
  • Nuts - almonds, walnuts, hazelnuts.
  • Seeds - soybean, corn, sunflower.

Vitamin E occurs in eight basic forms - alpha, beta, gamma, delta tocopherol and alpha, beta, gamma, delta tocotrienol. Alpha tocopherol has the highest potency.

The concentration of vitamin D in blood plasma is 300-1200 µg/dl.

Table: functions and food sources of vitamin K

Biological function of vitamin K Dietary sources of vitamin K
  • Participates in the formation of blood clotting factors (factor II, VII, IX and X) as a coenzyme.
  • Involved in blood clotting.
  • Necessary for the formation of proteins involved in bone calcification.
  • IInterferes with energy metabolism.
  • Foods of animal origin - eggs, offal, especially liver, milk.
  • Vegetables - spinach, broccoli, cabbage, Brussels sprouts, tomatoes.
  • Legumes.
  • Vegetable oils - soybean, sunflower, olive, peanut.

The source of vitamin K is also the intestinal microflora that can synthesize this vitamin (Escherichia coli, bacteria of the genus Proteus).

Vitamin K is sensitive to UV radiation and light. It breaks down during food processing such as cooking.

The concentration of vitamin K (specifically phylloquinones) in blood plasma is 0.5 - 5.0 ng/ml.

Sources of vitamins
The main sources of vitamins are foods of plant and animal origin. Photo source: Getty Images.


Today, vitamin-related avitaminosis is relatively rare, except in poor or developing countries.

Hypovitaminosis is much more common.

The low to almost negligible incidence of avitaminosis is mainly due to the easy availability of food and the development of the food industry, where individual foods are deliberately enriched with a wide variety of substances, including vitamins.

As a result, we do not find hypovitaminosis due to a lack of vitamins in the diet, but rather due to health reasons - the occurrence of various absorption disorders, abnormally increased excretion or conditions where the body requires higher doses of vitamins.

In general, there are several causes of hypovitaminosis that can be attributed to all kinds of vitamins.

The most common causes of a lack or complete vitamin deficiency include:

  • Insufficient intake of vitamins in the diet – lack or insufficient quantity of fresh and varied food.
  • Uniform nutrition – vegetarians, vegans, absence of animal source foods.
  • High consumption of foods preserved or cooked at high temperatures - boiling, frying, baking can inactivate some types of vitamins.
  • The presence of antivitamins, i.e. chemicals with a similar structure to vitamins, which, due to their similarity, occupy binding sites for vitamins on receptors or systems, thereby blocking their action.
  • Absorption disorders of the digestive tract, i.e. malabsorption disorders, celiac disease, Crohn's disease, inflammatory diseases, liver and pancreatic diseases, jaundice, diarrhea, taking antibiotics, etc.
  • Excretory disorders causing excessive elimination of vitamins, e.g. kidney disease.
  • Conditions with increased demands on vitamin intake than under normal circumstances, i.e. pregnancy, breastfeeding, periods of growth and development, stress, increased physical exertion, chronic diseases, infections, etc.
  • Dietary errors and addictions, i.e.excessive intake of carbohydrates, alcoholism, drugs.
  • Certain medications.
An example of an antivitamin for vitamin K is dicumarol that is used to treat patients prone to blood clots.
For vitamin B9 (folic acid), the antivitamin drug methotrexate, 5-fluorouracil or aminopterin, are used to treat cancer.

In addition to the aforementioned causes, there are also other specific causes, but they are already tied to a specific type of vitamin.

Malabsorption of fats may be the cause of fat-soluble vitamin deficiency.

Dialysis patients may have a vitamin B1 or Bdeficency.

Surgery in the gastrointestinal tract or the use of drugs to reduce the production of stomach acid (vitamin B12 is bound to protein in the diet, from which it is released only by the action of stomach acid) may contribute to vitamin B12 deficiency.

Vitamin C deficiency is typical of springtime due to the low content of the vitamin in the diet (spring fatigue).

In the case of vitamin D, the deficiency may be due to inadequate exposure to sunlight or found in people with dark skin.

Prematurely born babies and babies born with a low weight often develop vitamin E deficiency.

With vitamin K, hemorrhagic disease is encountered in newborns due to low passage of the vitamin through the placenta, low amounts of the vitamin in breast milk, and low production of the vitamin in the intestines in the first few weeks of the baby's life.


Symptoms of reduced levels of vitamins or vitamin deficiency are specific and characterise various types of vitamins.

The nature of these symptoms can almost always be derived from the biological function of the individual vitamins.

Next, we summarise the most common symptoms, disorders or diseases observed in relation to a given vitamin deficiency.

Vitamin A

  • Vision problems - problems with the adaptation of the eyes to darkness or twilight (or low light/dim light) blindness, night blindness, dryness of the conjunctiva, corneal damage, sensitivity to light, in more severe cases blindness.
  • Problems with the mucous membranes and skin (dryness, scaling, itching), anaemia.
  • Changes in the epithelium leading to respiratory tract infections, diarrhoea, inflammation of the intestines, formation of stones in the urinary tract.
  • Impaired fertility (even total infertility).
  • Damage to the bones and slow formation of tooth enamel.
  • Growth retardation and decreased cognitive function (thinking and memory).
Eye and vision disorder
A common symptom of vitamin A deficiency is eye and vision disorders. Photo source: Getty Images.

Vitamin B1 – thiamine

  • Symptoms of hypovitaminosis are fatigue, weakness, insomnia, lack of appetite, depressed mood, hallucinations.
  • Problems with organs with high energy turnover - heart, liver, kidneys, nervous system and skeletal muscles.
  • Avitaminosis can lead to the development of beriberi or Wernicke-Korsakoff syndrome.
  • Dry beriberi is manifested by degeneration of the nerves, disturbances in the sensitivity of the limbs, weakness and flaccidity of the muscles.
  • Cardiac beriberi is characterised by the presence of edema, increased heart rhythm, enlargement of the heart muscle and even heart failure.
  • Wernicke-Korsakoff syndrome affects the nervous system and is typical in alcoholism - confusion, disorientation, paralysis of the eye muscles, double vision, impaired mobility and memory loss.

Vitamin B2 – riboflavin

  • Inflammation of the corners of the mouth, inflammation of the oral mucosa and tongue, pallor and peeling of the oral mucosa.
  • Inflammation of the conjunctiva, overgrowth of blood vessels through the cornea, enlargement of the eyelids, cataracts.
  • Anaemia.
  • Skin diseases, dry skin, acne.

Vitamín B3 – niacin

  • Pellagra – "the three Ds": dermatitis (inflammation of the skin), diarrhea (frequent watery bowel movements), dementia (cognitive impairment).
  • Vitamin B12 absorption disorder.

Vitamin B5 – pantothenic acid

  • Skin disorders - inflammation, loss of pigment, hair loss.
  • Fatigue, weakness, headache, insomnia, lack of appetite, indigestion.
  • Anaemia, loss of sensation, burning sensation in the extremities.

Vitamin B6 – pyridoxine

  • Muscle weakness, the appearance of cramps.
  • Anaemia, affecting immunity.
  • Nausea, vomiting, diarrhoea, skin diseases, conjunctivitis.
  • Confusion, dizziness.

Vitamin B7 – biotin, also called vitamin H

  • Skin rashes especially in the eyebrows and face.
  • Nausea, lack of appetite.
  • Rarely muscle weakness.

Vitamin B9 – folic acid

  • The deficiency manifests itself primarily in rapidly dividing cells.
  • Blood disorders - lack of platelets, red and white blood cells.
  • Growth disturbances, general weakness, fatigue.
  • Inflammation in the oral cavity, indigestion.
  • It increases the amount of the amino acid homocysteine, which is considered a risk factor for atherosclerosis and heart disease.

Vitamin B12 – cyanocobalamin

  • Blood disorders - lack of platelets, red and white blood cells.
  • Nerve damage - impaired growth and sensitivity, decreased muscle tension, muscle flaccidity, convulsions, abnormal movements, paralysis, memory loss, depression, personality change.
  • It increases the amount of the amino acid homocysteine, which is considered a risk factor for atherosclerosis and heart disease.

Vitamin C

  • Symptoms of hypovitaminosis include fatigue or increased susceptibility to infections.
  • Bleeding conditions such as minor bleeding into the skin, mucous membranes, joints, muscles or in the digestive tract, increased bruising, anaemia.
  • Muscle weakness and bone pain.
  • Inflammation, redness and swelling of the gums.
  • Overall impaired wound healing.
  • Avitaminosis leads to scurvy - swelling and bleeding gums, tooth loss, subcutaneous bleeding, bruising, pain and bleeding in the joints, softening and impaired bone growth (especially in children). These disorders are related to impaired collagen formation and become apparent after about 1 to 3 months.
Zuby - skorbut
Závažný deficit vitamínu C vedie k vzniku skorbutu, ktorý sa prejavuje opuchom a krvácaním ďasien, až vypadávaním zubov. Zdroj foto: Getty Images

Vitamin D

  • Bone diseases leading to bone softening, deformities and fractures - rickets in children, osteomalacia in adults.
  • Muscle damage, reduced muscle strength and tension.
  • Decreased levels of calcium and phosphorus in the body.
  • Increased susceptibility to infections.
  • It contributes to the development of cardiovascular diseases, mental (depression, schizophrenia) and autoimmune diseases.

Vitamin E

  • Nervous and muscular disorders - degeneration of nerves, gait disorders, tendon damage.
  • Anemia caused by the disintegration of red blood cells, vascular permeability disorders, retinal hemorrhage.
  • Fertility disorders (even infertility).

Vitamin K

  • Hemorrhagic disease of newborns - bleeding into the mucous membranes and organs due to a decrease in the amount of blood clotting factors.
  • Blood clotting disorders.
  • Bleeding conditions in adults - bleeding from the nose, in the digestive or genitourinary tract, muscles or subcutaneous tissue.


The diagnosis of hypovitaminosis and avitaminosis is perform using various methods that can be applied to all types of vitamins and methods that are specific for a particular type of vitamin.

The most common methods used in diagnosis are as follows:

  • Blood tests – to determine the level of each vitamin in the blood serum and to assess any reduction or deficiency thereof.
  • Monitoring of symptoms or, in more severe cases, the presence of a disorder and disease characteristic of a deficiency of a given type of vitamin.
  • Monitoring the body's response to the administration of individual vitamins. When the condition improves, it is possible to determine the deficiency of a given type of vitamin.
  • Determining the presence of vitamins in the urine - based on the amount of excreted vitamins, their precursors or metabolites in the urine, it is possible to determine their level in the body.

Specific diagnostic methods that are already linked to a particular type of vitamin include, for example, an eye exam and the detection of eye disorders if vitamin A deficiency is suspected.

The level of homocysteine and methylmalonic acid of vitamin B12 are checked as their levels increase in the absence of this vitamin and cause cardiovascular disease.

When vitamin C deficiency is suspected, there will be an examination of the strength of the capillaries, followed by bleeding time measurements.

Monitoring calcium and phosphorus levels or a bone X-ray is typical of vitamin D deficiency.

Several blood tests are performed in the case of vitamin K and vitamin B9 defiicency: red blood cell maturation, platelet count, prothrombin time, fibrinogen level, etc.

Vitamin B9 is also involved in the assessment of nucleic acid formation.

Blood tests
One of the most common diagnostic methods for determining vitamin deficiency is a blood test. Photo source: Getty Images.


Vitamin deficiency occurs at two levels: the first level is hypovitaminosis, i.e. when vitamin levels fall below reference values.

The reduction of vitamin levels in the body is a process developing over several weeks to months.

Hypovitaminosis may not even show outwardly visible or noticeable symptoms, especially in transient or mild forms of hypovitaminosis.

In prolonged or more severe forms of hypovitaminosis, a wide range of disorders of individual body functions can develop.

The rate of development of deficiency symptoms depends on the nature and type of vitamins.

Fat-soluble vitamins are largely stored in the fatty components of the body, from which they are released gradually and slowly. Therefore, the symptoms of their deficiency are noticeable only after several months.

Water-soluble vitamins, on the other hand, are stored in the body in very small to almost non-existent amounts, so symptoms of deficiency will appear within a few days or weeks.

If the drop in vitamin levels is not compensated for, i.e. not treated in any way, the drop deepens and reaches the second level: avitaminosis.

Avitaminosis is characterised by a severe deficiency or even a complete lack of vitamins in the body. It is rare and develops over a long period of time.

With avitaminosis, the affected person is suffering from serious diseases and disorders, some of which can have permanent or even fatal consequences.

Individual disease manifestations of hypovitaminosis as well as diseases and disorders of the body due to a complete deficiency of specific types of vitamins are listed in the "Symptoms" section.

How it is treated: Avitaminosis

How is avitaminosis treated? Medicines, supplements, diet

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