Blog
Vitamins in the body: role, norms and consequences of deficiency

Vitamins are essential substances that participate in all vital processes in the body. They support the immune system, metabolism, the functioning of internal organs, and the health of skin, hair, and nails. Although vitamins are needed in relatively small quantities, their deficiency or excess can significantly affect human health.
Why are vitamins important for the body?
Each vitamin performs unique functions, ensuring the normal functioning of different body systems. Some of them help regulate energy metabolism, others promote cell growth, support the nervous system or strengthen the immune system.
The body is unable to synthesize most vitamins on its own, so they must be obtained from food or in the form of dietary supplements.
Main groups of vitamins and their functions
Vitamins are divided into water-soluble and fat-soluble.
Water-soluble vitamins
These vitamins do not accumulate in the body and are excreted in the urine, so they need to be regularly replenished through nutrition.
| Vitamin | Role in the body | Main sources |
|---|---|---|
| Vitamin C (ascorbic acid) | Supports immunity, promotes wound healing, antioxidant | Citrus fruits, berries, spinach, bell peppers |
| Vitamin B1 (thiamine) | Regulates the nervous system, participates in metabolism | Whole grains, nuts, legumes |
| Vitamin B2 (riboflavin) | Supports skin health, improves vision | Dairy products, eggs, green vegetables |
| Vitamin B3 (niacin) | Supports cholesterol levels, improves blood circulation | Meat, fish, peanuts |
| Vitamin B6 (pyridoxine) | Important for brain and nervous system function | Bananas, potatoes, chicken |
| Vitamin B9 (folic acid) | Important for pregnancy, supports blood formation | Green leafy vegetables, liver, avocado |
| Vitamin B12 (cobalamin) | Participates in the formation of red blood cells, supports the nervous system | Meat, fish, dairy products |
Fat-soluble vitamins
These vitamins can accumulate in the body, so their deficiency develops more slowly than water-soluble vitamins.
| Vitamin | Role in the body | Main sources |
|---|---|---|
| Vitamin A (retinol) | Responsible for vision, skin condition, strengthens immunity | Carrots, liver, dairy products |
| Vitamin D | Regulates calcium levels, strengthens bones | Sunlight, oily fish, eggs |
| Vitamin E (tocopherol) | Antioxidant, supports cell health | Vegetable oils, nuts, seeds |
| Vitamin K | Important for blood clotting and bone health | Spinach, broccoli, cabbage |
Vitamin deficiency: symptoms and consequences
Vitamin deficiency can lead to the development of various pathologies. The main symptoms of deficiency:
- Vitamin C deficiency → frequent colds, bleeding gums, fatigue
- Vitamin B12 deficiency → anemia, weakness, memory problems
- Vitamin D deficiency → brittle bones, muscle weakness, depression
- Vitamin A deficiency → vision impairment, dry skin
- Vitamin E deficiency → nervous system problems, muscle weakness
In the case of a long-term lack of vitamins, serious diseases such as rickets, anemia, vitamin deficiency, and even neurological disorders are possible.

How to determine the level of vitamins in the body
To find out if there is a deficiency or excess of vitamins, you can have a laboratory blood test.
Vitamin tests
- Vitamin D blood test – determines the level of 25(OH)D in the blood.
- Analysis for B vitamins – helps to assess the level of B1, B6, B9, B12.
- Analysis of antioxidant vitamins – determines level A, C, E.
- Coagulogram – helps assess vitamin K levels.
How to maintain vitamin balance
Proper nutrition
A balanced diet is the main way to get vitamins. Vegetables, fruits, dairy products, meat and fish should be present in the daily diet.Sunlight
Vitamin D synthesis depends on exposure to sunlight, so it is important to spend enough time outdoors.Taking vitamin complexes
If you have a significant deficiency, your doctor may recommend vitamin supplements. However, they should only be taken after testing and consulting a specialist.Giving up bad habits
Alcohol and smoking impair the absorption of vitamins, especially those of group B and C.
