Recent medical reports are alarming: 90% of residents in temperate regions suffer from vitamin D deficiency, with 60% experiencing a severe deficit. Why is this so dangerous, what are the consequences, and what causes this situation?
The Unique Nature of Vitamin D
Vitamin D (cholecalciferol) is unusual because the human body can, to some extent and under specific conditions, synthesise it independently, covering up to 80-100% of the body’s requirements. This process requires vitamin D precursors present in our skin and UVB radiation, which induces a simple chemical reaction: the biologically inactive provitamin D3 (7-dehydrocholesterol) is converted through a non-enzymatic photoisomerisation reaction to previtamin D, which then transforms into vitamin D3 under the influence of body heat.
However, many factors and environmental conditions disrupt this process. The most commonly cited include:
– The angle of sunlight, i.e., season and latitude
– Cloud cover
– Air pollution
– Skin complexion
– Use of sunscreen
– Exposure time and body surface area exposed to sunlight
In the UK, optimal conditions for vitamin D synthesis occur from May to September. Unfortunately, this year has seen few sunny days, making vitamin D supplementation advisable in autumn and winter.
The Role of Vitamin D in the Human Body
Vitamin D is essential for the human body for several reasons:
1. It facilitates the absorption of calcium and phosphorus ions from the digestive tract, regulating calcium-phosphate metabolism and positively affecting teeth and bones, specifically preventing rickets in children and osteoporosis in older adults.
2. It supports neuron regeneration, beneficially impacting the nervous system. In this context, it is presumed that adequate vitamin D levels prevent neurodegenerative diseases such as senile dementia and Alzheimer’s disease.
3. It stimulates the immune system, helping to fight infections and shortening their duration. It also has anti-inflammatory effects by inhibiting the production of pro-inflammatory cytokines.
4. It reduces the risk of type 1 diabetes and alleviates symptoms of type 2 diabetes by increasing insulin secretion.
5. It inhibits the differentiation and proliferation of cancer cells, which may be used in the prevention of certain types of cancer, although this is still at the research stage.
6. It inhibits cell proliferation, thus alleviating psoriasis symptoms.
7. It stimulates spermatogenesis (production and maturation of sperm) and inhibits endometrial growth.
Dietary Sources of Vitamin D
If skin synthesis is impossible due to unfavourable weather conditions, one can introduce vitamin D3-rich foods into the diet. These are primarily fatty products of animal origin, as vitamin D is fat-soluble:
– Liver
– Herring
– Mackerel
– Salmon
– Sardines
– Milk
– Egg yolk
– Cheese
Store shelves also offer products fortified with vitamin D, most commonly margarines, cereals, and powdered milk for children.
Vitamin D Requirements
Establishing norms regulating the body’s daily vitamin D requirements is challenging due to the possibility of its synthesis by the body. However, for Central European residents, the following safe doses of orally administered vitamin D (through food or supplements) have been determined:
– Infants 0-6 months: 400 IU/day
– Infants 6-12 months: 400-600 IU/day
– Children and adolescents: 600-1,000 IU/day
– Adults: 800-2,000 IU/day
– Pregnant women: 1,500-2,000 IU/day
*40 IU = 1 μg of vitamin D
Vitamin D Supplementation
If fish and liver rarely appear on the menu, one can reach for a ready-made vitamin D3 preparation from the pharmacy. These are mainly dietary supplements with vitamin D in the form of soft capsules, drops, or aerosol and come in various doses. Vitamin D preparations for children are a separate category, as they have lower requirements for this vitamin. Most often, vitamin D3 dietary supplements for children come in twist-off capsules for oral administration or in spray form.
Due to the body’s ability to store vitamin D, care should be taken that the total dose from food and supplements is not too high, as this can lead to overdose.
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Effects of Excess Vitamin D
Vitamin D3 (cholecalciferol) poisoning occurs at a level of 200 ng/ml, which is difficult but not impossible to achieve. Symptoms of excess vitamin D include nausea, vomiting, weakness, skin itching, constipation, increased thirst and frequent urination, and headache. Chronic persistence of these symptoms can lead to kidney stones and calcifications in the arteries, heart, and lungs.
Signs of Cholecalciferol Deficiency
Signs of vitamin D3 deficiency, which can be overlooked due to non-specific symptoms, include:
– Insomnia or restless sleep
– Muscle cramps
– Chronic fatigue
– Joint, bone, and muscle pain
– Periodontal diseases
– Weakened immune system
– Concentration problems
– Vision disturbances
– Headaches
– Diarrhea and lack of appetite
Additionally, in infants, there may be problems with the closure of the fontanelle, the appearance of bumps on the forehead, and excessive flattening of the back of the head (occiput).
Vitamin D Level Testing
If you experience the symptoms mentioned above and suspect a cholecalciferol deficiency, you can determine the level of vitamin D in your blood during blood tests ordered by your GP or privately at diagnostic centres. Assessment of total 25-hydroxy vitamin D (vitamin 25(OH)D – the technical name for this test) is performed based on a blood sample taken from a vein in the elbow crease. It’s best to consult a doctor with the received results to establish the daily dose of vitamin D supplement.
**Disclaimer**: This article does not constitute medical advice. Before taking any actions that may affect your life, health, or well-being, contact a doctor or other specialist to receive individualised advice. Never self-medicate; seek medical care from your doctor, and in case of disease symptoms or deterioration of your health condition, contact a specialist.
