Vitamin D, also known as calciferol, is a crucial component of our health. But did you know how broad its range of actions is in our body? From regulating minerals to supporting the immune system, vitamin D plays a key role. Learn more about the importance of this vitamin and how to ensure optimal levels in your body!
Vitamin D or calciferol is a fat-soluble vitamin, along with vitamins E, K, and A. Chemically, it belongs to the group of secosteroids and is the most similar to steroid hormones among all vitamins.
In the body, vitamin D has a broad range of effects, most notably its impact on the absorption of calcium, magnesium, and phosphate, as well as its role in supporting the immune system.
Vitamin D affects the absorption of various minerals in our body.
One of its key functions is the absorption of calcium from food through the digestive tract and maintaining optimal levels of calcium and phosphate, which promotes normal bone mineralization This is especially important for bone growth and healing after damage.
Calcium absorption from food is also crucial for maintaining the nervous system because calcium participates in many signaling pathways in our cells.
Normal levels of vitamin D prevent osteoporosis in adults, rickets in children, and many other diseases related to bone and muscle health.
In addition to its role in mineral absorption, vitamin D is also known for its positive impact on the immune system. In light of the recent COVID-19 pandemic, the positive effects of vitamin D on respiratory infections have come back into focus.
Interestingly, vitamin D was used as a treatment for tuberculosis, albeit unconsciously, before the invention of antibiotics. Patients were prescribed sun exposure as a form of treatment.
Another example of the unconscious use of vitamin D is the prescription of fish oils to children suffering from rickets.
Current studies show that vitamin D promotes the expression of proteins associated with our body’s antibacterial response. Many studies also show more frequent infections in people with vitamin D deficiency, and links have been established between vitamin D deficiency and multiple sclerosis, rheumatoid arthritis, diabetes, irritable bowel disease, and lupus.
Besides immune system and bone marrow cells, many other cells in our body have vitamin D receptors, suggesting that vitamin D also influences other processes in the body that are not yet fully understood.
Vitamin D deficiency is caused by insufficient intake of vitamin D through diet and inadequate exposure to sunlight, i.e., UV radiation.
People who do not eat fish, eggs, or dairy products are at increased risk of vitamin D deficiency. However, other conditions can also affect the absorption of vitamin D, such as irritable bowel syndrome (IBS), obesity, and gastric bypass surgery, which removes part of the small intestine.
Some symptoms of vitamin D deficiency in adults include:
In Children, Symptoms of Hypovitaminosis (Vitamin Deficiency) Are More Apparent, and Rickets is Common Among Children with Hypovitaminosis. Symptoms of Rickets Include:
Since vitamin D is fat-soluble, it can accumulate in the body as it is not excreted through urine like vitamins B or C. Instead, vitamin D accumulates in fat cells and the liver.
Due to this fact, it is advisable to consult with a healthcare provider before starting vitamin D supplementation and, if possible, to check serum vitamin D levels and be vigilant for any negative symptoms if they occur.
This risk is less pronounced with dietary intake of vitamin D due to relatively low amounts and the availability of vitamin D in food. Symptoms of vitamin D toxicity (hypervitaminosis) include:
Vitamin D is primarily found in animal-based foods, with the highest concentrations in fish (tuna, salmon, sardines, swordfish) and fish oils..
Nešto Slightly lower concentrations of vitamin D are found in:
In addition to animal-based foods, vitamin D can also be found in some mushrooms and algae, though in the form of vitamin D2. Animal-based foods contain vitamin D3, which is more efficiently absorbed in the body.
Moreover, many foods, such as milk and cereals, are fortified with vitamin D. Alternative sources of vitamin D include supplements containing vitamin D, which can be a useful option if we are unable to obtain sufficient vitamin D through diet and/or adequate sun exposure.
Many of us have probably said after a day outdoors or sunbathing at the beach that we have “absorbed some vitamin D,” but what is the actual connection between the sun and the synthesis of vitamin D in our body?
Sunlight is electromagnetic radiation that spans from infrared through visible light to ultraviolet (UV) radiation. For the purpose of discussing vitamin D, we will briefly focus on UV radiation.
UV radiation can be divided into UVA, UVB, and UVC radiation. UVB radiation is responsible for the synthesis of vitamin D, but also for the negative effects of sunlight (DNA damage, skin aging).
UVB radiation provides the energy necessary for the conversion of 7-dehydrocholesterol, a precursor, into vitamin D3 in our body.
The role of melanin is also interesting. Research shows that the efficiency of this conversion of 7-dehydrocholesterol into vitamin D3 depends on the amount of melanin, which protects deeper layers of the skin from the negative effects of UV radiation and consequently reduces UV radiation penetration.
Therefore, individuals with darker skin typically synthesize vitamin D3 more slowly.
Most sources suggest that just 10-30 minutes of sun exposure is sufficient to meet daily vitamin D needs. However, the exact duration can vary based on several factors, including:
While sun exposure is crucial for vitamin D production, it is important to be aware of the risks associated with excessive UV exposure and to use protective measures, such as sunscreen and seeking shade.
The two main forms of vitamin D are: vitamin D2 (ergocalciferol) and vitamin D3 (cholecalciferol). These two forms differ only in the length of their side chains, which form the structure of vitamin D.
Both are well absorbed in the small intestine, although vitamin D3 is somewhat more effectively bound to vitamin D3 carrier proteins and, therefore, is slightly better absorbed.
Vitamin D3 is predominantly found in animal-based foods, while vitamin D2 is present in plant-based foods that contain vitamin D.
It is recommended to take vitamin D supplements with or after a meal, as the absorption of vitamin D is enhanced by the presence of fats in the small intestine. Some supplements are provided as oil-based suspensions for this reason, while others in tablet or capsule form benefit from this consideration to maximize the effectiveness of the ingested dose.
Around half of the global population suffers from vitamin D deficiency. This issue becomes even more common in winter when sunny days are fewer, making vitamin D supplementation especially recommended during the winter months.
However, the exact duration for taking vitamin D depends on several factors, including:
Therefore, it is advisable to consult a doctor and, if possible, check vitamin D levels in the body through a blood test. It is also important to monitor any symptoms during the period of vitamin D supplementation. Despite lower reference values (recommended daily allowances) for vitamin D, many supplements come in much higher doses.
This is due to the bioavailability of vitamin D, meaning that the body may not metabolize all the ingested vitamin D. In other words, not all of the vitamin D consumed necessarily ends up in the bloodstream.
Hence, supplements are formulated in higher doses to ensure that the amount of vitamin D metabolized by the body approaches the recommended daily allowances.
| SEX | CONDITION | |||
| AGE/YEARS | F | M | PREGNANCY | LACTATION |
| 0-1* | 10 mg400 IU | 10 mg400 IU | ||
| 1-13 | 15 mg600 IU | 15 mg600 IU | ||
| 14-18 | 15 mg600 IU | 15 mg 600 IU | 15 mg 600 IU | 15 mg600 IU |
| 19-50 | 15 mg600 IU | 15 mg600 IU | 15 mg 600 IU | 15 mg 600 IU |
| 51-70 | 15 mg600 IU | 15 mg 600 IU | ||
| 71+ | 20 mg800 IU | 20 mg 800 IU | ||
From our Blog
More than one billion people globally have reduced vitamin D concentrations, which has led to this problem being called the "pandemic" of hypovitaminosis D, with serious consequences for public health.
Tingling in the hands is a common problem that affects many and is often associated with circulatory disorders as well as nerve problems.
Did you know that gingivitis is a problem faced by about 90% of people? Gum health is a key aspect of oral health, but it is often neglected until problems such as bleeding gums or periodontitis occur.
Zinc (Zn) is an essential mineral found in very small amounts in the body but is crucial for the functioning of the immune system and the normal operation of the body.
