9 questions and answers about vitamin D

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Vitamin D is an essential nutrient for the human body, playing a crucial role in maintaining bone health and the proper functioning of the immune system. Synthesized mainly by exposing the skin to sunlight, it plays a vital role in the absorption of calcium and phosphorus, which are essential for the formation and strengthening of bones.

Even though it is popular, vitamin D still raises uncertainty regarding aspects such as how to use it, dosage, benefits, contraindications and other factors. Therefore, Paula Molari Abdo, pharmacist from the University of São Paulo (USP) and technical director of Formularium, clarifies some doubts about this important nutrient. Check out!

1. What is vitamin D?

The call vitamin D, in reality, it is a hormone. It was called this way in reference to the raw material that we need to keep in the body to produce it: dehydrocholesterol. Its functions are so important and complex that it was called the vitamin D endocrinological system.

It consists of two forms: ergocalciferol (vitamin D2) and cholecalciferol (vitamin D3). Vitamin D2 is present in plants and some types of fish. Vitamin D3 is produced when the skin is exposed to ultraviolet B (UVB) radiation. “Only 20% of our needs come from diet. The other 80% is synthesized by the skin through sun exposure”, says Paula Molari.

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two. What determines the synthesis of vitamin D?

Vitamin synthesis depends on a series of factors such as skin pigmentation, geographic location, season, clothing, age, use of sunscreen and local weather conditions. Sometimes, vitamin D levels, for example, are considerably lower in black people compared to white people.

In Nordic latitudes, these levels reduce by around 20% from late summer to mid-winter. However, 30 minutes of daily sun exposure during the summer is sufficient, avoiding the sun between 10 am and 4 pm, when the radiation is most intense.

3. In which cases is the supplement recommended?

Before supplementing this nutrient, it is essential to consult a doctor. However, there are some groups that are more susceptible to vitamin D deficiency and, therefore, require supplementation, as well as the elderly, as aging is a risk factor, as skin atrophy (typical of advanced age) reduces the body’s ability to synthesize the nutrient. Furthermore, the vitamin is essential for fixing calcium in the bones, and is recommended to prevent the risk of falls and fractures.

Individuals with obesity are also at greater risk of deficiency, as the concentrations of active vitamin D metabolites are inversely proportional to body mass index. I.e, individuals with high body weight They possibly accumulate this vitamin, which is fat-soluble, in adipose tissue.

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Other groups that should also take supplementation are: pregnant women, breastfeeding women, children, individuals with a high skin type (since melanin limits the penetration of sunlight and reduces the production of cholecalciferol) and people with a little varied diet.

In addition to these, patients with rickets or osteomalacia; osteoporosis sufferers; patients with malabsorption syndromes (cystic fibrosis, inflammatory bowel disease, Crohn’s disease, bariatric surgery, among others); patients with kidney or liver failure; with hyperparathyroidism; individuals taking medications that interfere with vitamin D metabolism; and patients with granulomatous diseases and lymphomas.

4. How do I know if I have low vitamin D levels?

To find out if we have a deficiency, it is necessary to carry out a laboratory test, requested by a doctor, which measures the level of active vitamin D in the body. Values ​​considered normal, taking into account the balance of calcium in the blood and bone health, range from 20 to 32 ng/mL.

However, according to Paula Molari, experts agree that, to correct some diseases caused by its deficiency, reduce the risk of falls with fractures and maximize calcium absorption, the best dose is 30 ng/mL.

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5. How does a vitamin D deficiency compromise the body?

Vitamin D is unique among vitamins in that it functions like a hormone. In addition to its effects on phosphorus and calcium metabolism, recent evidence links its deficiency with the risk of developing other non-bone pathologies.

Some of these illnesses include: depressive disorder, cognitive decline, migrainemultiple sclerosis, type 2 diabetes, liver disease and cirrhosis, Hashimoto’s thyroiditis, sarcopenia, osteoporosis and osteopenia, rheumatoid arthritis, recurrent urinary tract infections (UTUS), asthma and allergic rhinitis, pre-eclampsia, vaginal atrophy induced by some chemotherapy drugs in breast cancer, atopic dermatitis and psoriasis.

6. Does it reduce the risk of cardiovascular events, such as heart attack and stroke?

Vitamin D plays an important role in the cardiovascular system through several mechanisms, such as inhibiting the migration and proliferation of cells into vascular smooth muscle, preventing vascular calcification. It also inhibits internal inflammation in the vessel walls, which can lead to vascular injuries.

“In addition, it regulates cardiac movement. Thus, it prevents the formation of thrombi and lowers blood pressure. All of these factors contribute to avoiding heart attacks and strokes”, points out Paula Molari.

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7. Can an overdose of vitamin D cause health risks? Which?

Vitamin D toxicity, often considered rare, can be fatal if not identified promptly. Excessive intake of the vitamin can cause nausea, vomiting, sensory changes, constipation, hypercalcemia, pancreatitis, acute kidney injury, among others. other conditions.

8. Is it possible to guarantee vitamin D levels through diet?

The best source is the synthesis of vitamin D by the skin when exposed to the sun. However, it is possible to guarantee this through diet. “However, few foods in our eating routine contain this vitamin in their composition. Therefore, they go unnoticed.”

Vitamin D is present in fish and vegetables rich in fat such as salmon, tuna, sardines, cod liver oil and avocado, also in egg yolks and oilseeds. Another great source is mushrooms.

9. Could vitamin D deficiency in childhood be related to mental disorders in adulthood?

A study of the The Journal of Nutrition assessed that low synthesis or lack of vitamin D in children may be related to behavioral problems in adolescence and, later, depression and schizophrenia in adults.

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“The discovery of vitamin D metabolites in the cerebrospinal fluid of healthy adults suggests that it may play a role in brain development and a functional action on the nervous system”, adds the expert.

“It is worth noting that vitamin D supplementation beyond the daily needs is not recommended for disease prevention or even to increase quality of life. Therefore, consult a doctor to assess whether you really need the supplement and what dosage will meet your needs”, concludes Paula Molari Abdo.

By Flávia Ghiurghi

The article is in Portuguese

Tags: questions answers vitamin

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