danger of hypervitaminosis from abuse of supplements

In recent decades, interest in Vitamin D has increased exponentially as its deficiency is associated with many diseases and there appears to be a high level of flaw of this micronutrient in the general population.

Since the chemical structure of vitamin D was determined in 1930, important advances have been made in research into its functions in the body. Research initially focused on the role of this compound and its metabolites in calcium homeostasis and bone metabolism.

Later, with the discovery of 25-hydroxyvitamin D (25(OH)D) in 1968 and 1,25-hydroxyvitamin D (1,25(OH)2D), later, research expanded and focused on its role. plays a role in the occurrence of immunological diseases, infections, cancer and chronic non-infectious diseases (cardiovascular diseases, obesity, type 2 diabetes, etc.).

(A common vitamin in the Mediterranean diet that is best for reducing pain.)

There is now no doubt that vitamin D plays a role in regulatory mechanisms of the immune system. In fact, its deficiency is associated with a worse prognosis in Covid-19 infection.

Growing deficit

Current epidemiological data show 40% of the European population is deficient in this vitamin, 24% of Americans and 37% of Canadians. These are really high numbers and may cause some concern. Population groups most at risk for developing hypovitaminosis These include pregnant women, children, the elderly, obese people, people with darker skin tones and people with little exposure to sunlight.

A person can meet part of his vitamin D needs through cutaneous synthesis from cholesterol, if they are exposed to sufficient solar radiation. It is difficult to indicate the minimum recommended time, since it depends on factors such as season, time of day, latitude, age or skin phototype.

A panel of experts from the Spanish Society for Research on Bone and Mineral Metabolism recommends that Caucasians receive 15 minutes of daily sun exposure on the face and hands between March and October. In older people and patients with osteoporosis, I advise you to extend it to 30 minutes. In both cases, it is necessary to use a protection factor of 15 to 30, depending on the latitude and intensity of UV (ultraviolet) radiation.

However, input through diet is also necessary. Good dietary sources of this nutrient include fatty fish (especially salmon and trout), full-fat dairy products, margarine, and fortified plant-based drinks.

What is the cause of the growing vitamin D deficiency? Factors such as increased use of sunscreen or a trend towards decreased consumption foods rich in fats may contribute to this situation.

When should you take supplements?

Currently, serum 25(OH)D concentrations are measured to assess vitamin D levels, although results may vary depending on the analytical method.

In general, values ​​above 20 nanograms per milliliter (ng/mL) are considered optimal for the general population, and values ​​above 30 ng/mL for people over 65 years of age, patients with bone disease, or chronic pharmacological treatment (corticosteroids, anticonvulsants…).

Values ​​between 12 and 20 ng/ml are considered insufficient, and values ​​below 12 ng/ml are considered insufficient. There is also clear concern about the risks associated with hypervitaminosis Dwhich is associated with 25(OH)D levels above 100 ng/ml.

Is it necessary or convenient to administer vitamin D supplements to people with adequate serum 25(OH)D levels to improve your immune responsethe question is controversial.

In this sense, a recent meta-analysis evaluated supplementation at 1000–2000 international units (IU) per day in healthy individuals and concluded that it did not significantly improve immune system function. It has also not proven useful as a means of preventing acute respiratory infections, influenza, Covid-19 infection, etc.

However, other authors have observed beneficial effects of this intervention in individuals with respiratory diseases, especially in those with vitamin deficiency. There are also conflicting results regarding its benefit in patients with Metabolic diseases and with neurodegenerative diseases.

The danger of hypervitaminosis

Consumption of vitamin D present in food is unlikely to cause problems, but indiscriminate supplementation, even if deficiency does not justify it, can cause chronic toxicity. For example, taking vitamin D supplements in doses above 4000 IU/day for a long time can increase serum 25(OH)D concentrations to values ​​above 50 ng/mL with a consequent risk of hypervitaminosis. . .

The most characteristic manifestation of hypervitaminosis D is hypercalcemiacharacterized by the appearance gastrointestinal symptoms (anorexia, nausea, vomiting, constipation…), weakness and fatigue. In the most severe cases this can lead to polyuria (excessive urine output) polydipsia (abnormal increase in thirst), kidney failure, ectopic calcifications (inappropriate), depression, confusion, bone pain, fractures and kidney stones.

In recent years, due to increased consumption of food additives, Toxicity cases have increased markedly. For example, a report from the US National Toxicology Data System indicates that overexposure to vitamin D has led to an increase in cases of hypervitaminosis, increasing from an annual average of 196 in the period 2000-2005 to 4,535 over a five-year period. period.

We must tread carefully

In conclusion, interest in vitamin D has increased significantly due to its association with a variety of diseases and possible, but perhaps not yet well-established, deficiency in the population. However, the effects of supplementation in people who do not have a deficiency They are not final at all..

There is evidence of its effectiveness in reducing the severity of respiratory diseases in people with a deficiency of the microelement in question. Hypervitaminosis D resulting from indiscriminate supplementation is a real risk.

and can be dangerous, causing hypercalcemia and other health problems.

Therefore, it is important to approach this issue with caution, always acting on the basis of scientific evidence, and using caution when taking or recommending vitamin D supplements.

Thanks to modern scientific evidence, the myth of supervitamin D is crumbling and the reality that more research is needed has prevailed.

* M. Carmen Vidal Caru is Professor in the Department of Nutrition and Bromatology, Torribera Food Campus, University of Barcelona.

* Maria Teresa Veciana Noguez is a professor of nutrition and bromatology. Torribera Food Campus, University of Barcelona.

* Natalia Toro Funes is a professor of nutrition and bromatology at the University of Barcelona.

*Sonia Sánchez Pérez is a postdoctoral fellow of Juan de la Cierva. Doctor of Food and Nutrition. Torribera Food Campus, University of Barcelona.

**This article was originally published on The Conversation.