SAO PAULO — Vitamin D was named as such when it was first discovered in 1910, but it wasn't until two decades later that its real structure was identified. In fact, it is a steroid hormone. Even today, the use of the term "vitamin" is a source of debate among health professionals.

Vitamin D deficiency is no longer considered a nutrition problem but rather an endocrine system disorder. In practical terms, the production of sufficient quantities of this hormone depends on sun exposure, not on diet.

Still, the deficiency has become pandemic all over the globe due to a drastic change in lifestyles, with the progressive urbanization of populations even in tropical areas, where living in confined and air-conditioned spaces and using sunscreen have become commonplace.

Today, nine in 10 people on the planet have unsatisfactory levels of vitamin D.

Traditionally, vitamin D is known to be essential for the metabolism of calcium and for good bone and teeth health. But scientific advances have unveiled more health benefits, some of which are very surprising. For example, vitamin D is a powerful anti-cancer agent and strengthens the immune system.

Following these discoveries, there have been debates about the ideal dosage for prevention or treatments. The diversity of its positive functions on our bodies drew the ironic and misguided reaction that a "vitamin" can be a panacea, capable of curing or preventing every ill. That said, prolific studies demonstrate that its benefits are myriad and very real.

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Sunbathing on a beach in Croatia — Photo: Alex Proimos

Thousands of scientific articles cite vitamin D deficiency as either a cause or a risk factor for about 100 disorders, including 17 types of cancer, hypertension, diabetes and autoimmune diseases, as well as cardiovascular and infectious diseases. Now with the Internet, never has misinformation had such short legs.

Our attachment to the basic principles of medical practice (first, do no harm, and second, always act in the patient's best interest) led us to use an innovative therapy, consisting of high doses of vitamin D under close supervision. As a result, a large majority of our patients carrying such diseases as multiple sclerosis can return to normal or almost normal lives, depending on the consequences of the disease prior to the treatment.

There is nothing as rewarding for somebody who has been defending these hypotheses. No pseudo-scientific arguments can argue with the facts.

*Walter Feldman is a doctor and former Brazilian Parliament member. Cicero Galli Coimbra is a neurologist and professor at the University of São Paulo.