Vitamin D. How to avoid deficit, when supplements can harm and how much sun do you really need

In recent years, Vitamin D has reached the center of attention: most of us do not have enough, and the consequences are not limited to fragile bones. Her deficit is related to several health problems, which makes this «Vitamin of the Sun» a hot topic.

Vitamin D: Sun, Food, supplements with collage Adevărul archive

Since identifying its chemical structure in 1930, researchers have gradually discovered the secrets of vitamin D. In the beginning, the attention was focused on its role in bone health and in regulating calcium – essential aspects, but only the beginning of the story.

In the 1960s, with the identification of the active forms of vitamin D, the researchers realized that its effects go far beyond the bones. It has been found to play an important role in the functioning of the immune system and in the prevention of diseases such as infections, cancer or cardiovascular disease, but also in disorders such as obesity and type 2 diabetes.

Today we know for sure that vitamin D is not only the ally of bones, but also of our immunity. Its deficiency can weaken the defense of the body, and recent studies have shown that low levels are related to more severe evolutions of Covid-19.

In this article you will find out who risks having vitamin D deficiency, how much sun is needed for optimal health, when supplements are useful and when they can become dangerous, as well as to avoid hypervitaminosis.

Vitamin D deficit: Who risks and how to prevent it

The 2020 data show that almost 40% of Europeans do not receive enough vitamin D – an alarm for public health. The situation is a little better in the US and Canada, but everywhere there are more vulnerable groups: pregnant women, children, the elderly, people with excess weight, those with darker skin and those who sit too little in the sun.

The good part is that the skin can produce vitamin D from cholesterol, with the help of sunlight. Problem? There is no “recipe” Universal for how long we have to stay in the sun. It depends on the season, hour, latitude, age and skin type. experts Spanish society to research bone and mineral metabolism Recommend, quote by the publication The Conversationfor people with open skin, 15 minutes of daily exposure of the face and arms between March and October. For elderly or osteoporosis patients, time may increase at 30 minutes. In both cases, SPF cream between 15 and 30 It remains important, adjusted after the intensity of the sun.

Food intake also remains essential. Good sources of vitamin D They are fatty fish, such as salmon and trout, full dairy products, margarine and fortified vegetable drinks.

In addition, some modern habits can worsen the deficit: frequent use of sunscreen and reducing healthy fat consumption may limit “The sun in the plate and on the skin” we need.

Vitamin D: When and who should take supplements

Today, the level of vitamin D is measured by the serum concentration of 25 (OH) D. Basically, over 20 ng/ml is considered optimal for most people, and over 30 Ng/ml for over 65 years, for people with bone problems or following chronic treatments such as corticosteroids or anticonvulsants. The values ​​between 12 and 20 Ng/ml indicate insufficiency, and below 12 Ng/ml we are already talking about deficit. At the opposite pole, excess vitamin D, called hypervitaminosis D, occurs at values ​​over 100 ng/ml and can be harmful.

The question that concerns many is: “Do I have to take supplements if I have normal levels?”. A meta-analysis of 2022 showed that daily doses of 1,000-2,000 IU did not significantly improve immunity to healthy people and did not prevent respiratory disease, flu or Covid-19.

However, other researchers have observed positive effects of supplementation in people with respiratory disorders, especially those with vitamin D deficiency. But, results on benefits in metabolic and neurodegenerative diseases are not yet confirmed. Basically supplements are not “A must” For everyone, but rather a tool for correcting deficiencies or support in specific cases.

Vitamin D in excess: risks and signs of hypervitaminosis

Vitamin D from diet rarely cause problems, but supplements “At random” They can be dangerous if the level in the body is already sufficient. The daily doses exceeding 4,000 IU in the long term can raise over 50 ng/ml serum concentrations, triggering hypervitaminosis D – that is, a dangerous excess in the body.

The most common sign is hypercalcemiawhich can cause nausea, vomiting, constipation, fatigue and weakness. In severe forms, excessive thirst, abundant urination, bone pain, fractures, kidney stones, calcifications in inappropriate places, depression and confusion, can occur.

The problem is not theoretical: cases of toxicity have exploded in recent years. A 2016 report of the national US toxicological data system shows that the annual average of cases of hypervitaminosis has jumped from 196 (2000–2005) to over 4,500 in the next five years, reflecting the increase of uncontrolled supplements.

Vitamin D supplements: When they are useful and when they can be dangerous

The interest in Vitamin D has exploded, especially because a lack of it is associated with various conditions, even if at the level of the general population the situation is not always clear. But when it comes to supplements for those who have no deficit, things are not simple: studies do not yet offer clear conclusions.

There is evidence that supplements can reduce the severity of respiratory diseases in people with deficiency, but too much vitamin D can cause hypervitaminosis, hypercalcemia and other serious health problems.

The message is simple: caution is the key. Take and recommend supplements only on the basis of scientific evidence. myth “Supervitamine D” It does not keep up with the reality – and the research continues to reveal what we know and still ignore about this essential vitamin.