New scales to measure optimal vitamin D levels

Despite being essential for health, new guidelines from the Endocrine Society suggest that measuring and supplementing vitamin D in the general population may be unnecessary as its benefits are not supported by science.

Although vitamin D is present in some foods naturally, we must access it in another way to reach the optimal levels that our body needs. In fact, we can say that It is not a vitamin in the strict sense of the word., since we are capable of producing it ourselves after sufficient exposure to the sun.

The problem is that, due to seasonal changes and the limited time we usually spend outdoors, in many cases we can only obtain the required amounts through fortified foods or supplements. What's more, in areas with many hours of sunshine per year such as the Mediterranean basin, more than 75% of the population registers low levels of vitamin D.

And despite these data, only half of those affected are prescribed supplements, as we observed in our study published in 2022. Does this make sense? Well, according to the new clinical guidelines of the Endocrine Society, which brings together more than 18 experts from more than 000 countries, yes: now the recommendation is even to stop measuring and supplementing vitamin D in the general population.

The role of vitamin D is unclear

Surprising as it may seem, the only conclusive and definitive evidence on the role of vitamin D in humans concerns the regulation of minerals and their impact on our bone health. The rest of the benefits attributed to this compound come from epidemiological and purely observational studies that have related its deficiency to a wide variety of disorders and diseases, including metabolic diseases or cardiovascular, autoimmune and infectious pathologies.

«The only conclusive and definitive evidence on the role of vitamin D in humans concerns the regulation of minerals and their impact on our bone health»

What does exist is a clear, evident and very strong relationship between vitamin D levels and death from all causes. In fact, the type of graph that represents it is called an inverted “J”: higher than normal vitamin D levels don't seem to affect much, while rRecords below 75 nmol/L (or 30ng/ml) are greatly related to increased mortality.

However, despite the multiple clinical trials carried out, could not be demonstrated that recovering optimal levels through supplements has an impact on the health parameters mentioned above, such as cardiovascular diseases.

There could be an error in the understanding of how this vitamin works, which also has rather hormonal functions. In fact, some experts have postulated that null results in trials are due to flaws in research design.

Another possible explanation is that vitamin D functions solely as a biomarker that alerts us that something is not working well. Thus, by exclusively improving its levels, we would not be treating the real cause of the problem.

For example, suppose that what makes us sick and increases our risk of dying is a lack of sun exposure or simply spending little time outdoors, and that vitamin D is a mere indicator of that insufficiency. In that case, reversing the deficit with supplements would only improve the warning marker, but not the actual problem.

But this, once again, It has not been proven by science and we must delve deeper into the underlying mechanisms.

What the new guidelines establish

Responding to evidence on the null effect of vitamin D supplementation, the Endocrine Society has presented some clinical guidelines to ensure its correct registration and prescription.

As we mentioned above, the new guidelines recommend that is no longer measured in the general population. This scientific institution even proposes removing the threshold of what until now are considered minimum levels: 30 ng/ml or 75 nmol/l.

On the other hand, the Endocrine Society defines which are the only risk groups that should be supplemented with vitamin D, based on sufficient evidence on its proper use. They are the following:

• In the minors from 1 to 18 years old, to prevent rickets and reduce the risk of respiratory infections.
• In people of more than 74 years, in order to reduce the risk of mortality.
• En pregnant women, to reduce the risk of preeclampsia, stillbirth, premature birth, birth of too small babies and neonatal mortality.
• In people with high risk prediabetes, to reduce the possibility of developing type 2 diabetes.

Experts add that measurement and supplementation may be indicated in non-pregnant people over 50 years of age who have presented other symptoms, such as women in menopause with hypocalcemia (low concentration of calcium in the blood).

These new guides therefore support the thesis that the Vitamin D deficiency cannot be attributed to causing any health problems other than those already defined. According to the Endocrine Society, measurement in the non-indicated population would only add unnecessary concern, regardless of its impact on minerals and bone health. Not to mention the financial savings that would result from stopping testing and prescribing supplements.

Some nuances

However, recording vitamin D levels – which does not involve a huge expense – perhaps should not be dismissed out of hand, as it can serve as an indication of sun exposure or spending time outdoors.

Also, when it comes to supplementation, No significant safety problems have been detected and there are sufficient doses with which to simply and effectively treat and prevent deficiency of this substance in the general population.

In short, the use of complements It is not counterproductive and could be beneficial if in the coming years we unravel more about the role that vitamin D plays in the functioning of the human body.

"In most situations, empirical vitamin D supplementation is economical, feasible, and acceptable to both healthy individuals and health professionals, and has no negative effects on health equity."

Endocrine Society

Source: The Conversation