19 Jun 2025

Is it necessary to stop taking vitamin D in the summer? Myths and truths about this nutrient

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In a country that leads in the number of annual sunshine hours, the curious thing is that Spain has a significant vitamin D deficiency. According to a study published in the journal Nature, 75% of the Mediterranean population suffers from a deficiency of this vitamin.

Furthermore, there is an increasingly widespread myth: during the months with the highest solar incidence, our levels of this vitamin increase. The truth is that this belief is not always the case. And we are going to explain why.

Even though we are more exposed to the sun in the summer, there are a series of factors that can affect the desirable levels of this nutrient, such as:

Being over 50 years of age.
Using sunscreen. (Be careful, this does not mean you shouldn't use it; on the contrary, it is essential, but its use reduces production by blocking UVB rays).
People with dark skin phototypes, because they require longer exposure times to reach the same levels as people with light phototypes.
People who are indoors during the central hours of the day.
People with excess body fat, because it captures and inactivates it.
People undergoing corticosteroid treatment, because it increases the destruction of this nutrient.

In fact, it is also common to hear that vitamin D produced by the sun is more “natural” and “better” than that from supplements. This is also incorrect.

The vitamin D that is ingested is physiologically the same as that produced by solar impact on the skin. Moreover, unlike the one generated on the skin, that from supplements provides the adequate and continuous amount over time. Skin-produced vitamin D has a limit; that is, after a certain amount of radiation, what the body receives is not converted into vitamin D, but into other undesirable reactions in the body and with high carcinogenic potential.

Therefore, although stopping its intake is not a far-fetched option, it is true that it leads to optimal vitamin D levels not being maintained during the summer months.

A deficiency that can make our body more susceptible to:

Suffering from bone pain
Muscle weakness
Being more prone to infections
Suffering from mood and sleep disturbances

Everything will depend on the dose consumed: for very high doses, above 2000 IU per day, it would be advisable to reduce or pause it during the summer period.

In this video, Dr. Isabel Viña explains it in detail:

As long as the doses are adequate, and taking into account each person's conditions, intake can be maintained every day of the year without any problems. In fact, it is even beneficial. And at IVB Wellness Lab, we have ensured that the quantity is the indicated and safest one.

Our supplement from the Essentials line, Vitamin D3+K2, is formulated to be taken chronically without increasing levels above normal. A product designed to:

Support bone and muscle health
Contribute to the normal absorption of calcium and phosphorus
Optimize the immune system
Maintain teeth in adequate condition
Improve cardiovascular health by contributing to normal blood clotting.

Bone and muscle health

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As a tip, if you want to further increase the absorption of this vitamin, we recommend combining it with our Total Magnesium for the best results.

Nutritional supplement to improve the synthesis of glutathione (our greatest antioxidant) in our body.

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With the summer myth debunked, we leave you with some of the most frequent myths below:

“The higher the vitamin D, the better”

Incorrect. Remember that “more is not better,” and the same applies to vitamin D. It has been demonstrated that:

Between 30-45 ng/mL: the values with the greatest health benefits
Between 40-60 ng/mL: during pregnancy and lactation.
Values above 70 ng/mL: are associated with a higher risk of cardiovascular death.

“If I take vitamin D supplements, I have to take calcium”

Incorrect. While it is true that one of the multiple functions of vitamin D is to increase calcium absorption to optimize bone mass synthesis, the calcium needed to cover ideal levels can be found in food.

Calcium supplements contain a very high amount of this mineral, exceeding the body's modulating capacity to fix it to the bone and causing it to be deposited in the arteries. A risk that can increase the development of hard atherosclerotic plaques and lead to cardiovascular death.

It is best to obtain calcium through foods such as almonds, tofu, calcium-enriched plant-based drinks, sesame seeds, dairy products, broccoli, kale, fortified soy drinks, and Chinese cabbage.

These foods not only provide calcium but also contain other beneficial micronutrients for bone health, such as magnesium and phosphorus, which work together with vitamin D to optimize bone quality.

Since vitamin D is fat-soluble, it is essential to accompany it with foods rich in healthy fats, such as avocado, olive oil, or nuts, to maximize its absorption.

Bone and muscle health

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Can vitamin D prevent the onset of diabetes?

Correct. The latest consensus guideline on vitamin D highlights its key role in preventing diabetes. So much so that in prediabetic adults, in addition to prescribing lifestyle improvements, they are often recommended to supplement with vitamin D preventively.

This is because it improves insulin metabolism, reduces chronic inflammation, and appears to better preserve the survival of the involved pancreatic cells. A solution that could reduce the risk of progression to type 2 diabetes.

Should pregnant women take vitamin D preventively?

Correct. The recommendations from major gynecological and endocrinology societies agree that vitamin D supplementation during pregnancy can reduce:

The risk of preeclampsia
Gestational diabetes mellitus
Intrauterine mortality
Premature birth
Small for gestational age birth
Neonatal mortality

To cover the daily intake of vitamin D3, our vitamin and mineral supplement VitalNatal Woman meets all these needs during the gestational period.

In the following video, you can see our doctor and Medical-Scientific Director of IVB Wellness Lab, Isabel Viña answers the question about why our Vitamin D sometimes comes out low: