Vitamin D and Its Importance for Cardiovascular Health

Vitamin D is related to bone metabolism. However, it also has benefits on cardiovascular health - read on!
Vitamin D and Its Importance for Cardiovascular Health
Maryel Alvarado Nieto

Written and verified by the doctor Maryel Alvarado Nieto.

Last update: 25 August, 2022

Did you know that vitamin D and cardiovascular health are related? First of all, it’s worth remembering that this nutrient is part of the fat-soluble vitamins, which also include A, E, and K. The human body is capable of synthesizing it from exposure to sunlight.

However, this production is limited, so it must be supplemented with regular consumption of foods containing it, especially fish. Even though its best-known benefits are related to calcium metabolism and bone health, scientific evidence suggests that it also has an impact on other body functions.

How is vitamin D produced?

Upon exposure to sunlight, the skin is able to convert a precursor molecule into cholecalciferol or vitamin D3, one of the inactive forms of the vitamin. However, the process depends on several factors such as season, time of day, and geographical latitude, and differs between populations.

The degree of skin pigmentation also interferes with the amount of ultraviolet rays that can stimulate vitamin D production. Age and cultural connotations also modify the time of exposure to sunlight and the skin exposed to the ultraviolet rays.

Food with vitamin D.
Although part of vitamin D is obtained through sun exposure, there are several foods that contain it too.

What are the options for supplementation?

Although skin production may ensure up to 95% of vitamin D deposition in the body, most of the world’s population is deficient in this element. This is why you need to ensure that you eat enough food items that contain it. Among the options are the following:

  • Natural foods such as fish, eggs, butter and liver.
  • Functional products, i.e. those that the food industry adds essential nutrients to.
  • Pharmacological supplements containing some of the forms of vitamin D.

Vitamin D metabolism: activation of the molecule

The precursor of vitamin D is cholecalciferol (vitamin D3), which is synthesized by the skin from sunlight. But there’s another inactive form: ergocalciferol or vitamin D2, which is synthesized by plants and can be consumed as an external source.

From any of these precursor molecules, activation must occur. For this to occur, the precursor binds to a protein that transports it to the liver, where a first transformation occurs when calcidiol is produced.

However, the molecule is still inactive and, because of this, requires a second hydroxylation. This process occurs in the kidney. This is where calcitriol is produced, which is the active form of vitamin D.

Calcitriol and the functioning of the body

As a fat-soluble molecule, vitamin D easily crosses the plasma membrane until it reaches the cell nucleus, where its receptor is located. There it binds to this element to regulate the transcription of several genes. For this reason, its multiple functions have been demonstrated.

Classical actions: calcium metabolism

Due to the presence of calcitriol, it is possible to increase the absorption of calcium and phosphorus from the diet in the intestinal lumen. In addition, its effect on bone allows the extraction of the mineral into the bloodstream, which raises the levels of calcium available to the body’s cells.

It also has an additional action on the kidney, as it stimulates the reabsorption of calcium and phosphorus to prevent large amounts of the minerals from being excreted in the urine. For these reasons, vitamin D is often associated with bone function, constituting the classic effects of the molecule.

Calcitriol: a versatile substance

The actions on calcium and phosphorus metabolism aren’t only those linked to vitamin D. In fact, the molecule’s receptor is located in most cells of the body, suggesting that its involvement in physiological processes is much broader than originally thought.

Thus, several investigations have been carried out to elucidate the other effects of vitamin D, which have been termed “non-classical”. Among these, calcitriol has been linked to the regulation of the immune system, its deficiency being associated with infectious and autoimmune diseases.

Similarly, it has been shown to have an effect on hormonal function. Its insufficient levels are related to an altered function of the pancreas, which favors the development of diabetes mellitus. As a regulator of cell growth, it may even be involved in cancer.

Cardiovascular health and calcitriol

On the other hand, the presence of nuclear receptors for vitamin D has been demonstrated in smooth muscle. Blood vessels have a muscular layer that allows them to contract and dilate to adapt to the needs of the body. This allows blood flow to be modified depending on requirements.

Due to the presence of these receptors, several investigations have been carried out to clarify the effects of calcitriol on blood vessels. It seems to be related to a decrease in contraction and improvement of endothelial function.

Vitamin D deficiency: does it cause arterial hypertension?

Calcitriol acts on an important system for regulating blood pressure: the renin-angiotensin-aldosterone system. The active molecule is able to inhibit renin, to ensure that the renin doesn’t stimulate the conversion of tensinogen to angiotensin. This prevents the increase in blood pressure.

Several studies have linked low levels of vitamin D to rising blood pressure. This evidence is even more noticeable in the winter months, when cutaneous cholecalciferol synthesis is decreased.

Vitamin D is now considered to have a beneficial effect on blood pressure regulation.

Cardioprotection with calcitriol

On the other hand, vitamin D deficiency has been linked to several conditions classified as risk factors for cardiovascular disease. In particular, metabolic syndrome, obesity, diabetes mellitus, dyslipidemia, and arterial hypertension.

These pathologies seem to have a relationship with low calcitriol levels, suggesting that hypovitaminosis D is involved in developing these conditions.

A man with a doctor.
Vitamin D is involved in cardiovascular health. In particular, it’s key to regulating blood pressure.

How do you know if there’s a vitamin D deficiency?

As there are two precursor molecules, the determination of cholecalciferol and ergocalciferol aren’t the most appropriate tests to measure vitamin D levels in the blood.

At present, it’s recommended that we use calcidiol values, as this is the most abundant form in the body and could better reflect the blood concentration.

However, there’s no consensus on what levels can be considered optimal for this nutrient. Most studies suggest that concentrations below 20 ng/ml should be classified as deficient, thus constituting hypovitaminosis D.

In fact, calcidiol determinations ranging between 20 – 30 ng/ml could be associated with an insufficient calcidiol reserve. Other parameters should be evaluated to objectively analyze the actual vitamin D status. These include parathormone levels and serum calcium.

How to take vitamin D supplements?

It’s clear that vitamin D plays an important role in cardiovascular health care. This is why it’s important to ensure an optimal intake of the nutrient. Given that sun exposure appears to be insufficient in many countries, dietary supplementation is the best option.

The consumption of fortified foods is usually the first choice. Of these, dairy products stand out. If required by the physician or nutritionist, vitamin D can also be obtained with cholecalciferol or ergocalciferol supplements.

Is there an ideal dose?

The recommended daily dose depends on the age and health status of the individual. However, it’s considered that 800 IU daily for an adult is enough to ensure an adequate vitamin D concentration. Despite this, each case should be considered on an individual basis.

Hypervitaminosis D is a rare disorder caused by vitamin D supplementation intoxication. In this condition, hypercalcemia occurs and its symptoms include symptoms such as the following:

  • Weakness
  • Loss of appetite and weight loss
  • Nausea
  • Muscle pain and stiffness
  • Kidney stones
  • High blood pressure

That said, it should be kept in mind that vitamin D benefits cardiovascular health and other essential body systems. Therefore, if you suspect a deficiency of this nutrient, it’s best to consult a professional. He or she will determine the best dose so that you don’t go from one extreme to the other.

All cited sources were thoroughly reviewed by our team to ensure their quality, reliability, currency, and validity. The bibliography of this article was considered reliable and of academic or scientific accuracy.

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This text is provided for informational purposes only and does not replace consultation with a professional. If in doubt, consult your specialist.