Vitamin D Toxicity and heart palpitations Title of article

Vitamin D Toxicity and Heart Palpitations: What You Need to Know

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While there are many health benefits associated with adequate intake of vitamin D, it’s also worth mentioning that there is such as thing as too much vitamin D. Vitamin D overdose, or hypervitaminosis D, is a real thing. But how much is too much? And what negative effects are associated with it? Does vitamin D really cause heart palpitations? If so, what else can too much vitamin D do? Keep reading to find out!

What Are Heart Palpitations?

First, let’s talk about heart palpitations. You aren’t normally aware of your heartbeat, however heart palpitations make your heart’s beating more noticeable. You may feel like your heart is beating harder, faster, or even missing beats.

This can last seconds, minutes, and sometimes even longer.

While heart palpitations are not always serious, they may lead to heart rhythm problems that need medical attention. You should always take note of when you notice a heart palpitation. Write down where you are, what you’re doing, etc. and talk with your doctor about it. You may be able to pinpoint a cause, such as:

  • increased stress or anxiety
  • food-related causes
  • medication-related causes
  • physical activity
  • smoking
  • or a possible medical condition

What is Vitamin D?

Next, let’s get familiar with vitamin D. Vitamin D, also known as calciferol, is an important fat-soluble nutrient that has many functions within your body. It is actually also considered a hormone according to the Endocrine Society because it is formed in your liver and kidneys.

The active form of the hormone vitamin D is called calcitriol.

Vitamin D helps your body absorb calcium and phosphorus. It keeps your bones strong and prevents chances of developing osteoporosis. It also prevents muscle cramps and spasms. Additionally, a good amount of evidence exists in supporting vitamin D in the prevention of brain and mood disorders including dementia, depression, and schizophrenia.

Know Your Numbers

When getting bloodwork done, it’s always important to know what your results mean. Compare your vitamin D level to the levels below. Where do you fall on this chart?

Serum 25-Hydrocyvitamin D Concentrations and Health

nmol/Lng/mLHealth Status
<30<12Associated with vitamin D deficiency, which can lead to rickets in infants and children and osteomalacia (soft bones) in adults
30 to <5012 to <20Generally considered inadequate for bone and overall health in healthy individuals
> or = to 50> or = to 20Generally considered adequate for bone and overall health in healthy individuals
>125>50Linked to potential adverse effects, particularly >150 nmol/L (>60 ng/mL)

Foods with Vitamin D

There aren’t a whole lot of food sources of vitamin D. And the ones available may not be ones that you eat on a daily basis.

Additionally, if you don’t care much for milk or fish or have allergies to these foods, fortified foods may be your best option for getting enough Vitamin D. Here are a few examples of foods high in vitamin D.

Picture showing multiple food items high in vitamin D and amount of micrograms each food contains.  Fortified cereal, cod liver oil, fortified milk, white mushrooms, sockeye salmon, eggs.

Since vitamin D is a fat-soluble vitamin, it is best absorbed when you eat these foods with a meal or snack containing some fat (think healthy fats such as nuts, nut butters, olive oil, avocado, dressing, etc.).

Other Sources of Vitamin D

The Sun

Bright sun shining on a dashboard where black sunglasses are sitting

You can also get vitamin D by exposing your skin to sunlight.

Keep in mind that you cannot get vitamin D through a window because windows block UV rays. Your skin must be directly exposed to the sun. It is also unlikely to get too much vitamin D from the sun because your skin limits how much vitamin D your body synthesizes.

It may be difficult for some people to get enough vitamin D throughout the year, depending on where they live. Those farthest away from the earth’s equator will get less than those living near the equator.

Likewise, in winter months, when it is very cold, people either don’t go outside often or are covered up with layers of clothing which prevent the sun’s exposure. Additionally, if it is overcast or if you are wearing lotion with SPF (Sun Protection Factor) to block the sun’s harmful ultraviolet rays, this may also block some of the skin’s ability to synthesize vitamin D.

Other factors contributing to how much vitamin D you get from the sun include age, skin color, body weight, and air quality.

Dietary Supplements

You can also get vitamin D from a supplemental liquid or pill form. The amount will vary depending on the supplement. There are also two different forms of vitamin D. These are vitamin D2 and vitamin D3.

Vitamin D2 (ergocalciferol)- a form of vitamin D that comes from plant sources such as yeast/mushrooms. This is the form used in fortified foods.

Vitamin D3 (cholecalciferol)- a form of vitamin D that comes from animal sources such as lanolin from sheep’s wool, egg yolk, liver, and fatty fish. This is the form that is already stored in your body.

Both vitamins D2 and D3 will raise your vitamin D levels. However, some evidence shows that the D3 form will raise it to a greater extent and maintain the level for longer.

If you also take a daily multivitamin, these can provide anywhere from ~12.5 mcg to 20 mcg (400 – 800 IU) of vitamin D per serving size. So if you are taking a vitamin D supplement in addition to a multivitamin, please keep this in mind.

And to be sure you are getting a supplement with the most accurate potency per the label, make sure it has the USP verification symbol. For some great info on USP verification, download the handout below.

Recommended Daily Allowance of Vitamin D

The amount of vitamin D you need depends on your age. According to the National Institute of Health, the recommend daily allowance of vitamin D for individuals aged 1-70 years old is 15 mcg per day (600 IU/day). However, if your vitamin D level is already very low, you may need to supplement with a much larger amount, called a loading dose, over a few weeks. And then follow with a smaller maintenance dose, which is still much larger than the RDA for vitamin D. This method of high-dose vitamin D therapy should always be done under the supervision of your doctor.

In the United States, about 25% of the population has a vitamin D level that is too low.

On the other hand, vitamin D toxicity is rare. However, almost all reports of vitamin D overload are from taking dietary supplements- not from the sun or eating vitamin D foods.

recommended daily allowance of vitamin D
Recommended daily allowance of vitamin D, according to The National Institute of Health’s Office of Dietary Supplements

Toxic Level of Vitamin D (Hypervitaminosis D)

Although hypervitaminosis D is rare, the incidence seems to have increased over the years. Research shows this is mainly due to errors in prescribing and administering supplements, although fortified foods can also be to blame.

With vitamin D supplementation, doctors and pharmacists may make errors in prescribing high dose vitamin D therapy. Or they may not monitor this therapy as closely as they should, leading to toxic blood levels of vitamin D over time.

Other cases are because patients themselves are purchasing over-the-counter (OTC) or online supplements and self-dosing. This can be potentially deadly since some supplements can contain much higher amounts of vitamin D than the label states.

You also have to be careful of fortified foods. Some US studies on vitamin D fortified foods also show wide variations in the amount stated versus the actual amount in the food.

The table below shows the tolerable upper intake level of vitamin D according to the National Institute of Health, however ranges between different organizations can vary slightly.

Tolerable Upper Intake of Vitamin D
Tolerable upper intake level of vitamin D, according to the National Institute of Health’s Office of Dietary Supplements

Symptoms of Too Much Vitamin D

Since vitamin D helps increase bone resorption, it makes sense that the more vitamin D there is, then the more calcium there is. Which is exactly what happens. The result is an excessive, and potentially toxic, amount of calcium in your blood. This is called hypercalcemia.

Most of the negative outcomes resulting from vitamin D toxicity are actually related to calcium. So finally, let me answer the question of whether vitamin D toxicity causes heart palpitations- along with some other negative side effects of course.

Irregular Heartbeat

Studies show that vitamin D deficiency puts you at risk for cardiovascular disease. However, excess levels of vitamin D also have negative effects on the cardiovascular system. Vitamin D overload CAN cause heart palpitations. But most research on vitamin D toxicity focuses on a more serious condition, called atrial fibrillation.

Atrial fibrillation is a condition in which the heart’s upper chambers beat out of sync with the lower chambers, causing blood to pool and clot. While this condition is different than a palpitation (which can be temporary or brought on by stressful situations), palpitations are known to be a symptom of AFIB.

One study shows that risk of atrial fibrillation (or AFib) is two and half times greater in those with excessive levels of vitamin D.

About 2.7 million people in the U.S. suffer from atrial fibrillation. And Afib has been linked to an increased risk of stroke, heart failure, heart attack, dementia, and even Alzheimer’s disease.

Renal Failure

Vitamin D toxicity may also lead to acute and/or chronic kidney injury. In cases of high-dose vitamin therapy, patients have been found to have calcium deposits in the tubules of the kidneys. In one study, it describes a 43-year-old women who was prescribed high-dose vitamin D therapy months before having issues. She developed acute kidney injury from her toxic levels of calcium and vitamin D and eventually needed temporary hemodialysis to correct it.

As you can see, because vitamin D is fat soluble and can be stored in adipose tissue, it is possible for it to build up to toxic levels even months after stopping vitamin D therapy.

These calcifications in the kidneys can also lead to kidney stone formation.

Calcification of Soft Tissue

This is basically the build up of calcium in your soft tissues, arteries, lungs, and heart. It occurs as a result of the increase in both calcium and phosphorus that occur from hypervitaminosis D.

Calcifications can sometimes be painless but it can also be linked with infections, injuries, and cancer.

GI Issues

Those suffering from toxic levels of vitamin D may also experience one or more gastrointestinal issues.

These include nausea, vomiting, constipation, diarrhea, abdominal pain, and possibly even pancreatitis.

Confusion

Confusion is another symptom resulting from the hypercalcemia that occurs in relation to vitamin D toxicity. This is because your central nervous system is being affected.

So having a high blood calcium level may make you feel lethargic, disoriented, or confused. You may even begin hallucinating.

Symptoms of Vitamin D Toxicity

Correcting Vitamin D Toxicity

Correcting a toxic level of vitamin D takes serious medical help. It involves being given fluids through your veins and being hooked up to and IV, taking medications that make you pee like crazy, and most importantly STOPPING YOUR VITAMIN D SUPPLEMENT ASAP.

You will likely also be asked to avoid eating high calcium foods like milk, yogurt, cheese, and calcium fortified foods.

Your labs will be monitored closely and over time your symptoms will hopefully resolve.

Conclusion

In conclusion, vitamin D toxicity causes more than just heart palpitations- much more in fact. What starts out as one issue, ends up causing a domino effect inside you, effecting multiple body processes.

If you’re wondering where your vitamin D level is, ask your doctor to have your bloodwork done. More individuals have low levels compared to high levels, for which high-dose vitamin D therapy is prescribed. This should only be done under strict supervision.

Don’t ever purchase a supplement online or OTC without your doctor knowing. And remember to check and see if it is USP-verified so you don’t end up overdosing yourself.

Many cases of vitamin D toxicity can be prevented with ongoing educational efforts focused on physicians and also with the development of clear and universal standards of care when it comes to treatment of low vitamin D levels. 

Share with me: Have you ever or are you currently taking vitamin D supplements? Did you learn anything new from this post? Comment below and let me know!

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