Yes, Vitamin D Toxicity Is a Thing. Here’s How To Avoid It.

April 6, 2023

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If you spend half of the year under clouds of snow or rain, taking vitamin D, also known as the sunshine vitamin, has probably crossed your mind.

The lack of UV rays puts a serious damper on our body’s ability to produce this fat-soluble vitamin, leading many people to reach for a supplement.

Fat-solubility is an important trait of vitamin D. Your body stores it in fat tissues, absorbs more when you eat it with fat, and it tends to build up in the body over time. This is different than water-soluble vitamins like C or B vitamins, which we lose quickly through urine and sweat if we get more than we need. Taking too much vitamin D for too long of a time can lead to vitamin D toxicity – meaning you can actually overdose on this vitamin.

Here are some tips to keep your vitamin D levels where they need to be without overdoing it.

Why take Vitamin D in the first place?

Vitamin D helps the body absorb calcium from the diet so that your bones stay hard and strong and muscles can contract the way they’re supposed to. It also plays a role in immune function, cell growth, managing inflammation, and glucose metabolism.

A 2022 review of global vitamin D status found that 24% to 49% of the population had vitamin D insufficiency, which is less than 50 nanomoles per liter (nmol/L), and 5% to 18% had vitamin D deficiency (less than 30 nmol/L). With potentially half the population experiencing less-than-ideal vitamin D levels, it’s no wonder people are counting on supplements to stay healthy.

Vitamin D is an essential fat-soluble vitamin that we can get in three different ways:

From exposing our skin to the sun: The UV rays trigger the body to produce this vitamin. Spending 5 to 30 minutes in direct sunlight twice a week should provide a sufficient amount.
From food: Vitamin D is found naturally in wild or UV-treated mushrooms, fatty fish, egg yolks, and is added to many dairy products and cereals.
From supplements: You can find vitamin D added to multivitamins or in individual supplements.

The recommended daily allowance (RDA) for adults ages 19 to 70 is 600 international units (IU), or 15 micrograms, of vitamin D daily. Supplements range from 200 IU to 10,000 IU, or more.

How to safely take vitamin D

Here are some common reasons people end up with less-than-ideal vitamin D levels and need a supplement for a boost.

You live somewhere far north of the equator or have a large portion of the year where clouds, snow, or rain make up the weather forcast
You spend most of your time indoors
You’re in your 40’s, 50’s, or older
You have darker skin
You’ve had gastric bypass surgery or have difficulty absorbing fat
You take steroids, statins, or another medication that interfered with vitamin D absorption

While these are common risk factors for having low vitamin D, they don’t automatically mean you need a supplement. The only way to know for sure if you need a supplement is to have your vitamin D levels tested, using a simple blood test prescribed by your doctor.

The Tolerable Upper Limit (TUL) for vitamin D is set at 4,000 IU or 100 micrograms per day. This means that doses at or under this amount shouldn’t lead to vitamin D toxicity and should be tolerated by most healthy adults.

What does vitamin D toxicity cause?

You won’t get vitamin D toxicity from too much sun exposure or eating too many foods high in vitamin D. But, taking too high doses of supplements for too long can cause dangerous levels to build up in the body.

Too much vitamin D can lead to excessively high levels of calcium. (Remember, vitamin D is needed for calcium absorption.) While this isn’t often life-threatening, it can cause a slew of very serious health conditions. Excess calcium can lead to nausea, stomach pains, vomiting, weakness, frequent urination, kidney stones, kidney failure, irregular heartbeat, loss of appetite, and confusion.

How to take Vitamin D without overdoing it

Taking the RDA of 15 micrograms of vitamin D daily, eating foods with vitamin D, and getting sun exposure is safe for most people.

If you have a medication condition, take medication, or suspect a vitamin D deficiency, consult with your doctor so they can test your levels. If you are deficient, a larger dose than 15 micrograms may be needed to bring your levels back to normal, and they can recommend and monitor a unique supplement regimen.