Why high dose vitamin D supplements could cause side effects
- Taking too much vitamin D causes side effects like nausea, vomiting, weakness, and abdominal pain.
- The average adult should take no more than 4,000 international units of vitamin D daily.
- Vitamin D toxicity can be treated by stopping your supplement and avoiding vitamin D foods.
With about one in four Americans having low levels of vitamin D, it's no surprise that many people may consider a supplement, especially since very few foods contain the essential nutrient.
Related Article Module: How to improve your absorption of the 4 important types of fat-soluble vitamins - A, E, D, and KHowever, vitamin D supplements can come with side effects, especially if you take a high dose. That's because vitamin D is fat-soluble, meaning it can accumulate in the body's fat stores, possibly reaching toxic levels.
Here's how to tell if you're taking too much vitamin D and what side effects it can cause.
How much vitamin D is too much?
Related Article Module: Vitamin D supplements: How much you should take each day, according to dietitiansTo avoid vitamin D toxicity, most adults should not take more than 4,000 IU/day of vitamin D supplements.
Therefore, if you're taking a vitamin D supplement you should have your blood levels checked every three to six months, according to Rajsree Nambudripad, MD, an integrative medicine specialist with Providence St. Jude Medical Center.
A healthy range for vitamin D blood concentration is between 60-80 ng/ml. So, you should stop taking any vitamin D supplements if blood levels exceed 100 ng/ml, which is when side effects may appear, says Nambudripad.
Side effects of vitamin D supplements
Vitamin D toxicity - which includes symptoms like confusion and abdominal pain - occurs when vitamin D reaches a concentration of at least 150 ng/ml in a person's blood.
Potential side effects of vitamin D toxicity include:
- Nausea
- Vomiting
- Abdominal pain
- Loss of appetite
- Weakness
- Excessive thirst and urination
- Kidney stones
- Confusion
- Pain
Warning: Extremely high levels of vitamin D can lead to kidney failure, an irregular heartbeat, and even death. Although, it's not clear at what blood levels these effects occur.
However, vitamin D toxicity is rare: "Generally you have to take a lot of vitamin D daily before you start to have toxic effects," says Erin R. McNeely, MD, an internist with Spectrum Health.
Excess vitamin D and calcium
Some of the side effects of vitamin D toxicity are due to and/or exacerbated by the fact too much vitamin D can cause hypercalcemia, or when blood levels of calcium are too high. That's because vitamin D facilitates the absorption of calcium.
If you experience any side effects of vitamin D toxicity, McNeely recommends stopping your supplement and avoiding calcium-rich foods like dairy, which can contribute to hypercalcemia. In most cases, that's all the treatment that is needed. Yet, some with hypercalcemia might also need IV hydration.
Once treatment is initiated, most people should start to feel better, but it may take awhile. For example, a 2011 case report of two people who took 1,000 times the recommended daily dose of vitamin D found that they had elevated calcium levels for a year, even after stopping supplementation and were experiencing symptoms. Though, after a year, their symptoms resolved and they had no long-term health consequences.
Insider's takeaway
Many people can benefit from vitamin D supplements, but it's a good idea to talk to your doctor or medical professional before taking high doses. They can help determine the right dose for you, and help you avoid side effects like nausea or confusion.
If you're taking more than 2,000 IU of vitamin D a day, be sure to get blood work every 3-6 months to make sure you're not building up too much vitamin D in your blood.