Your Vitamin D Supplement May Be Why You're Gassy and Bloated

Vitamin D is one of those essential nutrients that gets a lot of buzz. While it's a fat-soluble vitamin the body produces when exposed to the sun — which explains why it's commonly referred to as the "sunshine vitamin" — it's estimated that 50 percent of the global population has a vitamin D deficiency, according to a 2012 article published in the ​Journal of Pharmacology & Pharmacotherapeutics​.

Many people get their daily dose via supplements, and taking the proper dose — which is 600 IUs, per the National Institutes of Health (NIH) — is deemed "generally safe" by the Mayo Clinic. However, there's some thought vitamin D supplements may lead to a distended belly.

However, exceeding the recommended daily allowance of vitamin D for an extended period of time can bring about some unpleasant side effects. "Since vitamin D is fat-soluble, your body stores the excess — and this can lead to toxicity if you take too much of it," Angie Kuhn, RDN, director of research and nutrition at Persona Nutrition, tells LIVESTRONG.com.

She adds that typical symptoms of vitamin D overload include bloating and gas associated with constipation, diarrhea, upset stomach and other intestinal issues. FYI: Toxic amounts of vitamin D may also cause weakness, frequent urination and unexplained weight loss, along with damage to the heart, kidneys and blood vessels.

The best way to determine your current level of vitamin D is through a basic blood test panel, where the vitamin is measured in the form of 25-hydroxyvitamin D, aka 25(OH)D, according to the NIH. Levels 50 nmol/L (nanomoles per liter) and higher are considered sufficient for most adults. Anything over 125 nmol/L is likely to be toxic while levels under 30 nmol/L can indicate a deficiency.

This vitamin is necessary for multiple health benefits, such as building and maintaining strong bones and encouraging the absorption of calcium, a mineral that also contributes to bone health and helps with muscle function and nerve transmission.

"Vitamin D is also known to assist with digestive health, and it has anti-inflammatory and immune-modulating effects, so those deficient in this vitamin are more susceptible to infection," Kuhn says.

In fact, there's a high prevalence of vitamin D deficiency among patients with irritable bowel syndrome (IBS), according to a January 2018 study in the ​European Journal of Clinical Nutrition​. While additional research is required, these initial findings suggest vitamin D supplements may help relieve some of the common symptoms associated with IBS, such as constipation, diarrhea, bloating and abdominal pain.

"The body also uses vitamin D to make cholesterol, which is necessary to produce hormones, build tissue and create bile in the liver," Kuhn says. "And these effects have led to possible implications in the pathophysiology of immune-mediated diseases, including inflammatory bowel disease (IBD)."

The Bottom Line

Vitamin D may be best known for its vital role in bone health, yet it's also been shown to be an important nutrient in maintaining, as well as restoring, gastrointestinal wellbeing. So while getting enough of this vitamin can help keep chronic gas and bloating at bay, too much vitamin D can lead to digestive difficulties and result in gas and bloating.

Keep in mind that it's unlikely for Americans to have toxic levels of vitamin D, according to the NIH. In a ten-year study of more than 20,000 patients, only 37 people (0.2 percent) showed levels over 100 nmol/L, yet only one person was classified as clinically toxic with a 25(OH)D value of 364 nmol/L, according to the May 2015 study in ​Mayo Clinic Proceedings.​

Plus, the NIH adds that it's impossible to absorb toxic levels of vitamin D from the sun's rays. And since few foods contain vitamin D — it's found in fatty fish, such as salmon and tuna, as well as fortified cereals, milk and juices — taking regular megadoses of vitamin D supplements would be the most likely cause behind this rare diagnosis.