Can Vitamin D Deficiency Cause Constipation? Here’s What You Might Not Know

ByBob Burns

Updated April 02, 2025

How Is Vitamin D Tied to Gut Function?

Here’s the short version: vitamin D isn’t just hanging out in your bones—it’s also active in your gut.

Your intestines have vitamin D receptors (VDRs), which help regulate muscle contractions, immune defense in the gut lining, and the health of your microbiome (your good gut bacteria). When you’re low on D, all of this can go a little haywire.

Some research suggests that vitamin D helps activate the smooth muscles in the intestines to promote motility—aka, it helps things move. One study published in BMJ Open Gastroenterology found that over 80% of people with irritable bowel syndrome (IBS) had insufficient vitamin D levels, especially those with constipation-type IBS (IBS-C).

Translation? Low vitamin D may not cause constipation outright, but it could be a major part of the puzzle for people struggling with it.

So… Can Low Vitamin D Really Cause Constipation?

Yep, it can—at least in some people.

In a 2020 clinical review, researchers noted a “significant association” between vitamin D deficiency and functional gastrointestinal disorders, including chronic constipation. And a small pilot study out of Italy showed that people with chronic constipation saw measurable improvement in symptoms after 8 weeks of vitamin D supplementation.

We’re not saying it’s a miracle cure. But if your gut is already sluggish and you’re low on D, getting back to a healthy range might be the nudge your system needs.

Helpful sources:

• BMJ Open Gastroenterology: IBS and Vitamin D Study
• NIH: Vitamin D Fact Sheet

When to Suspect a Link

Wondering if this could be your issue? Here are some situations where vitamin D-related constipation might be on the table:

• You’ve had chronic constipation for months or years without success from typical treatments.
• You live in a northern climate or don’t get at least 15 minutes of sun 3x per week.
• You’re over 50 (your skin produces 75% less vitamin D than in your 20s).
• You’ve been diagnosed with IBS, especially the constipation-dominant type.
• You’ve previously tested low for vitamin D or never had your levels checked.

According to the CDC, about 42% of adults in the U.S. are vitamin D deficient, and rates are even higher in people with limited sun exposure or darker skin tones.

What You Can Do About It

If you think vitamin D might be playing a role in your digestive issues, don’t panic—there are steps you can take:

1. Get a blood test. Ask your doctor for the 25-hydroxy vitamin D test. Anything under 30 ng/mL is considered insufficient, and under 20 ng/mL is deficient.
2. Start supplementing (if needed). The Endocrine Society suggests 1,500–2,000 IU per day for adults who are deficient. But your doctor might go higher short-term if your numbers are very low.
3. Boost sun exposure. Aim for 10–30 minutes of mid-day sun on arms and face, a few times a week (safely!).
4. Focus on food. Fatty fish (like salmon), fortified dairy, and eggs are good sources—but keep in mind, food alone usually doesn’t provide enough D to correct a deficiency.
5. Support with magnesium. About 50% of Americans are magnesium-deficient, and low magnesium can impair your body’s ability to activate vitamin D. It also directly helps with constipation.

Last Bite

If you’ve been dealing with constipation and haven’t gotten answers from the usual diet-fiber-water routine, don’t overlook the possibility of vitamin D playing a role. It’s not the most obvious culprit—but sometimes the quiet ones are the trickiest.

You don’t have to stay uncomfortable or guessing. A simple blood test and a targeted plan can help your system feel a whole lot more regular.