Too much or too little vitamin D may not be linked to heartburn, but very high or very low doses may cause other issues. When it comes to vitamin D side effects, unless you've talked with your doctor, go with the Goldilocks approach and aim to get the dose just right.
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Read more: 6 Vitamins Useful for Acid Reflux
What Causes Heartburn?
The unpleasant burning sensation so aptly named heartburn is caused by acidic stomach juices flowing back up into the esophagus, according to the American College of Gastroenterology (ACG). When it happens often, it may be due to a condition called gastroesophageal reflux disease or GERD. Infrequent heartburn is different, and may not be full-blown GERD.
Many factors can contribute to heartburn or mimic the pain, including some supplements like potassium and iron, according to the Mayo Clinic, but you won't find vitamin D on that list.
Get the Right Amount of Vitamin D
The recommended daily amount of vitamin D is 600 to 800 IU, with older adults needing the higher end of that range, according to the Office of Dietary Supplements (ODS).
But even getting as much as 1,000 IU of vitamin D a day from a supplement (which some people do if they're worried about not getting enough through diet or sunshine) is very unlikely to cause any acid reflux issues, especially when taken with a meal, says Bonnie Taub-Dix, RDN, CDN, a registered dietitian nutritionist and the director and owner of BTD Nutrition Consultants in New York City. When side effects are reported, "they usually come from very high megadoses of vitamin D," she says.
- Fortified milk
Too Much Vitamin D and Heartburn
There's no evidence that getting too much vitamin D causes heartburn, but it might cause other issues.
Healthy adults who took vitamin D for three years at very high doses (4,000 and 10,000 IU) had significantly lower bone mineral density than those who took a much lower daily dose of 400 IU, according to an August 2019 study of 311 people in the Journal of the American Medical Association. Bone strength was similar across the groups.
Doses over 4,000 IU a day should only be taken when advised by your health care provider, per Harvard Health Publishing. If you think your heartburn is due to a high dose of vitamin D, talk to your health care provider. They'll be able to recommend other options, Taub-Dix says, like moving from a high weekly dose to a smaller daily one.
And, she adds, while unclear, there may be an indirect link between vitamin D and digestive issues. "Vitamin D also helps the absorption of calcium, and some say that it might be the calcium that causes the gastrointestinal upset," Taub-Dix says.
Can Vitamin D Prevent Heartburn?
Other studies have explored whether or not vitamin D helps gastrointestinal symptoms. A February 2019 randomized trial of 116 people in the International Journal of Preventive Medicine found that vitamin D helped improve irritable bowel syndrome symptoms.
This led some researchers to suggest vitamin D might actually be a treatment for heartburn or other symptoms of GERD, but an October 2016 study in the American Journal of Gastroenterology found no evidence of an association between a vitamin D deficiency and GERD symptoms or erosive esophagitis (irritation and inflammation of the esophagus caused by acid reflux).
In addition, a September 2017 trial in PLOS One showed there was no improvement when vitamin D was given to people with both a vitamin D deficiency and Barrett's esophagus, a condition in which acid reflux damages the esophageal lining.
If you're looking for relief from heartburn, vitamin D is not likely a factor in your approach. Instead, try to reduce heartburn symptoms by the following, according to the ACG:
- Avoid eating within two to three hours of bedtime.
- Limit alcohol, fatty foods, chocolate, citrus and tomato juice.
- Consider over-the-counter heartburn medication if you need it.
- American College of Gastroenterology: “Acid Reflux”
- Mayo Clinic: “GERD: “Can Certain Medications Make it Worse?”
- Office of Dietary Supplements: “Vitamin D”
- Bonnie Taub-Dix, MA, RDN, CDN, registered dietitian nutritionist, director, owner, BTD Nutrition Consultants, LLC; author, Read It Before You Eat It – Taking You from Label to Table; New York, New York
- Harvard Medical School: “Too Much Vitamin D May Harm Bones, Not Help”
- Journal of the American Medical Association: “Effect of High-Dose Vitamin D Supplementation on Volumetric Bone Density and Bone Strength: A Randomized Clinical Trial”
- International Journal of Preventive Medicine: “Effects of Vitamin D Supplementation in Patients With Irritable Bowel Syndrome: A Randomized, Double-Blind, Placebo-Controlled Clinical Trial”
- American Journal of Gastroenterology: “Associations of Vitamin D Deficiency and Hyperparathyroidism With Gastroesophageal Reflux Disease and Its Sequelae”
- PLOS One: “A Nonrandomized Trial of Vitamin D Supplementation for Barrett’s Esophagus”