Do Chocolate, Onions, or Mint Cause or Worsen Reflux?

If you have reflux, there are certain foods that every known medium says you should avoid. The news, the Internet, and even your doctor give you a list of foods that trigger reflux. Many people have heard that chocolate, onions, and mint aggravate reflux, but do they and why?

Are there scientific reasons why these foods supposedly trigger reflux or is it bunk?

Do Chocolate, Onions, or Mint Cause or Worsen Reflux?


Let us begin with an easily known common cause of reflux chocolate. There is some evidence that compounds in chocolate may reduce LES (lower esophageal sphincter, the body part that connects the esophagus and stomach, it opens to allow matter in and out of the stomach and closes tightly to limit reflux) function.1 2 Chocolate is comprised of polyphenols, caffeine, and theobromine. Polyphenols found in chocolate are fermentable in the gut. People with SIBO overgrowth may have increased gas production from their ingestion, putting excessive pressure on the LES and weakening it.3 Caffeine itself has been studied and confirmed for its weakened effects on the LES.4 5 Theobromine has also been implicated as a cause of reduced LES function.6 Caffeine and theobromine are both smooth muscle relaxers, which relax the LES, and in combination with the increased pressure of bacterial fermentation of chocolate polyphenols, lead to reflux.7

Chocolate consumption increases the release of serotonin within the intestinal tract which further relaxes the LES and triggers reflux.8

It was initially believed that the high-fat content of chocolate was the cause of its reflux inducing properties. However, defatted chocolate was used in later studies, to disprove chocolate’s fat content as a cause. Further studies confirmed that it was the chocolate polyphenols and xanthines (caffeine and theobromine) causing the reflux.9

VERDICT: True, chocolate does worsen reflux for most people.


Onions are a big cause of reflux for a lot of people, especially raw onions. Onions are high in fructans which are very fermentable in the gut and may place excessive pressure on the LES, causing stomach contents to go upwards into the esophagus.10

There is one invivo study done in 1990 where people ingested hamburgers and consumed a glass of water, one hamburger with raw onions and one later without. People without digestive issues saw no difference in monitored reflux or symptoms between the two meals. People that were suffering from digestive issues, however, reported increased reflux symptoms after the ingestion of the hamburger with added raw onions.11

VERDICT: Somewhat true, raw onions do worsen reflux. Some people, however, can tolerate cooked onions with little to no issues.


Mint is our first supposed trigger that has conflicting information. Menthol is the main component of the mint family that has a lot of medicinal benefits. Mint, despite its benefits, has been implicated in aggravating symptoms for many years.

Menthol supposedly weakens the LES on contact as a smooth muscle relaxer. Menthol blocks voltage-sensitive sodium channels in the neuromuscular junction. This blockage reduces neural activity in the muscles, which in turn relaxes the muscles and reduces muscle spasms.12 13

There was an invivo study done in the late 90’s that measured the LES pressure in people who took a spearmint extract that casts doubt on its negative effects on the LES. LES pressure did not change after consumption even with elevated doses of spearmint extract (spearmint contains a lot less menthol, which might be the reason it is better tolerated). However, people reported worsening reflux symptoms with increased dosages of spearmint. The researchers concluded that the “reflux” symptoms during the study occurred from mucosal irritation of the esophagus from spearmint ingestion and not from actual reflux of stomach contents.14

More recent studies, however, propose that menthol hinders proper esophageal peristalsis through smooth muscle relaxation and relaxation of the LES.15

Are the reflux symptoms from ingesting mint products from mucosal irritation or are they caused by esophageal peristalsis issues and LES relaxation? I believe more studies are needed to determine the true relationship between mint consumption and reflux. Currently, I recommend that products with mint should be avoided if you are suffering from reflux conditions.

VERDICT: Mostly true, mint seems to cause reflux for many people.

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