Are onions acidic?

In this article, we will answer the question, “Are onions acidic”? and discuss can onions cause heartburn or acid reflux?

Are onions acidic?

Yes, onions are acidic. Onions have a pH ranging from 5 to 5.8. This pH range truly depends upon whether the onions are cooked or raw. It also depends on the variety of the onion. It is closer to the neutral rating and not as acidic as the lime or lemon.

Onion lies on the acidic side of the pH scale. Different varieties have different pH like white onions and red onions have a pH of 5.8 on the scale but yellow onions have 5.6 pH.

It means that yellow onions are more acidic than red and white onions. Cooking can slightly reduce the acidity of onions.

Can onions cause heartburn or acid reflux?

Well, the answer depends on the person’s response to heartburn or acidic reflux. If a person doesn’t get acidic reflux and heartburn eating onions won’t cause any problem but if you have to get acidic reflux or heartburn eating onions may cause problems and you feel uncomfortable.

Eating a large amount of onion can cause severe symptoms of heartburn or acidic reflux. Cooking onion thoroughly can reduce acidity and lower the chance of acidic reflux and heartburn.

Which acid is present in the onion?

Sulphenic acid is present in onions. When you cut the onion, it releases the propanethiol S-oxide gas which reaches your eyes and reacts with water in the eyes and sulfuric acid produced that cause irritation in the eyes.

The pungency of onion is due to the Sulphur compound in the onion that is reduced upon cooking. But you can also reduce the pungency by different methods. Soaking an onion in ice water is the simplest way to reduce the pungency of the onion. You can also use vinegar or citrus juice to add flavour to the onion.

You can also coat onion in salt if you don’t like the crispness of the soak water onion. Salt gives them a soft texture. Simply cut the onion and coat them with salt and let it for 15 min. Then you can wash excess salt from the onion.

Take a bowl of water with vinegar and salt then add chopped onion in it and put the bowl in the oven for ten seconds.

Can cooked onion cause heartburn?

Onions are flavourful food and present in almost every dish that is used in daily life. However, onions trigger heartburn that is responsible for acid reflux.  Cooked onions can cause acid reflux but it depends on the person’s health.

Cooked onions are banned for a person who is suffering from heartburn. Raw onion can cause weakness in the sphincter of the oesophagus, which is a muscular structure of the oesophagus that prevents the flashback of acid from the stomach to the oesophagus. 

Onion has volatile oil which causes acid reflux. You can consume onion either in raw form, cooked, or baked if you haven’t the sign of heartburn or acid reflux.

What is heartburn?

Heartburn is the backflow of acid in the oesophagus when the sphincter of the oesophagus become weak and allow the escaping of acid from the stomach, as there is no protective layer in the oesophagus, so it causes irritation and inflammation and also causes a sensation of pain in the chest. 

If a person experiences such a sensation, he/she should contact a doctor immediately.

Other FAQs about Onions which you may be interested in.

How do you cut onions for spaghetti sauce?

Do Italians put onions in sauce?

Does cooking onions reduce acidity?

Foods that reduce acid reflux

  • Vegetables and fruits can lower the risk of acid reflux by reducing stomach acid
  • Whole grains are a rich source of fibre and fibre can reduce heartburn by absorbing acid in the stomach
  • Lean protein such as chicken, seafood and eggs can reduce acid reflux
  • Beans, peas and lentils are also good sources of fibre and can help acid reflux
  • Nuts and seeds also contain fibre and other nutrients and can absorb stomach acid
  • Yoghurt can soothe the irritation in the oesophagus and provide probiotics for intestine health
  • Replacing unhealthy fat with healthy fat can reduce the acid reflux in your stomach
  • Ginger can be used for gastrointestinal problems as it has anti-inflammatory properties

Foods that make acid reflux worse

  • Chocolate can make acid reflux worse as it contained caffeine and cocoa that is responsible for heartburn
  • Spicy can lower digestion and irritate the oesophagus and enhance acid reflux
  • Raw onion can cause the symptom of acid reflux
  • Garlic can also cause acid reflux and upset stomach


In this article, we answered the question, “Are onions acidic”? and discussed can onions cause heartburn or acid reflux?

If you have any questions or comments please let us know.