Are Leeks Low FODMAP? How To Add Onion Flavor For IBS

December 14, 2022 (Last Updated: December 19, 2022)
are leeks low fodmap

“Are leeks low FODMAP?” was the second question I asked (before garlic) after I found out onions were a huge no on the low FODMAP diet. It may seem small but “are leeks low FODMAP?” was on my mind because they’re the perfect low FODMAP substitute for onion on a  IBS low FODMAP diet.

Leeks are a vegetable that is part of the allium family which includes onions and garlic. Luckily, leeks are low FODMAP depending on how much the serving size is and which part of the leek is used.

We’re going to do a deep dive into leeks, cover some other onion-like substitutes and I’ll share some of my favorite low FODMAP leek recipes:

So let’s find out, leek: is it low FODMAP?

Are Leeks Low FODMAP?

Yes, leeks are low FODMAP but specifically only the green parts. According to Monash, the green parts of the leek (leek leaves) are low FODMAP at 1 cup or 100 grams!

This is great for anyone eating low FODMAP because leeks are the best way to add onion flavor without the pain that comes from eating or tears of chopping an onion. It’s a win-win. But what about the rest of the leek vegetable?

The bulb (white and yellow parts) of a leek has a red light indicator next to it. It is only low FODMAP at 14 grams or 1 tablespoon. Servings of ¼ cup or 18 grams contain moderate fructan and higher serves of ½ cup or 75 grams is high FODMAP.

Leeks are a great way to add onion flavor on a low FODMAP diet and here are a few reasons why they’re better than onions.

Reasons Why Leeks Are Better Than Onions

are leeks low fodmap

I never thought much of leeks until I started the low FODMAP diet but I’ve come to love them and even found reasons why they’re better than onions.

  • Leeks are tear-free: I hate chopping onions because I cry buckets but leeks won’t make you cry and that’s a point in my book.
  • Not potent: Have you ever taken a whiff of your hands after you’ve chopped some onions? What about rubbing your eyes? Leeks are not potent and your hands won’t reek after handling them. Your eyes are safe to be rubbed without stinging too.
  • No bad breath: Onions will have your hands and mouth reeking of, well, onions but leeks aren’t that bad. Just a faint whisper of lunch or dinner. 
  • Onion flavor without the pain: Leeks are in the same family as onions and will add onion flavor to a dish without the pesky FODMAPs and pain that comes with eating onions.  

Honestly, I think I’d still choose to cook with leeks even if my stomach deems onions tolerable one day. To add to the list of why leeks are better than onions, the next section is a list of medically backed benefits of leeks.

4 Benefits Of Leek

are leeks low fodmap

Not only are leeks FODMAP friendly but you can benefit from adding them to your diet [1]:

1. They’re Rich In Fiber

Leeks are a good source of fiber. Fiber is important to digestion and keeps you regular (if you catch my drift).

2. Leeks Are Nutritious

Leeks are filled with vitamins like vitamin K and C, which is beneficial for bone health. They’re also a good source for minerals like iron, manganese and folate.

3. Rich In Antioxidants

Leeks have lots of antioxidants like quercetin, kaempferol and allicin. I’m not a scientist but I know antioxidants are good for you and they help keep you healthy. So, bring on the leeks.

4. They Help Boost Your Immune System

Leeks boost your immune system because of the vitamins, minerals and antioxidants.

And while they have more benefits than I’ve listed, leeks can also affect some people negatively. Let’s have a look at some of the side effects of leeks in the next section.

4 Possible Side Effect Of Leeks

Leeks are safe to eat and have a lot of health benefits but not everyone will react positively to this vegetable. These are just a few side effects you may experience with leeks:

Allergic Reaction

Some people are actually allergic to leeks. It’s not very common but it is a possibility. Allergic reactions include swelling, itching, rash and or difficulty breathing. 

Please avoid leeks if you are allergic or start to experience allergic reactions and seek medical attention if necessary. No allergic reaction but have an upset stomach after eating some leeks? 

Digestive Issues

Leeks are high in fiber and although that may be helpful for digestion, eating too much fiber can actually back you up and cause constipation. Eating large amounts of leeks may give you an upset stomach or digestive issues.

Avoid this by eating this vegetable in moderation or in small portions. Another side effect of leeks? Bloating.


Leeks are not FODMAP free and only the green parts of the leek tested low FODMAP. Even then, leeks can trigger IBS symptoms in some people. At the very least, you may be bloated, experience gas or abdominal pain. 

High Blood Sugar

This was news to me but apparently, leeks can cause a blood sugar spike because of their high starch content. Make sure to eat leeks in moderation if you have diabetes or if you’re watching your blood sugar level.

Leeks are very nutritious and I tolerate the yellow-ish parts of a leek pretty well but my partner can’t even eat a leek, green parts or not. The hallmark of the low FODMAP diet is that we’re all different and have unique tolerances. 

The low FODMAP diet serves as a guideline. So, maybe you can tolerate leeks or maybe you can’t. Maybe, you’re lucky and onions don’t affect you. The important thing to do is listen to your body

How To Clean & Cook Leeks

Leeks are dirty and I mean dirty as in filled with dirt because they grow in soil. There are specks of dirt and sand in between the leaves even when you’ve washed them multiple times. 

Tip: Avoid cutting leeks vertically and then washing them. That doesn’t remove all the dirt and can even move the dirt from the top of the leek to the bottom. 

The best way to clean a leek is to rinse everything first and then cut it horizontally like this:

Put the chopped leek in a large bowl filled with water and mix everything around. This will encourage all the dirt trapped in between the layers to fall into the bottom of the bowl.

Scoop out the leek leaves and let them dry over some kitchen towel. It’s tempting to just drain them in a colander but that’ll be like pouring the dirt on top of them. 

You can remove the light yellow bits but I keep them because I can tolerate them but the yellow portion is part of the bulb and that is higher in FODMAPs. Keep them or toss them, it’s up to you and your tolerances. Everyone is different.

Leeks are great onion substitutes and can be treated the same way. Leek leaves are a lot more fibrous so they take longer to cook. My favorite way to use leeks is to flavor stocks or broths, in stew, sliced thinly and fried as a garnish or chopped thick and braised in mustard and stock.

Now that we’ve answered the basic questions like, “is leek low FODMAP” or “are leeks low FODMAP,” let’s tackle some other frequently asked questions about leeks, onions and more!

Leek FAQ

are leeks low fodmap

This section will cover the frequently asked questions that pop up when discussing leek FODMAP and more.

Are Leeks Low FODMAP Than Onions?

Yes, onions are completely off limits while the green parts of leeks are low FODMAP in serving sizes of 1 cup or 100 grams. The yellowish white parts of the leek bulb is higher in FODMAPs and is tolerable up to 14 grams or 1 tablespoon. 

Are Leeks As Gassy As Onions?

The green parts of leeks are low FODMAP but still do contain fructans and can trigger symptoms like gas and bloating but it should be less than onions. 

Onions, garlic, shallots, and the white part of leeks or spring/green onions are high FODMAP. This means that we have a harder time digesting them and this can lead to gas and bloating.

Can Leeks Trigger IBS?

Leeks are alliums like onions and garlic which trigger IBS symptoms. Most individuals with IBS should be able to tolerate the green part of the leeks with little issue. The white and yellow parts of the leek bulb may trigger more severe IBS symptoms than the green parts because they are higher in FODMAPs.

Can I Have Leeks With IBS?

Yes! Monash University tested leeks and the green leaves are low FODMAP at 1 cup or 100 grams. The yellow and white parts of the leek are higher in FODMAPs and have a small serving size of 14 grams or 1 tablespoon.

Are Leeks Bad for IBS?

Generally, vegetables that are part of the allium family like leeks, onions and garlic will impact a person with IBS negatively but Monash has tested the green parts of the leeks to be low FODMAP. Everyone’s tolerances are different though so carefully introduce this ingredient into your diet and see how your body reacts.

With all of the leek related FODMAP questions out of the way, let’s go over some other leek related vegetables in the next section.

So, we’ve covered everything I could possibly think of about leeks but this section will help answer any questions you may have about some vegetables that are related to leeks like onions or spring/green onions.

Are Onions Low FODMAP?

All onions are high FODMAPs but there are plenty of solutions to this problem. A common low FODMAP onion substitute is green leeks, green spring onions, onion infused olive oil or an Indian herb called Asafoetida or hing.

Is Cooked Onion Low FODMAP?

Cooked or raw, all onions are high in FODMAPs and should be avoided unless you’ve passed the fructan phase and know that your body can tolerate them. The only onions that are low FODMAP according to Monash’s App are pickled onions.

Is Onion Powder Low FODMAP?

Onions and onion powder are not low FODMAP. They’re very high in FODMAPs but here are some low FODMAP onion substitutes you can try: green leeks, green spring onions, onion infused olive oil or an Indian herb called Asafoetida or hing

Are Spring Onions Low FODMAP?

Whether you googled, “are spring onions low FODMAP?” or “are green onions low FODMAP?” the answer is similar to leeks. The green parts of this vegetable are low FODMAP but the white parts are off limits. The white part of the green onion is called the bulb and it’s high FODMAP.

That’s the end of this, “are leeks low FODMAP?” article folks. What’s your favorite way to add onion flavor to your low FODMAP meals? Sometimes, I don’t even bother but it’s nice to know that there are options!

Wonder, is garlic low FODMAP? I’ve got you covered with this post right here. More about FODMAPs and ingredients here:
Mushrooms & FODMAPs

Are Olives Low FODMAP?

Low FODMAP Mushrooms Safe For IBS

Is Ginger Low FODMAP?

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