About Leeks

This post contains updated information as of 1/2023 per new lab testing by Monash University and FODMAP Friendly.

Are leeks (Allium ampeloprasum var. porrum) low FODMAP? Yes, there are portions of the green leaves and the white bulb that are low FODMAP.

Leeks Have Been Lab Tested

Both Monash University and FODMAP Friendly have both lab tested leeks.

Monash University Lab Results

Monash University has lab tested leeks and recommends 1 cup (100 g) chopped leaves (green parts only) as a low FODMAP serving. Please note that this is almost double the weight that they previously reported.

Monash University has now also reported that 2 generous tablespoons of finely chopped bulb, or 14 g, are also low FODMAP.

Here is what that 14 g amount of bulb looks like:

14 g of leek bulb in glass dish on scale

This is great news and will add loads of flavor to our low FODMAP cooking.

14 g of leek bulb in glass dish

(BTW, for a while Monash had an entry on the app for a blended leaf/bulb portion of ½ cup (38 g) being low FODMAP, but since it did not specify how much of each part of the plant, it was a fairly useless entry. They have now removed that information.)

Leek greens

Monash University Lab Results

FODMAP Friendly does have three leek listings: leaves, bulb and “leek”, which we take to be leaves and bulb combined.

FODMAP Friendly lab testing results are as follows:

½ cup (37 g) of leek leaves is low FODMAP, but there is a Max Serve of 83 g (no volume given).

Leek bulb Passes and is low FODMAP in amounts of 46 g (no volume given).

Then there is the app entry for “leeks”, which we believe is a combo of leaves and bulbs. Since we do not know the ratio, this is a hard one to interpret. They state “1 leek” at 83 g is low FODMAP, with a Max Serve of 416 g (no volume given).

What Is A Leek?

Allium ampeloprasum. OK so here’s the deal with these vegetables from the onion family that look like giant scallions.

And this is important because common white and yellow onions are high FODMAP and yet, if you are like us, you want onion-y flavor. That’s where the green parts of the leek come in, and the small amount of white bulb.

We chop leek greens all the time and use them like onions! True, they are milder than a traditional onion, but they come into constant use in our recipes. We sauté them as a base for soups, stews and anywhere we would normally use an onion. So get familiar with leeks!

The darker green parts that considered very low FODMAP are rather tough; we do not care for them raw. But sliced thinly, they sauté up very nicely

leeks with and without greens copy

How to Buy

Sometimes we see leeks in supermarkets with hardly any of the green leaves attached (see image above). This is not going to work for us FODMAPers. Sometimes they are touted as “trimmed” leeks and for most buyers this would be a boon, as they won’t be paying extra for the greens, which are normally NOT used (these in the foreground of the image above). Find a source where the green parts are intact (like the leeks in the background of the image). Choose firm stalks. They should look fresh, with no wrinkling, and be flexible, indicating moistness.

How to Store

Store in the refrigerator, wrapped in paper towels for up to 5 days or even more, depending on how fresh they were when purchased.

How to Prep & Use

Leek greens cutting
Use our image above to help you ascertain how to divide the leek into green leaves and bulb portions.

Sometimes there are some very firm outer leaves that we discard. Once you have separated the green parts, they need to be washed thoroughly. Leeks often come with a bit (or a lot) of sand embedded in-between the tight and numerous layers. You can either chop and then wash and dry, or separate the layers carefully, wash well, dry, then chop.

leeks cutaway of greens

What To Do With The White Bulb Ends

Even if you use the small amounts of bulb, you will have a to left over. Store them in a zip lock freezer bag until you have a good amount and find a friend or soup kitchen – or a neighbor through the Buy Nothing Project site who does not have IBS – and offer them to them for soup making. You could even make a gift of them with a bag of potatoes for folks to make vichyssoise.

Nothing Better Than Home Grown

And if you are lucky enough to be able to plant them, like we do at The Farm, you will never be without! Here is our harvest of leeks tucked in their bed in the foreground. Amy portions you don’t eat can go into the compost.

Leeks growing at Roja Home Farm.

The Takeaway

You can use leeks in low FODMAP cooking as long as you pay attention to which parts of the plant you use, and your portion size. Using the green leaves on their own is the most straightforward way to use leeks. We understand that Monash’s information can be confusing. When you look on the app, the bulb entry has a Red Light/High FODMAP designation, but if you click through you will see the low FODMAP/Green Light 14 g amount more clearly. You CAN have 14 g of bulb; it is low FODMAP in that amount.

As with any food, the lab test results are recommendations of where to start the exploration of your relationship to FODMAPs and that particular food. A prudent approach would be to start using leek greens only, and slowly try adding some bulb into your cooking to assess your reaction.