Recipes | Baking

The Best Low FODMAP Lemon Bars

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Our Low FODMAP Lemon Bars feature a crisp, buttery crust (with a secret) baked to a golden hue, topped with puckery lemon filling. Classic lemon bars made low FODMAP, gluten-free and lactose-free! We love turning traditional desserts into treats that we can all share without triggering our IBS. I made umpteen versions and didn’t rest until I came up with what I think is the absolute best. Bake them and see!

And don’t miss my Lemon Poppy Seed version at the end of the recipe.

horizontal image of lemon bars on black plates; red ranunculus in vase; green napkin
Our lemon bars have a secret ingredient in the crust, which we think makes them the best ever!

Everyone Loves Lemon Bars

While I was developing and testing recipes for my book, The Low-FODMAP Diet Step by Step, I asked folks what dessert they wanted in a low FODMAP form and lemon bars came up again and again. I do have a recipe for them in the book, but this recipe is new and improved and the version I make now.

vertical overhead image of lemon bars on black plates; red ranunculus in vase
Want to cut your bars easily and cleanly? Follow our simple directions.

What’s The Secret?

The secret is xanthan gum. Let me explain.

Making a crisp, buttery shortbread-like crust is key to many bars and desserts, so you can imagine that this is something I have made hundreds (thousands?) of times between writing 17 books and owning a bakery. 

The issue is when you want a gluten-free version there is a definite taste shift as well as a change with the texture.

Taste wise I have found many approaches to be off-putting, with a funny flavor due to the various gluten-free flours or flour blends used. After many tries, I have settled on using the Bob’s Red Mill 1 to 1 Gluten Free Baking Flour and like it very much. You will also have success with King Arthur Measure For Measure.

And yes, even though these flour blends contain xanthan gum, you need more!

main vertical image of lemon bars on black plates with red ranunculus in yellow vase
Look at that distinct crisp crust – and how rich & smooth the lemon filling is.

Xanthan Gum Helps Texture

Texture however was the biggest obstacle. Gluten free flour blends can often create a very sandy and crumbly texture in the end result, but I discovered that the addition of a little xanthan gum added to this kind of classic crust makes all the difference in the world. That is my secret and I now share it with the world.

With its addition the crust holds together perfectly, just like a conventional wheat-flour based shortbread crust.

Xanthan gum is not a FODMAP issue. You can read more in our article, Are Xanthan Gum & Guar Gum Low FODMAP?

lemon bar chart
I made A LOT of lemon bars! Gotta work hard to get it right!

Frequently Asked Questions

Why Is The Butter Melted?

Beginning with melted butter makes this recipe easier, plus it gives the crust a nice crisp texture.

Do I Have To Use Additional Xanthan Gum Even If My Flour Blend Contains It?

Yes. This recipe was developed with Bob’s Red Mill 1 to 1 Gluten Free Baking Flour, which contains xanthan AND it requires the additional xanthan gum. Always use the ingredients called for – especially when baking – for results like the images showcase.

If you want more tips & tricks and information on substitutions, check our ebook on Low FODMAP Baking.

Do I Have To Use Freshly Squeezed Lemon Juice?

Yes. Yes, you do. Listen, if a recipe calls for a teaspoon of lemon juice and it is part of a slew of other ingredients and not the focus, then you can get away with not using fresh. When lemon is the star, as in this recipe, freshly squeezed makes all the difference in flavor.

Why Is There No Vanilla Extract Used?

You will see some lemon bar recipes that call for vanilla extract. I used to make a lemon mousse that did, in fact. In that recipe I thought it rounded out the flavor and made for a more complex experience. In lemon bars I don’t want anything getting in the way of tart, puckery lemon flavor. No vanilla. Period.

How Do I Know When The Filling Is Set?

I take pains to give you time cues as well as visual cues in my recipes. Please follow them for best results. This is a perfect example of a recipe where you cannot insert a toothpick to “test clean”. The lemon filling might look a tad jiggly but remember that there is residual heat in the pan, and it will continue to cook once it is out of the oven.

Can Lemon Bars Be Made Ahead? 

Lemon bars are a dessert that I like to eat as freshly made as possible. Certainly, the day they are baked is best. You can, however, prep and bake the crust the day before, if you like. (I don’t think it saves you much time).

Do I Need To Refrigerate Them?

Lemon bars are best refrigerated, to keep the layers distinct and tasting as good as they can be.

How Do You Cut Lemon Bars Cleanly?

I use two methods. I use a long, sharp, thin bladed knife, like a slicing knife. Many chef’s knives are too bulky. I also like using a bench scraper and cutting by pressing straight down. No matter which implement you use, you should rinse it off with water and wipe clean between cuts. I typically use warm or room temperature water.


overhead image of lemon bars on black plate with confectioners sugar on top

How To Make Low FODMAP Lemon Bars

Preheat oven to 350°F (180°C). Position rack in center of oven. Line an 8-inch (20 cm) square pan with parchment paper overhanging two sides and coat paper and inside of pan with nonstick spray; set aside.

lining an 8-inch square pan with parchment paper

For the Crust: Whisk together the melted butter, sugar, salt and xanthan gum in a medium bowl.

melted butter, sugar, salt and xanthan gum in glass bowl

Stir in flour just until combined.

incorporating flour into butter and sugar to make lemon bar crust

Pat into prepared pan in an even layer.

using hands to pat crust into 8-inch pan for lemon bars
Use your fingers to pat in the crust evenly.

Bake for about 20 to 25 minutes or very light brown all over.

For the Filling: While the crust is baking, whisk together the sugar and flour in a clean bowl, then whisk in the lemon juice. I LOVE this OXO reamer to make my freshly squeezed lemon juice really easily.

OXO citrus reamer, held in hand, with cut lemon half

Whisk in the eggs one at a time just until combined; do not overmix or you will create air bubbles that mar the surface of your finished bars.

lemon juice, sugar and eggs whisked together in glass bowl, with whisk in bowl
A few bubbles might appear, which is OK, just do not whisk vigorously.

When the crust is done, turn the oven down to 325°F (165°C), pour filling over crust and bake for about 18 to 22 minutes or until set. The edges of the filling will look firm, but the center can still have a little jiggle and wiggle as it will continue to cook when you take it out of the oven due to retained heat of the pan. Cool pan on rack. 

lemon bars just out of the oven in an 8-inch square pan
See how the edges are set and even coming away from the sides of the pan a bit, when done.

Bars are easier to cut if chilled for at least an hour. To cut, first lift edges of parchment to bring the bars up and out of the pan.

cutting lemon bars on a white board

Peel parchment down to expose sides of bars. Cut into 16 squares. I like to use either a sharp, slicing knife, run under warm water and dried between cuts, or I use a metal bench scraper, which allows you to press straight down and make nice straight lines, similarly rinsing and drying between cuts.

Bars are ready to serve, or store refrigerated in an airtight container in single layers for up to 4 days.

lemon bar held in hand with bite taken out

You can also dust with confectioners’ sugar right before serving, if you like. Use a very fine-mesh strainer to apply.

sifting confectioners sugar over lemon bars 2
For some folks a lemon bar is just not “done” without a shower of confectioners’ sugar. Do this right before serving.

Are you ready to make our gluten-free Low FODMAP Lemon Bars? We promise you that they are the best found anywhere.

closeup of lemon bars on black plate

More Luscious Lemon Recipes

Looking for more lemon inspiration? Check these out:

FODMAP Information

Our recipes are based on Monash University and FODMAP Friendly science.

  • Dairy: The low FODMAP diet is not a dairy-free diet. It is however, low in lactose. Many dairy ingredients are low in lactose, such as heavy cream and many cheeses.
  • Eggs: Eggs are high in protein and do not contain carbohydrates, according to Monash University.
  • Lemon Juice: Monash University has lab tested lemon juice and it is low FODMAP in ½ cup (125 g) amounts.
  • Sugar: Monash University and FODMAP Friendly have both lab tested white, granulated sugar. Monash states that a Green Light low FODMAP serving size of white sugar is ¼ cup (50 g). FODMAP Friendly simply states that they have tested 1 tablespoon and that it is low FODMAP. Regular granulated white sugar is sucrose, which is a disaccharide made up of equal parts glucose and fructose. Sucrose is broken down and absorbed efficiently in the small intestine. 

Please always refer to the Monash University & FODMAP Friendly smartphone apps for the most up-to-date lab tested information. As always, your tolerance is what counts; please eat accordingly. The ultimate goal of the low FODMAP diet is to eat as broadly as possible, without triggering symptoms, for the healthiest microbiome.

sifting confectioners sugar over lemon bars
horizontal image of lemon bars on black plates; red ranunculus in vase; green napkin
5 from 3 votes

The Best Low FODMAP Lemon Bars

Our Low FODMAP Lemon Bars feature a crisp, buttery crust (with a secret) baked to a golden hue, topped with puckery lemon filling. Classic lemon bars made low FODMAP, gluten-free and lactose-free! We love turning traditional desserts into treats that we can all share without triggering our IBS. I made umpteen versions and didn’t rest until I came up with what I think is the absolute best. Bake them and see!

Low FODMAP Serving Size Info: Makes 16 bars; 16 servings; serving size 1 bar

Makes: 16 Servings
Prep Time: 15 minutes
Cook Time: 50 minutes
Total Time: 1 hour 5 minutes
Author: Dédé Wilson

Ingredients:

Crust:

Lemon Filling:

Preparation:

  1. Preheat oven to 350°F (180°C). Position rack in center of oven. Line an 8-inch (20 cm) square pan with parchment paper overhanging two sides and coat paper and inside of pan with nonstick spray; set aside.
  2. For the Crust: Whisk together the melted butter, sugar, salt and xanthan gum in a medium bowl. Stir in flour just until combined. Pat into prepared pan in an even layer.

  3. Bake for about 20 to 25 minutes or very light brown all over.
  4. For the Filling: While the crust is baking, whisk together the sugar and flour in a clean bowl, then whisk in the lemon juice. Whisk in the eggs one at a time just until combined; do not overmix or you will create air bubbles that mar the surface of your finished bars. When the crust is done, turn the oven down to 325°F (165°C), pour filling over crust and bake for about 18 to 22 minutes or until set. The edges of the filling will look firm, but the center can still have a little jiggle and wiggle as it will continue to cook when you take it out of the oven due to retained heat of the pan. Cool pan on rack.

  5. Bars are easier to cut if chilled for at least an hour. To cut, first lift edges of parchment to bring the bars up and out of the pan. Peel paper down to expose sides of bars. Cut into 16 squares. Bars are ready to serve or store refrigerated in an airtight container in single layers for up to 4 days. You can also dust with confectioners’ sugar right before serving; use a very fine-mesh strainer to apply.

Notes:

  • Lemon zest will add even more lemon flavor to your bars – but it will also add a slightly chewy texture to the filling. If you want to max out with lemon flavor, add 1 to 2 teaspoons of very light and fluffy lemon zest (created with a Microplane) to the filling – and some to the crust!
  • For Lemon Poppy Seed Bars: Add 2 teaspoons of poppy seeds to the crust along with the flour. Proceed as directed.
  • You might be used to seeing Lemon Bars with a dusting of confectioners’ sugar and if that is your preference, by all means, dust away. I think it detracts from the lovely sourness of the lemons, but this is simply a personal preference. Sift a layer of confectioners’ sugar on top of the bars after you have peeled away the parchment, before or after slicing, but always right before serving, for best result.
  • I also love these served on a plate with a few raspberries. Try it!

FODMAP Information

Our recipes are based on Monash University and FODMAP Friendly science.

Dairy: The low FODMAP diet is not a dairy-free diet. It is however, low in lactose. Many dairy ingredients are low in lactose, such as heavy cream and many cheeses.
Eggs: Eggs are high in protein and do not contain carbohydrates, according to Monash University.
Lemon Juice: Monash University has lab tested lemon juice and it is low FODMAP in ½ cup (125 g) amounts.
Sugar: Monash University and FODMAP Friendly have both lab tested white, granulated sugar. Monash states that a Green Light low FODMAP serving size of white sugar is ¼ cup (50 g). FODMAP Friendly simply states that they have tested 1 tablespoon and that it is low FODMAP. Regular granulated white sugar is sucrose, which is a disaccharide made up of equal parts glucose and fructose. Sucrose is broken down and absorbed efficiently in the small intestine.

Please always refer to the Monash University & FODMAP Friendly smartphone apps for the most up-to-date lab tested information. As always, your tolerance is what counts; please eat accordingly. The ultimate goal of the low FODMAP diet is to eat as broadly as possible, without triggering symptoms, for the healthiest microbiome.

Course: Dessert
Cuisine: American

Nutrition

Calories: 182kcal | Carbohydrates: 30g | Protein: 2g | Fat: 7g | Sodium: 49mg | Potassium: 1mg | Fiber: 1g | Sugar: 18g | Calcium: 1mg | Iron: 1mg

All nutritional information is based on third-party calculations and should be considered estimates. Actual nutritional content will vary with brands used, measuring methods, portion sizes and more. For a more detailed explanation, please read our article Understanding The Nutrition Panel Within Our Recipes.