Why Do Nuts Make My Stomach Hurt?

You started eating healthy.

Your breakfast is an egg and a kale smoothie.

Your lunch is a chicken salad with organic greens.

Your snack is a Greek yogurt and a handful of nuts.

But, wait – after eating that almond and cashew mix your stomach begins to rumble.

This healthy eating thing is supposed to make me feel good! That $200 I spent at Whole Foods shouldn’t make me hunch over in pain!

I can relate. I have skin breakouts and gut troubles when eating certain nuts, like walnuts. And this is not uncommon. Many people who partake in an elimination diet realize they feel better after eliminating certain foods, like nuts and seeds. I think the more common elimination ah-ha moments are grains and dairy. That said – nuts can be pesky, too!

So, what’s the deal? Why, for some of us, does our stomach rumble after eating nuts?


Science 101 – Phytic Acid

Buckle up for some science! Nuts have a compound called phytic acid. Also called phytates.

Phytic acid is like a magnet for minerals.

Let’s say we’ve eaten a mineral-rich salad with nuts on top. If the nuts are raw (raw nuts contain more phytic acid – more on that in a sec), the phytic acid in the nuts can grab on to some minerals present in the digestive tract – typically calcium, magnesium, iron, potassium and zinc - and not allow those minerals to be absorbed by the gut.

Phytic acid is sometimes referred to as an ‘antinutrient’ because it interferes with the absorption of nutrients – it’s against the nutrients.

On top of stealing minerals, phytic acid can limit the secretion of digestive enzymes, including trypsin which breaks down protein, and amylase which breaks down starches.


Reducing the Phytic Acid Load

As pointed out in this Weston A. Price article, traditional cultures soaked their nuts as part of the preparation process:

“It is instructive to look at Native American preparation techniques for the hickory nut, which they used for oils. To extract the oil they parched the nuts until they cracked to pieces and then pounded them until they were as fine as coffee grounds. They were then put into boiling water and boiled for an hour or longer, until they cooked down to a kind of soup from which the oil was strained out through a cloth. The rest was thrown away. The oil could be used at once or poured into a vessel where it would keep a long time.
By contrast, the Indians of California consumed acorn meal after a long period of soaking and rinsing, then pounding and cooking. Nuts and seeds in Central America were prepared by salt water soaking and dehydration in the sun, after which they were ground and cooked.”

By soaking, then dehydrating or roasting the nut, some of the phytic acid breaks down and reduces some of the mineral-stealing action.

Maybe these traditional cultures were on to something. And anecdotally, many people find after soaking and roasting nuts, they can digest nuts with ease!



We can't forget to mention that nuts are fairly high in Omega-6 fats – most especially walnuts, almonds, Brazil nuts, pine nuts and pecans. 

Omega-6 fats are the pro-inflammatory fats. We do need some Omega-6 fatty acids. If we get banged up, or get a cut, we need to be able to mount an inflammatory response. But it’s so easy to overdo Omega-6s, even if we’re eating a healthy diet.


Getting to the nut of it

Many people experience digestive distress – stomach aches, bloating, digestive issues - when consuming nuts. If that’s you, here are some way to tackle your tummy nut troubles:

1) Reduce the amount of nuts you eat

With the abundance of nut butter, trail mixes, nut flours, nut-based cookies, desserts and treats, it’s easy to overdo it on nuts. Plus, nuts are very convenient!  

Almond, walnuts and hazelnuts have a large phytic acid load.

If you’re eating a lot of almonds – which many people eating a healthy diet do – think about reducing the number of almonds you eat on a daily basis.

Also, some health food stores carry raw, sprouted nut butters -- worth a shot!


2) Try soaking and roasting

Recall that by soaking, then dehydrating or roasting the nut, some of the phytic acid breaks down and reduces some of the mineral-stealing action.

  • Place nuts and 1 tablespoon of salt into a glass or ceramic bowl.
  • Soak nuts for 6-8 hours.
  • Drain water.
  • Spread nuts in a single layer on a baking sheet.
  • Dehydrate in oven at 150-200 F for 12-24 hours, turning once or twice.
  • Let cool and store in an airtight container.


3) Looking at the rest of your plate

Grains, nuts, seeds and beans have phytic acid. If you’re eating a lot of nuts, along with a large quantity of, say -- brown rice, chickpeas and chia seeds – your gut lining could be irritated by the excessive phytates and contribute to leaky gut

If your stomach is constantly in knots, you may want to try an elimination diet. An elimination diet will shine a light on that pesky knot-inducing culprit by eliminating common gut irritants like artificial sweeteners, gluten-containing grains, dairy and legumes.  When you reintroduce the culprit, your stomach will churn, and you’ll have an elimination winner on your hands. 


Nuts can be a healthy source of fat and a rich-source of minerals. However, if you're experiencing digestive issues, try soaking and roasting your nuts for (hopefully) improved digestion!