As I’ve recently experienced first hand, yes it can.
But it’s not always easy to notice.
Because you’re likely only eating a tablespoon or two at a time, eating rancid flax typically won’t cause more than mild stomach issues.
How to Tell If Ground Flax is Expired
There are really only 2 ways to tell if it’s gone bad:
- Smell – This is the most reliable way. If it smells weird (almost fishy), it’s gone bad. It can help to go smell fresh ground flax at a bulk foods section and compare it to your own.
- Stomach issues – If you’re eating a few tablespoons, you may feel unwell later in the day (up to several hours after eating). For me, I noticed I was having stomach pains and discomfort while running about 6-8 hours after eating (confirmed to the flax causing issues after a few tests).
Smell is the best way to tell, as you may not notice the stomach issues unless you eat a lot of flax.
Why Does Flaxseed Go Bad?
There are many reasons that food can go bad.
However, there are 2 main concerns when it comes to ground flax: rancid fats and mold.
Rancid Fats in Flaxseed
Unsaturated oils in foods become rancid when they are oxidized (exposed to oxygen).
If you didn’t know already, flax has a ton of polyunsaturated fat (mainly omega 3s), which is part of why it’s so healthy.
That makes flax particularly sensitive to oxygen.
If your flax is not sealed tightly, or there’s a hole in your bag, it can quickly go bad.
Mold Growth in Ground Flax
Ground flax is often used to make flax “eggs”.
It soaks up and retains the water.
But food and moisture don’t go well together, and in this case, can cause your flax to go moldy. You may or may not be able to see this easily.
That’s why if moisture does happen to get in your ground flaxseed, you need to be extra cautious about whether or not it’s gone bad.
It’s easy to tell if you might have an issue because your flax will form hard blocks (like mine below – whoops!):
How to Prevent Ground Flax From Going Bad
I bought a large bag of ground golden flaxseed from Costco and then basically did everything wrong.
Sucks for me, but good for you. It led me to do research to find out what I should have done instead.
Here’s how you should use ground flax:
- Store it in the fridge after opening it.
- Use an airtight container.
- Keep away from moisture (that includes wet spoons you may use to measure it).
Summary and How Long Flaxseed Lasts
Since flax can go bad so easily, you don’t really want to take any chances on flax past it’s expiry date.
In general, if stored properly, ground flax lasts a few months in the fridge, and just a few weeks on a shelf.
I recommend not buying too much at a time unless you’re sure you’ll eat it. You can also freeze a portion of it, which should keep it from going bad for much longer.