Vegan Diarrhea: How to Fix Loose Stool on a Vegan Diet

I’ve been vegan for 13 years, and I’ve experienced the full range of stool consistency as I’ve altered my diet. I’ve also talked with dozens of vegans who had diarrhea, gas, and related issues—especially at first. So if you’ve got the runs… there is light at the end of the tunnel.

Vegan diarrhea is often caused by a dramatic increase in fiber when switching to a plant-based diet. However, there are many potential causes. To ease symptoms, try reducing your fiber intake—then add it back gradually. You may want to keep a food journal and limit beans while adjusting to the diet.

Below, I’ll share a longer list of foods to be careful with, a digestive enzyme that helps a lot of vegans, tips on how to prepare your beans for less gas, and other issues that could be causing your diarrhea.

The Most Likely Problem: Fiber

Beans and whole grains tend to have a lot of fiber… that most people aren’t used to.

If you’re dealing with serious diarrhea, you’ll likely want to go see your physician to make sure it’s nothing too serious. Diarrhea can be caused by many things, including infections, deficiencies, and chronic conditions.

That said, based on everything I know…

If you’re having loose stool as a new vegan, you probably increased your fiber intake too quickly.

This is very common in new vegans, and it can lead to several digestive issues from gas and bloating to, yes, potentially diarrhea.

Your gut contains trillions of bacteria that basically eat your “leftovers.” And feeding them lots of fiber is a generally a good thing. In fact, vegans tend to have healthier gut microbiomes than meat-eaters (source)…

But you need to take it slow.

Things can get out of balance when you switch things up so suddenly.

It’s still okay if you want to go vegan overnight. In fact, I did that myself, and I wrote a whole guide on how to do it—there’s nothing inherently diarrhea-causing about veganism… But you may need to adjust the specific foods you’re eating.

So let’s cover that next.

Which Foods Cause Diarrhea on a Vegan Diet?

Below, you’ll find a list of the top potentially diarrhea-causing foods on a vegan diet. But first, let me say this: The #1 way to troubleshoot your loose stool—or any issue relating to diet—is to keep a food journal.

A screenshot from Cronometer, my favorite app for tracking nutrients, calories, and just remembering what I ate each day. You can sign up free at this link.

Personally, I’ve used the app Cronometer with great success for fixing issues like vegan gas, persistent acne, and weight-loss plateaus.

Whichever app or tool you use, I highly recommend tracking which foods you’re eating, your total fiber intake, and how your stools are changing.

That said, I especially like Cronometer because it shows all your nutrients. You can easily see which ones you’re getting and which ones you’re missing.

You won’t have to track forever. But it’ll help you gain awareness of which foods cause problems for you.

Here are some potential problem foods to monitor:

  • Beans
  • Lentils
  • Peas
  • Hummus
  • Broccoli
  • Cauliflower
  • Cabbage
  • Artichokes
  • Spicy seasonings you’re not used to
  • High-fiber cereals like Fiber One and All-Bran
  • Other whole grains with a lot of “roughage”
  • Garlic and onion
  • Coffee
  • Artificial sweeteners

You may find other problem foods that are specific to you, too.

Some people have problems with gluten and wheat, even in its processed forms like white bread. But if your diarrhea started after going vegan, you should look at foods you’ve just added.

[Related post: 17 Tips to Stop Farting So Much on a Vegan Diet.]

My Experience with Loose Stool as a Vegan

My loosest stool ever was the result of drinking big five-banana smoothies every day.

Within my 13 years as a vegan, I’ve switched up my exact diet many different times. And I’ve seen how each “version” of a vegan diet affected my stool consistency.

The loosest stools I ever had was when I was on a “high-carb low-fat” (HCLF) vegan diet, drinking huge smoothies of fruit and greens every day.

Basically, I made smoothies with 5 bananas, 2 cups of strawberries, and a bunch of spinach… Every day. (I wrote more about this wacky diet here.)

Anyway… It really softened things up back/down there! So, take note: Even fruits and greens can add a lot of extra fiber your body’s not used to, if you’re eating them in big quantities.

The firmest stools I’ve had as a vegan was when I was eating lower-carb and avoiding grains. I tested that diet for a while because it seemed like grains were causing my acne.

My meals almost looked like I was eating vegan keto! I had lettuce or cooked veggies with vegan protein like mock meats or tofu.

Without eating grains, my poop actually became a little too hard, and I was concerned I wasn’t getting enough fiber. Once I added oatmeal back to my diet, my stool consistency got back in the sweet spot.

Side Note: This lower-carb diet I tried actually did help a fair amount with my acne. If you struggle with acne, I really recommend checking out my blog post all about fixing acne on a vegan diet. I seriously share things in that post that took me years of studying and experimenting to learn!

Anyway, enough about acne. Let’s get back to poop. So what’s the takeaway from all this?

Whole grains and fruit contain quite a bit of fiber, and I’ve witnessed myself how they can soften up your stool! That is normally a healthy thing—but if your stools are too soft and runny… try cutting back on some high-fiber foods especially.

Focus on These Lower-Fiber Vegan Foods

Reducing your fiber intake to troubleshoot an issue like diarrhea or gas can be tricky. You want to be healthy… but most healthy food has fiber!

Remember, you’ll likely only need to reduce your fiber intake temporarily to troubleshoot your diarrhea. And on that short time scale, it’s not a big problem to keep eating things like white rice, white pasta, or white bread.

That said, if you want to focus on colorful, healthy plant foods with low fiber, here are some options:

  • Cooked potatoes or sweet potatoes with no skins
  • Juiced vegetables (most fiber is removed)
  • Melons (cantaloupe, honeydew, watermelon)
  • Nectarines
  • Papayas
  • Peaches
  • Plums
  • Carrots
  • Beets
  • Asparagus tips
  • Tomato sauce
  • Acorn squash (no seeds)
  • Tofu
  • Seitan
  • Dark chocolate

Also, keep this in mind: Most vegetables are much less likely to cause digestive issues if you cook them really thoroughly. So feel free to have more vegetables that aren’t on this list—but cook them longer to make them soft and easy to break down.

2 More Tips for Vegan Fiber Overload

Eating lower-fiber as you transition isn’t the only thing you can try. Here are two more tips:

1. Try This Digestive Enzyme

The vegan version of Beano. It helps digest high-fiber foods like beans. A life-saver for many vegans. Here’s the Amazon link.

Some people may continue to have trouble with beans and other high-fiber foods, even when easing into them gradually. In this case, you may want to try a digestive enzyme.

Basically, you want the vegan version of Beano… It’s called Vegan Bean-Zyme (Amazon link).

It has the same active ingredient as Beano (alpha galactosidase), which has been shown in studies to be safe and effective. It helps break down the fibers in foods like beans and broccoli, so there’s not as much left to break down in your gut.

For many people, Vegan Bean-Zyme turns out to be the magic bullet for gas, diarrhea, and other digestive upset. Just take it with your meals. Simple, cheap, and quick!

2. Do This With Your Beans

Beans are such a common cause of gas and other digestive issues on a vegan diet that it’s worth addressing them specifically.

Here are a few tactics you can use to reduce the chances of beans giving you problems:

1. Watch your portion size. This one is common sense, and it applies to any potential problem foods. Sometimes a small portion will be okay, and you’ll only have problems with big servings of it. So try and see!

2. Rinse your beans. This one made a huge difference for my vegan gas issues. Whether you have canned beans or you’re soaking and cooking dry beans, rinse away the “bean juice.” It contains a lot of the oligosaccharides that can cause problems.

3. Cook your beans thoroughly. Especially when preparing beans from dry, make sure they are cooked all the way and soft. That will be easier for your stomach and small intestines to break down and digest.

4. Choose tofu or tempeh instead. Tofu and tempeh are both made of soybeans. So they have similar health benefits as beans—and they’re even higher in protein. Meanwhile, they have less fiber, so they’re usually easier to adjust to.

Other Possible Causes of Vegan Diarrhea

Too much fiber is not always the cause of diarrhea in vegans. There are many other potential causes, and I’ll list some of the most likely below.

That said, if you’re struggling with diarrhea and temporarily reducing your fiber intake hasn’t helped, you may want to talk to a physician.

Trying to self-diagnose these other causes could be difficult and time-consuming, and leave you frustrated with no certainty of which is the problem.

Zinc Deficiency

Cashews are one of the many zinc-rich nuts and seeds.

Full-blown zinc deficiencies are not common among vegans—but vegans tend to have lower zinc levels than meat-eaters.

And zinc deficiency can cause all kinds of issues, one of which is diarrhea.

In fact, the World Health Organization lists zinc sulfate as a treatment for diarrhea in children. (source)

If zinc deficiency suspected to be the problem behind your diarrhea, you have supplement options and food options.

I actually personally take a zinc supplement of 30mg per day (this one) because I have acne-prone skin, and zinc helps with that (source). (Again, I share more about acne nutrition in my big post on that subject.)

But there are plenty of vegan foods high in zinc you can just eat, too:

  • Tofu
  • Cashews
  • Hemp seeds
  • Sesame seeds
  • Pumpkin seeds
  • Many other nuts and seeds
  • Tahini
  • Quinoa
  • Oatmeal

For more on supplementation as a vegan, check out my review of the Future Kind multivitamin. It’s my personal solution to hitting the big 3 nutrients that vegans often lack.

Food Allergy or Intolerance

You may just have an allergy or sensitivity to one specific food. Wheat and soy are probably the most likely culprits, if this is the case.

People with celiac disease have a real nasty reaction to wheat protein specifically (gluten), which can include diarrhea.

Again, using a food journal can help you identify problem foods specific to you, whether they are for reasons of fiber, food intolerances, or anything else.

If you find out you’ve got a soy intolerance and you want to stay vegan, check out these resources:

SIBO, IBS, IBD, and More

The following conditions are not necessarily likely to be the cause for vegan diarrhea, but they are always possibilities:

Small Intestine Bacterial Overgrowth (SIBO): An overgrowth of bacteria up into your small intestine (from your large intestine). SIBO is cited as a cause for many digestive issues, including gas, cramps, acid-reflux, and especially diarrhea. (source)

Irritable Bowel Syndrome (IBS): IBS is not super well understood, but it typically involves intermittent pain in the abdomen, along with a range of possible bowel symptoms, including diarrhea or constipation, that flare up along with the abdominal pain. (source)

Inflammatory Bowel Disease (IBD): This term includes two conditions—Crohn’s disease and ulcerative colitis. With IBD, the large intestine becomes inflamed and many digestive symptoms, including diarrhea, can be observed. That said, a vegan diet is not known to cause IBD—in fact, it may help prevent it. (source, source)

You can also catch an infection like a stomach bug that will give you diarrhea. Or it could be food poisoning. Or something else. Since diarrhea is just watery stool, it could be triggered by many different things.

In a new vegan, diarrhea is often an effect of a dramatic change in the foods eaten, such as the increase in fiber. In that case, I would recommend temporarily reducing your fiber intake and just easing back into it gradually.

If you suspect it may be another issue, if you have other symptoms, or if you want a professional opinion, be sure to consult your physician.

Two More Recommendations for Your Vegan Journey

1. This is the best vegan multivitamin I’ve found in 13 years of being vegan. It has vitamin B12, vitamin D, omega-3—and nothing else. Translation: It only has the nutrients vegans are actually low in. Read my full review of Future Kind’s multivitamin here (with 10% discount).

2. This is the best vegan starter kit I know of. It’s a bundle of 9 beautiful e-books that help you transition to a healthy plant-based diet—the right way. The advice is spot-on, and it has print-outs and checklists that make it easy to implement. Read my full review of Nutriciously here.

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