The one smoothie mistake that’s making you bloated

Some days, your wellness habits are on point. You get up, blend a delish smoothie loaded with fruit, protein powder, and maybe some collagen (why not?), and even make it to your a.m. workout with minutes to spare. But then it hits you: that oh-so-uncomfortable bloated feeling. WTF?

It’s a problem Corina Crysler, MS, certified nutritionist and owner of the Ontario-based organic juice and wellness shop Moonshine Juicery, hears about all the time. And she knows exactly what the culprit is: “Fruit and protein should never be mixed,” she says. Ditto greens and protein. “When they’re combined, it can cause gas, bloating, and heartburn.”

So where does this leave your breakfast smoothie habit? Is your blender fated to a future of dust-gathering on your countertop (next to that electric egg cooker you swore you’d use)?

Keep reading to find out why protein, fruits, and veggies don’t mix—plus, how to build the perfect smoothie.

Fruit and protein require different digestive juices

According to Crysler, our bodies break down food using two different types of digestive juices: acidic and alkaline. “Protein requires acidic juices while fruit requires alkaline,” she says. “So when you mix them together, your stomach has to produce both and they essentially knock each other out.” When this happens, she says, the food you just ate can become stuck in the GI tract, which can lead to some, er, unpleasant side effects.

Food combining (as the practice of separating food groups for optimal digestion is counter-intuitively called), isn’t backed up by scientific evidence, but it does have a long history in ancient practices like Traditional Chinese Medicine and Ayurveda. Crysler says a big part of TCM takes into account the timing and combination of the foods you eat, and one part of that is keeping fruit consumption separate from the rest of your meal. “According to Chinese medicine, fruit should be eaten 20 minutes before or after anything else,” Crysler says.

How to build the perfect smoothie

Unfortunately, swapping your bananas for kale isn’t the easy fix you’re after: Vegetables require alkaline digestive juices, too. If you want to get your protein in, Crysler’s best advice is to stick with mixing your go-to powder with water. “You should also cap your protein at 15 or 20 grams per serving, depending on your size, because your body doesn’t really know how to handle more than that at once,” she says.

But this doesn’t mean you’re destined for a smoothie-less life. “I am not anti-fruit,” Crysler promises. “Fruit is great for digestion.” It’s just not a great hiding place for your protein. For the healthiest blend, Crysler says you should add greens to your fruit-filled recipe. And to boost your smoothie’s digestive abilities, Chinese medicine dictates you choose water over dairy for your mixer—or Crysler says to go for a yogurt-like kefir, which is loaded with probiotics to help you break all the ingredients down.

So you can still have your protein and drink your smoothies, too—just not at the same time.

If you want to be conscious of your sugar intake while you blend up your smoothie, use this fruit pyramid as a guide. Plus, five tips to perfect your protein intake.

Originally published August 18, 2017; updated May 22, 2018.