If you’ve spent any time in a health food aisle or scrolled through vegan TikTok, you’ve seen it. It looks like fish food. It smells like a locker room at first, but then weirdly like a sharp cheddar. People call it "nooch." It’s nutritional yeast. But if you actually look at what is in nutritional yeast, it’s not just some magical dust that makes kale taste like Cheetos. It’s a specific, deactivated fungus that has a pretty wild nutritional profile once you peel back the marketing.
Most people think they’re eating some kind of miracle supplement. Honestly, it’s just Saccharomyces cerevisiae. That’s the same species used to brew beer or bake sourdough, but with a massive catch: it’s dead.
Think about that for a second. You aren't eating live cultures like you would in kombucha or yogurt. The yeast is grown—usually on a diet of beet molasses or cane sugar—and then harvested, washed, and dried with heat. This heat kills the yeast, "deactivating" it so it can't make your bread rise or turn your stomach into a brewery. What’s left behind is basically the concentrated essence of the cell's interior.
The Protein Breakdown: Why it’s more than a seasoning
Let's talk about the protein. When you ask what is in nutritional yeast, the first thing that hits you is the sheer density of amino acids. It’s a complete protein. That’s actually a big deal for a plant-based food. It contains all nine essential amino acids that our bodies can’t manufacture on their own.
You get about 8 grams of protein in just two tablespoons. For perspective, that’s more than a large egg or a glass of milk. Because it’s a cellular product, you’re basically eating the building blocks of life in a concentrated, flaky form. It’s dense. It’s efficient.
✨ Don't miss: I Hate You Don't Leave Me: What Most People Get Wrong About Borderline Personality Disorder
But it’s not just "protein." It’s the specific balance. You’ve got high levels of lysine, which is often the "limiting" amino acid in grains. If you’re eating a lot of rice or wheat, throwing nooch on top isn't just for flavor—it’s actually completing the protein profile of your meal. It’s chemistry on a plate, even if it just feels like salty dust.
The Vitamin B12 Elephant in the Room
Here is where it gets a little confusing for people. Natural yeast? It doesn't actually have B12. Not naturally.
If you pick up a bag of "unfortified" nutritional yeast, you’re getting great B-vitamins like B1, B2, and B6. You’re getting folate. But you aren't getting B12. Most of the stuff you buy at Trader Joe’s or Whole Foods is "fortified." This means manufacturers literally add synthetic vitamins back into the flakes at the end of processing.
Why? Because vegan and vegetarian diets are notoriously low in B12, which is essential for nerve function and making DNA. Since nooch became a staple of the vegan world, it became the "delivery vehicle" for B12. When you check the label and see 500% of your daily value, that’s not the fungus doing the work. That’s a lab helping the fungus out. Some brands, like Sari Foods, offer unfortified versions for people who want to avoid synthetic additives, but you have to check the label. If you don't see Cyanocobalamin or Methylcobalamin on the ingredient list, it’s probably not in there.
📖 Related: Why looking at pics of c section before your due date is actually a smart move
Glutamate and the "Fake Cheese" Mystery
Why does it taste like cheese? This is the question everyone asks. It’s not a chemical flavoring. It’s actually naturally occurring glutamic acid.
You’ve heard of MSG (monosodium glutamate). People freak out about it, but glutamates are just amino acids that signal "umami" to your brain. When the yeast cells are broken down during processing, the proteins fragment, releasing these glutamates. It’s the same reason aged parmesan or sun-dried tomatoes taste so savory.
It’s savory. It’s salty-adjacent. It hits the back of your tongue and tells your brain you're eating something rich and fatty, even though it’s virtually fat-free.
Trace Minerals and the Power of Beta-Glucan
Beyond the big hitters, there is a lot of "micro" stuff going on. Nutritional yeast is a decent source of selenium and zinc. Selenium is one of those things you don't think about until your thyroid starts acting up, and zinc is, well, zinc—everyone wants it for their immune system these days.
Then there are the beta-glucans. These are a type of fiber found in the cell walls of the yeast. There’s actually some fascinating research, like studies published in the British Journal of Nutrition, suggesting that the beta-glucan in Saccharomyces cerevisiae can help support the immune system and potentially lower cholesterol. It’s the same type of "heart-healthy" fiber you find in oats, just in a much more concentrated, fungal form.
Is there a downside? (The stuff nobody mentions)
Nothing is perfect. Even nooch.
First, there’s the purine issue. Because nutritional yeast is made of cells, it’s high in nucleic acids. When your body breaks these down, it produces uric acid. For 95% of people, this is totally fine. But if you struggle with gout or kidney stones, eating massive amounts of nutritional yeast might not be the best move. It’s something doctors rarely mention because nooch is seen as a "health food," but the concentration of purines is real.
Then there is the Tyramine. Some people who get migraines are sensitive to tyramine, an amino acid derivative found in fermented or aged foods—including nutritional yeast. If you find yourself with a throbbing headache after a night of "nooch-popcorn," you might be one of the unlucky ones.
Also, let's be real about the fiber. It’s high. If you go from zero to three tablespoons a day, your gut might have some... opinions. It’s not a gentle transition for everyone. Gas is a common "unspoken" side effect for the uninitiated.
How to actually use what is in nutritional yeast
You don’t just eat it with a spoon. Well, some people do, but that’s weird.
The best way to use it is as a binder or a flavor enhancer. Because it’s dry and flaky, it absorbs moisture.
- The Popcorn Classic: Spritz some olive oil or lime juice so the flakes actually stick. Otherwise, they just settle at the bottom of the bowl.
- The Sauce Secret: Whisk it into cashew cream or even just a standard béchamel. It thickens the sauce and adds that yellow, cheesy hue.
- The Pesto Hack: If you’re making dairy-free pesto, swap the parmesan for an equal amount of nutritional yeast. The texture is surprisingly similar once it hits the pine nuts and basil.
- Roasting Veggies: Toss cauliflower or broccoli in oil and nooch before putting them in the oven. The yeast toasts and creates a nutty crust that’s honestly better than actual cheese sometimes.
The Verdict on the Yellow Flakes
So, what is in nutritional yeast? It’s a dead fungus packed with complete protein, a boatload of B-vitamins (usually added), and a specific type of fiber that might actually keep you from getting sick. It’s a powerhouse.
It’s not "fake." It’s just processed in a way that preserves the nutrients while killing the leavening power. Whether you use it because you're vegan or just because you like the taste of savory popcorn, it’s one of the few "superfoods" that actually lives up to the nutritional hype on the back of the bag.
🔗 Read more: Why Do My Farts Smell Like Sewage? The Real Reasons Your Gas Is Toxic
Your Next Steps for Nooch Success
Don't just buy the first container you see. If you're ready to integrate this into your kitchen, here is exactly how to do it right:
- Check the fortification: Look at the label. If you want B12, make sure it’s listed. If you prefer whole-food sources and take a separate B12 supplement, seek out "unfortified" brands to avoid synthetic folic acid.
- Storage matters: Light and air are the enemies of B-vitamins. Store your yeast in a dark, cool place or an opaque airtight container. If it stays in a clear jar on a sunny counter, it loses its nutritional punch within weeks.
- Start slow: Begin with one teaspoon a day to see how your digestion handles the fiber and the purine load.
- Experiment with heat: Don't be afraid to cook with it. While some vitamins are heat-sensitive, the protein and minerals in nutritional yeast are remarkably stable, so it works just as well in a baked casserole as it does as a raw garnish.