Written by the Spacemilk team · Last updated October 2026

Nutritional yeast and yeast protein both start with yeast, but they're different foods: nutritional yeast is the whole yeast cell, deactivated and dried into flakes, while yeast protein is the protein isolated from the cell, with the rest filtered out. That changes the numbers. A typical ¼-cup serving of nutritional yeast has about 8g of protein along with fiber and carbs, while a serving of Spacemilk yeast protein delivers 20g of complete protein. Nutritional yeast still wins on B vitamins when fortified, savory flavor and price.

Is yeast protein the same as nutritional yeast?

No. Both usually come from the same organism, Saccharomyces cerevisiae, the yeast behind bread, beer and wine. What's different is how much of the cell ends up in the food.

Product	What it is	Live yeast?
Nutritional yeast	Whole yeast cells grown as a food, deactivated with heat and dried into flakes or powder	No, but the whole cell is there
Brewer's yeast	Whole yeast cells, traditionally from beer brewing, deactivated and dried, often sold as a supplement	No, but the whole cell is there
Yeast protein isolate (Spacemilk)	The protein isolated from non-GMO baker's yeast, with the rest of the cell filtered out	No

Spacemilk is made by growing baker's yeast in water through fermentation, then separating the protein, filtering it and drying it. What ends up in the bag is protein isolate with no live or active yeast. Because it comes from a single-celled organism, it's a single-cell protein: not whey, and not plant.

How much protein is in nutritional yeast vs yeast protein?

Whole dried yeast is roughly 40% to 55% protein by weight, depending on the product. The rest is mostly carbohydrate, including a lot of fiber from the cell wall. USDA data for whole dried yeast lists about 40g of protein and 27g of fiber per 100g (USDA FoodData Central), and nutritional yeast labels in the same database run from about 40g to 56g of protein per 100g.

Isolating the protein is what moves the number. Spacemilk Unflavored is a single ingredient, yeast protein isolate, and a 25g scoop delivers 20g of protein, about 80% by weight.

Per serving	Nutritional yeast (about ¼ cup, 15g)	Spacemilk Unflavored (1 scoop, 25g)
Protein	About 8g	20g
Protein by weight	About 40–55%	About 80%
Calories	About 60	100
Total carbohydrate	About 5g	3g
Fiber	About 3g	1g
Sugar	0g	0g
Vitamin B12	Only if fortified (varies widely)	None added

Nutritional yeast figures are typical label values from USDA FoodData Central branded entries; check your own product, because serving sizes and fortification vary. Spacemilk figures are from our Nutrition Facts panel.

To get 20g of protein from nutritional yeast, you'd need around two and a half ¼-cup servings, close to ⅔ cup of flakes, with about 150 calories and 8g of fiber along for the ride.

Can nutritional yeast work as a protein powder?

It can add protein, but it isn't built for that job. Most people use a tablespoon or two as a seasoning, which adds a few grams of protein: a useful contributor across a day, not a 20g serving.

Yeast protein isolate is made to be the protein. Spacemilk scores 1.0 on PDCAAS (Protein Digestibility Corrected Amino Acid Score), the highest possible, the same as whey and egg. It carries all nine essential amino acids. Yeast protein, the protein in Spacemilk, was shown in a 2024 double-blind randomized controlled trial to match whey for building lean muscle and strength in men over 40 doing resistance training (Briskey et al., 2024, Journal of Food and Nutrition Research). That study tested yeast protein as an ingredient, not nutritional yeast, and not Spacemilk as a finished product. For the full comparison, read Yeast protein vs whey.

Brewer's yeast vs yeast protein: what's different?

Brewer's yeast is whole yeast too, so it lines up with nutritional yeast rather than with yeast protein. It's sold as flakes, powder or tablets and often tastes bitter unless it has been debittered. Like nutritional yeast, it brings the whole cell, nucleic acids included.

Those nucleic acids matter if you're watching purines. In a study that measured purines in 270 foods, a brewer's yeast supplement came in at about 2,996mg per 100g, among the highest of anything tested (Kaneko et al., 2014, Biological and Pharmaceutical Bulletin). Yeast cells are naturally rich in nucleic acids, which is where purines come from (Jach et al., 2022, Metabolites). Spacemilk contains about 38mg of purines per serving, and our process includes a step that reduces the yeast's nucleic acids. The full comparison is in Yeast protein, purines and gout.

Does yeast protein taste like nutritional yeast?

No. Nutritional yeast is prized for its savory, nutty, cheese-like flavor, and that flavor comes from the whole cell. Isolating the protein leaves most of it behind. Spacemilk Unflavored tastes neutral and disappears into recipes, and the flavored versions taste like what they say: Vanilla like a classic vanilla milkshake, Chocolate like the milk at the bottom of a bowl of chocolate cereal.

Where nutritional yeast wins

Nutritional yeast is a good food, and for some jobs it's the better pick.

• B vitamins. Whole yeast naturally carries B vitamins such as thiamin and folate, and many nutritional yeasts are fortified with more. Vitamin B12 is the one to watch: plant foods don't naturally contain it, but fortified nutritional yeast can supply 8.3 to 24mcg per ¼ cup, several times the 2.4mcg Daily Value (NIH Office of Dietary Supplements). If you rely on nutritional yeast for B12, check that your label says fortified. Spacemilk isn't fortified with vitamins, so don't rely on it for B12.
• Flavor. Nothing else gives that savory, cheesy depth to popcorn, pasta, sauces and tofu scrambles.
• Cost. A shaker of flakes usually costs less per serving than a protein powder, and a little goes a long way as a seasoning.
• Whole food and fiber. You get the whole cell, including its fiber. If more fiber is your goal, nutritional yeast delivers it.

Plenty of people use both: nutritional yeast for flavor and vitamins, and a yeast protein shake for a reliable 20g of protein.

Where yeast protein wins

• Protein per serving. 20g of complete protein in one scoop, with a PDCAAS of 1.0.
• Fewer extras. 0g sugar, 3g to 6g of carbs depending on flavor, and formulated to be low in FODMAPs.
• Free from all 9 major allergens: dairy, soy, gluten, eggs, tree nuts, peanuts, fish, shellfish and sesame.
• Tested and published. Every batch is independently third-party tested, and the results are on our testing page.

Who it's for, and who should check with a doctor

Yeast protein may suit you if you want a full serving of complete protein without dairy or other major allergens, or you like the idea of yeast but not the savory taste in your shake.

Nutritional yeast may suit you if you want savory flavor, extra fiber, or a fortified source of B vitamins in your meals.

Check with your doctor or allergist first if you have a known yeast allergy, which is extremely rare. Neither product contains live yeast, but both are yeast-derived. Read more in Can you have yeast protein with a yeast allergy or candida? Also talk to your doctor if you have gout or high uric acid, a condition that affects how much protein you should eat, you're pregnant or nursing, or you're choosing a protein for a child.

Frequently asked questions

Is nutritional yeast a good source of protein?

It's a useful one: about 8g per ¼ cup. For 20g in one serving, a protein isolate is the more practical route.

Is Spacemilk made from nutritional yeast?

No. Spacemilk is the protein isolated from non-GMO baker's yeast. It isn't nutritional yeast, and it doesn't taste like it.

Does yeast protein have B12 like nutritional yeast?

B12 isn't naturally present in nutritional yeast; it's added when the product is fortified. Spacemilk isn't fortified, so don't count on it for B12.

Where can I learn more?

Our Science page summarizes the research on yeast protein, and our FAQ covers ingredients and allergens. Ready to try it? Shop Spacemilk Complete Protein. Your first order is covered by our 30-day guarantee: if it's not right for you, choose a replacement, store credit or a refund.