Kathleen,

I wasn’t familiar with yeast protein, so I ran it through past Claude AI. Claude says:

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What yeast protein is: It’s derived from Saccharomyces cerevisiae (baker’s/brewer’s yeast), typically processed to remove the cell wall and concentrate the protein. The “fermented” label mostly just means it’s produced via fermentation, which is how yeast is grown — it’s not fermented in the way, say, tempeh is.

Amino acid profile: The claims are broadly accurate. Yeast protein is a complete protein with all essential amino acids. It has a PDCAAS score of 1.0, matching animal proteins like whey. It does better than pea or rice protein on metrics like methionine content, which is often the limiting amino acid in plant proteins.

Digestibility: In a TIM-1 digestion model, yeast-based protein was comparable to casein and whey in terms of digestibility. That’s a meaningful finding. Processing matters though — in vitro protein digestibility of processed brewer’s spent yeast was almost twice that of unprocessed yeast (73% vs. 40%). The commercial powders are processed, so this works in their favor.

Human trial evidence: One randomized controlled trial had 79 participants consume 40g daily of yeast protein, whey protein, or placebo alongside 8 weeks of resistance training. Both the yeast and whey groups showed gains in trunk and total lean mass, while the placebo group did not. In a subpopulation with inadequate dietary protein intake, both yeast protein and whey protein significantly increased lean mass and muscle strength compared to placebo (https://pubs.sciepub.com/jfnr/12/5/9/). It’s a legitimate piece of evidence — though it was industry-funded (Angel Yeast), which is worth noting as a caveat.

What’s missing: There’s very little independent, non-industry-funded research. Almost all the positive data traces back to Angel Yeast (the ingredient manufacturer behind “AngeoPro”), and there are no long-term trials or head-to-head comparisons with, say, pea+rice blends at matched doses. The brands your reader mentions (Mille, SuperYou) likely use Angel Yeast’s ingredient or something similar.

Bottom line: For someone who needs a convenient, vegan, high-quality protein supplement to hit 1.6g/kg without excess calories, yeast protein is a perfectly reasonable option. It’s complete, well-digestible, and has at least one decent RCT behind it. The superiority claims vs. pea/rice are slightly oversold — a well-formulated pea+rice blend is also complete and digestible — but yeast protein is not worse, and may be mildly better on some metrics. There’s no reason to avoid it.

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I hope that helps!

Merete,

> does the overall ratio of amino acids matter?

No, it doesn’t.

Dan,
You’re right, it looks like I forgot to double the amount of each amino acid in 1 slice of whole-wheat bread. I’m sorry for the inconvenience it caused you (and anyone else).

I could no longer find the exact entries (or they’ve changed the amounts) in the USDA database, so I’ve replaced the numbers and extrapolated the protein and amino acid amounts in whole-wheat bread from whole-wheat flour. I’ve linked them to the entries in the USDA database in the spreadsheet.

Torin,
Most vegans don’t need to use protein powder. You might use an app to calculate how much protein you get on most days to be certain that you’re meeting your needs which I’d assume to be about 1.1 g/kg of body weight.

I’m never sure if I need Protein Powder or not [currently I use a half a scoop of mixed pea & rice PP]. I’m a bit concerned about the lead issue.
I eat decent protein sources like a tin of baked beans every day for lunch, lentils and more legumes in curry 4 days a week, oatmeal with soymilk every day, 4 Linda McCartney Sausages a week [over 2 dinners], etc.

I go walking 6 days a week for about 30 minutes. I do pushups 6 days pw, a small amount of dumb bell weights 3 days pw.

I’d like your thoughts.

Thank you.

Thank you for your kind words. I hope your gallstones improve—good luck!

Thanks Jack. I’m a (mostly WFPB) vegan who gets cold sores and I’ve been taking lysine for years. I’ve only recently discovered the gallstones issue after finding out through a routine ultrasound that I have loads of small gallstones. I’m hoping by not supplementing with lysine anymore they will go away. Hopefully I can keep the cold sores at bay by upping lysine from food instead. Thanks for all you do. This site is one of my most trusted sources of unbiased vegan health info. I really appreciate it.