Plant protein side effects

Plant protein powders are generally well tolerated; the most commonly reported issues are digestive — bloating, gas or fullness, especially when starting a new protein powder or increasing daily protein quickly. We have no clinical trial on the specific fava bean and yeast protein blend in our product, so the picture below draws on the closest comparable research and what's actually printed on our label.

What the research on plant protein and digestion shows

A small randomized crossover trial gave 9 postmenopausal women a 29.5 g serving of almond protein powder, a 29.5 g serving of whey protein, a placebo and water, then tracked gastrointestinal symptoms over 180 minutes. Symptom burden was low across all four drinks, with no severe symptoms reported and no meaningful difference between the plant (almond) protein and whey. That's reassuring as far as it goes, but it's a different plant protein (almond, not fava bean or yeast), a tiny sample, and a single acute dose — not a trial of our blend, and not a chronic-use study.

We found no published clinical trial testing gastrointestinal tolerance specifically for fava bean protein isolate or for YESTEIN™ fermented nutritional yeast protein, the two proteins in our blend. That's a real gap, not a finding either way, and we're not going to imply otherwise.

What's actually on our label that could affect digestion

Per two-scoop serving: 1 g of dietary fiber and 1 g of total sugar, sweetened with stevia leaf extract rather than sugar alcohols — sugar alcohols are a common cause of bloating and gas in other protein powders, and ours doesn't use one. MCT Oil Powder is also in the blend; our label doesn't state how many grams of it are in a serving, so we can't speak to a dose-related effect one way or the other for this specific ingredient.

What to do if a shake doesn't sit well

• Start with a smaller amount (part of a scoop) and build up, rather than a full two-scoop serving on day one.
• Take it with food rather than on an empty stomach.
• Mix it fully — clumped powder is more likely to sit heavy than a well-blended shake.
• If symptoms persist beyond the first week or two, or are severe, stop and talk to a doctor rather than pushing through.

Questions people ask

Does plant protein powder cause bloating?

It can, as with any new protein powder or fiber source, though the one relevant trial we found — comparing a different plant protein (almond) to whey — reported low symptom burden for both. We have no trial on our specific blend.

Is plant protein powder bad for your skin, hair, or hormones?

We found no research linking a fava bean and yeast protein blend to skin, hair or hormonal effects, and we're not making a claim in either direction.

Are plant protein side effects different for women?

We found no trial that reported digestive or other side effects separately by sex for this type of protein blend.

Related reading: how much plant protein should you take a day, who should not take plant protein, and how to choose a good plant protein.