Short answer

• Plant-based: Generally Jain-friendly (choose seed/bean/grain sources; avoid roots and fungi/algae additives).
• Whey: Conditionally acceptable for many lay Jains if truly vegetarian and free from animal‑rennet and other non‑Jain additives; many conscientious Jains now avoid it due to dairy‑industry himsa.
• Yeast-based: Not Jain in traditional practice (yeast is a fungus; deliberate cultivation/killing of countless one‑sensed beings and involves fermentation).

Details

• Plant proteins that are typically fine: pea, soy, rice, hemp, chickpea, mung, quinoa. Avoid blends that include:

- Roots (e.g., beetroot, ashwagandha) which Jains traditionally do not eat. - Fungi/algae/microbe ingredients (mushroom, mycoprotein/Quorn, spirulina, chlorella, probiotics).

• Whey protein:

- Acceptable for many Shravaks only if: - Derived from vegetarian cheese (microbial/acid‑set) or paneer whey; not from animal rennet cheese. - No egg/gelatin, fish oil, vitamin D3 from lanolin, or non‑veg enzymes. - Lecithin from soy/sunflower is fine. - Note: Because modern dairy often involves significant himsa, many Jains choose to avoid whey altogether.

• Yeast-based protein: Traditionally avoided. Yeast (like other fungi) is one‑sensed life; producing “nutritional/deactivated yeast” still entails intentionally cultivating and then killing organisms, which conflicts with ahimsa.

Tradition notes

• Both Śvetāmbara and Digambara household codes have historically allowed milk and its products with care, and both discourage/avoid roots and microorganisms. During Paryushan/Chaturmās, many observe even stricter avoidance of fermented items.

Practical checklist before buying

• Ingredients: confirm only seeds/beans/grains; no roots, fungi, algae, probiotics.
• Processing aids: vegetarian rennet only; plant/microbial enzymes; no animal‑derived carriers or vitamin D3 from lanolin.
• Certifications: vegetarian symbol; scrutinize “natural flavors,” enzymes, and “probiotics.”
• Flavors/sweeteners: plant‑based are fine; the Jain concern is source, not taste.

If you want simple: choose a plain, unflavored plant protein made from pea/rice/soy/hemp with soy or sunflower lecithin; avoid yeast- or fungus‑based powders; and treat whey as acceptable only if you are comfortable with dairy and it’s verified vegetarian.