Kosher protein powder: whey, casein and plant protein

By the KosherVitamins.com team · Updated November 13, 2026

Protein powder is one of the most popular items in our sports nutrition section, and the kosher questions depend on what the protein is made from. Here is how whey, casein and plant proteins compare.

Why protein powder needs a hechsher

According to the NIH Office of Dietary Supplements, most protein powders contain whey. Protein powders are food: they are mixed, flavored and sweetened, and they often contain several protein sources plus flavors, gums and sweeteners. All of these need to be covered by a reliable kosher certification.

Whey and casein: dairy

Whey and casein both come from milk. Whey is a by-product of cheese making, so its kashrus depends on how the cheese was made (including the rennet) and how the whey was processed. The OU explains that whey from a non-kosher cheese process cannot be used in kosher products. Kosher whey and casein powders are dairy (D), so they are not mixed with meat meals.

Cholov Yisroel

A regular OU-D or other plain D symbol on whey means cholov stam. If you keep Cholov Yisroel, you don't have to give up whey: Cholov Yisroel whey protein is made, and we carry it from several brands, including Nutri-Supreme Research whey protein (many flavors, including stevia-sweetened), Maxi Health Naturemax and Maxi Whey and Qualify whey protein drink mix, plus Cholov Yisroel protein bars from Grab1 and Oola. These Cholov Yisroel powders are made with whey protein concentrate; a Cholov Yisroel whey isolate is hard to find (see below). Look for “Cholov Yisroel” on the label. Some poskim are lenient about powdered whey that is not Cholov Yisroel, so ask your rabbi about your custom. See our Cholov Yisroel guide.

Whey isolate vs. whey concentrate

Both are whey; the difference is how much the whey is filtered. The kashrus questions are the same for both, so check the symbol either way.

• Whey protein concentrate (WPC) keeps more of the milk sugar (lactose) and fat. Under the American Dairy Products Institute (ADPI) standard it has at least 25% protein; the WPC 80 grade commonly used in protein powders is about 80% protein, with roughly 4–10% lactose and 4–8% fat. It usually costs less and has a creamier taste.
• Whey protein isolate (WPI) is filtered further to at least 90% protein, with typically only about 0.5–1% lactose and 0.5–1% fat. It usually costs more and mixes thinner. Many people who are sensitive to lactose find isolate easier to take, but isolate is still dairy (D) and is not lactose-free; ask your doctor if you have a dairy allergy.

Many powders blend the two, so read the ingredient list: the first protein listed is the main one. Isolates we carry include Bluebonnet 100% Natural Whey Protein Isolate and NutraBio 100% Whey Protein Isolate; these are not Cholov Yisroel. If you keep Cholov Yisroel, the choice today is a Cholov Yisroel concentrate, or a pareve plant protein if you want something lower in lactose.

Plant proteins: usually pareve

Pea, rice, soy, hemp and other plant proteins are usually pareve, which makes them a good choice if you want a shake with or after a meat meal, or if you prefer a pareve shake. Plant proteins still need certification: the OU notes that pea protein production often includes outsourced steps, such as spray drying, that need their own supervision.

Collagen protein

Collagen powders are a different category, made from animal hides, skins or fish. Most collagen on the market is not kosher. See our collagen guide.

Passover

Year-round certification does not cover Passover. Peas and soy are kitniyot; the OU says pea protein cannot be used in its Passover-certified products. Flavored powders may also contain chametz ingredients. See our Passover guide.

Checklist

• A reliable kosher symbol on the container.
• Dairy (whey, casein): marked D; check for Cholov Yisroel if you keep it.
• Isolate vs. concentrate: isolate is 90%+ protein with less lactose and fat; concentrate costs less.
• Pareve (pea, rice, soy, hemp): good with meat meals.
• Flavored powders: the flavors and sweeteners must be covered too.
• Passover: needs separate Passover certification; peas and soy are kitniyot.

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Frequently asked questions

More guides

• Kosher certification symbols on vitamins and supplements
• How to tell if a vitamin or supplement is kosher
• Kosher capsules and gelatin: softgels, veggie caps and fish gelatin
• Kosher for Passover vitamins and supplements
• Kosher fish oil and omega-3
• Kosher probiotics: dairy vs. pareve
• Kosher vitamin D: D3, D2 and vegan options
• Is glucosamine kosher? Shellfish vs. vegetarian glucosamine
• Is collagen kosher? Bovine, fish and vegan options
• How to choose a kosher multivitamin
• Kosher prenatal vitamins: what to look for
• Kosher vitamins for kids: gummies, chewables and liquids
• Cholov Yisroel vitamins and supplements
• Is creatine kosher? Powder, capsules and gummies
• Kosher toothpaste and mouthwash
• Kosher protein bars: dairy, pareve and Cholov Yisroel
• Kosher cough drops and throat lozenges: is Ricola kosher?
• Kosher iron supplements: tablets, liquids and chewables

Sources

• NIH Office of Dietary Supplements: dietary supplements for exercise and athletic performance
• OU Kosher: whey and its kashrus explained
• OU Kosher: whey
• STAR-K: wheying the kosher possibilities
• American Dairy Products Institute: whey protein concentrate standard
• American Dairy Products Institute: whey protein isolate standard
• OU Kosher: certifying pea protein
• OU Kosher: kosher nutraceuticals and supplements, principles and process