How Is Protein Powder Made? Types and How to Choose
How whey, casein and plant protein powders are made, how the types differ, how much to take and how to choose one, with sources. Checked October 2026.
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I am Fred, a marketer, not a doctor or dietitian. This is the starting page for everything about protein powder on this site: how the powder in the tub is actually made, what separates the main types, what the research says it does, how much to take, and how to pick one without trusting the label blindly. AI helps me draft; every claim links to its source. Checked October 2026.
The short answer
- How it is made: whey powder is the liquid left over from cheese making, filtered to concentrate the protein and spray-dried. Plant powders are made by dissolving the protein out of peas, soy or rice, separating it, and drying it.
- Which type: whey if you eat dairy, whey isolate if lactose bothers you, a pea or soy based powder if you avoid animal products. Casein is the slow option. Collagen is not a substitute for any of them.
- Does it work: with strength training, extra protein adds a modest amount of strength and muscle. Past about 1.6 g of protein per kg of body weight a day, more does not add muscle (Morton et al., British Journal of Sports Medicine, 2018).
- How much: 20–40 g per serving; timing matters much less than your total for the day (International Society of Sports Nutrition position stand, 2017).
- How to choose: look for a certification you can find in the certifier's own database, check heavy-metal test results, and compare price per 25 g of protein, not price per tub.
How is protein powder made?
Whey and casein: from cheese making
Milk protein is roughly 80% casein and 20% whey. To make cheese, rennet or acid is added to milk; the casein clumps into curd, and the liquid that drains off is whey. US regulations define whey exactly that way: the liquid left after separating the curd in cheese making. One pound of cheese leaves about nine pounds of liquid whey (USDA technical report on whey protein concentrate, 2015).
That liquid is about 93% water and less than 1% protein; most of the rest is lactose (USDA technical report on whey protein concentrate, 2015). To turn it into protein powder, manufacturers:
- Pasteurize the whey.
- Ultrafilter it: membranes hold back the large protein molecules and let water, lactose and minerals pass through.
- Diafilter: add water and filter again to wash out more lactose and minerals.
- Evaporate and spray-dry the concentrated liquid into powder.
Stopping earlier gives whey protein concentrate, which ranges from 34% to 85% protein; filtering further gives whey protein isolate, with at least 90% protein and very little fat or lactose (USDA technical report on whey protein concentrate, 2015). Hydrolyzed whey goes one step further: enzymes break the protein into shorter pieces, which makes it more expensive and a little bitter. Flavor, sweetener and thickeners are blended in at the end, which is why a flavored scoop usually has less protein than an unflavored one.
Casein powders come from the curd side of milk. Micellar casein is separated from skim milk by filtration and keeps casein's natural structure, which is why it digests slowly.
Plant proteins: extracted, then dried
Pea protein is usually made by milling dried yellow peas, dissolving the protein in slightly alkaline water, removing the starch and fiber, then lowering the acidity so the protein drops out of the liquid, where it is collected, neutralized and spray-dried. Some producers use dry fractionation instead, separating protein from starch by particle size without water, which usually gives a lower-purity concentrate (Harasym et al., Molecules, 2025). Soy protein isolate is made in a similar wet process from defatted soybean flakes.
Ready-to-drink shakes are a different product: many are made from milk that is ultrafiltered to concentrate its protein and remove most of the lactose, the same membrane idea used for whey, applied to whole milk. They are convenient and cost more per gram of protein than powder.
The main types compared
| Type | Made from | Protein in the powder | Lactose | Worth knowing |
|---|---|---|---|---|
| Whey concentrate | Cheese whey, filtered | 34–85% (most sports powders use about 80%) | Some | Cheapest dairy option; can upset lactose-sensitive stomachs |
| Whey isolate | Whey, filtered further | At least 90% | Very little | Usually tolerated by people with mild lactose intolerance; costs more |
| Hydrolyzed whey | Whey pre-digested with enzymes | Usually isolate level | Very little | Costs the most; no clear muscle advantage for most people |
| Casein | The curd part of milk | About 80% or more | Some | Digests slowly; often taken before sleep |
| Pea | Yellow peas, wet-processed | About 80% or more | None | Cheapest per gram of protein in my data; less leucine than whey |
| Soy | Defatted soybeans | About 90% (isolate) | None | Complete plant protein; a common allergen |
| Rice, hemp and blends | Brown rice, hemp seed, mixes | Varies widely | None | Blends combine plants to balance amino acids |
| Collagen | Animal hides, bones or fish skin | About 90% | None | Not a complete protein; does not replace the types above |
Whey percentages are from the USDA technical report on whey protein concentrate, 2015; the other figures are typical ranges, so check the label of the product you are looking at.
Is whey better than plant protein?
Per gram, dairy proteins are digested more completely. In a direct comparison, the amino acids in whey isolate, whey concentrate and milk protein were more digestible than those in pea protein concentrate and soy isolate (Mathai et al., British Journal of Nutrition, 2017). Whey also has more leucine, the amino acid most linked to switching on muscle building. Plant powders close part of the gap by blending sources or by using a slightly bigger scoop. If you do not eat dairy, a good pea or soy powder is a reasonable choice; see the best vegan protein powders comparison.
What protein powder actually does
Muscle and strength. The largest analysis I found pooled 49 trials with 1,863 people doing strength training for at least six weeks. Protein supplements added, on average, about 2.5 kg to the one-rep max and 0.3 kg of lean mass compared with training alone. The effect was smaller in older people and larger in people who already trained, and it stopped growing above a total intake of about 1.6 g of protein per kg of body weight a day (Morton et al., British Journal of Sports Medicine, 2018). One author has received funding from the US dairy industry.
Convenience. The honest main benefit: protein powder is an easy way to reach a protein target without many extra calories. The ISSN position stand says most people who exercise can get enough protein from food, and supplements are a practical way to do it (International Society of Sports Nutrition position stand, 2017).
Weight loss. Protein powder is food, not a fat burner. It helps only to the extent that it replaces something higher in calories and keeps you full.
Kidneys. In healthy adults, an analysis of 28 trials found that higher-protein diets did not change kidney function differently from normal-protein diets (Devries et al., Journal of Nutrition, 2018). If you have kidney disease, ask your doctor first; that advice is different.
How much to take, and when
- Per day: 1.4–2.0 g of protein per kg of body weight from all sources is enough for most people who exercise (International Society of Sports Nutrition position stand, 2017). For a 70 kg person that is about 100–140 g a day, mostly from food.
- Per serving: 20–40 g of protein, or about 0.25 g per kg of body weight (International Society of Sports Nutrition position stand, 2017).
- Timing: once total daily protein is accounted for, taking it right around a workout made no clear difference to strength or muscle in a meta-analysis of 20–23 trials (Schoenfeld et al., 2013). Take it when it is convenient. Casein before bed is an option if you like the idea of a slow protein overnight (International Society of Sports Nutrition position stand, 2017).
- How to take it: with water for the fewest calories, with milk for extra protein, or in a smoothie, oatmeal or yogurt.
Safety: what the label does not tell you
In the US, the FDA does not approve dietary supplements before they are sold; the company is responsible for safety and for an accurate label. Protein powders are also a known source of heavy metals. In October 2025 Consumer Reports tested protein powders and shakes and found that plant-based products averaged about nine times more lead than dairy-based ones (Consumer Reports, Oct 2025, updated Jan 2026). That does not make every plant powder unsafe, but it is a reason to look for published test results.
Third-party certifications such as NSF Certified for Sport and Informed Choice check what is in the tub against what is on the label and screen for banned substances. A certification only counts if you can find the product in the certifier's own database; a logo on a web page is not proof.
How to choose a protein powder
- Pick the type from the table above: dairy or plant, and isolate if lactose is a problem.
- Check the protein per scoop and the ingredient list. A long list of fillers, or a "proprietary blend" without amounts, is a reason to look elsewhere.
- Look up the certification in the certifier's database, not on the brand site.
- Check heavy-metal results where they exist, especially for plant powders.
- Compare price per 25 g of protein: price ÷ (servings × grams of protein per serving) × 25.
Detailed comparisons on this site: best vegan protein powders, best protein powder for women, and, if you are looking at collagen, best collagen supplements.
Examples by type
One example of each common type from my comparisons, so you can see what the numbers look like. Prices are one-time iHerb US prices checked on 20 and 27 October 2026; check the current price before you buy.
Whey blend, certified: Optimum Nutrition Gold Standard 100% Whey
24 g protein per scoop · $2.33 per 25 g of protein · $64.99
A mix of whey isolate, concentrate and hydrolyzed whey. NSF Certified for Sport (confirmed in the NSF database). In the 2025 Consumer Reports test, the chocolate version had 56% of Consumer Reports’ daily lead level of concern (0.5 mcg) in one serving.
Whey isolate, cheapest: California Gold Nutrition Sport Whey Protein Isolate
27 g protein per scoop · $1.90 per 25 g of protein · $30.80
Unflavored whey isolate from iHerb’s own brand, with the lowest price per gram of protein among the whey isolates I compared. I found no third-party certification for it.
Hydrolyzed whey isolate: Dymatize ISO100 Hydrolyzed Whey Protein Isolate
25 g protein per scoop · $2.97 per 25 g of protein · $59.41
Pre-digested whey isolate, Informed Choice certified (confirmed in the database). You pay extra for hydrolysis, which has no clear muscle advantage for most people.
Pea protein, cheapest overall: NOW Foods NOW Sports Pea Protein
24 g protein per scoop · $0.91 per 25 g of protein · $23.53
Single-ingredient, unflavored yellow pea protein isolate, the cheapest per gram of protein of all the powders I compared. I could not verify its Informed Sport listing because the database blocked automated access.
How I chose
- Facts about manufacturing come from a USDA technical report and a 2025 scientific review; health claims come from meta-analyses and position stands, linked where they appear.
- Product examples come from my detailed comparisons, which use only iHerb US listings, certifications found in the certifier's own database, and published lead tests.
- I did not test or taste these products.
Frequently asked questions
Is protein powder made from milk?
Whey and casein powders are; whey is the liquid left after making cheese. Pea, soy, rice and hemp powders are made from plants and contain no milk.
Is protein powder processed food?
Yes. Whey and plant proteins are filtered or extracted and then dried, and flavored powders add sweeteners and thickeners. Unflavored powders with one ingredient are the least processed option.
Can I build muscle without protein powder?
Yes. Total daily protein and training are what matter; powder is a convenience (Schoenfeld et al., 2013).
Which type of protein powder is best?
For most people who eat dairy, whey: it is well digested, high in leucine and cheap per gram. Isolate if lactose bothers you; pea or soy if you avoid dairy.