How to Choose a Protein Powder: Types, Purity and Labels

TL;DR: Grams per serving is the number every label shouts and the least useful one on its own. Three others decide whether a protein powder is worth buying. Density: what share of the scoop is actually protein — grams of protein divided by grams per serving, and a good isolate runs over 90% protein by weight. Quality: US protein-content claims rest on a scoring system called PDCAAS, while the FAO has recommended a better one, DIAAS, that labelling rules still don’t use. Purity: in 2025 an independent round of testing on 23 protein powders and shakes found more than two-thirds carried more lead in a single serving than the tester’s own level of concern of 0.5 micrograms a day — a threshold the industry disputes, and one California has a bill to replace with mandatory lot testing from January 1, 2028. Start with your goal, then check those three.

Start here: what are you actually buying it for?

Pick the row, then use the rest of this article to read the label against it.

What types of protein powder are there, and how do they differ?

The type determines digestion speed, how much lactose comes along, and what you pay per gram of protein.

• Whey concentrate — the most common and usually the cheapest. More of the milk comes with it, meaning more lactose, carbs and fat per scoop, and a lower protein share by weight.

• Whey isolate — processed further to strip most of the lactose, fat and carbs. Higher protein share, faster digesting, costs more.

• Casein — digests slowly and thickens in liquid. Suited to long gaps between meals rather than immediately post-training.

• Blends — combine sources to spread digestion across a longer window. Useful when the powder is a meal component rather than a workout drink.

• Beef protein isolate — a non-dairy animal option, often used alongside whey.

• Plant proteins (pea, rice, hemp, soy) — the option if you avoid dairy. Single plant sources vary in amino acid profile, which is why many products combine two or more.

Notice what that list doesn’t include: exact protein percentages by type. Those numbers get quoted confidently all over the internet and they vary by manufacturer and process, so instead of repeating a range we can’t source, here’s how to get the real figure for the specific tub in your hand.

How much of the scoop is actually protein?

This is one division, and it separates products that look identical on the front of the label.

Protein density = grams of protein ÷ grams per serving.

A scoop delivering 25 g of protein out of a 28 g serving is roughly 89% protein by weight. The same 25 g out of a 40 g serving is 63% — the other 15 grams are carbs, fat, flavoring, thickeners and whatever else is in the formula. Same headline number on the front, materially different products, and the only way to tell is the division.

Two practical notes. First, the input you need is the serving size in grams, which lives at the top of the Supplement Facts or Nutrition Facts panel — not on the marketing copy. Second, and in fairness: plenty of product pages don’t publish that serving weight, ours included. If you’re shopping online and the serving weight isn’t there, the panel photo usually has it, and if it doesn’t, that’s worth an email to the brand.

For reference, Pro Series Protein Isolate publishes “over 90% protein by weight” — that’s the figure this calculation is designed to surface, and it’s the one to ask any brand for.

Is there a real measure of protein quality?

Yes, and it’s a better story than “complete protein.”

Protein quality is about the amino acid profile and how much of it you actually digest and absorb. The score underpinning US protein-content claims on labels is PDCAAS — the protein digestibility-corrected amino acid score. As a 2017 review in Nutrition Reviews describes it, regulatory frameworks in the United States are underpinned by PDCAAS, while Canada’s use the protein efficiency ratio.

The Food and Agriculture Organization of the United Nations has recommended replacing it. The successor is DIAAS, the Digestible Indispensable Amino Acid Score. A 2016 review in the same journal explains that the FAO “recently recommended the adoption of a new and improved scoring system” and that DIAAS is “based on the relative digestible content of the indispensable amino acids… and the amino acid requirement pattern,” measured using the true ileal digestibility of each amino acid — that is, measured at the end of the small intestine rather than inferred from what leaves the body.

The 2017 review is direct about why that matters: DIAAS addresses “methodological concerns about the PDCAAS… through introduction of the use of ileal amino acid digestibility coefficients and untruncated protein scores.” Untruncated is the key word — PDCAAS caps scores at 1.0, which flattens the difference between a good protein and an excellent one.

The catch, and the reason you’ve never seen DIAAS on a label: it isn’t in the rules yet. The same review notes that “before the DIAAS is widely adopted within regulatory frameworks, a comprehensive assessment is required.”

So the honest state of play: the protein claim on a US label rests on a metric the FAO has moved past, the better metric exists but isn’t required, and almost nobody publishes it voluntarily. Until that changes, “quality” is something you infer from the named source and its digestibility rather than read off a number.

How do you know a protein powder is clean?

Until recently this was a question you could wave away with “buy a reputable brand.” It isn’t any more.

In October 2025, Consumer Reports published its first protein-powder heavy-metal testing in 15 years. Across 23 products, it reported that “for more than two-thirds of the products we analyzed, a single serving contained more lead than CR’s food safety experts say is safe to consume in a day—some by more than 10 times.” At the extreme, “a single serving of these protein powders contained between 1,200 and 1,600 percent of CR’s level of concern for lead, which is 0.5 micrograms per day.” Its researchers also noted that “nearly all the plant-based products CR tested had elevated lead levels.”

Three things to hold in mind while reading that, because they change what it means:

1. 0.5 µg/day is Consumer Reports’ own level of concern, not a federal limit. Every percentage above is measured against CR’s threshold. There is no equivalent FDA limit for lead in protein powder to compare it to.
2. 23 products is a sample. It’s “more than two-thirds of the products CR tested,” not two-thirds of the category.
3. The industry disputes the method. The Council for Responsible Nutrition — the supplement industry’s trade association, so an interested party — responded that “important context is missing—specifically how products were selected, whether testing reflected typical consumer use, and how its ‘levels of concern’ were derived,” and argued that “without harmonization to established federal benchmarks, or even actual safety risk, such proprietary thresholds can overstate risk and cause unnecessary alarm.”

You can hold both: the testing found real lead in real products, and the threshold it was measured against is one organization’s judgment rather than a legal standard. What you shouldn’t do is conclude that because the threshold is disputed, the finding is nothing.

Regulators are moving regardless. California’s Senate Bill 1033 would require manufacturers of protein products sold in the state to test “a representative sample of each lot of the product for heavy metals” — defined in the bill as “arsenic, cadmium, lead, and mercury” — and to put a testing statement on the outer package and on the product page for anything sold online. As drafted, it would prohibit non-compliant protein products from sale in California commencing January 1, 2028. It’s an introduced bill, not law, and bills change or die. But the direction is lot-level testing with public results, which is a meaningfully higher bar than “third-party tested” on a label.

What to do with this as a shopper: treat “third-party tested” as an unfinished sentence. Tested for what, and can you see it?

What should not be in a protein powder?

Added sugar you didn’t ask for. Check the Added Sugars line rather than Total Sugars alone; dairy proteins carry some naturally occurring sugar, which is not the same thing.

Gums and thickeners, if you react to them. Xanthan and guar gum are texture ingredients, not villains, but they bother some people’s digestion. If shakes reliably make you bloated, they’re worth ruling out.

How our three options compare

Ours are in here, so read this as disclosure rather than a recommendation, cons included.

The verdict by use case: the blend if you want one tub for general daily use, the isolate if you’re managing carbs and fat closely or want the highest protein share, the ready-to-drink shakes if the real obstacle is that you don’t mix a shake when you’re busy. The whole range is in all protein.

For how much of any of this you actually need per day, the ISSN position stand on protein and exercise is the reference we’d point you to, and we’ve broken down the practical version in how much protein you need to build muscle and optimizing your protein routine.

When you don’t need protein powder

If you’re already hitting your protein target from food, a powder adds convenience and nothing else. That’s a real benefit — it’s just not a nutritional one, and it’s worth being clear about which you’re buying.

Chicken, eggs, dairy, fish, and legumes cover the same ground, generally cost less per gram of protein, and come with nutrients no powder replicates. Powder earns its place when you’re short on time, short on appetite, travelling, or trying to add 30 grams without adding a meal. If none of those is your situation, skip it and spend the money on groceries.

Frequently Asked Questions

What’s the difference between whey isolate and concentrate? Isolate is processed further to remove most of the lactose, fat and carbs, so it delivers a higher share of protein per gram and digests faster. Concentrate keeps more of the milk and usually costs less.

How do I check how much of a scoop is protein? Divide grams of protein by the serving size in grams from the Supplement Facts panel. Over roughly 80% is a lean product; over 90% is an isolate-grade one.

Does protein quality actually matter, or is it marketing? It matters, but the label doesn’t measure it well. US protein claims rest on PDCAAS; the FAO has recommended DIAAS, which uses ileal digestibility and untruncated scores, and it isn’t yet in US labelling rules.

Should I be worried about heavy metals in protein powder? It’s worth attention rather than alarm. Consumer Reports’ 2025 testing of 23 products found most exceeded its own 0.5 µg/day level of concern for lead in one serving; the industry disputes how that threshold was derived; and California has a bill that would mandate lot-level testing from 2028 if enacted. Look for a named third-party program you can verify.

Is plant protein worse than whey? Not worse, different — single plant sources have less complete amino acid profiles, which is why blends are common. Note also that nearly all the plant-based samples in the CR testing showed elevated lead levels, so verification matters more, not less.

The Bottom Line

Choose on your goal first, then check three numbers instead of one: how much protein per serving, what share of the serving that is, and whether the brand will tell you who tested it and for what. Protein quality has a better metric than the one on the label, purity is now a live question rather than an assumed one, and a “proprietary blend” where the protein should be named is a reason to put the tub down. If your protein already comes from food, you don’t need any of this.

Shop Jocko Protein Powder →

Disclaimer: This content is for informational purposes only and is not medical advice. Dietary supplements are not intended to diagnose, treat, cure, or prevent any disease. Consult your healthcare professional before starting any new supplement, especially if you have a medical condition, take medications, are pregnant, or nursing.

Related Articles:

• How Much Protein Do You Need to Build Muscle?
• A Science-Backed Breakdown for Optimizing Your Protein Routine

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