Protein powders fall into two broad camps: animal-based and plant-based. Within those categories, there are roughly a dozen distinct types, each with different protein concentrations, digestion speeds, amino acid profiles, and best-use scenarios. The right one depends on your dietary needs, digestive tolerance, and goals.
Whey Protein: The Most Popular Option
Whey is the liquid left over when milk is curdled during cheese production. It digests quickly, making it a go-to choice around workouts. Whey also has the highest leucine content of any common protein source, at about 13.6% of its total protein. Leucine is the amino acid most responsible for triggering muscle repair and growth, which is a big reason whey dominates the market.
Whey comes in three forms:
- Whey concentrate is the least processed. It contains up to 80% protein by weight, with the rest being fat, carbs, and lactose (typically 3 to 8 grams of lactose per serving). It’s the most affordable option and has a creamier taste.
- Whey isolate goes through additional filtering to strip out most of the fat and sugar, landing at 90% or more protein by weight. Lactose drops to less than 1 gram per serving, which makes it a workable option for many people with mild lactose sensitivity.
- Whey hydrolysate is pre-broken into smaller protein fragments, so your body absorbs it faster. It’s the most expensive form and tends to taste more bitter. Athletes recovering from intense training sometimes prefer it, but for most people the speed difference over isolate is marginal.
Casein: The Slow-Release Alternative
Casein comes from the same milk as whey but behaves very differently. It forms a gel-like substance in your stomach, which slows digestion considerably. In studies tracking blood amino acid levels over seven hours after ingestion, casein delivered a steadier, more prolonged release compared to whey’s sharp spike and drop. This makes casein popular as a nighttime protein, taken before bed to supply amino acids during sleep.
The taste and texture of casein are thicker than whey, almost pudding-like when mixed with less water. Some people use this to their advantage, mixing it into a thick shake that feels more filling. It’s less ideal immediately after a workout, when faster absorption is more useful.
Soy Protein
Soy is one of the few plant proteins that contains all nine essential amino acids, making it a complete protein. Its digestibility score (called DIAAS) is 91 out of 100, which puts it well above most other plant sources and closer to dairy. Soy’s leucine content sits around 8%, notably lower than whey’s 13.6% but higher than most plant alternatives.
For people avoiding dairy entirely, soy is the plant protein with the strongest research supporting muscle-building outcomes. It blends smoothly and has a relatively neutral flavor. The main hesitation some people have involves soy’s plant estrogen compounds, though large reviews have found no meaningful hormonal effects at normal supplemental doses in men or women.
Pea Protein
Pea protein, made from yellow split peas, has become the most popular plant-based powder. It scores a 70 on the DIAAS scale, which is respectable for a plant source and means your body can use a good portion of what you consume. Pea protein is naturally free of the top allergens (dairy, soy, gluten, eggs), giving it broad appeal.
Its main limitation is that it’s low in the amino acid methionine. This is easily solved by pairing it with rice protein, which is high in methionine but low in lysine (where pea excels). Many commercial “plant blend” powders use this pea-rice combination for exactly this reason. On its own, pea protein has a slightly earthy, grainy taste that some brands mask better than others.
Rice Protein
Rice protein scores lower on digestibility than pea or soy, with a DIAAS of about 47. It’s not a complete protein on its own, lacking adequate lysine. That said, it’s one of the most hypoallergenic options available, rarely causing digestive issues. You’ll most often find it blended with pea protein rather than sold solo. When combined, the two create a complete amino acid profile that approaches dairy protein in quality.
Hemp Protein
Hemp protein comes from ground hemp seeds and is technically a complete protein, containing all nine essential amino acids, though some are present in small amounts. It’s lower in total protein per scoop than whey or pea (usually 10 to 15 grams per serving versus 20 to 25 for others), and it brings along more fat and fiber. That fiber can be a benefit if you’re looking for a whole-food-style supplement, but it also gives hemp a gritty texture and distinctly nutty, earthy flavor.
Hemp works best as a nutritional supplement rather than a serious muscle-building protein. The extra fiber and healthy fats make it a reasonable addition to smoothies when your primary goal is overall nutrition, not maximizing protein intake per calorie.
Egg White Protein
Egg white protein powder is made from dried, pasteurized egg whites. It’s a complete protein with a biological value on par with whey, meaning your body absorbs and uses it very efficiently. Its DIAAS score is 1.01 (essentially a perfect 100), the highest of any common protein source. For people who can’t tolerate dairy or soy but still want top-tier protein quality, egg white is the strongest choice.
It’s virtually fat-free and carb-free. The downside is cost (it’s typically more expensive than whey) and texture. Egg white protein can foam when blended and has a distinct taste that doesn’t disappear behind flavoring as easily as whey does.
Beef Protein Isolate
Beef protein isolate is made by hydrolyzing beef into a concentrated powder. Research suggests it can deliver muscle and strength gains comparable to whey, though its leucine content is slightly lower, meaning it may not trigger muscle repair quite as strongly per serving. Where beef protein stands out is in its amino acid profile: it’s especially rich in glycine, proline, and hydroxyproline, nutrients that support collagen formation and connective tissue health.
This makes it an interesting option for people focused on joint health alongside muscle building, or for those following a paleo-style diet that excludes dairy. Taste varies widely by brand, and lower-quality versions can have an off-putting meaty flavor.
Collagen Protein
Collagen peptides are everywhere right now, but they serve a fundamentally different purpose than traditional protein powders. Collagen is not a complete protein. It’s missing or very low in several essential amino acids, which limits its ability to build muscle. A controlled trial in older women compared 30 grams of whey to 30 grams of collagen taken twice daily for six days. Whey significantly increased muscle protein synthesis both at rest and after exercise, while collagen showed only a small increase after exercise and no meaningful effect at rest.
Collagen’s real value is for skin elasticity, joint comfort, and gut lining support. If those are your goals, collagen is worth considering as an add-on. But it shouldn’t replace a complete protein powder if you’re trying to build or maintain muscle.
How Plant Proteins Compare to Dairy
The gap between plant and animal proteins is real but often overstated. The digestibility scores tell the story clearly: egg white protein scores a near-perfect 101, soy comes in at 91, pea at 70, and rice at 47. Whey isolate lands in the same top tier as egg white. These numbers reflect how much of the protein your body actually absorbs and puts to use, not just what’s listed on the label.
For practical purposes, you can close most of the gap with plant proteins by eating slightly more per serving (an extra 5 to 10 grams) or by choosing blends that combine complementary amino acid profiles. A pea-rice blend, for example, checks nearly every box that whey does.
Heavy Metals and Contaminants
One issue worth knowing about: protein powders can contain trace heavy metals like lead and cadmium. An analysis of 160 protein powders from 70 top brands found that 47% exceeded certain safety guidelines for heavy metals. Plant-based proteins contained three times more lead than whey-based alternatives, largely because plants absorb metals from the soil they grow in. Organic products had three times more lead and twice the cadmium of non-organic options, a counterintuitive finding that likely relates to the types of soil used in organic farming.
Chocolate-flavored powders had up to 110 times more cadmium than vanilla. If minimizing heavy metal exposure matters to you, choosing a whey or egg white protein in a vanilla or unflavored variety is the simplest move. You can also look for brands that publish third-party testing results for contaminants.
Choosing the Right Type for Your Goals
- Muscle building on a budget: Whey concentrate gives you the best bang for your money, with the highest leucine content and strong digestibility.
- Lactose sensitivity: Whey isolate (under 1 gram lactose per serving), egg white, or a pea-rice blend.
- Fully plant-based diet: A pea-rice blend for muscle building, or soy isolate for the closest single-source match to whey’s amino acid quality.
- Joint and skin support: Collagen peptides as a supplement alongside a complete protein source.
- Minimal allergen risk: Rice protein or pea protein, both free of dairy, soy, gluten, and eggs.
- Overnight recovery: Casein, taken before bed to provide a slow, sustained amino acid release.