The best protein sources, ranked by biological value, are whey, eggs, milk, fish, lean poultry and meat, and soy. Most animal proteins and soy are complete, meaning they contain all nine essential amino acids in useful amounts. Other plant proteins are slightly lower quality on their own but combine easily across a varied day of eating. This guide ranks top sources and explains how to choose the right mix for your goals.
What Makes a Protein Source “Best”?
Three criteria separate higher-quality proteins from lower-quality ones:
- Completeness. A complete protein contains adequate amounts of all nine essential amino acids.
- Biological value (BV). A measurement of how much of the nitrogen absorbed from a protein is retained and used by the body.
- Digestibility. The PDCAAS and the newer DIAAS scores combine amino acid content with how much the body absorbs.
High scores in these measures matter most when protein intake is near the minimum. When you eat well above the minimum, total intake and variety matter more than any single food’s score.
Biological Value Table
| Source | Biological Value | Complete? | Protein per Serving |
|---|---|---|---|
| Whey protein isolate | 104 | Yes | 24 g / scoop |
| Whole egg | 100 | Yes | 6 g / large egg |
| Cow’s milk | 91 | Yes | 8 g / cup |
| Casein protein | 77 | Yes | 24 g / scoop |
| Fish (cod, salmon, tuna) | 83 | Yes | 17-27 g / 3 oz |
| Beef | 80 | Yes | 22-26 g / 3 oz |
| Chicken | 79 | Yes | 26-31 g / 3 oz |
| Soy protein | 74 | Yes | 7-17 g / serving |
| Quinoa | 73 | Yes | 8 g / cup cooked |
| Lentils | ~50 alone | Low in methionine | 18 g / cup cooked |
| Wheat protein (seitan) | 54 | Low in lysine | 25 g / 3.5 oz |
| Peanuts | 55 | Low in methionine | 7 g / oz |
Top Animal Protein Sources
Eggs
Eggs are the gold standard, scoring 100 on the biological value scale. Two large eggs provide 13 grams of complete protein and all nine essential amino acids in near-ideal ratios. The yolk adds choline, B12, and vitamin D.
Poultry
Skinless chicken breast packs 31 grams of protein per 3.5-ounce cooked serving with minimal fat. Turkey breast is nearly identical. Both are staples for anyone tracking calories alongside protein.
Fish and Seafood
Salmon, tuna, cod, sardines, and shrimp deliver high-quality protein with omega-3 fatty acids. The American Heart Association recommends two 3.5-ounce servings of fatty fish weekly for heart health.
Lean Red Meat
Top sirloin, tenderloin, eye of round, and 93/7 ground beef pack 22-26 grams of protein per 3-ounce serving. Red meat is also a leading source of iron, zinc, and vitamin B12. Keep portions moderate and build meals around it rather than centering on large cuts.
Pork
Pork tenderloin is as lean as chicken breast and has similar protein density. It is also relatively inexpensive.
Top Dairy Protein Sources
Greek Yogurt
Straining multiplies the protein to about 20 grams per cup for nonfat plain Greek yogurt, compared to 9 grams in regular yogurt. Skyr is similar.
Cottage Cheese
Low-fat cottage cheese provides about 19 grams of protein per cup and is rich in slow-digesting casein, which makes it a popular bedtime snack for sustained amino acid release.
Milk
One cup of skim or low-fat milk provides 8 grams of complete protein. Ultra-filtered milks (such as Fairlife) deliver 13 grams per cup with the same calcium benefits.
Cheese
Hard cheeses like cheddar and Parmesan concentrate protein to 7-10 grams per ounce. They are calorie dense, so measure portions if weight is a goal.
Top Plant Protein Sources
Soy Foods
Tofu, tempeh, edamame, and soy milk are the only plant proteins considered complete on their own. A cup of edamame has 17 grams, tempeh has 17 grams per 3 ounces, and firm tofu has 15 grams per 3.5 ounces.
Legumes
Lentils and beans provide 15-18 grams of protein per cooked cup along with significant fiber. They are incomplete (low in methionine) but pair well with grains, seeds, or nuts across the day.
Seitan
Made from wheat gluten, seitan leads plant sources for sheer density at 25 grams per 3.5 ounces. Not suitable for anyone avoiding gluten.
Nuts, Seeds, and Whole Grains
Pumpkin seeds, almonds, peanuts, oats, and quinoa each deliver 6-9 grams per typical serving, mostly to support daily variety rather than serve as a primary protein base.
Protein Supplements and When to Use Them
Supplements are useful when whole foods are inconvenient or protein targets are high (athletes, older adults, people recovering from illness, vegetarians building muscle).
| Supplement | Protein / Scoop | Notes |
|---|---|---|
| Whey protein isolate | 24-28 g | Highest BV; fast absorption; lactose-low |
| Whey protein concentrate | 20-24 g | Contains more lactose; lower cost |
| Casein protein | 24 g | Slow release; good before bed |
| Soy protein isolate | 20-25 g | Complete plant option |
| Pea protein isolate | 20-25 g | Hypoallergenic; pair with rice for completeness |
| Blended plant (pea + rice + hemp) | 20 g | Complete amino acid profile |
| Collagen peptides | 10-20 g | Not complete; do not count as only protein source |
The National Institutes of Health notes that protein powders are generally safe for healthy adults, but they are regulated as supplements rather than foods. Look for third-party testing (NSF Certified for Sport, Informed Choice).
Combining Plant Proteins
To get all essential amino acids from plants, combine a legume with a grain, nut, or seed. You do not need to eat them in the same meal; the body pools amino acids across the day. Classic pairings:
- Beans and rice
- Hummus and pita
- Lentil soup with whole-grain bread
- Peanut butter and whole-grain toast
- Tofu stir-fry with brown rice
How Much Protein You Need
The recommended dietary allowance for adults is 0.8 grams per kilogram of body weight. Active adults, older adults, and people managing weight loss often benefit from 1.0-1.6 grams per kilogram. That means 55-110 grams daily for a 150-pound adult.
Spread protein across meals: aim for 20-30 grams per meal to maximize muscle protein synthesis and blood sugar stability. For more on portioning and pairings, see our guides to good sources of protein and high-protein low-carb foods, plus the main diet and nutrition hub.
Protein and Prediabetes
Protein-rich meals raise blood sugar less than carb-heavy meals and support the satiety needed for weight loss, a first-line strategy for reversing prediabetes. Pair protein with fiber-rich vegetables and whole grains to flatten post-meal glucose curves.
The Bottom Line
The best protein sources by quality are eggs, whey, dairy, fish, lean meats, and soy. Plant proteins are slightly lower in biological value but work well in a varied diet with simple pairings. Target 20-30 grams of high-quality protein at each meal from a mix of animal and plant foods, and use supplements when whole foods are impractical. Variety plus consistency beats chasing any single “best” source.
