What Is Protein and Which Foods Provide It?

Protein is a nutrient made of amino acids that your body uses to build and repair muscle and other tissues, make enzymes and hormones, and support immune function. You get it from both animal and plant foods, and the amount varies widely by food. This explainer covers what protein does, how to tell complete from incomplete sources, which foods provide it, and how to compare protein content so you can meet your needs.

What Protein Does in the Body

Protein is not a single substance but a family of molecules built from chains of amino acids. Your body breaks dietary protein into amino acids and reassembles them into the proteins it needs. Its main roles include:

• Structure and repair — muscle, skin, bone, and organ tissue
• Enzymes — proteins that drive chemical reactions, including digestion
• Hormones — some hormones, such as insulin, are proteins
• Immunity — antibodies are proteins that help defend against pathogens
• Transport and storage — proteins carry substances through the blood and store nutrients

Because your body does not store amino acids the way it stores fat, you need a regular supply from food.

Essential Amino Acids: Complete vs Incomplete Protein

Your body can make many amino acids, but nine are essential — you must get them from food. This distinction drives the common "complete vs incomplete" framing:

Incomplete sources are not inferior — they simply need pairing. Eating complementary plant proteins across the day (for example, beans with rice, or peanut butter with whole-grain bread) supplies the full set of essential amino acids. You do not need to combine them in the same meal; the overall daily pattern is what matters.

Foods High in Protein

Amounts below are approximate and vary by cut, variety, and preparation. Use them as a starting point, then check specific values in a nutrition database or label.

Animal sources

• Chicken breast — roughly 30 g per 100 g cooked
• Lean beef — roughly 26 g per 100 g cooked
• Salmon — roughly 25 g per 100 g cooked
• Eggs — about 6 g per large egg
• Greek yogurt — roughly 10 g per 100 g
• Milk — about 8 g per cup

Plant sources

• Soybeans / tofu / tempeh — roughly 15–17 g per 100 g (soy is a complete protein)
• Lentils — roughly 9 g per 100 g cooked
• Chickpeas and most beans — roughly 7–9 g per 100 g cooked
• Quinoa — about 4 g per 100 g cooked
• Nuts and seeds — roughly 5–7 g per 30 g (almonds, peanuts, pumpkin seeds)
• Peanut butter — about 7 g per 2 tablespoons

Plant foods also deliver fiber and micronutrients, so combining categories is a practical way to hit protein targets without relying on a single source.

How to Read a Label and Compare Protein

To compare protein across foods, use the same two numbers every time:

1. Grams of protein per serving — found on the Nutrition Facts panel.
2. Serving size — because "per serving" is meaningless without it.

A food with 12 g protein per 30 g serving is more protein-dense than one with 12 g per 100 g. When comparing packaged foods, check that serving sizes are similar, or convert both to protein per 100 g for a fair comparison.

For whole foods without labels — meat, fish, produce, grains — use a nutrition database to look up values. Tools like MyFoodData let you log foods and view comparisons of everything you log, and its recipe calculator lets you tab the ingredients and view the amino acid profile of a recipe. That is useful when you want to check whether a plant-based combination covers all essential amino acids rather than just counting total grams.

Practical Daily Intake and Tips

General guidance for healthy adults is roughly 0.8 g of protein per kilogram of body weight per day, though needs rise with activity level, pregnancy, and age. For a 70 kg adult, that is about 56 g per day. Athletes and older adults often need more; individual needs vary, so treat this as a baseline rather than a prescription.

Tips for meeting your needs:

• Anchor each meal with a protein source — eggs at breakfast, beans or meat at lunch and dinner.
• Combine plant proteins across the day rather than worrying about each meal.
• Use a tracker to see your actual intake instead of estimating. Logging a few typical days reveals patterns quickly.
• Check amino acid profiles for plant-heavy diets, not just total grams, to confirm you are covering the essentials.

If you have a health condition that affects protein needs, such as kidney disease, follow guidance from your clinician rather than general targets.