Have you had your protein today? While this powerhouse shouldn’t displace other nutrients in your diet (such as the complex carbohydrates in fruits, veggies, and whole grains), it’s right up there as an important macronutrient. Amino acids are the building blocks of protein. The specific amino-acid sequence and length of the amino-acid chain determine how a particular protein behaves. Let’s take a look at a few different kinds.

Whey

Whey is the liquid component of dairy products. It appears to have some unique health properties, thanks to powerful ingredients that may strengthen the immune system. It’s rapidly absorbed by the body, making it ideal for consumption after a workout. Make sure you don’t pour off the liquid in a yogurt container. That contains whey protein. Stir it in!

Casein

Casein is the main protein in milk. You can also get casein from cottage cheese, yogurt, and many meal-replacement products and protein powders. Casein is absorbed more slowly than whey because it curdles in the stomach–hence its designation as a slow-acting or time-release protein. One of its benefits is an anticatabolic effect: It protects against muscle breakdown.

Eggs

Eggs are a great source of high-quality protein. In fact, some experts consider the amino-acid profile of eggs to be the best of all food sources. After versatility, the next best thing about eggs is that they are a cost-effective source of protein. A dozen provides almost as much protein (about 84 grams) as a pound of beef (112 grams).

Soy

The popularity of soy has surged, along with the number of foods that now have soy alternatives (think Tofurkey). Soy had even been granted a thumbs-up by the US Food and Drug Administration to carry the following health claim on food labels: “Diets low in saturated fat and cholesterol that include 25 grams of soy protein a day may reduce the risk of heart disease.”

Each protein type has unique characteristics. That means we shouldn’t rely on just one protein food as our exclusive source of muscle-building nutrition. Go for variety.