Along with fats and carbohydrates, protein is one of the macronutrients we need to live.
Our bodies use proteins from food to build and repair tissues, as well as make hormones, enzymes, and other things that are vital to our health.
Traditionally, meat has been thought of as our main source of protein, but there are plenty of diverse protein sources out there.
We talked to nutritionist Stephanie Cramer, administrative dietitian at Cedars-Sinai Clinical Nutrition Services, to help us understand the differences in protein sources.
Found in: meat, poultry, eggs, dairy, fish
Cramer: The human body needs 20 different amino acids. Our bodies create 11 of them (these are called “non-essential amino acids”), but we must get the other 9 from food (essential amino acids).
Animal proteins, such as meat, eggs, and milk, are complete proteins, meaning they provide all of the essential amino acids our body needs. Animal products provide the highest-quality protein sources.
On the flip side, several studies have linked red meat consumption to an increased risk of heart disease, stroke, and early death.
Further studies have shown that eating more processed red meat may actually increase the risk of dying from heart disease. Processed meats include smoked meat, sausage, hot dogs, salami, bacon, and canned meat.
Found in: beans, legumes, nuts, seeds, quinoa, leafy greens such as broccoli and kale, whole grains
Cramer: Certain plants can be excellent sources of protein, often with fewer calories and fewer potentially harmful effects than animal products.
Some plant proteins, such as quinoa, are complete proteins—which means they contain all 9 essential amino acids that we need. Others are missing some amino acids, so it is important to eat a variety of foods to get all 9.
Studies show that people on vegetarian or vegan diets (which often rely on plant protein) are at a lower risk of certain diseases including cancers, type 2 diabetes, hypertension, obesity, and ischemic heart disease.
Found in: dairy products such as milk, cheese, and yogurt, whey protein supplements, hydrolyzed-whey infant formula
Cramer: Whey protein is a popular dietary protein supplement and one of the main proteins found in dairy products; it’s a byproduct of cheese manufacturing.
Its biological components have been shown to demonstrate a range of immune-enhancing properties. Whey can also work as an antioxidant, antihypertensive, antiviral, and antibacterial agent.
Whey is also used in some infant formulas to help reduce colic and in supplements because it is believed to benefit exercise performance.
Found in: soybeans (edamame), miso, soy sauce, tofu, tempeh
Cramer: Soy protein is found in soybeans, a legume that does not contain cholesterol and is low in saturated fat.
Soybeans are one of the only vegetable foods that contain all 9 essential amino acids. They are also a good source of fiber, iron, calcium, zinc, and B vitamins.
Eating soy protein in place of animal protein has been found to reduce bad cholesterol and triglycerides, which are linked to heart disease. Other studies have shown that soy contributes to blood sugar control and reduced body weight.
One serving a day (e.g., 1 cup soymilk, ½ cup tofu or soybeans) may be effective for cancer prevention because the phytochemicals in soy may prevent tumors from creating blood vessels that would promote tumor growth.