Vegans are often asked this question.
Protein is an important component of every cell in the body; it is the building block of bones, muscles, cartilage, skin, and blood. Your body uses protein to maintain and repair tissue and to make enzymes and hormones. Protein is crucial for your immune system, heart, and respiratory functions. (info from WebMD)
I need about 50 grams of protein per day, and I easily meet or exceed this amount.
To calculate your protein (and other nutrient) needs, go to NutritionData’s Daily Needs Calculator.
Some sources of protein for us include:
18 grams = 1 cup of lentils
15 grams = 1 cup black beans
11 grams = ¼ of a package of SoyBoy tofu
8 grams = sprouted grain English muffin
7 grams = ¼ cup almonds
5 grams = 1 cup brown rice
4 grams = 1 cup steamed broccoli
All plants contain protein; plants are so rich in protein that they can supply the protein needs of the earth’s largest animals: elephants, hippopotamuses, giraffes, and cows. So of course, the protein needs of humans can be met by eating only plants. Plants are the original source of protein; they can synthesize all of the amino acids that are used to build proteins, but animals cannot. (info from McDougall Newsletter)
For more information see Protein in a Vegan Diet.