Principles of Protein

Protein is one of the three contributors of calories in our diet (the other two are carbohydrates and fat). We need to consume enough protein every day to maintain adequate health. Every cell in your body contains protein; it’s needed to build and repair muscle and maintain a healthy immune system among many of functions. 

Think all the way back to your high school biology class and you may remember that different proteins are made by combining any of the 20 amino acids, or “building blocks” of protein. Humans can produce 11 of the 20 amino acids. The other nine amino acids must be supplied from food, and are considered “essential” indicating that it is essential that we consume regularly.

When we digest protein, the protein is broken back down into its amino acid components. These amino acids then enter the bloodstream. Once there, your body reassembles them as proteins for various uses such as tissue repair and muscle building and maintenance.

Animal Sources 
Animal sources of protein such as meat, fish, poultry, eggs and milk products are considered complete proteins because they contain all nine essential amino acids. While animal sources are great sources of protein, they can also come with a heavy dose of saturated fat. Portion size is important to consider, two to three servings of protein-rich food will meet the daily needs of most adults.
Here are a few examples of how much protein is in a typical serving of some animal-based protein sources. 
• 3 ounces of cooked lean meat, poultry, or fish (a portion about the size of a deck of playing cards): provides about 21 grams of protein
• 1 egg : provides about 7 grams of protein
• 1 ounce of cheese (about the size of a 9V battery): provides about 7 grams of protein
• 1 cup of milk or yogurt: provides about 7 grams of protein

Plant Sources
Many plant sources of protein such as beans, peas, nuts, seeds and grains are considered incomplete proteins because they lack one or more of the essential amino acids. It used to be thought that since some plant sources of protein have amino acids that other do not, the best way to ensure completeness was to pair certain plant source-proteins together at a meal, this was called protein complimenting. We now know that the eating a variety if plant sources of protein over the course of a day or several days ensures adequate intake and there is no need to protein compliment at every meal. Choosing plant sources of protein several times a week does not make you a vegetarian, but substituting a lentil burger for a cheeseburger several times a month will provide plenty of protein without the heart-unhealthful saturated fat. 

Here are a few examples of how much protein is in a typical serving of some plant-based protein sources. 

• ½ cup of cooked beans or lentils~ provides about 7 grams of protein
• 1/3 cup of hummus: provides about 7 grams of protein
• ½ cup edamame (shelled): provides about 17 grams of protein
• ½ cup firm tofu: provides about 20 grams of protein