It’s well known that protein is an essential building block of life, but the details of complete versus incomplete proteins are less understood. The good news is you don’t really need to understand in most cases.
The topic comes up most often when discussing vegan and vegetarian diets, since most animal products are classified as complete proteins. This means they contain adequate quantities of all nine “essential” amino acids the body needs to form proteins but does not produce on its own and must obtain from food.
There are 11 other nonessential amino acids our bodies do produce, which bind with these other nine to create proteins that build and repair muscle and other body tissue, regulate pH levels, balance fluids, produce antibodies and perform many other bodily functions.
The nine essential amino acids are histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan and valine. Many of them are found within foods that are incomplete proteins, but not at high enough levels to meet your body’s needs.
Besides meat, fish, dairy, eggs and other animal-based sources, complete proteins also include a few plant sources like soy, quinoa, hemp and buckwheat.
You can find just about everything else that contains protein under “incomplete proteins,” including vegetables, nuts, seeds, beans and legumes and fruits (not a huge source but every little bit counts).
In the past people, especially vegans and vegetarians, have been advised to “pair” proteins at every meal to form a complete protein, such as peanut butter on bread or beans with rice. But today, most nutritionists say eating a varied diet each day will provide the nutrients you need.
The bottom line is that everybody needs to consume protein, around 50 grams daily though recommendations vary with age and activity level. With all the potential proteins available to us, you’re likely to eat all of the essential amino acids in the course of a day, though if you have any concerns, ask your health care providers.