By Roberta H. Anding, MS, Baylor College of Medicine and Texas Childrens HospitalEdited by Kate Findley and proofread byAngelaShoemaker, The Great Courses DailyUnlike fat and carbohydrates, our bodies cannot store protein, which makes it essential to have a daily intake of protein in our diets. Photo By Oleksandra Naumenko / ShutterstockWhy We Need Complete Proteins
Before learning how to combine proteins, first its important to understand why this is necessary. As human beings, we have, unfortunately, an endless ability to store fat. And, we have a small ability to store carbohydrate in our muscles and our liver.
We cannot, however, store protein. In order to make new protein, the body needs a daily supply of amino acids.
If we cant store protein, any loss of body protein is going to represent loss of function. All the functions of protein, including the benefits that protein provides for post-surgery recovery, infant growth, and immune system support, will be lost as well. Thus, amino acids are needed to replenish our bodys supply of protein.
Some proteins contain all of the essential amino acids that we need to build new proteins. Theyre often called complete proteins. Usually, they are of animal origin, such as milk, cheese, chicken, fish, and red meat.
An exception to the rule is soybean, which is a plant protein and can be found in tofu. Soybean is as equally nutritious as the other sources of complete proteins that contain all of the essential amino acids.
Other proteins can be missing an essential amino acid, or theyre not contained in an adequate amount. These are called incomplete proteins. Theyre lacking one or more essential amino acid.
Most breads contain between two and three grams of protein per serving, but its not a complete protein. Similarly, nuts, rice, beans, and vegetables are all good sources of protein, but are incomplete by themselves.
Theyre going to need something else to balance out the essential amino acid thats missing. This is called combining proteins. You combine a protein that complements the missing amino acid in an alternative way, making a complete protein.
If you have a missing amino acid, or that amino acid is in short supply, protein synthesis stops. It doesnt slow. It stops, because youre missing the structures to complete that protein.
This is called a limiting amino acid. Thats why its important to make sure youre getting a balance of protein-containing foods.
The only time I ever really see an issue with this in the United States is in people who decide to become vegan, Professor Anding said.
Vegans eliminate all sources of animal protein, and you can be very healthy on a vegan diet. You just have to be wise in the way that youre combining proteins.
For example, cereal grains are low in the essential amino acid lysine, and soybeans and other beans can be used in place of low-lysine foods to complement that. Red beans and rice is a great example of complementary proteins. Peanut buttera nutand breada grainare also complementary proteins.
We used to believe that you had to have two incomplete proteins, like rice and beans, at the same meal. Science doesnt support that belief any longer. You should still have them within the same day, but you dont have to eat them within the same meal.
Therefore, if you like to start out your day with a spoonful of peanut butter and a banana, you have an incomplete protein, but if you have a granola bar later in the morning, youve now had that missing essential amino acid. It wasnt at the same meal, but it was on the same day. Its not difficult to balance amino acids if youre eating on a frequent basis.
Professor Roberta H. Anding is a registered dietitian and Director of Sports Nutrition and a clinical dietitian at Baylor College of Medicine and Texas Childrens Hospital. She also teaches and lectures in the Baylor College of Medicines Department of Pediatrics, Section of Adolescent Medicine and Sports Medicine, and in the Department of Kinesiology at Rice University.
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Complete Your Diet and Optimize Your Health by Combining Proteins - The Great Courses Daily News
