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The Difference Between Complete and Incomplete Proteins

Reviewed by Dan Brennan, MD on June 01, 2021

Protein is an important food group to include in your diet. Your body needs protein to build bones, muscles, cartilage, and skin. It also needs protein to repair cells and tissues, make and regulate hormones, supply oxygen to blood and other key areas, and aid in digestion. 

Eating protein-rich foods can also help you maintain a healthy body weight by making you feel full for longer. It stops you from wanting to eat more and filling yourself up with excess calories that can cause weight gain.‌

Having protein or amino acids before, during, or after exercise can help you recover faster, build your immunity, and help grow and maintain lean body mass. Lean body mass is the weight in your body that is free from fat.‌

It is important not only to get the right quantity of protein in your diet but also to make sure you’re eating the right types of proteins. Not all proteins are created equal.

Complete and Incomplete Proteins

‌A protein is formed out of 20 different types of amino acids (organic compounds) all connected to each other. Our body makes 11 types of amino acids on its own. But we need to get the remaining nine types of amino acids, called "essential amino acids" through other sources, such as the food we eat. The nine essential amino acids are histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine.

Incomplete proteins. If the protein you eat doesn’t have all the nine types of amino acids you need to get from food, it’s called an "incomplete protein." Incomplete proteins examples include:

  • Nuts and seeds
  • ‌Whole grains (like brown rice or whole-wheat bread)
  • ‌Vegetables
  • ‌Legumes in the form of lentils, peas, and beans. 

Complete proteins. If the protein you eat has all the 9 types of amino acids you need to get from food, it is called a "complete protein." Great sources of complete proteins are:

  • ‌Fish
  • ‌Poultry (chicken, duck, or turkey)
  • ‌Eggs
  • ‌Dairy products (milk, yogurt, or cheese, for example)
  • ‌Beef or pork
  • ‌Soy products, such as tofu and edamame  

‌This doesn’t mean that if you’re a vegetarian or vegan, your options for complete proteins are limited.

Complete Proteins for Vegetarians

‌If you’re a vegetarian or a vegan, experts recommend you eat a variety of different proteins in the form of nuts, seeds, lentils, and whole grains on a daily basis so that you’re forming complete proteins in your diet.  ‌

There are also a few sources of complete proteins that you can get from food. Among them are quinoa, buckwheat, and hempseed. But you may not get the same amount of protein that you would get from animal sources for the same serving size.

Amount of Protein You Need in a Day

Consult your doctor, registered dietitian, or nutritionist to get advice and develop a diet plan that helps you get the nutrition you need. ‌Generally, you should be aiming for 0.36 grams of protein per pound of your body weight daily. 

Also, remember to space out your proteins throughout the day. Our bodies can only take in 25 to 40 grams of protein at one time.

If you do a lot of exercising or intense training, you may need more protein than average. Protein and amino acid supplements can help you meet your daily protein needs. But don't overdo these.

Protein powders can seem like an easy way to get some protein into your diet if meeting your protein intake for the day is a challenge. But protein powders can contain sugars, artificial flavorings, thickeners, and toxic chemicals that can be harmful to your health.

It is recommended that you get your proteins from a large variety of food sources. But sometimes, chemical-free powders may be suggested, under medical supervision, when you have certain medical conditions.  

Harmful Effects of Proteins

You should try to eat a wide variety of low-fat sources of proteins as part of a well-balanced healthy diet. However, you should take care to not eat too much protein. Eating too much protein daily puts you at a higher risk for:

‌Some people have amino acid metabolic disorders which are hereditary (inherited from parents) medical conditions. Their bodies are not able to break down amino acids properly or they are not able to get amino acids into the cells. 

Treatment options for amino acid metabolic disorders include special diet plans, medicines, and supplements. Talk to your doctor if you are interested in these options.

Show Sources

SOURCES:

Cleveland Clinic: "Body Mass Index and Body Fat," "Do I Need to Worry About Eating ‘Complete’ Proteins?" 

Harvard Health Publishing: "The hidden dangers of protein powders," "When it comes to protein, how much is too much?" 

MedicineNet: "What Are the Nine Essential Amino Acids." 

MSD Manual Consumer Version: "Overview of Amino Acid Metabolism Disorders."

Piedmont Healthcare:  "What is a complete protein?" "Why is protein important in your diet? 

Phys Sportsmed: "Protein for exercise and recovery." 

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