More About Macronutrients: Protein

We always hear that eating more protein-rich foods like fish and eggs is good for you, but what are the specific benefits of maintaining a steady protein intake? Let's find out.

Home > Food & Nutrition > More About Macronutrients: Protein

What is Protein?  

Credit: Shutterstock (protein structure)

Protein is sometimes referred to as a single molecule when discussing nutrition labels, but they are in fact a complex molecule made up of amino acids. There are 20 common amino acids categorized as essential or non-essential. Essential amino acids cannot be synthesized by the body so they must be obtained from food.  Non-essential amino acids can be synthesized internally.  

Essential Amino Acids   Non-essential Amino Acids  (*Conditionally Essential)  
Histidine  Alanine * 
Isoleucine  Arginine 
Leucine  Asparagine 
Lysine  Aspartic acid 
Methionine  Cysteine * 
Phenylalanine  Glutamic acid 
Threonine  Glutamine * 
Valine   Glycine * 
  Proline * 
  Tyrosine * 


* Non-essential amino acids may become ‘conditionally essential’ in special cases like times of illness, stress, or wound healing.  

What are the functions of protein?

Credit: Shutterstock
  1. Provides energy: Protein provides 4kcal per gram and is the most satiating macronutrient so it can help with weight loss by reducing hunger. 
  2. Required for growth and development.  
  3. Builds and repairs cells and tissue: Protein is needed for muscle protein synthesis.  Building muscle isn’t just about looks; it can increase resting metabolic rate and improves blood sugar control.   
  4. Important for body processes such as blood clotting, immune response, vision, and production of hormones, antibodies, and enzymes.  A fun fact is that everything active in the body is a protein!  
  5. Provides structure: Protein is part of skin, nails, muscle, and bone.  
  6. Balances body fluids: Protein is found in most body fluids and proteins regulate the process to maintain fluid balance.  

Where can we find protein?  

Protein bowl.

Credit: Shutterstock

Protein is found in a huge range of plant and animal foods. Good animal choices include lean skinless poultry, seafood, and eggs. It is recommended to limit or completely avoid red and processed meats and poultry due to health and environmental concerns. Good plant choices include legumes, nuts, seeds, and whole grains, while vegetable protein can also contribute. Plant proteins have the added bonus of containing fiber and phytochemicals. Phytochemicals are not found in animal products and are mostly removed in processed foods such as soy protein isolate.  

Lysine is an amino acid that vegans should make sure to get enough of. Lysine is found in peanuts, beans, lentils, peas, soybeans (tofu, tempeh, soy milk), and to a lesser extent pumpkin seeds and quinoa. An amino acid for athletes to consider (vegan especially) is leucine since it important for muscle protein synthesis. Plant proteins do not need to be combined since eating a variety will ensure adequate intake.  

Food   Portion Size   Calories   Protein (Grams) 
Tofu   3 oz   123  8 
Lentils   1 cup (198 g)  202  18 
Black bean  1 cup (172 g)  228  16 
Chickpea  1 cup (164 g)  268  15 
Quinoa   1 cup (185 g)  222  8 
Edamame   1 cup (155 g)  188  18 
Peanuts   1 oz (28 g)  166  7 
Chia seeds   1 oz  138  5 
Salmon   3 oz  155  22 
Egg, large    71  6 
Chicken, skinless   3 oz  141  28 

 How much protein do you need every day? 

The recommended daily value for protein is a hotly debated topic and can vary depending on age, pregnancy or breastfeeding, illness, disease, injury, and activity level. The current minimum requirement for most healthy adults is 0.8 g/kg but you can consume a slightly higher amount to error on the side of caution.  

  • Average person (vegan or omnivore): 1 g/kg 
  • Elderly (impaired absorption): 1.0-1.3 g/kg
  • Athlete (training type / volume / muscle mass goal): 1.2 g/kg- 2.0 g/kg
  • Muscle protein synthesis (max utilization): 25-30 grams or 0.4 g/kg per 2-4 hours  

(The unit “g/kg” refers to grams of protein per kilogram of your body weight.)

Research suggests that it is ideal to spread out protein intake for maximum muscle protein synthesis. There is some research in opposition of this theory, but for now, it is ideal to spread it out over 2–4-hour intervals or up to 2 hours post exercise.  

Start Adding Protein to Your Diet

You are likely getting enough protein and a diverse array of amino acids if you are eating a varied diet. There is no need to over-think or worry about protein when you don’t consume a lot of sugary and processed foods. If you are after a superhero like six pack or have specific athletic performance goals, protein timing and amount requires some planning. There is little concern about too much protein unless you have impaired kidney function or are eating so much that plant foods are being crowded out.

Protein gets a lot of special attention, and it is well deserved. However, there are two other important macronutrients (fat and carbs), less we forget, that are also important for body function. They are not the villains that they are sometimes made out to be and I will cover this in future blog posts.