Protein is another one of three essential macronutrient groups. Apart from providing energy in the form of 4 calories per gram, proteins are mostly used as building blocks and are the major structural component of all body cells. Because of these properties, they are crucial for growth, development, and maintenance of a healthy organism.
Proteins are essentially numerous amino acids linked into polypeptide chains by peptide bonds. In order for amino acids to be absorbed, long chains have to be broken down by HCl during the digestion process.
Because proteins are mainly used as building blocks, they are very rarely used for energy. Actually, they are the last resort for the body to look for energy when food is not available. Recap of energy source chain
How much protein should you consume? As always, it depends on many factors. The amount of protein needed depends on overall energy intake, energy expenditure, body weight, age, physical activity as well as personal goals. For a regular person, it is recommended to consume about 0.8g of protein per every kilogram of body weight. So if you weigh 70kg, you should aim to consume 56g of protein throughout the day. Just for reference, a medium chicken breast has 30g of protein. An active person should aim for consuming 1.2g – 1.8g of protein per every kg of body weight. Various research studies suggest that increased protein intake is recommended during pregnancy, breastfeeding, injury or weight loss.
No matter what your personal goals are, you shouldn’t exceed 2.5g of protein per kilogram of body weight.
The body cannot store excess protein and therefore it has to be excreted.
When combined with increased urea production, over time creates excessive stress on the kidney. In addition, excess protein consumption also increases Calcium excretion which over time contributes to kidney stone production.
There are 20 amino acids. All of them are necessary for the basic body processes such as a buildup of the DNA structure, immune cells, blood cells and hormone production. Nine of them are essential, meaning that they cannot be produced by the body and therefore must be taken in from food. They are present in food in different ratios and based on those we can rank foods on their completeness. A complete protein is one that contains all 9 essential amino acids. The remaining eleven amino acids are non-essential and the body can synthesize them from the food that is consumed.
Animal products such as Meat, Dairy, Eggs, Soy, and Fish are complete proteins by themselves. However, a complete protein can be also made by the combination of the right kinds of plant-based foods.
Don’t worry! It is not necessary to consume all the essential amino acids within one meal in order for them to turn into complete protein. According to a study done by the University of Michigan, it is enough to consume a variety of amino acids throughout the day. So as long as you vary your protein sources throughout your day, you are doing great!
Foods which are surprisingly moderately high in protein are Legumes, Nuts, Seeds, Dark Green Leafy Vegetables and Whole grains such as Millet, Buckwheat or Quinoa. Fruits and Root vegetables, on the other hand, contain very little protein, so although they should accouter for a great portion of your daily diet, don’t rely on them as your main protein sources.