Food nutrition - (2) PROTEINS

Food nutrition - (2) PROTEINS

February 28, 2018

Food nutrition -  PROTEINS


This blog is for chefs to study and learn more about knife skills, food nutritions, cooking science and technique.


And today’s subject is ‘PROTEINS’ the second page of food nutrition topic.

Let’s begin.

What are proteins?


Proteins are the basic units that are found in all cells in our bodies. Proteins make up the majority of bones and muscles. They are found mainly in meat, fish, eggs, dairy products, grains, beans, peas, are made up of chains of amino acids. There are about 20 different amino acids we get from food.

What does protein do in our body?

1. Body composition

Proteins are necessary for the growth and maintenance of all body tissues.

In particular, a large amount of protein is required for the growth period in which tissue formation is vigorous, the pregnancy period, and the lactation period.

In addition, once a formed cell’s life is over, it is decomposed and excreted. Proteins need to be supplemented to maintain tissue that is being re-synthesized into new cells, so protein is needed every day.

When we digest and absorb these foods, the chains are broken down into individual amino acids. Our bodies then build up new chains with the amino acids in the right order to form different parts of our bodies such as hair, muscle or a hormone.

2. Acid base equilibrium

Protein is a positive substance having carboxyl group and amino group, which maintains the pH of the body fluid to between from neutral to weakly alkaline. That is, the pH of the body fluid is maintained by the buffering action which acts as an acid when the body fluid becomes alkaline and acts as an alkali when it is acidic.

3. Moisture equilibrium

Albumin and globulins in the blood help maintain moisture balance.

These proteins can't get out through capillary blood vessels as they are large in molecular weight, so they keep the vascular osmotic pressure higher than the tissue and make most of moisture stay on the blood vessels.

If you don't get enough protein, the water in your blood will absorb to tissues, the amount of protein will decrease and causing edema.

4. Immune function

Protein is a component of cells used for immune system and it is a major component of antibodies produced by immune cells and it makes our body resistant to disease.

5. Enzyme, Hormone synthesis

Enzymes and hormones regulate metabolism in our bodies, and these regulators are made from protein.

 If even one amino acid is lacking, hormone synthesis is not achieved. So you must ingest enough amino acid from your diet.

Proteins and health


1. Deficient intake

  a. Kwashiorkor

Kwashiorkor is a severe form of malnutrition, caused by a deficiency in dietary protein. The extreme lack of protein causes an osmotic imbalance in the gastro-intestinal system causing swelling of the gut diagnosed as an edema or retention of water.

Extreme fluid retention observed in individuals suffering from kwashiorkor is a direct result of irregularities in the lymphatic system and an indication of capillary exchange. The lymphatic system serves three major purposes: fluid recovery, immunity, and lipid absorption. Victims of kwashiorkor commonly exhibit reduced ability to recover fluids, immune system failure, and low lipid absorption, all of which result from a state of severe undernourishment. Fluid recovery in the lymphatic system is accomplished by re-absorption of water and proteins which are then returned to the blood. Compromised fluid recovery results in the characteristic belly distension observed in highly malnourished children.

  b. Marasmus

Marasmus is a form of severe malnutrition characterized by protein deficiency. It can occur in anyone with severe malnutrition but usually occurs in children. A child with marasmus looks emaciated. Body weight is reduced to less than 62.36% of the normal (expected) body weight for the age. Marasmus occurrence increases prior to age 1, whereas kwashiorkor occurrence increases after 18 months. It can be distinguished from kwashiorkor in that kwashiorkor is protein deficiency with adequate energy intake whereas marasmus is inadequate energy intake in all forms, including protein. This clear-cut separation of marasmus and kwashiorkor is however not always clinically evident as kwashiorkor is often seen in a context of insufficient caloric intake, and mixed clinical pictures, called marasmic kwashiorkor, are possible. Protein wasting in kwashiorkor generally leads to edema and ascites, while muscular wasting and loss of subcutaneous fat are the main clinical signs of marasmus.

2. Excessive intake

If you consume too much protein than you need, it is harmful to your body.

Especially when a large amount of animal protein is ingested, the loss of calcium through the urine during the neutralization of the acidic amino acid metabolites is increased.

It also increases the risk of osteoporosis associated with lack of exercise, excessive drinking and smoking.

In addition, eating too much protein can damage kidneys. Your kidneys have to work harder to get rid of the extra urea(nitrogen) and waste products of protein metabolism.

The recommended daily amount of protein is 56 grams for the average man and 46 grams for the average woman. It is about 15 to 20% of the energy intake.

Vegetable proteins & animal proteins

It used to be thought that vegetable proteins were of a low quality than animal proteins. But it has since been shown that this is not true. Vegetable sources have less protein per unit weight than meat products but the quality is the same. Overall, Vegetable proteins are a healthier option because they contain more fiber and a lot less fat than animal protein foods.


Next topic is fats.



Jamie Yang.