1 – Protein Structure
Proteins make up one of the main three macronutrient categories, the other two being carbohydrates and fats. From a structure perspective, proteins, like fats and carbohydrates, are composed of hydrogen and carbon molecules arranged in specific patterns. However, unlike fats and carbohydrates, proteins also contain nitrogen as part of their amino groups. Amino acid is the smallest unit of protein.
The building blocks of proteins, amino acids, have four main characteristics. They contain a central carbon called the alpha or alpha carbon, an amino group (NH2) on one end, a carboxyl group (COOH) on the other end, and a side chain or R group. And this is the side chain that differentiates one amino acid from another.
2 – Proteins’ Function in the Body
In addition to serving as an energy source both during exercise and at rest, proteins build and repair body tissues, become hormones or facilitate the action of hormones, balance the body’s systems, and aid in the transportation of other nutrients within the body. Furthermore, although our body’s metabolic processes can make some specific amino acids, without a diet high in the essential amino acids (those amino acids our body can’t synthesise) we cease to function.
Essential and Nonessential Amino Acids
Proteins in all living species are made up of the same set of 20 amino acids. There are two types of amino acids, essential and nonessential. Essential amino acids, as the name implies, are essential to the body because the human body lacks the metabolic pathways required to make and synthesize those amino acids. For this reason, they must be obtained from a diet. On the other hand, nonessential amino acids are those that can be made by the body.
Without eating a diet rich in amino acids, in particular, the essential ones, daily amino acid breakdown in the body creates a net negative protein balance. If the amino acid intake falls below daily amino acid breakdown, substances like enzymes and structural proteins are cannibalized. And if this process continues for a long time, vital functions shut down. For this reason, supplying the body with essential amino acids each day is crucial for overall health and bodily functions.
| 8 Essential Amino Acids | 8 Conditionally Essential Amino Acid | 4 Addional Essenail Amion Acids |
|---|---|---|
| They must be achieved through the diet because the body can’t make them. | They are necessary for some special populations without adequate synthesis. | They are required for infants and growing children. |
| Lysine | Serine | Histidine |
| Isoleucine | Histidine | Cysteine |
| Valine | Glutamine | Arginine |
| Methionine | Tyrosine | Tyrosine |
| Leucine | Glutamine | |
| Pheylalanine | Arginine | |
| Threonine | Cysteine | |
| Tryptophan | Glycine |
3 – What are the Good Sources of Protein?
Each gram of protein contains 4 calories. Protein makes up about 15% of a person’s body weight. Protein in the diet can be obtained from a wide variety of foods including legumes, meat, fish, dairy, soy, nuts, grains and some vegetables.
Complete and Incomplete Protein
For determining protein quality, the Food and Agriculture Organisation of the United Nations (FAO) released a report in 2013 that recommended the Digestible Indispensable Amino Acid Score (DIAAS) measuring standard, which is an advanced and more accurate method, and replaced the Protein Digestability Corrected Amino Acid Score (PDCAAS) measuring standard, which had been recommended since 1993.
In terms of quality, there are complete and incomplete proteins. Complete proteins are those that rank the highest on the measuring systems such as PDCAAS and DIAAS. It means that complete proteins provide all the essential amino acids in adequate amounts in the body. Animal sources such as fish, meat, poultry, milk, eggs, and cheese are considered complete proteins. Although lower in total protein amount in comparison with animal sources, some plant-based sources such as hempseed, quinoa, buckwheat, and amaranth are also considered complete.
As a good rule of thumb, most plant-based sources are incomplete. It means that they lack one or more of the essential amino acids. However, by following a balanced plant-based diet that varies in types and colours, one may get all the essential amino acids. For instance, one may have a complete protein meal by this combination: legumes that are limited in essential amino acid tryptophan but contain an adequate amount of lysine with wheat and/or rice that are limited in lysine and high in tryptophan.
4 – How many Grams of Protein Does One Need?
When discussing protein amounts, there is a contradiction between those who follow and support a specific diet plan. In general, it’s said that a sedentary, generally healthy adult, should consume a [minimum] of 0.8 grams of protein per kilogram of body weight per day. For example, if a person is 60 kg, he or she should consume 48 grams of protein per day.
On the other hand, the need may be increased from 0.8 to about 1.4 to 2 grams of protein per kilogram of body weight for those who do high-intensity training and weight lifting. Furthermore, a higher protein intake than 0.8 grams per kilogram is also recommended during periods of low energy intake or low carbohydrate intake. Additionally, some research indicates that a diet high in protein may increase satiety and improve metabolism, immune function, weight management, and performance.
There were some concerns based on the fact that individuals with kidney disease and kidney failure experienced a worsening of function when eating a diet high in protein. However, recent studies suggest that eating a higher protein diet has no renal stress in those with healthy kidneys, as well as, suggestions of kidney stones, calcium loss, etc., are all unsupported.
5 – Protein and Amino Acid Supplements
One of the main necessities of taking a supplement is in situations when one can’t obtain an adequate amount of that nutrient from the diet. The same is true with protein and amino acid supplementation too.
Protein and amino acid supplements have become popular with a host of specific goals in mind and using such supplements at the right time would be effective in improving performance and recovery. For instance, using BCAA supplements (leucine, isoleucine, and valine), in particular, leucine, have gained in popularity in enhancing post-exercise recovery. Or each glutamine and arginine supplement has been used for improving gastrointestinal health and wound healing respectively. The list of amino acid supplements and their uses can go on and on.
It’s noteworthy that, whenever possible, getting any nutrients from whole food is preferable to supplements. It’s because whole food has many other nutrients that you get. Besides other essential nutrients, in the case of protein supplements, lean and whole food has a lower glycemic index or value too.