Protein Structure

Proteins make up one of the main three macronutrient categories, the other two being carbohydrates and fats. From a structural 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. An 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.

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 synthesise 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.

A diet low in amino acids, especially the essential ones, leads to a net negative protein balance due to daily amino acid breakdown in the body. If the amino acid intake falls below the daily amino acid breakdown level, substances like enzymes and structural proteins are cannibalised. 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.

What are the Good Sources of Protein?

Each gram of protein contains 4 calories. Protein constitutes 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), which is an advanced and more accurate method, and replaced the Protein Digestability Corrected Amino Acid Score (PDCAAS), which had been recommended since 1993.

In terms of quality, there are complete and incomplete proteins. Complete proteins are those that rank 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.

Generally speaking, the majority of plant-based sources fall short. 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 with this combination: legumes that are limited in the essential amino acid tryptophan but contain an adequate amount of lysine with wheat and rice that are limited in lysine and high in tryptophan.

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, we recommend a higher protein intake than 0.8 grammes per kilogramme during periods of low energy or low carbohydrate intake. A diet rich in protein may also boost satiety and enhance immune system function, metabolism, weight control, and performance, according to some research.

Concerns arose because individuals with kidney disease and kidney failure experienced a worsening of function when consuming a high-protein diet. However, recent studies suggest that eating a higher protein diet has no renal stress in those with healthy kidneys, as well as that suggestions of kidney stones, calcium loss, etc., are all unsupported.

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 supplements, 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, has gained in popularity for 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. This is because whole foods provide many additional nutrients that are beneficial for you. In addition to other essential nutrients, lean whole foods also have a lower glycaemic index or value compared to protein supplements.