PROTEIN

Proteins are broken down in the stomach during digestion by enzymes known as proteases into smaller polypeptides to provide amino acids for the organism, including the essential amino acids that the organism cannot biosynthesize itself. Aside from their role in protein synthesis, amino acids are also important nutritional sources of nitrogen.

Proteins, like carbohydrates, contain 4 kilocalories per gram as opposed to lipids which contain 9 kilocalories and alcohols which contain 7 kilocalories. The liver, and to a much lesser extent the kidneys, can convert amino acids used by cells in protein biosynthesis into glucose by a process known as gluconeogenesis. The amino acids leucine and lysine are exceptions.

Dietary sources of protein include meats, eggs, nuts, grains, legumes, and dairy products such as milk and cheese of the 20 amino acids used by humans in protein synthesis, 11 "nonessential" amino acids can be synthesized in sufficient quantities by the adult body, and are not required in the diet (hough there are exceptions for some in special cases. The nine essential amino acids, plus arginine for the young, cannot be created by the body and must come from dietary sources.

Most animal sources and certain vegetable sources have the complete complement of all the essential amino acids in adequate proportions. However, it is not necessary to consume a single food source that contains all the essential amino acids, as long as all the essential amino acids are eventually present in the diet: see complete protein and protein combining.

Different proteins have different levels of biological availability (BA) to the human body. Many methods have been introduced to measure protein utilization and retention rates in humans. They include biological value, net protein utilization, and PDCAAS (Protein Digestibility Corrected Amino Acids Score) which was developed by the FDA as an improvement over the Protein Efficiency Ratio (PER) method. These methods examine which proteins are most efficiently used by the body. In general they conclude that animal complete proteins that contain all the essential amino acids such as milk, eggs, and meat are of most value to the body.

Egg whites have been determined to have the standard biological value of 100 (hough some sources may have biological values higher, which means that most of the absorbed nitrogen from egg white protein can be retained and used by the body. The biological value of plant protein sources is usually considerably lower than animal sources. For example, corn has a BA of 70 while peanuts have a relatively low BA of 40.

The body is unable to store excess protein. Protein is digested into amino acids which enter the bloodstream. Excess amino acids are converted to other usable molecules by the liver in a process called deamination. Deamination converts nitrogen from the amino acid into ammonia which is converted by the liver into urea in the urea cycle. Excretion of urea is performed by the kidneys. These organs can normally cope with any extra workload but if kidney disease occurs, a decrease in protein will often be prescribed.

Many researchers think excessive intake of protein forces increased calcium excretion. If there is to be excessive intake of protein, it is thought that a regular intake of calcium would be able to stabilize, or even increase the uptake of calcium by the small intestine, which would be more beneficial in older women.

Specific proteins are often the cause of allergies and allergic reactions to certain foods. This is because the structure of each form of protein is slightly different; some may trigger a response from the immune system while others remain perfectly safe. Many people are allergic to casein, the protein in milk; gluten, the protein in wheat and other grains; the particular proteins found in peanuts; or those in shellfish or other seafoods.

Whey Protein Isolate is more expensive from the Whey concentrate because of its high quality and also contain higher biological value. Isolate contain more protein and less fat and lactose per serving. Whey protein isolate is the highest yield of protein currently available, and it come from milk. Whey protein is the easiest to be absorb into the muscle. Hydrolyzed whey protein isolate can significantly increase glutathione. It can provide protection against prostate cancer.

Whey protein begins as a watery byproduct of cheese manufacturing. In its crude state, whey is about 93% water, 6.5% lactose, 0.9% protein and 0.2% vitamins, minerals, and fat-soluble nutrients. In this form, whey is not of much benefit to athletes, but with gentle low-temperature processing and filtration, this liquid can be stripped of most of its lactose, fat, cholesterol and water to yield concentrated whey powders containing anywhere from 34 to 89% protein. Because whey protein concentrate is produced from a liquid as a byproduct of the cheese manufacturing process, it needs to be processed to turn it into anything useable. This process, the boiling and mixing and removing of the non-essential ingredients, is a complicated, painstaking process that takes the liquid from its original form into the final product.

What is the difference between Whey protein Isolate and Whey Protein Concentrate?

This is a very commonly asked question and also an important one. Many whey powders are made up of either whey protein isolate, concentrate or a mixture of the two and it is important to have an understanding of the two.

The main difference is that whey protein Isolate is processed further in order to remove the fat and lactose. This provides a ‘purer’ protein; in fact over 90% of whey protein isolate is protein (by weight.) This is beneficial as lower levels of fat are a plus for the diets of bodybuilders and when whey is being used for weight loss. Lower lactose levels are also a plus for those who are lactose intolerant and also reduce the chance of a ‘bloated’ feeling that can accompany some protein supplements.

It is not all positive for Whey Protein Isolate however. Because of its higher protein ratio, isolate comes generally at a higher retail price. Biologically, the filtering process isolate undertakes removes some of the alpha lactoglobulins and lactoferrins that are important immune boosters.

Whey Concentrate has lower protein availability, anything from 29% up to 89% in some cases. Concentrate is high in levels of lactose and anyone suffering from lactose intolerance needs to be very cautious. Concentrate however can cost less so can be better depending on what your budget is. Whey Concentrate also is low in levels of cholesterol, which is another advantage in consideration to diets.