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Protein and Amino Acids

What Is Protein?

Protein makes up the bulk of skeletal muscle mass and represents approximately 65% of the body's total protein content. This amount can be increased by combining resistance training with a high protein diet. Protein is the basic structural material of all tissue and muscle cells. Proteins in the form of enzymes, antibodies, hormones, neurotransmitters, nutrient transporters and cell membrane receptors control every biochemical reaction which occurs throughout our bodies.

Most proteins are long molecules composed of amino acid units. Proteins range in size from two or three amino acids known as peptides, to a thousand. Even though many of the foods we eat contain protein, our body does not use these proteins intact. Instead, dietary protein is broken down into amino acids, which are then absorbed into the blood stream and transported into specific cells. They are reassembled into the new proteins needed by those specific cells. Amino acids are made up of hydrogen, carbon, oxygen and nitrogen. Our genes are responsible for encoding the amino acid sequence which is used to form proteins. Different shaped proteins perform different functions throughout the body.

Amino Acids

There are twenty amino acids, nine of which are considered essential because your body cannot synthesise them and must be consumed in your diet. The non-essential amino acids can be synthesised from one another. When your body is deficient in even a single essential amino acid, it will break down muscle tissue to obtain it. Some of the amino acids are glucogenic which means that they can be converted into glucose, others are ketogenic which means they can be converted into ketones. These processes are quite common when the body is in a calorie restricted state. Body-builders suffer from frequent muscle breakdown (catabolism) due to insufficient protein intake and/or inadequate quantities of the nine essential amino acids. Ideally for the body to make the best use of amino acids, a variety of amino acids especially the nine essential ones should be made available through our diets. If we consume excess amounts of certain amino acids they may not be used in the synthesis of protein but alternatively converted into a range of molecules including glucose, ketones or fatty acids; the nitrogen is lost through urine in the form of urea. The essential amino acids and recommended daily intake in human Adults mg per Kg body weight:

  • Leucine 14mg
  • Isoleucine 10mg
  • Valine 10mg
  • Phenylalanine 14mg
  • Tryptophan 3mg
  • Histidine 28mg
  • Threonine 7mg
  • Methionine 13mg
  • Lysine 12mg

In order to maintain existing muscle mass, the average adult needs to consume 0.85-1.1 grams of protein per kilo of bodyweight each day. If you are an athlete you should be consuming between 1.3-1.55 grams of protein per kilo of bodyweight each day and if your a body-builder looking to gain mass you should be consuming between 2.0-3.5 grams of protein per kilo of bodyweight each day.

There are many rumours about protein and its consumption in excess. Some people claim eating excess protein should be avoided as it has negative effects on the kidneys, however there is also research indicating this is untrue unless the person already has kidney complications. Some people also claim the body can only absorb 30 grams of protein every 3 hours. This was a rumour started by a company who wanted to justify their quantity of protein in their product. The amount of digestible protein varies from person.

Protein rich foods include beef, poultry, dairy products, fish, beans and many nuts but unfortunately some of these sources are rich in saturated fat. Too much saturated fat can have negative effects on blood lipid profiles therefore we recommend you limit the amount of protein you ingest which come from sources high in saturated fat. Since bodybuilders usually find it difficult to find sufficient protein through regular meals they usually supplement additional protein through powders. A lot of these powders are mixed with other nutrients to provide more efficient absorption or greater effects.

Protein powders

Protein powders are often used by body-builders to increase the amount of protein taken in without the trouble of having to cook meals. There are many different types of protein powders. Some are combined with carbohydrates to form mass building shakes for extra calories. Some have creatine added to them to draw water into muscle cells. Here's a little information about some of the protein powders on the market.

Whey is a form of protein which can be found in milk and dairy products. The proteins in these dairy products can be separated from each other using various techniques. Whey used to be considered a useless by-product of the cheese processing technique, however when it was discovered that whey actually was a high quality protein, methods of distilling it into a powder containing little or no fat and lactose were developed, and whey has since been used in a wide variety of protein supplements.

Whey protein is a complete protein containing all the nine essential amino acids and it compares favourably to other proteins in quality. The concentration of branch chain amino acids (BCAA) is higher in whey than in any other protein source. The three BCAA's - Leucine, Isoleucine and Valine are unique in that they can be taken up by skeletal muscle instead of having to be metabolised by the liver. Because BCAA's are faster acting than other amino acids, they are able to serve as fairly efficient muscle energy source during exercise and as a ready source of raw material for muscle protein synthesis after exercise. Whey is also considered a fast acting protein because it can be absorbed into the bloodstream from the intestines faster than other proteins.

Whey protein is also rich in the precursors for glutathione. Gluthathione is a peptide consisting of three amino acids: gamma-glutamic acid, cysteine and glycine. Glutathione plays an important role in the neutralising of free radicals and also serves as a potent detoxifier in the body. Whey protein comes in a number of forms:

Whey protein hydrolysate A hydrolysate is a protein that has had some of its peptides broken into shorter chains of aminos. This is an expensive whey protein however it's not very popular due to its bitter taste from the hydrolysis.
Whey protein isolate This is a pure form of whey protein that has almost all its lactose removed. This product may be useful for individuals who are lactose intolerant.
Whey protein concentrate The most common form of whey protein. Its inexpensive and can be incorporated into many types of products. One of the drawbacks in the past was it contained high levels of lactose, however now it can be produced lactose free.

Casein

Casein is the other protein distilled through cheese production. It's significantly different from whey protein. Its an excellent source of glutamine which is a crucial amino acid for strength training athletes.

Casein consists of a fairly high number of proline peptides, which do not interact. There are also no disulphide bridges. As a result, it has relatively little secondary structure or tertiary structure. Because of this, it cannot denature.

Two disadvantages of casein are that it has fewer concentrations of BCAA's than whey and it contains more lactose.

Casein digests more slowly than whey and therefore is an excellent source of protein for growth over long periods of time as it's able to sustain muscle protein synthesis for longer durations. It's recommended that body-builders take a casein supplement before bed to minimise protein loss during the overnight fast.

Soy is rich in BCAA's but contains only a small amount of the essential amino acid methionine. Most forms of soy protein are highly digestible and therefore fast acting, but soy protein is generally considered a lower quality protein than casein or whey.

Soy protein isolates fortified with methionine are available these days and are a comparable quality to casein and whey. And one big advantage of soy protein is that it contains no lactose, so those who are lactose intolerant can use it.

Many athletes avoid soy protein because it contains plant hormones which have been shown to have an estrogenic affect on the body. In other words they mimic the actions of the female sex hormone in certain tissues of the body. However this does not mean that soy reduces the testosterone levels and inhibits muscle hypertrophy, as there is no evidence of this as of yet.

Summary

  • Protein is an essential nutrient for survival. You should increase your dietary intake of protein if your an athlete or a bodybuilder looking to gain mass.
  • Try to get your protein from a variety of food sources to vary the amino acids in your diet and prevent muscle breakdown.
  • Limit your daily protein as excess protein can be converted into carbohydrate or fat.
  • Consume a casein based protein around bedtime for a long slow digestion of protein through the night.
  • Consume a whey based protein around training times for quick absorption.

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