Protein Requirements
Protein is one of the macro nutrients along with fat and carbohydrate. The body needs protein to build, repair and maintain the human body, and not just for muscle but for most tissues of the body, being about 50% of the dry weight of most cells. Protein should make up somewhere between 15-25% of total energy intake. Recommended daily intake ranges from a minimum of 0.8 grams per kilogram of bodyweight for inactive adult women, to around 2.0 gms/kg/bw for athletes and heavy exercisers like bodybuilders. Protein intakes in excess of this are difficult to justify for health or athletic performance when other macronutrients are available.
Protein consists of chemical units called amino acids, of which there are many, but only 20 that synthesize protein in animal nutrition. Of those, only 10 are "essential" in adult human nutrition because the body cannot make them. This means they must be eaten regularly.
These 10 must be obtained from food every day because the body cannot story excess amino acids in a rapidly available form, but it can break apart muscle protein to obtain any shortages. (Bodybuilders and athletes please note.) These 9 are: histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, valine and arginine. However, cysteine, taurine, tyrosine, and arginine are essential amino-acids in children because they are not able to synthesize these amino acids at an early age. In addition, arginine is essential for children but not adults.
Sources and Quality of Protein
Although just about all foods have some protein, the major sources are animal foods like meat, eggs and dairy, and plant foods such as nuts and beans and grains. Not only is it important for protein foods (or meals) to contain all the essential amino acids, but they need to be in ideal proportions to achieve an adequate growth and repair function in the human body. When the ideal protein specifications are met they are generally called "complete proteins." Animal foods are complete proteins, but some vegetable sources are not.
The Protein Digestibility Corrected Amino Acid Score (PDCAAS) is a formal, preferred measure of protein quality developed and accepted by the US Food and Drug Administration and the World Health Organization. Here are some examples, 1.00 being the highest quality:
- 1.00 - casein, milk
- 1.00 - egg white
- 1.00 - soy protein isolate, beans
- 1.00 - whey protein isolate, milk
- 0.92 - beef
- 0.91 - soybeans
- 0.78 - chickpeas
- 0.76 - fruits
For weight training, fitness, and athletic endeavour in general, getting sufficient quality protein is all you need to be concerned about. Bodybuilders aiming for the very last ounce of hypertrophy often wring their hands over the best protein supplement powders to use - casein, whey, egg, soy -- and the various chemical refinements such as isolates and hydrolysates. Real benefits from one or the other in bulk or performance over the long term have not been established in any scientific study, although whey may hold a theoretical edge. Either way, there is going to be very little in it, considering the range of factors that influence muscle growth and definition.
Types of Protein Powder Supplements
Depending on how you classify various products, protein powder supplements fall into four basic categories. However, there are many products and formulations, and some will suit more than one category. Most are reconstituted to make shakes, and some are provided as ready-to-drink shakes.
Body Bulk and Recuperation These products are for people who have either been ill and need supplemental liquid food product to help them recover lost weight; or for helping very lean people to add body mass for the purposes of health or to sustain healthy weight. The powder products generally have a wide spectrum of nutrients including protein, fat, carbohydrate, and vitamins and minerals in proportioned quantities.
Weight Loss Meal Replacement These products are meal replacement products specifically designed to help obese and overweight people regulate their energy intake while maintaining a balanced diet. These are usually relatively high in protein and low in carbohydrate.
Bodybuilding Meal Supplements Such products are usually high in protein (up to 60 grams/serve), moderately low in carbohydrate and very low in fat, plus various vitamins, minerals and even bulk builders like creatine. Even cheaper is skim milk powder, which has proved to be quite adequate as an anabolic aid to muscle growth. In fact, skim milk powder may offer the best bang for buck if you don't need the fancy brand names products.
Pure Protein Powders Basic protein powder supplements offer little else but protein in the form of various extractions, isolates or hydrolysates of egg, casein, whey or soy protein. They are often the cheapest source of protein gram for gram in brand products.
Choose this option if you eat a healthy diet and want protein supplementation pure and simple.
