Dietary proteins are divided into two kinds of proteins: complete proteins, which include all essential amino acids in the exact amounts required by the body for growth and incomplete proteins, which are deficient in one or more essential amino acids.
Essential amino acids play major roles in performance, recovery and reactions to stress. Complete proteins supply the correct ratio of amino acids needed to promote muscle synthesis. The ratios are important because in order for the body to build muscle, all the essential amino acids must be available at the same time.
A deficiency of even one essential amino may suppress critical metabolic functions, which are necessary for the repair and buildup of tissues including muscles. Moreover, it has been assumed that a deficiency of essential amino acids would limit protein synthesis (and growth) proportionally to the extent of deficiency.
High Quality Complete Proteins:
High Quality Complete Proteins Include:
Lean red meats (top round, lean sirloin, and flank)
Non-fat or low fat dairy products
Protein From Animal Sources:
Protein that comes from animal sources contains all of the essential amino acids that we need. The obvious problem with animal proteins is that they can also contain large amounts of saturated fats, which can not only make you fat but put you at risk for heart disease and stroke. Fortunately, fat from animal proteins can easily be avoided proper food education that will help you make the right choices. Protein animal products include:
Although tuna, chicken breasts, turkey, and other white fish are very good low-fat and high-protein sources lean red meat will provide you with better gains. Besides being packed with protein, they're good sources of B vitamins, iron and zinc. There are several studies have shown that people consuming red meat gained more mass than those consuming chicken and tuna, the other “meats” of choice in the bodybuilding community.
Tips For Purchasing:
When purchasing ground meat check the labels, since most stores offer several types of ground meat, with varying percentages of fat by weight. Look for packages with the lowest fat percentage - 15 percent or less.
Look for moistness and bright color. Red or pink meat can be a sign of freshness, although vacuum-packed meats may look slightly purplish for lack of exposure to air. Avoid meat that looks brown, as it may be spoiled.
Avoid meat that is heavily marbled. Marbled meat is streaked with fat. Look for meat with the least amount of visible fat. Choose lean cuts.
Lean cuts of beef include round, chuck, sirloin or tenderloin. Lean pork includes tenderloin and loin chops. Look for USDA Choice or USDA Select grades of beef rather than USDA Prime, which usually has more fat content.
When at home do not consume meat that does not smell fresh. Consumption of rancid protein has shown to be a source of health issues later in life.
With all that being said, it is also important to note that because the biological Value (BV) of meat can be 80 or less, more meat will have to be eaten to get the needed protein (as opposed to proteins with a higher Biological Value) which is often not desired during a low calorie diet.
Poultry can be an excellent source of protein, and is often a primary staple of those trying to lose weight, as well as competitive athletes, including bodybuilders.
The key however is to select lean cuts, limit added oils and condiments, and choose a low fat preparation method (broil, bake or steam; not fry).
The leanest poultry choice is white meat from the breast of chicken or turkey, without the skin. Although skinless dark meat is leaner than some cuts of beef or pork, it has nearly twice the fat calories as does white meat, so avoid the dark meat.
Tips For Purchasing:
Many grocery stores have both ground chicken and ground turkey, most of which is not low fat because they include more fattening parts of the bird, including skin, and actual fat in the grinding process. In these cases the ground poultry can actually have more fat than many cuts of beef. To make the leanest choice, choose ground breast meat, or look for extra lean (99%) low-fat ground chicken or turkey.
Fish is high in protein, but low in saturated fat and cholesterol, making it a good substitute for poultry and meat. However, when selecting fish especially if you plan to eat it uncooked (e.g., sushi/sashimi) it is of paramount importance to select a reliable seafood source.
Be aware that even large chain supermarket or a specialty fish market can offer seafood that has been mishandled, or is close or past it's best date for consumption.
Tips For Purchasing:
Look for fresh seafood. Fresh fish has a moist, bright surface with shiny, well-attached scales. Also look for bright pink or red gills and firm, springy flesh.
Avoid seafood that is dry, flaky, discolored and is overly fishy-smelling. Consumption of rancid fish can cause several health issues; food borne diseases, and make you very ill.
Milk is a nutrient rich complete ideal food. Milk contains all the essential nutrients required for growth. Milk is also rich in many vitamins and minerals such as calcium, phosphorus, sodium, potassium vitamin A, thiamine, riboflavin and nicotinic acid and vitamin B12 which is absent in vegetarian food items.
The proteins of milk are of a high biological value cow's milk provides 3.2gm of protein and 67kcl of energy per 100 ml. Buffalo milk provides even more (4.25gm of protein and 117kcl of energy) per 100 ml. For a comparison of nutritional value of various milks refer to the table below.
The all important protein from milk comes from the milk solids (Milk is composed of approximately 87% water and 13% solids). The solids contain approximately 37% lactose, 30% fat (2/3 of which is saturated fat) and 27% protein. The protein is comprised of casein (about 80%) and whey protein about 20 %).
Protein From Plant Sources:
Legumes are a class of vegetables that includes beans, peas and lentils - are typically low in fat, contain no cholesterol and are high in protein, iron, folate, potassium, magnesium, and phytochemicals.
Phytochemicals are a group of compounds that may help prevent chronic diseases such as cardiovascular disease and cancer. They are also a good source of fiber which has also shown to reduce the risk of developing diabetes and help lower blood cholesterol levels, which can reduce your risk of heart disease.
However, most legumes with the exception of soy are not complete proteins (i.e., they do not contain all of the essential amino acids that we need) which are why they are not preferred by bodybuilders. Beans, for example, are very high in total protein with about 12 -15 grams per cup, however, beans do not contain the essential amino acid methionine.
Similarly, grains are lack the essential amino acid lysine. Because protein from most plants lacks certain amino acids, it has a lower biological value than protein from animal sources.
There are some ways to balance out the amino acid profile. It has been frequently pointed out that combining two incomplete sources of vegetable protein such as rice and beans provides you with the full complement of essential amino acids.
The most common source of plant protein regarding consumption is soy protein. Soy has been consumed for more than 2,000 years by people throughout East Asia.
In Western countries, soybeans had attracted people's attention only since the 1960s as an economical and high-quality vegetable protein source for humans.
Soy is found most commonly in the United States as tofu, but other common sources include, soy flour, soy nuts, soy milk, soybeans, “meat analog” products, such as soy sausages, burgers, franks, and cold cuts, all of which are intended as substitutes for their animal-based counterparts.
The main reported benefit of soy is that it is reported to help lower cholesterol. Data show that substitution of soy protein for animal protein is associated with significant decreases in total cholesterol (LDL-C) and triglycerides, while maintaining high density lipoprotein cholesterol (HDL-C)-the good cholesterol-concentrations.
Soy also contains isoflavones which can act as antioxidants, which help reduce the risk of cancers. Isoflavones are also reported to reduce the risk of arteriosclerosis (plaque buildup in the arteries). Isoflavones improve bone retention and lumbar vertebral bone mineral combating osteoporosis.
Note: isoflavones do act as weaker plant-based estrogens it is currently not recommended that women who have had or are at risk of developing hormone dependent tumors consume a large amount of soy.
So, while soy can be beneficial, especially as a means to decrease saturated fat in the diet, moderate consumption is best under these circumstances. Other reported health benefits of soy include:
Low in saturated fat and high in other healthful compounds.
Contains genistein which is reported to can block cancer development and prevent tumors from creating blood vessels, thus blocking nourishment to the tumorous cells.
Contains phytates (plant chemicals) which also have antioxidant effects.
In order to reap the purported health benefits of soy, it is recommended that 25 grams or more of soy protein be consumed per day.
1 cup of tofu provides approximately 20 grams of soy protein.
2 cups of soy milk, provides approximately 20 grams of soy protein.
An 8-ounce glass of plain soymilk contains 10 grams of protein.
One soy protein bar delivers 14 grams of protein.
A quarter cup of roasted soy nuts contains 19 grams of soy protein.
Four soy “sausage” links provides approximately 24 grams of soy protein.
Two soy “burgers” provides approximately 20-25 grams of soy protein.
One-half cup of tempeh (a chewy made from whole, cooked soybeans used as a meat substitute) provides 19.5 grams of protein.
Common Whole Food Soy Products
Miso is a fermented soybean paste used for seasoning and in soup stock.
Soy protein also is found in many “meat analog” products, such as soy sausages, burgers, franks, and cold cuts, as well as soy yogurts and cheese, all of which are intended as substitutes for their animal-based counterparts.
“Soymilk,” is actually not milk, but a soy beverage produced by grinding dehulled soybeans and mixing them with water to form a milk-like liquid. Soymilk, sometimes fortified with calcium, comes plain or in flavors such as vanilla, chocolate and coffee. For lactose-intolerant individuals, it can be a good replacement for dairy products. It can be consumed as a beverage or used in recipes as a substitute for cow's milk.
Soy flour is created by grinding roasted soybeans into a fine powder. The flour adds protein to baked goods, and, because it adds moisture, it can be used as an egg substitute in these products. It also can be found in cereals, pancake mixes, frozen desserts, and other common foods.
Tempeh is made from whole, cooked soybeans formed into a chewy cake and used as a meat substitute.
Textured soy protein is made from defatted soy flour, which is compressed and dehydrated. It can be used as a meat substitute.
Tofu is made from cooked puréed soybeans processed into a custard-like cake. It has a neutral flavor and can be stir-fried, mixed into “smoothies,” or blended into a cream cheese texture for use in dips or as a cheese substitute. It comes in firm, soft and silken textures.
Other Sources Of Plant Protein:
Other sources of plant protein include some starchy foods and vegetables as well, although their protein content is fairly low (see Table 1).
Methods of Assessing Protein Quality:
Biological Value (BV):
Proteins are ranked according to Biological Values (BV), arbitrary numbers given to protein to show comparisons in their availability within the body.
At the time the system was introduced eggs were given the highest Biological Value of 100 because they are the most bio-available natural protein. Afterwards whey was isolated from milk and shown to have a higher Biological Value, and depending on the process used can yield percentage from 104 to 154 on the scale.
The Biological Value is based on how much of the protein consumed is actually absorbed and utilized by the body. It is an attempt to measure how efficiently protein is used in the body. The higher the amount of protein (nitrogen) that is actually retained, the greater the Biological Value.
To determine a food's Biological Value, scientists provide a measured intake of protein, and then note the nitrogen uptake vs. nitrogen excretion. A biological value of 100 is maximal, since a Biological Value of 100, means that all of the protein absorbed has been utilized with none lost, therefore it is impossible to have a Biological Value over 100.
When a protein supplement is listed as having a Biological Value over 100, the company has intentionally manipulated the number for marketing purposes or perhaps unintentionally confused Biological Value with another method of rating protein quality, such as perhaps the Chemical a comparison of the amino acid pattern in an ideal reference protein to a test protein and therefore the number can exceed 100.
Why Protein Biological Value Is NOT The Best Measure Of Protein Quality For The Athlete.
The biological value is not a universally accepted measure of protein quality because of several factors. For example, Biological Value testing is always done in the fasting state, which affects nitrogen uptake differently from what takes place when subjects are in a fed state.
Simply put, fasting changes the way the body absorbs nitrogen in protein. When this is done the utilization actually increases. As we all know this is not how bodybuilders eat.
Additionally, bodybuilders and athletes are a unique subset of the general population in that their needs and metabolisms are uniquely different from sedimentary people and the general population.
For instance, athletes in general will often have increased metabolic requirements for amino acids such as tyrosine, methionine-SamE or lysine-carnitine, which serve as building blocks for stress hormones and energy compounds.
These amino acids are often required in extra amounts by athletes due to high-energy demand and the need to perform under extreme mental and physical stress. Therefore, athletes generally speaking often will need extra protein with extra essential as well as conditionally essential amino acids which is why the Biological Value system alone is not a practical method to measure protein quality/needs for athletes, especially bodybuilders.
Why Protein Biological Value May Be Misleading:
The Biological Value of proteins has been measured via nitrogen balance. A positive nitrogen balance generally indicates high Biological Value and vice-versa.
There are however some serious concerns regarding the accuracy of this evaluation system. Biological Value tests are based on studies that measured protein utilization in a tightly controlled feeding environment, that doesn't resemble real life situations.
Furthermore, these tests were conducted primarily on proteins in their raw state, overlooking the fact that most protein foods are habitually consumed in a processed or cooked form.
Processing and cooking significantly change the amino score and Biological Value of raw protein foods. To make the matter even more confusing, protein Biological Value studies were based on small servings (100 to 200mg per kilogram of body weight).
In such a small servings, even inferior proteins are almost fully utilized with a relatively high Biological Value score. Unfortunately, these high scores dramatically decline when protein is consumed in normal or large amounts, such as with athletes or bodybuilders, a fact that must be calculated when designing a nutritional program.
The most efficient conventional method to evaluate protein quality is the so-called PDCAAS (Protein Digestibility Corrected Amino Acid Score) developed by the Food and Agriculture Organization.
Factors That Promote Or Suppress Protein Biological Value:
The variables that influence protein Biological Value and utilization may appear as contradictory and somewhat confusing. Nonetheless, to put some order to this madness, here is a list of protein Biological Values most enhancing vs. most suppressing factors.
Note that real life protein Biological Value would likely indicate how much of it could be utilized for actual growth.
Real-Life Protein Biological Value Is Enhanced By:
Small servings of proteins
High calorie intake
Fasting and under eating
Raw (unprocessed) state of food
Free-form amino acid supplementation
Probiotics and enzymes
Protein Biological Value Is Suppressed By:
Low calorie intake
Protein denaturing (such as exposure to high heat)
Single source of protein
Large portions proteins
Excessive intake of dietary fiber
Vitamin and mineral deficiencies
*Biological Value measures the amount of protein (or more precisely - the nitrogen) retained in the human body per gram of protein absorbed. The measure started out as a percentage - with a whole egg being the best - 100% nitrogen absorbed.
However, as whey processing got better whey became a better source of protein than an egg. This would mean that whey would have to score higher than 100, which (because that number is a percentage) is not possible. So either the percentage must be dropped - because greater than 100% does not make much sense (and then whey can score the reported 159 Biological Value) or the reference point (the egg) would have to be dropped or lowered). This is one reason why Biological Value is no longer the measure of choice.
Upside Of High Biological Value Products:
Because high Biological Value products are easily absorbed by the body, consuming them immediately upon waking (when the body is hungry for protein) and immediately following training is ideal.
High Biological Value products can also be of great value when on a calorie restricted diet because of greater high Biological Value products has a higher utilization. In other words, when you are dieting higher quality (higher Biological Value) protein allows you to take in fewer calories for the amount of protein consumed.
Downsides Of High Biological Value Products:
The downside of the rapid is that the protein is rendered useless within the body quickly. This is why large amounts of high Biological Value products, like whey should not be consumed in large quantities.
High Biological Value products, like whey should be consumed more frequently (every 40-60 minutes) and in smaller quantities (15-20 grams), to avoid this problem. Consuming 50 grams of whey in one sitting will result in 25 to 50 percent of the product being wasted (assuming the protein has not denatured).
Protein Efficiency Ratio (PER):
The Protein Efficiency Ratio is a measure of protein quality that assesses how well a given protein supports weight gain in laboratory animals.
The Protein Efficiency Ratio had been a widely used method for evaluating the quality of protein in food from 1919 until just recently. In fact it was the Protein Efficiency Ratio that was used by the U.S. Food and Drug Administration as the basis for the percent of the U.S. Recommended Daily Allowance (USRDA) for protein shown on food labels.
The Protein Efficiency Ratio is not the preferred for evaluating the quality of protein in food today the method uses a rat assay to measure protein quality.
Rats do not use protein in the exact same method as humans do, resulting in the method overestimating methionine needs (due to the greater need for methionine in rats for their hair production).
This problem with the Protein Efficiency Ratio to measure protein quality leads to a relative overestimation of the quality of animal protein, and an relative underestimation of the quality of at least some plant protein.
The Protein Efficiency Ratio should not be totally neglected however because athletes require more sulfur amino-acids-(Methionine, Cysteine) for growing quality muscle fiber after exercise expenditure than sedimentary people.
Such information could prove very useful in medicine because it could allow identification of an optimal diet for control of antioxidant levels. Therefore the Protein Efficiency Ratio can provide valuable information is used in conjunction with other assessment tools. The following table lists the Protein Efficiency Ratio of common protein sources.
Any protein that has a higher PER value than 2.7 is considered an excellent quality protein.
Net Protein Utilization (NPU) Method:
The Net Protein Utilization (NPU) Method of evaluating protein quality reflects the amount of protein eaten versus the amount of protein retained (or in other words the ratio of the nitrogen used for tissue formation versus the amount of nitrogen digested).
Amino Acid Score (AAS)
The Amino Acid Score (AAS) is a fast, consistent, and inexpensive chemical technique considered used to measure indispensable amino acids present in a protein.
It compares the values with a reference protein and rates the protein based upon the most limiting indispensable amino acid. The following is the Amino Acid Score for some common protein sources:
Protein Digestibility Corrected Amino Acid Score (PDCAAS) Method:
The Protein Digestibility Corrected Amino Acid Score is the latest method for calculating protein quality, accounting for the digestibility of a food protein from its amino acid profile content.
Protein Digestibility Corrected Amino Acid Score was developed by the Food and Agriculture Organization (FAO) to address some of the issues noted with the Protein Efficiency Ratio and Biological value methods.
It compares a test protein to a standard based on the amino acid requirements of humans (as opposed to rats). This method is the Amino Acid Score (AAS) with an added digestibility component.
This method is internationally recognized as the preferred method when evaluating protein digestibility. How it works is that an ideal protein that meets all of the essential amino acid requirements of the human body is given a relative value of “1.0”. Protein Digestibility Corrected Amino Acid Scores can't be higher than the “Complete Score” of 1.0.
It is endorsed by the US Food and Drug Administration because the method provides a protein-quality rating that's much closer to reality for human metabolism, vs. the PER and other methods.
The Protein Digestibility Corrected Amino Acid Score method is patterned after the amino-acid needs of 2-5 year old humans. This is not necessarily a bad thing, since this group matches or exceeds amino-acid requirements for older children and adults, however it is not based on the needs of bodybuilders and athletes whose amino-acid requirements differ from the subject group.
While the Protein Digestibility Corrected Amino Acid Score system measures both amino acid content and digestibility this evaluation system fails to notice that protein quality and utilization can change according to additional variables such as:
The amount of calories
Methods of cooking
Level of pH
Naturally occurring enzyme inhibitors
Temperature and rate of degradation
The overall nutritional composition of meals
All these variables significantly affect protein utilization. There is also a growing number of nutritional experts that feel this method needs further refinement and additional changes may be seen in the future.
Protein Digestibility (PD) Method:
The proportion of food protein absorbed is called “Protein Digestibility”.
This method makes attractive mixing high Biological Value-proteins with low Biological Value-protein favoring maximal muscle growth potential with minimal body fat gain and minimal serum cholesterol volume. By mixing high Biological Value-proteins with low Biological Value-protein the rating scale elevates the vegetable amino acid profile of soy to its animal-based counterparts.
Proteins are broken down into proteoses and polypeptides to provide amino acids. Most protein digestion takes place in the duodenum (a hollow jointed tube connecting the stomach to the jejunum, largely responsible for the breakdown of food in the small intestine). The overall contribution from the stomach is small.
Duodenum: The duodenum is largely responsible for the breakdown of food in the small intestine. Two very important ducts open into the duodenum, namely the bile duct and the pancreatic duct. Brunner's glands are only found in the duodenum and they secrete mucus. These mucus filled glands are composed of simple cube-shape epithelial cells. The duodenum wall is composed of a very thin layer of smooth muscle cells that forms the muscularis mucosa.
Almost all protein is absorbed when it reaches the jejunum (the central of the three divisions of the small intestine lying between the duodenum and the ileum), with only a small amount of amino acids remaining in the epithelial cells used for synthesis of new proteins (such as the intestinal proteins which are constantly being digested, recycled and absorbed from the small intestine). Amazingly enough, only 1% of ingested protein is typically excreted in the feces.
Proteins are typically classified into two groups based on their rate of digestion. The rate of digestion can have important effects on protein balance within the body. It is this balance between protein synthesis and protein breakdown determines muscle gain.
Protein is generally characterized as “fast digesting” or “slow digesting”. “Slow digesting” proteins release amino acids into the blood at a slower, and steady pace, can minimize waste, improve utilization deter catabolism, and promote muscle synthesis for up to 420 minutes (some products have funded their own studies which promote positive nitrogen balances for up to 720 minutes).
They include all protein food sources such as eggs, chicken, fish, dairy products and supplemental protein powders containing milk and casein (isolates or concentrates.
“Fast digesting” proteins can rapidly raise blood amino acids create a quick and short-lived increase in protein synthesis, and as such are often referred as “anabolic” proteins.
“Fast digesting” proteins include whey isolates, whey concentrates or any one of the protein hydrolysates Both rapidly and slowly digested proteins offer significant benefits to athletes. Research has shown that proteins that enter the blood stream rapidly significantly increase protein synthesis.
Proteins that enter the blood stream slowly have a pronounced effect on protein breakdown, significantly inhibiting it even at low quantities. Both types of protein should be used in strategic fashion to alter protein metabolism in favor of net protein deposition (i.e. muscle growth).
Protein needs vary by person depending upon age, weight, sex, activity level and overall health. Experts are still not entirely sure how much protein we need and estimates have been revised often in recent years. The protein RDA suggests that we eat approximately 10-15 percent of calories as protein in our daily diet.
It is widely agreed that athletes and bodybuilders need more protein than the recommended dietary allowance, or RDA. Why? Because weight training and exercise is a form of stress. The body requires higher amounts of branched chain amino acids during and following exercise as they are absorbed directly by the skeletal muscles versus first being metabolized through the liver, like other amino acids.
For physique athletes or body-weight athletes interested in increasing lean body mass while minimizing fat mass, excess protein intake above “need” is required to maintain positive nitrogen balance.
The requirements of carbohydrates, protein, micro and macronutrients as well as overall calories increase with physical activity, therefore the recommended amount of protein must change to meet the body's needs.
With a calorie sufficient diet, protein requirement values needed to maintain positive nitrogen balance of both weight trained and endurance trained athletes constitutes intakes of approximately 30% of total daily calories.
A diet consisting of approximately 40% protein may be a good starting point for those that are insulin-sensitive or insulin-resistant to make up for the reduction of carbohydrates within the diet of such individuals.
This averages out to be about 1.5-2.0g/kg of body weight (1.5-2.0g/kg) for the average natural bodybuilder. However, during dieting or anabolic drug use, more protein may be needed and/or beneficial.
It is important that a bodybuilder gets an adequate amount of protein. However, protein consumption should be based on need. If high quality protein sources are consumed in small amounts 30 to 40 grams every 2 to 3 hours, or more optimally 15-20 grams every 1 to 2 hours, 6 to 7 times a day, the overall amount of protein due to increased efficiency and utilization can be reduced.
It is also very important to increase water consumption so that the kidneys run smoothly and successfully eliminate the toxic byproducts of protein metabolism. It is important to remember that if the kidneys don't get the water they need our health deteriorates rapidly.
Drawbacks Of High Protein Diets:
Although high-protein diets generally aren't harmful for people in good health, high protein diets may increase the risk to several organs within the body. For instance:
The liver and kidneys are put under strain because they have to detoxify and eliminate unusually high quantities of protein by products (ammonia/ketones). Kidney problems may also be exacerbated in people with diabetes.
There is an increased risk of developing gout and gall bladder colic.
Greater losses of body calcium may increase the risk of osteoporosis.
Therefore anyone who has kidney, liver disease, and a family history of osteoporosis or any chronic health condition should consult their physician before starting a high protein diet.
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About the Author Jeff Behar
Jeff Behar, MS, MBA, is a well-known health, fitness, wellness author and anti aging, champion natural bodybuilder (2014 Masters Grand Prix Champion, 2015 California State Masters Champion), and a recognized health, fitness and nutrition expert with over 30 years of experience in the health, fitness, disease prevention, nutrition, and anti-aging fields.
As a recognized health, fitness and nutrition expert, Jeff Behar's has been featured on several radio shows, TV, and in several popular bodybuilding publications such as Flex, Ironman and in several highly regarded peer reviewed scientific journals. Jeff Behar is also the CEO and founder www.MuscleMagFitness.com and www.MyBesthealthPortal.com and a Medical Commentator on exercise for The American Academy of Anti-Aging Medicine, the worlds largest medical academy for anti-aging and regenerative medicine, provides medical professionals with the latest Anti-Aging, regenerative, functional and metabolic medicine.
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