Casein or Whey?

Alicat

It would be very interesting to have a view views on this subject, slow releasing protien vs fast releasing protein.

Any ideas greatly appreciated. In order for the body to remain anabolic and not catabolic i understand that the body needs to stay in a positive nitrogen state, and this can only be acheived by using protein.

I understand that getting the right balance here is the key to great growth as the body stays in a anobolic state.

thanks

crazycal1

why not just drink your whey with milk-(ive used nothing but food for the last year so it maybe beneficial, but definetly not essential)

Alicat

regards food cal im at a disadvantage here, as the only foods i like are the unhealthy ones, so i tend to supplement foods with whey and casein at nght b4 bed. Breakfast porridge and whey mid morn myoplex dinner chicken and little rice or big cod on its own, mid afternoon myoplex, tea time work out then carbs and 10 mins later another whey then 20 minutes ill have my tea like potatoes and steak or pasta and chicken then casein b4 bed.

What u think?

crazycal1

i forgot to say i drink most of my protein-milk

einsteins mind was the key to all things...to understand more than to know.

www.extremenutrition.co.uk

Young Gun

use the different shakes at different times when they are essential.

Casein when u don't expect another protein source for an extended period of time. Whey when u need protein to be quickly absorbed ie post workout and first thing in the morning when you body needs it most.

AS regards food your diet would benefit greatly from eating real food and a wide variety of it as food is better absorbed due to having the essential nutrients and minerals to facilitate this which simple whey does not.

As regards your main protein source though it depends ultimately on the range and amount of amino acids as to how effective it is.

Nick500

The answer is most definitely both.

whey is fast protein for times when you want fast protein, like first thing in morning, pre and post workout, casein is slow protein for when you want a slow release, like in MRP formulas (although would normally have a blend with whey), or before bed...

What crazycal is getting at is true, if you just add skimmed milk to whey then essentially you get a blend and thats OK for times when you want a slow protein... so whey is definitely the more beneficial if you were only going to have 1 protein powder.

Nick

Young Gun

You may find this helpful

Amino Acids & Bodybuilding
By Barry Finnin, PhD, and Samuel Peters
From Muscle & Fitness Magazine, April 1996


Why do so many bodybuilders know so little about amino acids and protein, the differences in their form and the best times to ingest them? With nothing less that optimal muscle growth at stake, time invested in a little research can pay big dividends - both in terms of physical size and dollars saved.

Amino acids are the building blocks of proteins and muscle tissue. All types of physiological processes relating to sport - energy, recovery, muscle / strength gains and fat loss, as well as mood and brain function - are intimately and critically linked to amino acids. It's no wonder amino acids have become major players in athletes' supplementation, especially among bodybuilders.



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What are Amino Acids?

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The 23 or so amino acids are the molecular building blocks of proteins. According to one accepted classification, 9 are termed indispensable amino acids (IAA, sometimes called essential), meaning that they must be supplied from some food or supplement source; the others, which used to be classified simply as nonessential, are now more correctly termed dispensable amino acids (DAA) or conditionally indispensable, based on the body's ability to synthesize them from other amino acids.

You may not give it much thought when you sink your teeth into a chicken breast (or lentil stew), but the content and balance of amino acids, particularly the ratio of IAA to DAA, is what determines the body and health building value of a protein food or supplement. But that isn't all that matters.

In addition to being influenced by the carbohydrates, fats and total calories associated with it, protein quality is related to the amount of the specific aminos within both the IAA and DAA categories (for example, the amount of glutamine and branched chain amino acids, or BCAAs - leucine, isoleucine and valine). While the amount of IAAs are generally of greater importance, the DAAs are also significant because they're synthesized too slowly to support maximum growth. Even if a source has a perfect amino acid profile for a given individual and lifestyle, another important factor - to what extent these acids are actually delivered to the tissues when needed - must be considered. That, in turn, raises the issues of digestion, absorption, actual bioavailability and the potential value of supplementation.



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What is Bioavailability?

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Eating quality food is the most common way to get amino acids into the diet, especially high protein foods like lean meats and nonfat dairy products. Even some vegetables and legumes can offer high levels of most amino acids. For serious athletes and those on the run, protein powders and pure free form amino acids provide a convenient and effective means to supplement dietary needs.

Why would people pay relatively large sums of money for only a few grams of pure cheaply? Because of bioavailability.

Bioavailability gauges the extent to which an administered substance reaches its site of action or utilization in the body. Bioavailability is thus a measure of the efficiency of delivery - how much of what is ingested is actually used for its intended purpose.

Conceivably, two diets could contain exactly the same amount of particular amino acids (the same amino acid profile) but have significant differences in their absorption. A number of factors affect amino acid bioavailability (see Factors Affecting Amino Acid Bioavailability.

The most reliable way to deliver specific amino acids is to administer the particular amino acids themselves. The most bioavailable source for oral use is powdered free form amino acids.

A singular (unbonded) amino acids can specifically elevate its level in the general circulation within 15 minutes, making it readily available for metabolism at the site where it's needed. Hence, for example, the recommendation to use BCAAs before, during and after training both to prevent central / mental fatigue, as well as to provide a source of energy to help prevent muscle protein catabolism and to speed recuperation.



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Applications to Bodybuilding

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Muscle tissue will grow in the presence of a number of factors, including exercise, hormones (growth hormone, insulin, testosterone and thyroid) and nutrients. Nutrition science has advanced to the point where athletes who supplement with free form amino acids can get IAAs, high in BCAA content, to the muscles much more effectively.

The key is the window of opportunity that occurs immediately after exercise, when the muscle is especially receptive to nutrients and the blood flow to the exercised muscles remains high. The solution to optimizing recovery and growth in this case could include eating a small meal composed of protein with both simple and complex carbohydrates.

This isn't the current high tech approach, however. For one, if you trained hard, chances are - even if a convenient and light, nutritious meal was readily available - you wouldn't feel like eating. More important, a high protein meal won't put significant levels of amino acids into your bloodstream until a couple of hours after you eat it, especially if blood flow to the gastrointestinal tract has been diminished by a hard training session. The bottom line: Even if you eat the right foods soon after training, the nutrients will arrive at the muscle too late to take full advantage of the window of opportunity.



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Directed Amino Acids

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Supplement manufacturers recognized the potential value of free-form amino use was limited by their expense and a relative lack of convincing supportive research for a number of years, their popularity has recently increased dramatically. Prepackaged workout and recovery drinks containing hydrolyzed (predigested) proteins and often some free-form amino acids now fill gym refrigerators. Capsules and powdered free-form amino acids, although still somewhat expensive, are likewise being used by increasing numbers of top amateur and professional athletes.

The value of free-form amino acids is first and foremost that they don't require digestion. The term 'free-form' means exactly that: They are free of chemical bonds to other molecules and so move quickly through the stomach and into the small intestine, where they're rapidly absorbed into the bloodstream.

Upon absorption, amino acids are processed by the liver. When you eat a steak, for example, only relatively few amino acids escape the metabolic actions of the liver. Yet the liver can process only so many at one time, and taking a dose of 3-4 grams of rapidly absorbed amino acids exceeds the liver's capacity, resulting in the aminos being directed to the tissues that require them, such as muscle in the case of bodybuilder recovering from training. Thus, the concept of 'directed amino acids'.

While sound in theory, does it work in practice? As early as 1990, the Bulgarian national weightlifting team began trials to determine if free-form amino acids were a boost to muscular growth. The work was so successful that part of the study was replicated on the Colorado Springs Olympic Training Center. Since then, top bodybuilders and powerlifters around the world today - including Mr. Olympia Dorian Yates, and 'Mr. Powerlifting' Ed Coan - have benefited from this new research.



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Amino Acids for Energy

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Many misconceptions exist about the muscle contraction and the use of energy substrates during heavy during heavy, high-intensity weight training. When you're engaged in a repetitive power workout, a substantial portion of your energy comes from noncarbohydrate sources. When muscle contracts, it uses its stores of adenosine triphosphate (ATP, a substance vital to the energy processes of all living cells) for the first few seconds. The compound used to immediately replenish these stores is creatine phosphate (CP). The recent explosion of creatine supplements in the market attests to its value to hard training bodybuilders and other strength / power athletes.

CP is made from three amino acids: arginine, methionine and glycine. To keep CP and ATP levels high, these amino acids must be elevated in the bloodstream. Traditionally, these proteins have been supplied by foods in the diet. Elevating levels of these amino acids or of CP with conventional foods takes a great deal of time (for digestion) and isn't specific, typically providing levels of fats and carbohydrates that may or may not be desired. The use of free-form amino acids, alone and in combination with creatine supplements, can provide directed source of energy for power and growth.



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Amino Acids & Fat Loss

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In fat loss, two major processes must occur: 1) the mobilization and circulation of stored fats in the body must increase; and 2) fats must be transported and converted to energy at the powerhouse site of cells, the mitochondria. Several nutrients can assist in the conversion of fat to energy, including lipotropic agents such as choline, inositol and the IAA methionine which, in sufficient quantities, can help improve the transport and metabolism of fat.

Supplementation with complete IAA mixtures, BCAAs and glutamine can also help keep calorie and food volume down while providing targeted support directly to the muscles, liver and immune systems so critical to optimizing body composition.



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Reducing Muscle Catabolism

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The human body has the innate ability to break down muscle tissue for use as an energy source during heavy exercise. This muscle catabolism can cause muscle soreness, shrinkage of muscle tissue and may even lead to injury.

This enemy to bodybuilders is part of a process known as gluconeogenosis, which means producing or generating glucose from noncarbohydrate sources. The part of this reaction that of importance to bodybuilders is known as the glucose - alanine cycle, in which BCAAs are stripped from the muscle tissue and parts of them are converted to the amino acid alanine, which is transported to the liver and converted into glucose.

If you consume supplemental BCAA's. the body does not have to break down muscle tissue to derive extra energy. A study conducted recently at the School of Human Biology, University of Guelph, Onterio, Canada, confirmed that the use of BCAA's (up to 4 grams) during and after exercise can result in a significant reduction of muscle breakdown during exercise.

In addition to BCAAs, arginine is another amino acid that may benefit bodybuilders. Though it did not live up to its early hype, which touted the amino acid's ability to raise growth hormone level, new data indicate that arginine - in large but safe and affordable doses - may be able to raise GH levels by up to 1,000%.



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Free-Form vs. Di & Tripeptides

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The form an amino acid takes has been a confusing subject for a number of years, partly because of research that demonstrated superior absorption of purified di- and tripeptides fragments. Di- and tripeptides are simply two and three amino acid molecules bound together, respectively, as opposed to the single molecules of free-form amino acids.

The fact is, pure, powdered free-form amino acids are absorbed from the small intestine into the bloodstream and are available to the tissues very quickly. The problem with pure di- and tripeptides isn't their bioavailability but �3Ü available to consumers. Moreover, hydrolyzed proteins such as whey and lactalbumin are not necessarily good sources of di- and tripeptides. They generally contain very few of these amino acid combinations, and what few they have may get lost in the general wash of longer chain peptides contained in these hydrolysates.

So while pure di- and tripeptides are efficient in their ability to be absorbed into the bloodstream, pure free-form amino acids are equal or superior for bodybuilders and other athletes and more important, are as close as your nearest health food store.



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Factors Affecting Amino Acid Bioavailability

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How fat you eat a protein source and the length of time it takes for the digested amino acids to be available for use by the body are determined by a number of factors, which include:


Cooking - Amino acids are more or less sensitive to heat. For example, arginine is extremely stable and will decompose only if exposed to sustained temperatures about 470 degrees F. Carnitine decomposes at temperatures of 284 F. Cooking, in addition to killing micro-organisms, makes the long spiral polypeptide chains unwind, causing the amino acid to become more exposed when it reaches the digestive system.

Physical nature of the food, whether solid, liquid, powder or tablet; whether and to what extent chemically predigested and the type and amounts of binders, fillers and other nutritive and non-nutritive materials.

Status of the digestive system - Genetics, age, overall health and specific diseases and illnesses.

Metabolism or utilization by the intestine before absorption - such as occurs with glutamine.

Metabolism or utilization in the liver before transfer to the general circulation - For maximal directed effects, amino acids should be taken on an empty stomach and in a dosage that enables significant quantities to reach the target tissues.


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Amino Acid Form Comparison & Usage Guide

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Form Function/Value Pros Cons Recommended Usage
Free-Form Does not require digestion; small amounts quickly absorbed into bloodstream. Nutrients absorbed into bloodstream quickly, available to muscle or other tissues; helps prevent muscle catabolism. Relatively expensive. For example, glutamine: 3-5 grams, 1-5 times per day before or between meals; same for mixture of IAAs.
Hydrolyzed Predigestion speeds entry into digestive system, but often contains longer chains that must be broken down. Whey and lactalbumin are examples. Predigestion speeds absorption Contains longer chains, which must be broken before being absorbed into bloodstream. For maximum mass . strength gains or during periods of high stress or gastrointestinal problems: 20-30 grams, 1-3 times per day; for optimal health maintenance: 20 grams once per day.
Branched Chain Aids in the formation of alanine from glucose during exercise as well as glutamine from glucose and alphaketo glutarate. Can be converted into energy to prevent muscle catabolism. Relatively expensive form of energy for muscle action. During hard training: 4-5 grams 2-5 times per day, especially before and after training. Optimal ratio for normal use is 2:1:1 (leucine : isoleucine : valine), although higher leucine content immediately before and after exercise is okay.
Di-Tripeptides Two or three molecule amino acids that are quickly digested. Depending on conditions, may significantly increase nitrogen retention. Short chains for moderately fast digestion and absorption. Cost, availability, taste, osmolality. Usually found in highest quality hydrolyzed protein supplements (see doses above).



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The Amino Acid Guide

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There are three types of amino acids; the indispensable amino acids, the conditionally dispensable amino acids, and the dispensable amino acids. Indispensable amino acids, also called essential amino acids, must be supplied to the body from food or supplements. Conditionally dispensable amino acids are based on the body's ability to actually synthesize them from other amino acids. Dispensable amino acids, also called nonessential amino acids, can be synthesized by the body from other amino acids. Here is the amino acid guide and their benefits.


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The Indispensable Amino acids

Isoleucine

A branched chain amino acid readily taken up and used for energy by muscle tissue.
Used to prevent muscle wasting in debilitated individuals
Essential in the formation of hemoglobin


Leucine

A branched chain amino acid used as a source of energy
Helps reduce muscle protein breakdown
Modulates uptake of neurotransmitter precursors by the brain as well as the release of enkephalins, which inhibit the passage of pain signals into the nervous system.
Promotes healing of skin and broken bones.


Valine

A branched chain amino acid
Not processed by the liver; rather actively taken up by muscle
Influences brain uptake of other neurotransmitter precursors (trptophan, phenylalanine and tryosine).


Histadine

One of the major ultraviolet absorbing compounds in the skin
Important in the production of red and white blood cells; used in the treatment of anemia
Used in the treatment of allergic diseases, rheumatoid arthritis and digestive ulcers.


Lysine

Low levels can slow protein synthesis, affecting muscle and connective tissue
Inhibits viruses; used in the treatment of herpes simplex
Lysine and Vitamin C together form L-carnitine, a biochemical that enables muscle tissue to use oxygen more efficiently, delaying fatigue
Aids bone growth by helping form collagen, the fibrous protein that makes up bone, cartilage and other connective tissue.


Methionine

Precursor of cystine and creatine
May increase antioxidant levels (glutathione) and reduce blood cholesterol levels.
Helps remove toxic wastes from the liver and assists in the regeneration of liver and kidney tissue


Phenylalanine

The major precursor of tyrosine
Enhances learning, memory, mood and alertness
Used in the treatment of some types of depression
Is a major element in the production of collagen
Suppresses appetite


Threonine

One of the amino detoxifers
Helps prevent fatty buildup in the liver
Important component of collagen
Generally low in vegetarians


Tryptophan

Precursor of key neurotransmitter serotonin, which exerts a calming effect
Stimulates the release of growth hormones
Free form of this amino acid is unavailable in the U.S.
It is only available in natural food sources

Conditionally Dispensable Amino Acids

Arginine

Can increase secretion of insulin, glucagon, growth hormones
Aids in injury rehabilitation, formation of collagen and immune system stimulation.
Precursor of creatine, gamma amino butric acid (GABA, a neurotransmitter in the brain)
May increase sperm count and T-lymphocyte response


Cysteine

Detoxifies harmful chemicals in combination with L-aspartic acid and L-citruline
Helps prevent damage from alcohol and tobacco use
Stimulates white blood cell activity


Tyrosine

Precursor of the neurotransmitters dopamine, norepinephrine and epinephrine, as well as thyroid and growth hormones and melanin (the pigment responsible for skin and hair color).
Elevates mood


Dispensable Amino Acids

Alanine

Major component of connective tissue
Key intermediate in the glucose alanine cycle, which allows muscles and other tissues to derive energy from amino acids
Helps build up the immune system


Aspartic Acid

Helps convert carbohydrates into muscle energy
Builds immune system immunoglobulins and antibodies
Reduces ammonia levels after exercises


Cystine

Contributes to strong connective4e tissue and tissue antioxidant actions
Aids in healing processes, stimulates white blood cell activity and helps diminish pain from inflammation
Essential for the formation of skin and hair


Glutamic Acid

A major precursor of glutamine, proline, ornothine, arginine, glutathione, and GABA
A potential source of energy
Important in brain metabolism and metabolism of other amino acids.


Glutamine

Most abundant amino acid
Plays a key role in immune system functions
An important source of energy, especially for kidneys and intestines during caloric restrictions.
A brain fuel that is an aid to memory and a stimulant to intelligence and concentration


Glycine

Aids in the manufacture of other amino acids and is a part of the structure of hemoglobin and cytochromes (enzymes involved in energy production)
Has a calming effect and is sometimes used to treat manic depressive and aggressive individuals
Produces glucagon, which mobilizes glycogen
Can inhibit sugar cravings


Ornithine

May help increase growth hormone secretion in high doses
Aids in immune and liver function
Promotes healing


Proline

A major component in the formation of connective tissue and heart muscle
Readily mobilized for muscular energy
Major constituent of collagen


Serine

Important in cells' energy production
Aids memory and nervous system function
Helps builds up immune system by producing immuno-globulins and antibodies


Taurine

Aids in the absorption and elimination of fats
May act as a neurotransmitter in some areas of the brain and retina

Young Gun

And this

protein
What can high-protein foods do for you?
Keep your immune system functioning properly
Maintain healthy skin, hair and nails
Help your body produce enzymes
What events can indicate a need for more high-protein foods?
Muscle wasting
Weight loss
Fatigue and weakness
Frequent infections
Severe edema (fluid retention)
Slow growth and development in children
Excellent sources of protein include tuna, shrimp and cod.



Description
Function
Deficiency Symptoms
Toxicity Symptoms
Cooking, storage and processing
Factors that affect function
Drug-nutrient interaction
Nutrient interaction
Health conditions
Supplements
Food Sources
Public Recommendations
References



Description
What is protein?
Protein was the first substance to be recognized as a vital part of living tissue. In fact, the word protein comes from the Greek word proteos, which means “primary” or “taking first place,” indicating the importance of this nutrient in the function of the body. Accounting for 20 percent of our body weight, proteins perform a wide variety of functions throughout the body as vital components of body tissues, enzymes, and immune cells.

Proteins are complex molecules comprised of a combination of different amino acids, which are compounds that contain carbon, oxygen, hydrogen, nitrogen and sometimes sulfur. Amino acids link together in specific numbers and unique combinations to make each different protein.

Protein is an essential component of the diet, because it provides the amino acids that the body needs to synthesize its own proteins. Simply speaking, there are two types of amino acids: essential amino acids and non-essential amino acids. Essential amino acids are those that our body cannot synthesize on its own, so we must obtain them in our diet. The essential amino acids are isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, valine, arginine, and histidine.

Conversely, the nonessential amino acids are those that the body can manufacture, so it is not necessary to obtain them in the diet. The nonessential amino acids include glutamate, alanine, aspartate, and glutamine. Certain amino acids, such as proline, serine, tyrosine, cysteine, taurine, and glycine, are considered to be conditionally essential, meaning that under certain physiological circumstances the body is unable to manufacture them, so they must be obtained through the diet.

The body is only able to make the proteins it needs when there are sufficient quantities of all the necessary amino acids in the so-called “amino acid pool.” If we are deficient in essential amino acids, the body will be unable to make proteins and will have to break down muscle proteins to obtain the amino acids it needs.

As a result, it is imperative that our daily intake of food contains each of the essential amino acids, which is easily accomplished by eating a variety of vegetables, beans, whole grains, nuts, seeds, and meat and animal products if desired.

How it Functions
What is the function of protein?
Protein, providing 4 calories per gram, is an important source of energy for the body, when carbohydrates and fats are not available. In addition to using protein to generate energy for cellular function whenever necessary, the body uses the amino acids contained in the protein we eat to manufacture its own proteins. The proteins synthesized by the body perform a variety of important physiological functions:

Production and maintenance of structural proteins: The body manufactures several structural proteins, such as myosin, actin, collagen, elastin, and keratin, that maintain the strength and integrity of muscles, connective tissues (ligaments and tendons), hair, skin, and nails.
Production of enzymes and hormones: All of the enzymes, which are compounds that catalyze chemical reactions in the body, are made from protein. In addition, the hormones involved in blood sugar regulation (insulin and glucagon) as well as the thyroid hormones are synthesized from proteins.
Production of transport proteins and lipoproteins: Certain proteins are used by the body to carry various substances to body tissues. These transport proteins include hemoglobin (carries oxygen), transferrin (carries iron), ceruloplasmin (carries copper), retinol-binding protein (carries vitamin A), albumin and transthyretin (both carry other proteins). Lipoproteins participate in the transportation of fat and cholesterol.
Production of antibodies: Antibodies, which are proteins, play an important role in the immune system by attaching to antigens (viruses, bacteria, or other foreign invaders), thereby inactivating the antigens and making them more visible to the immune cells (called macrophages) that destroy antigens.
Maintenance of proper fluid balance: Proteins participate in the maintenance of osmotic pressure, which controls the amount of water that is found inside of cells.
Maintenance of proper acid-base balance: Due to their ability to combine with both acidic and basic substances, proteins help to maintain the normal acid-base balance in the body.
Deficiency Symptoms
What are deficiency symptoms for protein?
Both adults and children can live healthfully on a low intake of protein, assuming they eat a sufficient amount of calories and all of the essential amino acids are present in the diet. As a result, the symptoms of protein deficiency are most often seen in impoverished people who have limited access to food.

Protein-energy malnutrition, caused by low intake of both protein and calories, is especially common in children in underdeveloped nations, because children require more protein per kilogram of body weight than adults to support the rapid growth and development that occurs during childhood.

According to the World Health Organization, approximately 300 million children throughout the world suffer from growth retardation due to protein-energy malnutrition. Additionally, children with protein-energy malnutrition have a 40% mortality rate, due to increased susceptibility to infections.

In developed countries, protein-energy malnutrition is most likely to affect people who have suffered severe physical trauma that increases protein needs (for example, extensive skin burns) or those who have a medical condition or psychological problem that impacts their desire or ability to eat. The elderly are also at risk for protein-energy malnutrition.

There are two types of protein-energy malnutrition: marasmus and kwashiorkor. Marasmus is a state of semi-starvation that can occur in people of all ages who have limited access to food, but is most common in non-breastfed children given diluted infant formula. The symptoms of marasmus include weight loss, muscle wasting, loss of visible fat stores, weakness and fatigue, and frequent infections due to diminished activity of the immune system.

Kwashiorkor, a Ghanian word for "the evil spirit that infects the child", was first described in 1933 and typically occurs in children younger than 4 years old fed diets high in carbohydrates with little or no protein. Symptoms of kwashiorkor include muscle wasting, edema (fluid retention), and an enlarged and fatty liver, with the preservation of visible fat stores.

Because meat and dairy foods are a primary source of protein in the American diet, many nutritionists caution that those following a vegetarian or vegan diet may be at risk for protein deficiency. However, vegetarians and vegans who eat a variety of vegetables, grains and legumes can easily meet or exceed current protein requirements.

Toxicity Symptoms
What are toxicity symptoms for protein?
Excessive intake of protein over many years may lead to kidney problems and/or accelerated bone loss eventually leading to osteoporosis. Due to the lack of a dose-response relationship at higher levels of protein intake, the National Academy of Sciences (NAS) decided not to set a Tolerable Upper Limit (UL) for protein in 2002. However, the NAS did note that the building blocks of protein, called amino acids, should not be consumed in amounts significantly above the amounts found in food.

Because the kidneys play a primary role in protein metabolism, individuals with end-stage kidney disease must carefully monitor their intake of protein.

Impact of Cooking, Storage and Processing
How do cooking, storage, or processing affect protein?
When cooked or agitated (as occurs when egg whites are beaten), proteins undergo physical changes called denaturation and coagulation. Denaturation changes the shape of the protein, thereby decreasing the solubility of the protein molecule.

Coagulation causes protein molecules to clump together, as occurs when making scrambled eggs. Overcooking foods containing protein can destroy heat sensitive amino acids (for example, lysine) or make the protein resistant to digestive enzymes.

Factors that Affect Function
What factors might contribute to a deficiency of protein?
Protein digestion and metabolism involves the stomach, pancreas and liver. Hydrochloric acid, secreted by the stomach, is necessary for the initial digestion of protein. Pancreatic enzymes participate in the breakdown of protein. And the liver controls amino acid metabolism.

Consequently, any medical condition that comprises the function of the stomach, pancreas, or liver may negatively impact protein status. In addition, the ability of the body to manufacture non-essential amino acids may be hampered with inadequate intake of vitamin B6.

Individuals with bacterial or viral infections and those who have experienced severe physical trauma use up their protein stores rapidly, and may need to increase their intake of protein.

Drug-Nutrient Interactions
What medications affect protein?
Any medication that decreases the secretion, or neutralizes the action, of hydrochloric acid in the stomach may negatively impact protein digestion. Such medications include prescription and over-the-counter antacids (for example, Tums and Rolaids) and histamine blockers (for examples, Tagamet and Pepcid).

In addition, the steroidal anti-inflammatory medications (for example, prednisone) can cause muscle wasting. Consequently, physicians sometimes recommend that patients taking these medications increase their intake of protein.

Nutrient Interactions
How do other nutrients interact with protein?
Various proteins bind and carry certain vitamins and minerals including iron, copper, calcium, vitamin A, and vitamin D. As a result, inadequate protein intake may impair the function of these nutrients.

Health Conditions
What health conditions require special emphasis on protein?
Although adequate protein intake is necessary for health, protein is not often used therapeutically. However, high dietary intake of protein is beneficial for people who have experienced severe physical trauma and may be helpful for athletes. Additionally, several individual amino acids including glutamine, lysine, phenylalanine, tyrosine, arginine, and cysteine are commonly used therapeutically.

Form in Dietary Supplements
What forms of protein are found in dietary supplements?
A wide range of protein powders are available. Especially popular at present are those that contain soy protein, as soy has received much attention for its potential to prevent cardiovascular disease and cancer.

Food Sources
Introduction to Nutrient Rating System Chart
The following chart shows the World's Healthiest Foods that are either excellent, very good or good sources of this nutrient. Next to each food name you will find the following information: the serving size of the food; the number of calories in one serving; DV% (percent daily value) of the nutrient contained in one serving (similar to other information presented in the website, this DV is calculated for 25-50 year old healthy woman); the nutrient density rating; and the food's World's Healthiest Foods Rating. Underneath the chart is a table that summarizes how the ratings were devised. Read detailed information on our Nutrient Rating System.


World's Healthiest Foods ranked as quality sources of:
protein
Food Serving
Size Cals Amount
(g) DV
(%) Nutrient
Density World's
Healthiest
Foods Rating
Cod, Pacific, Fillet, Baked, Broiled 4 oz-wt 119.1 26.03 52.1 7.9 excellent
Tuna, Yellowfin, Baked/Broiled 4 oz-wt 157.6 33.99 68.0 7.8 excellent
Shrimp, Mixed Species, Steamed, Boiled 4 oz-wt 112.3 23.71 47.4 7.6 excellent
Snapper, Baked 4 oz-wt 145.2 29.82 59.6 7.4 very good
Venison 4 oz-wt 179.2 34.25 68.5 6.9 very good
Halibut, Baked/Broiled 4 oz-wt 158.8 30.27 60.5 6.9 very good
Tamari (Soy Sauce) 1 tbs 10.8 1.89 3.8 6.3 good
Scallops, Baked, Broiled 4 oz-wt 151.7 23.11 46.2 5.5 very good
Turkey Breast, Roasted 4 oz-wt 214.3 32.56 65.1 5.5 very good
Chicken Breast, Roasted 4 oz-wt 223.4 33.79 67.6 5.4 very good
Greens, Mustard, Boiled 1 cup 21.0 3.16 6.3 5.4 very good
Beef Tenderloin, Lean Broiled 4 oz-wt 240.4 32.04 64.1 4.8 very good
Lamb, loin, roasted 4 oz-wt 229.1 30.15 60.3 4.7 very good
Liver, Calf 4 oz-wt 187.1 24.53 49.1 4.7 very good
Spinach (boiled, with salt) 1 cup 41.4 5.35 10.7 4.7 very good
Lettuce, Romaine 2 cup 15.7 1.81 3.6 4.2 good
Mushrooms, Crimini, Raw 5 oz-wt 31.2 3.54 7.1 4.1 very good
Chinook Salmon Fillet-Baked/Broiled 4 oz-wt 261.9 29.14 58.3 4.0 very good
Asparagus, Boiled 1 cup 43.2 4.66 9.3 3.9 very good
Broccoli (pieces, steamed) 1 cup 43.7 4.66 9.3 3.8 very good
Tofu, Raw 4 oz-wt 86.2 9.16 18.3 3.8 very good
Soybeans, Cooked 1 cup 297.6 28.62 57.2 3.5 very good
Mozzarella Cheese, Part Skim, Shredded 1 oz-wt 72.1 6.88 13.8 3.4 very good
Chard, Boiled 1 cup 35.0 3.29 6.6 3.4 very good
Tempeh, Cooked 4 oz-wt 223.4 20.63 41.3 3.3 good
Yogurt, Cow Milk, Low Fat 1 cup 155.1 12.86 25.7 3.0 good
Egg, Hen, Whole, Boiled 1 each 68.2 5.54 11.1 2.9 good
Collard Greens, Boiled, Drained 1 cup 49.4 4.01 8.0 2.9 good
Cauliflower (boiled, drained) 1 cup 28.5 2.28 4.6 2.9 good
Lentils, Boiled 1 cup 229.7 17.86 35.7 2.8 good
Split Peas, Boiled 1 cup 231.3 16.35 32.7 2.5 good
Beans, Kidney, Cooked 1 cup 224.8 15.35 30.7 2.5 good
Kale, Fresh, Boiled 1 cup 36.4 2.47 4.9 2.4 good
Beans, Lima, Cooked 1 cup 216.2 14.66 29.3 2.4 good
Beans, Black, Boiled 1 cup 227.0 15.24 30.5 2.4 good
Milk, Cow, 2% 1 cup 121.2 8.13 16.3 2.4 good
Brussels Sprouts, Boiled 1 cup 60.8 3.98 8.0 2.4 good
Green Peas-Boiled 1 cup 134.4 8.58 17.2 2.3 good
Beans, Navy, Cooked 1 cup 258.4 15.83 31.7 2.2 good
Beans, Pinto, Cooked 1 cup 234.3 14.04 28.1 2.2 good
Miso (Soybean) 1 oz 70.8 4.06 8.1 2.1 good
Mushrooms, Shiitake, Raw 8 oz-wt 87.2 4.98 10.0 2.1 good
Greens, Turnip, Cooked 1 cup 28.8 1.64 3.3 2.0 good
Beans, Garbanzo, Cooked 1 cup 269.0 14.53 29.1 1.9 good
Green Snap/String Beans, Boiled 1 cup 43.8 2.36 4.7 1.9 good
Seeds, Mustard 2 tsp 35.0 1.88 3.8 1.9 good
Milk, Goat 1 cup 167.9 8.69 17.4 1.9 good
Cabbage (shredded, boiled) 1 cup 33.0 1.53 3.1 1.7 good
Squash, Summer, All Varieties 1 cup 36.0 1.64 3.3 1.6 good
Peanuts, Raw 0.25 cup 207.0 9.42 18.8 1.6 good
Pumpkin Seeds, Dried 0.25 cup 186.7 8.47 16.9 1.6 good
Rye, Whole Grain (1 cup cooked) 0.33 cup 188.7 8.31 16.6 1.6 good
Garlic 1 oz-wt 42.2 1.80 3.6 1.5 good
Oats, Whole Grain 1 cup 145.1 6.08 12.2 1.5 good
Tomato, Red, Raw, Ripe 1 cup 37.8 1.53 3.1 1.5 good
World's Healthiest
Foods Rating Rule
excellent DV>=75% OR Density>=7.6 AND DV>=10%
very good DV>=50% OR Density>=3.4 AND DV>=5%
good DV>=25% OR Density>=1.5 AND DV>=2.5%



Public Health Recommendations
What are current public health recommendations for protein?
Recommendations for protein intake are based on the concept of "nitrogen balance." Protein contains nitrogen, and as proteins are broken down in the body, nitrogen is excreted. Consequently, nitrogen must be continually replaced through the diet (as protein) so that the body can continue to make proteins.

For most adults, an even nitrogen balance is ideal, meaning that the amount of nitrogen provided in the diet is equivalent to the amount of nitrogen excreted. In contrast, children require a positive nitrogen balance to support growth and development, meaning that more nitrogen is supplied by the diet (as protein) than is eliminated. Pregnant and lactating women also require a positive nitrogen balance.

In 2002, the National Academy of Sciences (NAS) set Recommended Dietary Allowances (RDAs) for protein for all age groups 7 months and older, and Adequate Intake (AI) levels for infants 0-6 months of age. The daily standards set by the NAS were as follows: