Protein is one of the basic and essential foods [ There are seven major classes of nutrients: carbohydrates, fats, fibre, minerals, protein, vitamin, and water] in everyone’s diet. Most of us know proteins as the meat in our diet but few realize that protein is made up of many molecules of different amino acids or that amino acids are found in foods other than meats.

This article briefly reviews the role of amino acids in the diet and addresses some of the controversies about proteins and whether vegetarians can get adequate protein from sources other than meat.  

% Protein in Diet:

Protein is so abundant in the foods Americans eat that most of us, children and adults alike, consume more than we need. This has contributed to a growing controversy about the amount and the kind of protein we should be eating. Indeed, many persons are concerned that vegetarians may not be getting enough protein in their diets while scientists argue that meat eaters may be eating too much protein! Adding fuel to the controversy is research that points to over-indulgence of protein may be contributing to many of our chronic health problems. [ Cordain ]

WHAT IS THE DIFFERENCE BETWEEN A PROTEIN AND AN AMINO ACID?

Amino acids are the building blocks of proteins. Another way of thinking of this is to compare amino acids to the beads of a necklace. Without the string to hold them together, amino acids are just beads. The amino acids in formula are different from amino acids in food because they are already broken down. Because they are already separated from each other, they are absorbed quickly and all at once, giving the body a small amount of time to use them.

 A protein is a chain of amino acids connected together. You can think of this like a beaded necklace. The beads (amino acids) are connected together by a string (bond), which forms a long chain (protein). Therefore, a protein is "intact" or "whole."

 Proteins are connected together; free amino acids are not.

So how much protein do we need?

The Dietary Reference Intakes, previously recommended dietary allowance (RDA), for protein is based on how much you weigh. Although the National Academy of Sciences initially set the amount of RDA at about 0.4 grams protein for every pound of body weight, they then added an additional 0.4 grams as an added margin of safety; thereby advocating 0.8 grams of protein for every pound of body weight. It is the doubling of the protein RDA that has been hidden and misinterpreted when discussing the amount of protein really needed in our diets!

On the other hand, the World Health Organization has established a minimum daily requirement for protein to be approximately 5 percent of daily calorie intake. Trumble ] Since these allowances, as measured in grams, are difficult to comprehend, it may be easier to just express the amount ingested as percent [ % ] calories of the daily diet. Thus, the percent amount of protein recommended varies from about 2.5 % to 35 % [ Nutrient levels in diet ].

Adding fuel to the controversy are studies showing that people can lead healthy, active lives while consuming only 2.5 percent of calories a day as protein equivalent to 20 grams a day for an adult male, and even less for an adult female. Trumble Article by Tremble: Protein cvoncerns is no longer active.

Except for malnourished people in third-world nations [ whose diets are low in all nutrients ] protein deficiency is virtually unheard of. Nevertheless, in the United States, where we are practically drowning in a sea of protein, people still feel the need to load up on protein-rich foods, consuming all the fat and cholesterol that usually come with them. [ You can easily meet your protein needs by choosing a balanced diet with approximately 10-35% of your total daily calories coming from protein.  Protein Needs - US Guidelines on Protein and Diet  UCLA Protein Info ]

The body does not have a storehouse for protein as it does for carbohydrates [ glycogen in the liver and muscles ] and fat. Protein must be continuously ingested in order for the body to maintain optimal health. Now, while the body does not have a storehouse per se, it does have a sort of “pool” of amino acids in the form of those that are in the bloodstream at any given time. Amino acids in the blood have a half-life of roughly 4-6 hours.

So what is protein and what does it do?  

Proteins are large, complex molecules that play many critical roles in the body. They do most of the work in cells and are required for the structure, function, and regulation of the body’s tissues and organs.

Proteins are made up of hundreds or thousands of smaller units called amino acids, which are attached to one another in long chains. There are 22 different types of amino acids that can be combined to make a protein.

Of the twenty-two standard amino acids, eight are called essential amino acids because the human body cannot synthesize them from other compounds at the level needed for normal growth, so they must be obtained from food. However, the situation is quite complicated since cysteine, taurine, tyrosine, histidine and arginine are semi-essential amino acids in children, because the metabolic pathways that synthesize these amino acids are not fully developed in children. The amounts required also depend on the age and health of the individual, so it is hard to make general statements about the dietary requirement for some amino acids.

When protein is consumed, the body breaks it down into amino acids, the building blocks of all proteins. Some of the amino acids are designated nonessential. This does not mean that they are unnecessary, but rather that they do not have to come from the diet because they can be synthesized by the body from other amino acids. Other amino acids are considered essential, meaning that the body cannot synthesize them, and therefore must obtain them from the diet.For example:

Need more than Amino Acids in the diet  

Just as vitamin D and calcium intake by themselves do not help unless other nutrients or co-factors are present in the diet, so amino acids need co-factors to make them available to the body cells and organs.  The body constantly conducts many complicated series of chemical reactions in precisely controlled ways to keep us healthy. Over 5,000 reactions occur every second in a cell. By utilizing the natural substances in optimal quantities to re-establish a normal balance, you can help correct the cause of some disease processes in a non-toxic way.

Amino acid metabolism disorders are becoming recognized as a major factor in many disease processes. Helping medical doctors to better understand this relationship between amino acids and diseases are metabolic tests.One such test is amino acid analysis of urine or plasma to assess vitamin and mineral status. Many of the enzymes which catalyze the inter-conversion of amino acids require vitamin and mineral co-factors to function optimally. In many cases where incomplete conversion of one product to another is due to sluggish enzymes, this may indicate a functional need for increasing levels of a co-factor. Article by Sahley: Nutrients is no longer active.

Another misunderstood aspect of food ingestion is the assumption by many that our digestive system absorbs all or most of the quantities of vitamins, minerals and amino acids that are stated in the supplemental labels.It is what ends up in the blood stream that really counts and not what is advertized in the label.

 Do you need to eat meat to get adequate protein in the diet?

The answer is “No!” Although it is important to consume the full range of amino acids, both essential and nonessential, it is not necessary to get them from meat, fish, poultry, and other complete-protein foods. In fact, because of their high fat content-as well as the use of antibiotics and other chemicals in the raising of poultry and cattle [ and toxic chemical build up in fish ] --- most of those foods should be eaten in moderation.

The American Dietetic Association (ADA) in its 1988 position paper on vegetarianism, stated that intentional combining of amino acid foods, is not necessary. A varied diet of grains, beans, plant seeds and vegetables provides all the essential amino acids, even without intentional combining. As physician John A. McDougall, M.D. has written, "...the combination of amino acids in proper proportions takes place long before our foods reach the dinner table. Nature has designed vegetable foods to be complete. If people living before the age of modern dietetics had to worry about achieving the correct protein combinations in their diets, our species would not have survived for these millions of years." [ Trumble ]

Plants and amino acids:

Fortunately, there is a good alternative way to get amino acids than from meat and dairy products. You can get more than enough amino acids from high-fiber, low-fat, plant-based foods.

It should be obvious by now that the seeds of plants are store-houses of amino acids. Plants need amino acids for growth and maintenance! Amino acids are required by plants throughout all their growing stages and especially in germination or when seeds begin to grow as embryos into plants. Amino acids are the starting points for the synthesis of cellular molecules including vitamins, nucleotides, chlorophyll, enzymes, proteins and so on. Because of their importance in plant germination, seeds are rich sources of amino acids.

Seeds  provide the same nutrition for humans and animals as plants. In fact, the majority of food consumed by human beings are seed-based foods. Edible seeds include: cereals (such as maize, wheat, and rice), legumes (such as beans, peas, and lentils), flaxseeds and nuts. Oilseeds are often pressed to produce rich oils, such as sunflower, rapeseed (including canola oil), and sesame.  One of the earliest food recipes made from ground chickpeas is called hummus, which can be traced back to Ancient Egypt times.

Plants, of course, are able to make all the amino acids. Humans, on the other hand, do not have all the enzymes required for the biosynthesis of all of the amino acids.

 Conclusion about Proteins:  

Conclusion: Plants can supply adequate amounts of all amino acids to maintain your health. Animal protein and vegetable protein probably have the same effects on health.  So which should you eat and how much? 

Here is some good advice from the Harvard School of Public Health:  "It’s the protein package that’s likely to make a difference. A 6-ounce broiled porterhouse steak is a great source of protein—38 grams worth. But it also delivers 44 grams of fat, 16 of them saturated. That’s almost three-fourths of the recommended daily intake for saturated fat. The same amount of salmon gives you 34 grams of protein and 18 grams of fat, 4 of them saturated. A cup of cooked lentils has 18 grams of protein, but under 1 gram of fat.

So when choosing protein-rich foods, pay attention to what comes along with the protein. Vegetable sources of protein, such as beans, nuts, and whole grains, are excellent choices, and they also offer healthy fiber, vitamins and minerals. The best animal protein choices are fish and poultry. [ For more protein sources check references for: Protein_Foods ] If you are partial to red meat, stick with the leanest cuts, choose moderate portion sizes, and make it only an occasional part of your diet. " Article ny Harvard School of Public health “The Nutrition Source Protein,” is no longer active.

Essential amino acids make up over 50% of every protein in your body, so a deficiency in any one of them can have detrimental effects on muscle preservation, athletic training, recovery, and more—which is why Essential Amino Acids are the ideal supplement to fuel your performance.

Option:   A protein supplement consideration for vegetarians is brewer’s yeast. Brewer's Yeast, labeled nutritional yeast, is a good source of protein for vegetarians because over 50% of its weight is protein. A nutritional analysis of Brewer’s Yeast, made by Lewis Labs, states the following on the label: