Introduction
     Being vegetarian does not mean your diet will be lacking in protein. Most plant foods contain protein and in fact it would be very difficult to design a vegetarian diet that is short on protein. Excess dietary protein often leads to health problems. It is now widely acknowledged that one of the benefits of a vegetarian diet is that it contains appropriate (meaning ideal for all lifestyles) but not excessive protein.
     Proteins are made up of smaller units called amino acids. Proteins help our bodies build and maintain muscles, bones, hormones, enzymes, and many other body tissues. Proteins are made of building blocks and combinations of these amino acids form the proteins that exist in all living creatures. Our bodies make 12[twelve] of the amino acids; the other 8[eight]*, refered to as essential amino acids, must be obtained by dietary sources. Our bodies use these acids to aid in synthesizing our own amino acids.
     Unlike animal products, individual plant foods may not contain all the essential amino acids in the ideal proportions, However, this is utterly irrelevant as the typical varied vegetarian diet means adequate amounts of proteins/amino acids are consumed throughout the day. Too much protein (sustained levels above 0.4grams per pound of body weight) can quickly lead to the development of arthritis and many other health ailments. Animal proteins require a longer period of time and greater amounts of energy expended for the body to tear apart and reassemble, meaning that plant sources are more readily used by the human body.
     The claim that veg(etari)ans are at risk of protein deficiency is a disgusting lie that can lead to an individual doing serious harm to their body by buying into the absurd notion and consuming excessively high, unsafe amounts. No reputable organization or knowledgeable dietician/nutritionist will claim that these groups of individuals need to take any special precautions in this matter.

Structure & Functions
     Proteins are highly complex molecules comprised of linked amino acids. Amino acids are simple compounds containing carbon, hydrogen, oxygen, nitrogen and occasionally sulphur. Amino acids link together to form chains called peptides. Each protein has its own unique number and sequence of amino acids which determines their particular structure and function. Proteins are broken down into their constituent amino acids during digestion which are then absorbed and used to make new proteins in the body.

The eight essential amino acids required by humans are:
isoleucine,
leucine,
lysine,
methionine,
phenylalanine,
threonine,
tryptophan, and
valine,
[*For children, histidine is also considered to be an essential amino acid.]

Proteins are essential for growth and repair.
     They play a crucial role in virtually all biological processes in the body. All enzymes are proteins and are vital for the body's metabolism. Muscle contraction, immune protection, and the transmission of nerve impulses are all dependent on proteins. Proteins in skin and bone provide structural support. Many hormones are proteins.
Protein can also provide a source of energy. Generally the body uses carbohydrate and fat for energy but when there is excess dietary protein or inadequate dietary fat and carbohydrate, protein is used. Excess protein may also be converted to fat and stored.

Dietary Sources
     Most people assume that animal protein is superior to the protein found in plant foods and is full of essential amino acids as well. In reality, all the amino acids in animal foods derived from the vegetation the particular animal consumed, whether it be the grain fed to cows and chickens or the plankton, algae, or kelp the swordfish swallowed.
     Plant-based foods are the source of all the essential amino acids, and they also have significant amounts of protein. For instance, asparagus, broccoli, and tofu are all around 40 percent of calories. Watercress weighs in at a whopping 83 percent! Good sources of protein for vegetarians include nuts and seeds, pulses, soya products (tofu, soya milk and textured soya protein such as soya mince), cereals (wheat, oats, and rice).
     It's a common misconception that you need to combine plant proteins at each meal or in each dish to make them form "complete proteins" or proteins that contain all the essential amino acids. This is not necessary, and even the American Dietetic Association agrees that eating a diet rich in a wide variety of fruits, vegetables, and grains will provide you with all your amino acids and protein needs and minerals to boot. Plus, plant-based foods are cholesterol free and low in calories and fats, unlike their animal-based equivalents.
     Our bodies can better and more easily utilize plant-based protein sources than meat-based sources because they are built for them. Human saliva contains a carbohydrate-digesting enzyme, referred to as salivary anylase, which is responsible for the digestion of starches. Animal-based protein contains very small amounts of carbs.

Defining "Quality"
     Different foods contain proteins, each with their own unique amino acid composition. The proportions of essential amino acids in foods may differ from the proportions needed by the body to make proteins. The proportion of each of the essential amino acids in foods containing protein determines the quality of that protein. Dietary proteins with all the essential amino acids in the proportions required by the body are said to be a "high" quality protein, however, truly high-quality protein will not contain harmful substances.
     If the protein is low in one or more of the essential amino acids the protein is thought to be of a "lower" quality. The amino acid that is in shortest supply is called the limiting amino acid. Protein quality is usually defined according to the amino acid pattern of egg protein, which is regarded as the "ideal". As such, it is not surprising that animal proteins, such as meat, milk and cheese tend to be considered of a "higher" protein quality than plant proteins. This is why plant proteins are sometimes erroneously referred to as "low" quality proteins.
     Many plant proteins are "low" in one of the essential amino acids. For instance, grains tend to be short of lysine whilst pulses are short of methionine. This does not mean that vegetarians or vegans go short on any essential amino acids. A well-balanced vegetarian or vegan will easily supply all the protein and essential amino acids needed by the body. The "need" to "combine" proteins at every meal is a failed hypothesis that was disproven decades ago.
     Previously, it had been thought that protein combinations were needed within a single meal. However, it is now known that this is not necessary as the body keeps a short-term store of the essential amino acids. It was once thought that various plant foods had to be eaten together to get their full protein value, otherwise known as protein combining or protein complementing. We now know that intentional combining is not necessary to obtain all of the essential amino acids.¹ As long as the diet contains a variety of grains, legumes, and vegetables, protein needs are easily met.

References
1. Position of the American Dietetic Association: vegetarian diets. J Amer Diet Assoc 2003 Jun;103(6):748-65.

Examples of Varying Quality
Protein Sources	Single Servings	Protein Content [grams]
Good sources
Chick peas Brown rice Baked beans Broccoli Tofu Lentils Soya milk Muesli Peanuts	200g or 7oz 200g or 7oz 225g or 8oz 100g or 3½oz 140g or 5oz 120g or 4¼oz ½ pint 60g or 2¼oz 30g or 1oz	16.0g 4.4g 11.5g 3.1g 10.3g 9.1g 8.2g 7.7g 7.3g
Fair sources
Potatoes Carrots Apples Porridge Bread	200g or 7oz 1 1 160g or 6oz 2 slices	2.8g 0.4g 0.3g 2.4g 7.0g
Poor sources
Cream, double Cow's milk* Butter/margarin Vegetable oil Sugar or syrup Egg, boiled* Hard cheese*	20g or 2/3oz ½ pint 1 30g or 1oz	0.3g 9.2g None None None 7.5g 6.8g

*high-quality sources of protein do not contain large amounts of saturated fat or any cholesterol, and most importantly won't raise ones risks of becoming ill, and, as a bonus, will provide minerals and vitamins as well as other vital nutrients in the form of complex carbohydrates and phytochemicals.

Required Intakes
     How much protein does your body really need? It's recommended that 1 out of every 10 calories you take in should come from protein, and exactly how much that amounts to depends on your weight. The Recommended Daily Allowance (RDA) for protein is a little less than 1/2gram per each pound you weigh. But most Americans consume 4 to 8 times their daily requirement of protein, which translates to 15 to 20 percent of their caloric intake coming from protein. For vegans, roughly 10 to 12 percent of their calories come from protein.
     The old Recommended Daily Amounts (RDA's) have now been replaced by the term Reference Nutrient Intake (RNI). The RNI is the amount of nutrient which is enough for at least 97% of the population. Research has shown that we do not need as much protein as previously thought. The recommended amounts of protein for adults and children has more than halved in the last 20 years.

To find out your average individual need, simply perform the following calculation:
Body weight (in pounds) X 0.36 = recommended protein intake (in grams)

     However, even this value has a large margin of safety, and the body’s true need is even lower for most people. Protein needs are increased for women who are pregnant or breastfeeding. In addition, needs are also higher for very active persons. As these groups require additional calories, increased protein needs can easily be met through larger intake of food consumed daily. Extra serving of legumes, tofu, meat substitutes, or other high protein sources can help meet needs that go beyond the current RDA.

Guideline: Reference Nutrient Intakes
Age	grams
Infants 0 to 3 months 4 to 6 months 7 to 9 months 10 to 12 months	12.5g 12.7g 13.7g 14.9g
Children 1 to 3 years 4 to 6 years 7 to 10 years	14.5g 19.7g 28.3g
Males 11 to 14 years 15 to 18 years 19+ years 50+	42.1g 55.2g 55.5g 53.3g
Females 11 to 14 years 15 to 18 years 19+ years 50+	41.2g 45.4g 45.0g 46.5g
Pregnancy <= 18 years	51g
Lactation <= 18 years	53-56g

     Increased protein needs during pregnancy and breast feeding are usually met simply by the extra calories from more food. Because infants and children are growing they require more protein than adults (proportional to their body weight). Children on a balanced diet usually get enough protein as long as they are getting enough energy (or calories). RNI values for protein are valid only if energy needs are also met. If energy needs are not met then dietary protein is used for energy rather than tissue growth and repair. This is not generally of concern to vegetarians as plant sources of protein tend to also be a good source of carbohydrate, used for energy.
     Contrary to popular belief athletes and those who engage in a lot of exercise do not necessarily need extra protein as the extra energy required for strenuous activity is best supplied by carbohydrates. The extra protein needs of a body builder can usually be supplied by an increased energy intake from more food. Whilst vegetarian diets usually meet or exceed protein requirements, they are typically lower in total intake of protein than non-vegetarian diets. This lower protein intake may well be beneficial as high protein intake has been associated with osteoporosis and aggravating poor or failing kidney functioning. It is recommended that protein intake should not exceed twice the RNI.
     The conventional [backward] diet guidelines suggest that humans should acquire a large amount of their protein quotas from meats & animal sources like chicken, eggs, etc... unlike a pure vegetarian diet which acquires its intake from high-quality plant protein sources.

Can the pure vegetarian (vegan) diet provide enough protein for sound human health?
     The medical community agrees about the distinct health advantages of a pure vegetarian diet, but the protein question stays with us because animal products have been promoted by the industries that produce them, sell them, and want people to think of them as the best source of protein. This assumption is wrong and is very harmful, as a quick study of the facts about daily requirements of protein and nutrition shows.

The Importance of Protein
     Protein is essential to human health. Our bodies [hair, muscles, fingernails, and so on] are made up mostly of protein. As suggested by the differences between our muscles and our fingernails, not all proteins are alike. This is because differing combinations of any number of 20[twenty] amino acids may constitute a protein. In much the same way that the 26 letters of our alphabet serve to form millions of different words, the 20[twenty] amino acids serve to form different proteins. Amino acids are a fundamental part of our diet. While 12[twelve] of the 20[twenty] can be manufactured by the human body, the other 8* cannot.¹ These "essential amino acids" can easily be provided by the standard balanced vegan diet.

How Much Protein?
     As babies, our mothers' milk provided the protein we needed to grow healthy and strong. Once we start eating solid foods, non-animal sources can easily provide us with all the protein we need.¹ Only 10 percent of the total calories consumed by the average human being need be in the form of protein.²
     The Recommended Dietary Daily Allowance for both men and women is 0.8 grams of protein for every kilogram (2.2 pounds) of body weight (>0.4g/lb).³ People with special needs (such as pregnant women) are advised to get a little more. Vegans should not worry about getting enough protein; if you eat a reasonably varied diet and ingest sufficient calories, you will undoubtedly get enough protein.
     Protein deficiency, or "kwashiorkor," is very rare in the U.S. and is usually diagnosed in people living in countries suffering from famine.⁴ (famines, ironically, that are intimately linked to the consumption of animal proteins in affluent countries!) By contrast, eating too much animal protein has been directly linked to the formation of kidney stones and has been associated with cancer of the colon and liver.^5,6 By replacing animal protein with vegetable protein, you can improve your health while enjoying a wide variety of delicious foods.

Protein Sources
     While just about every vegetarian food contains some protein, the soybean deserves special mention, for it contains all the essential amino acids and surpasses all other food plants in the amount of protein that it can deliver to the human system. In this regard, it is nearly equal to meat. The human body is able to digest 92 percent of the protein found in meat and 91 percent of that found in soybeans.⁷
     The many different and delicious soy products (such as tempeh, soy "hot dogs" and "burgers", Tofutti brand "ice cream", soy milk, and tofu) available in health and grocery stores suggest that the soybean, in its many forms, can accommodate a wide range of tastes. Other rich sources of non-animal protein include legumes, nuts, seeds, yeast, and freshwater algae.
     Although food yeasts ("nutritional yeast" and "brewer’s yeast") do not lend themselves to forming the center of one's diet, they are extremely nutritious additions to most menus (in soups, gravies, breads, casseroles, and dips). Most yeasts get about 50 percent of their calories from protein⁸.
Here are some examples of vegetarian foods with high sources of plant protein:

PROTEIN IN LEGUMES:
Garbanzo beans, Kidney beans, Lentils, Lima beans, Navy beans, Soybeans, Split peas

PROTEIN IN GRAINS:
Barley, Brown rice, Buckwheat, Millet, Oatmeal, Quinoa, Rye, Wheat germ, Wheat, hard red, Wild rice

VEGETABLE PROTEIN:
Artichokes, Beets, Broccoli, Brussels sprouts, Cabbage, Cauliflower, Cucumbers, Eggplant, Green peas, Green pepper, Kale, Lettuce, Mushrooms, Mustard green, Onions, Potatoes, Spinach, Tomatoes, Turnip greens, Watercress, Yams, Zucchini

PROTEIN IN FRUITS:
Apple, Banana, Cantaloupe, Grape, Grapefruit, Honeydew melon, Orange, Papaya, Peach, Pear, Pineapple, Strawberry, Tangerine, Watermelon

PROTEIN IN NUTS AND SEEDS:
Almonds, Cashews, Filberts, Hemp Seeds, Peanuts, Pumpkin seeds, Sesame seeds, Sunflower seeds, Walnuts (black)

Hemp Protein Powder
     One excellent product to look for is hemp seed protein. Hemp seed is an nutritious dietary source of easily digestible gluten-free protein. It provides a well-balanced array of all the amino acids, including 34.6 grams of protein for each 100 grams. The fatty acid profile of the hemp seed is extremely beneficial, containing omega-6 and omega-3 fatty acids in a virtually ideal ratio. Other beneficial aspects of hemp seed include a strongly favorable unsaturated-to-saturated fat ratio; a high content of antioxidants; and a wide variety of vitamins and minerals.

Animal Protein
     The concern with bone health arises from the fact that muscle protein has a high sulphur content. When people eat too much of this meat protein, sulfuric acid forms within our bodies which must somehow be neutralized to maintain proper internal pH balance. One way our bodies can buffer the sulphuric acid load caused by meat is with calcium borrowed from our bones. Cheese is also a leading source of these sulphur-containing proteins.⁹ People on high meat diets can lose so much calcium in the urine that it can actually solidify into kidney stones.¹⁰ Over time, high animal protein intakes may leach enough calcium from the bones to increase one's risk of osteoporosis. People may be peeing their bones into the toilet along with the ketones.

     The Harvard Nurse's Health Study, which followed over 85,000 nurses for a dozen years, found that those who ate more animal protein had a significantly increased risk of forearm fracture. While plant-based proteins did not show a deleterious effect, women eating just a serving of red meat a day seemed to have significantly increased fracture risk.¹¹ Other studies have linked meat consumption to hip fracture risk as well.¹²

     Furthermore, a 2003 review of the safety of low carbohydrate/high protein diets reeled off an alarming list of potential problems: "Complications such as heart arrhythmias, cardiac contractile function impairment, sudden death, osteoporosis, kidney damage, increased cancer risk, impairment of physical activity and lipid [cholesterol] abnormalities can all be linked to long-term restriction of carbohydrates in the diet."¹³

References
1 University of Arizona, Department of Biochemistry and Molecular Biophysics, “Amino Acids Problem Set,” The Biology Project, 25 Aug. 2003.
2 Paula Kurtzweil, “‘Daily Values’ Encourage Healthy Diet,” U.S. Food and Drug Administration, 2003.
3 Food and Nutrition Board, “Dietary Reference Intakes for Energy, Carbohydrates, Fiber, Fat, Protein and Amino Acids (Macronutrients),” National Academy of Sciences (2002): 10-1.
4 U.S. National Library and the National Institutes of Health, “Kwashiorkor,” MEDLINEplus Medical Encyclopedia, 11 Jul. 2002.
5 Gary C. Curhan et al., “A Prospective Study of Dietary Calcium and Other Nutrients and the Risk of Symptomatic Kidney Stones,” The New England Journal of Medicine 328 (1993): 833-8.
6 Kathleen M. Stadler, “The Diet and Cancer Connection,” Virginia Tech, Nov. 1997.
7 Gertjan Schaafsma, “The Protein Digestibility-Corrected Amino Acid Score,” Journal of Nutrition 130 (2000):1865S-1867S.
8 USDA National Nutrient Database for Standard Reference, “Leavening Agents, Yeast, Baker’s, Active Dry,” 16 Jul. 2003
9 Proceedings of the Nutrition Society 62(2003):867.
10 Journal of Pediatrics 117(1990):743.
11 American Journal Epidemiology 143(1996):472.
12 American Journal of Clinical Nutrition 73(2001):118.
13 Asia Pacific Journal Clinical Nutrition. 12(2003)396.