The phrase “you are what you eat” coined by nutritionist Victor Lindlahr in the 1920s has etymological roots dating as early as the 1800s in French and German sources. This idiom has endured through the 1960s hippie movement and into modern catch-phrasing, serving as an accurate illustration of the effects of dietary nutrition on our bodies. When we digest food, we absorb essential nutrients to supplement elements that our bodies cannot synthesize efficient levels of.

In the case of dietary proteins, this phrase can be taken literally, but preferably not in the way Hannibal Lector interpreted it. Proteins are the building blocks of every cell in every structure of the human body, serving as critical components in all vital bodily functions.

All proteins are coded by a unique chain of amino acids. With 21 different amino acids appearing in human genetics, and some proteins boasting a peptide chain sequence over 20 thousand amino acids long… the protein possibilities are incalculable. Different types of proteins serve different purposes in the body, consuming protein in excess may still result in deficiency of particular amino acids. To ensure optimal intake of these nutrients, protein should be consumed from a variety of natural sources.

See: Amino Acids for a breakdown of these specific protein components and where to find them.

Structural Proteins

Fibrous proteins that act as the building blocks of the body.

  • Collagen– in muscles, cartilage, skin, tendons and bones.
  • Keratin– in skin, hair, teeth and nails.
  • Elasticin-– in blood vessels, tendons and ligaments.

Storage Proteins

Store mineral ions and amino acids for use in essential body functions. High concentrations found in gluten, seeds and legumes.


Stores Iron and protects from adverse effects. Iron is a component of hemoglobin in red blood cells, and in cytochromes responsible for cell metabolism.


Found in mammalian milk, stores Calcium, Phosphorous, carbohydrates and amino acids for embryonic development.


Found in eggs, stores amino acids for embryonic development. When metal ions reach toxic levels in the blood, ovalbumin can prevent absorption in the GI tract.


Produced in endocrine glands and transmitted through the bloodstream, humans secrete and circulate about 50 major hormones that act as chemical messengers between cells.

For a comprehensive breakdown of hormones in the human body, see: Hormone Table by Professor John W. Kimball, Harvard PhD.


Produced in the pancreas, regulates blood sugar and metabolism of carbohydrates, fats and proteins. Inefficient production or utilization of insulin can lead to various forms of diabetes.


Derived from the amino acid tyrosine, precursor of epinephrine / adrenaline. Dopamine functions as a neurotransmitter in the brain, and acts as a local chemical messenger in digestive, circulatory and immune systems.

Norepinephrine / Noradrenaline

Primarily functions as a neurotransmitter, produced continuously in brain-stem nuclei that respond to stress and panic. Small amounts of noradrenaline are also produced as a hormone derived from dopamine in adrenal glands associated with the kidneys. Increased noradrenaline activity acts on alpha receptors to constrict blood vessels, restrict passage in urinary and GI tracts, enlarge pupils, and excite hair follicles. Alpha receptors are located primarily in smooth vascular muscles where sensitivity to noradrenaline promotes insulin production in the pancreas, increases conversion of blood glucose into energy, and increases blood pressure.

Epinephrine / Adrenaline

Produced in the adrenal medulla as a hormone derived from noradrenaline, production only occurs under stress. Similar to noradrenaline, increased production of adrenaline acts on alpha receptors to promote insulin production, increase conversion of blood glucose into energy, and increase blood pressure. Adrenaline also acts on beta receptors to promote glucose production in the pancreas, increase hormonal production in the pituitary gland, and increase breakdown of fats. Adrenaline is commonly administered in cases of severe allergic reaction to prevent anaphylactic shock.


Produced in the pineal gland, regulates sleep and circadian rhythm.


Derived from the amino acid tryptophan, produced primarily in the GI tract to facilitate intestinal movements. Serotonin also acts as a neurotransmitter to regulate sleep, appetite, mood and cognitive functions. Ascorbic acid is a required component in serotonin, to promote production of this hormone pair proteins with foods rich in Vitamin C.

Estrogens and Androgens

Produced in the ovaries or testes, regulate reproductive functions.


Serve as catalysts for chemical reactions that speed up metabolic processes in all systems of the body. Essential minerals are required as co-factors in order for many of these reactions to occur. Coenzymes are a co-factors that separate from the protein component of the enzyme to serve as catalysts and transfer components between enzymes. Vitamins are often required in the formation of coenzymes.

Digestive Enzymes

Essential in metabolic processes, humans rely primarily on four categories of digestive enzymes to break down food into functional components and excrete waste:


Enzymes that convert complex carbohydrates into simple sugars. Salivary amylase, activated by chewing, converts complex carbohydrate starches to the disaccharide sugar maltose. Pancreatic amylase, secreted into the small intestine, continues the digestion of carbohydrates into the simple sugar glucose.


Enzymes that convert proteins into amino acids. Pepsin, a proteolytic enzyme produced in the stomach, breaks proteins down to short-chain poly-peptides when activated by glutamic acid in the stomach. Trypsin, released from the pancreas into the small intestine, completes protein digestion by breaking proteins and poly-peptides down further to amino acid components.


Enzymes that convert dietary fats into glycerol and fatty acids. Gastric lipase, produced in small amounts in the stomach, aids in digestion of fats from butter. Pancreatic lipase, secreted into the small intestine, completes digestion of dietary fats by converting to fatty acids and glycerol.


Enzymes that convert nucleic acids into sugars, bases and phosphates. Produced in the pancreas, nucleases break DNA and RNA down into nucleotides for further digestion in the small intestine.

Other Digestive Enzyme Functions
  • Maltase and Sucrase— produced in the small intestine, break down specific sugars into glucose.
  • Lactase— produced in the small intestine, breaks down the specific milk sugar lactose into glucose and galactose.
  • Renin— produced in the stomach, breaks down milk proteins by converting to peptides, to be fully digested by pepsin.
  • Gelatinase— produced in the stomach, breaks down gelatin and collagen, to be fully digested by pepsin and trypsin.

Defensive Proteins


Proteins produced in white blood cells, carry out core functions of the immune system.

Transport Proteins

Carry ions, molecules and macro-molecules across cell membranes for essential functions.


Facilitate selective diffusion across cell membranes in passive transport from areas of high-concentration to areas of low-concentration.


Bind with specific ions and molecules to facilitate active transport across the cell membrane from areas of high-concentration to areas of low-concentration.


Catalyze breakdown of ATP, releasing energy to facilitate active transport across cell membranes from areas of low-concentration to areas of high-concentration.


Receive and respond to chemical signals for regulation of substances entering and leaving cells, activation of enzymes, and stimulation of glands.

  • Transmembrane– ion channel-linked (ionotropic) receptors, G protein-linked (metabotropic) hormone receptors, and enzyme-linked hormone receptors.
  • Intracellular– found inside the cell, include cytoplasmic receptors and nuclear receptors.

Genetically designated molecules that bind to specific receptors are known as ligands.

Acetylcholine Receptors

Acetylcholine Receptors (AChRs) receive the ligand Acetylcholine (ACh) to stimulate skeletal muscle contractions. ACh was the first known neurotransmitter, confirmed by Nobel Prize winner Otto Leowi. Acetylcholinesterase (AChE) facilitates the breakdown of ACh to terminate transmissions. In the nervous system ACh regulates muscle contractions, sensory perceptions, REM sleep, attention, memory, motivation, arousal and reward. Choline, a B-complex vitamin, is an essential component in ACh.

Muscarinic Acetylcholine Receptors (mAChRs) are metabotropic and can be excited by muscarine, found in the amanita-muscaria mushroom.

Nicotinic Acetylcholine Receptors (nAChRs) are ionotropic receptors that can be excited by nicotine, found in tobacco. When activated, these ligand-gated ion channels are permeable to the mineral ions Sodium, Potassium and Calcium. Stimulation of nAChRs in the adrenal medulla by ACh ligands triggers secretion of the hormones noradrenaline and adrenaline. The neuro-muscular autoimmune condition known as Myasthenia Gravis is characterized by degradation of nAChRs by autoantibodies (IgG1 or IgG3).

Contractile Proteins

Motor proteins regulate muscle, cardiac, and cellular movements.


Found in cell cytoskeletons, responsible for intracellular motor functions like cell division.


Motor protein that catalyzes breakdown of ATP to generate movement, works with actin to facilitate muscle contractions.

Optimal Food Sources

  • Tuna
  • Salmon
  • Halibut
  • Octopus
  • Cod
  • Shrimp
  • Scallops
  • Sardines
  • Shellfish
  • Tilapia
  • Alligator
  • Ostrich
  • Wild Boar
  • Chicken
  • Turkey
  • Pheasant
  • Venison
  • Beef
  • Lamb
  • Pork
Animal Products
  • Eggs
  • Cottage Cheese
  • Greek Yogurt
  • Parmesan
  • Romano
  • Mozzarella
  • Goat Cheese
  • Swiss
  • Cheddar
  • Milk
  • Soybeans
  • Lentils
  • Peas
  • White/Navy Beans
  • Pinto Beans
  • Kidney Beans
  • Black Beans
  • Lima Beans
  • Garbanzo Beans
  • Green Beans.
  • Spinach
  • Asparagus
  • Artichoke
  • Collards
  • Beet Greens
  • Chard
  • Bok Choy
  • Broccoli
  • Kale
  • Cauliflower
  • Soybean Sprouts
  • Lentil Sprouts
  • Alfalfa Sprouts
  • Brussels Sprouts
  • Bean Sprouts
  • Green Gram / Mung
  • Bengal Gram Sprouts
  • Broccoli Sprouts
  • Radish Sprouts
  • Clover Sprouts
Nuts and Seeds
  • Squash Seeds
  • Pistachios
  • Almonds
  • Sunflower Seeds
  • Sesame Seeds
  • Flaxseed
  • Hemp
  • Chia Seeds
  • Cashews
  • Walnuts
  • Tofu
  • Tempeh
  • Miso
  • Mushrooms
  • Potatoes
  • Spirulina
  • Sea Vegetables
  • Grape Leaves
  • Garlic
  • Wasabi Root

Amino Acids

Proteins are responsible for most bodily structures and functions. Amino acids are responsible for constructing and regulating proteins. Every protein in the human body is encoded by 21 core amino acids, but nine of those nutrients can never be synthesized in the body, and six more can only be synthesized under certain conditions. To maintain vital bodily functions, these essential nutrients must be consumed from dietary sources. See: Proteins for an overview of complete proteins and where to find them.


Can never be synthesized in the human body, must be consumed from dietary sources.

Branched-Chain Amino Acids

Promote protein synthesis for muscle growth, encourage retention and reuse of amino acids in muscle cells, and reduce protein breakdown in muscle loss and fatigue. Vitamin B7 is required to assist break down and absorption, inefficient biotin levels when metabolizing branched-chain amino acids can lead to a condition known as Maple Syrup Urine Disease.


Most effective in promoting protein synthesis for muscle growth and repair. Leucine stimulates production of insulin in the pancreas and promotes muscle cell absorption of blood glucose without use of insulin but inhibits insulin-stimulated absorption. May lower levels of serotonin and dopamine in the brain.

  • Optimal herbivorous food sources for leucine– avocado, sea vegetables, pumpkin, rice, watercress, turnip greens, soy, peas, beans, figs, raisins, dates, apples, blueberries, bananas, olives, nuts and seeds.

Less effective in encouraging protein synthesis for muscle building, but more effective in reducing blood sugar for use as energy during exercise. Isoleucine has no effect on insulin or glucose production, but it increases absorption of glucose into muscle cells without insulin resistance, and significantly increases energy output during exercise.

  • Optimal herbivorous food sources for isoleucine– grains, legumes, leafy greens, berries, nuts and seeds.

Least effective in muscle building and most resistant to insulin-stimulated blood sugar regulation. Valine aids in removal of excess nitrogen from the liver and transport as needed, reducing and possibly reversing the effects of liver and gallbladder disease. Valine deficiency has been indicated in degenerative neurological conditions characterized by damage to the fatty myelin layer that insulates nerve cells.

  • Optimal herbivorous food sources for valine– beans, legumes, soy, mushrooms, spinach, broccoli, peanuts, avocado, apples, berries, oranges, figs, apricots, grains, nuts and seeds.
Optimal food sources for branched-chain amino acids
  • Fish– two 4 ounce servings will meet daily requirements
  • Eggs
  • Dairy
  • Soy
  • Sea vegetables

Sulfur Containing Amino Acids

Aid in the detoxification of potentially harmful substances in the body.


Crucial component in methylation, converts toxins into water-soluble substances to prepare for excretion. Arsenic, mercury, lead, and aromatic hydrocarbons, among other potentially toxic substances, require methylation as part of detoxification.

  • Optimal herbivorous food sources for methionine– oats, rice, beans, soy, legumes, sea vegetables, onions, chocolate, dried fruits, nuts and seeds.

Can be synthesized from serine if sufficient methionine levels are present. Cysteine works with dispensable amino acids glycine and glutamic acid to form glutathione, a powerful antioxidant, and binding molecule required to enable detoxification of certain toxins including pesticides and methyl bromides.

  • Optimal herbivorous food sources for cysteine– soy, oats, bell peppers, legumes, grains, nuts and seeds.
Optimal food sources for sulfur containing amino acids
  • Fish– one 4 ounce serving will meet daily requirements
  • Legumes
  • Nuts and Seeds

Aromatic Amino Acids

Absorb ultraviolet rays to release energy or emit light. Tryptophan has the strongest fluorescent properties followed by tyrosine and phenylalanine. Herbicides and antibiotics inhibit synthesis of aromatic amino acids, rendering them toxic to plants and micro-organisms that rely on this process to sustain vital functions. Humans and other animals are built to function without the necessary components to synthesize aromatic amino acids, but exposure to herbicides and antibiotics can still inhibit utilization of these essential nutrients and may have negative impact in other systems of the body. When consumed by humans, aromatic amino acids work with B-complex Vitamins to regulate hormone production and mental health.


Used in synthesis of Vitamin B3 (niacin), can be converted into the hormones serotonin and melatonin by certain cells in the nervous system. Turkey meat has high levels of tryptophan, when consumed in excess this can cause drowsiness, but the real culprits behind the Thanksgiving nap are serotonin and melatonin.

  • Optimal herbivorous food sources for tryptophan– quinoa, soy, nuts, seeds, oats, sea vegetables, squash, roots, mushrooms, asparagus, leafy greens, avocado, peppers, figs, apples, oranges, bananas, beans and legumes.

Regulates central nervous system functions and aids in production of the hormones melatonin, dopamine, noradrenaline and adrenaline. Phenylalanine can cross the blood-brain barrier, making it particularly effective in regulation of pain, appetite, mood and concentration.

  • Optimal herbivorous food sources for phenylalanine– soy, sea vegetables, pumpkin, avocado, beans, legumes, rice, quinoa, dried fruits, leafy greens, berries, olives, nuts and seeds.

Regulates pain sensitivity, metabolism, mood and stress response mechanisms. Tyrosine is required to metabolize phenylalanine, which is required to produce tyrosine. Both tyrosine and phenyalanine are required to synthesize the hormones dopamine, noradrenaline and adrenaline.

  • Optimal herbivorous food sources for tyrosine– soy, nuts, seeds, grains, beans and legumes.

Essential in tissue growth and repair, production of red and white blood cells, and detoxification of toxic metals. Histidine works with Vitamins B3 and B6 to produce histamine, which aids in digestion, triggers immune response to allergens, and stimulates sexual arousal. Deficiency can contribute to Rheumatoid Arthritis and deafness due to nerve damage.

  • Optimal herbivorous food sources for histidine– cantaloupe, sea vegetables, potatoes, cauliflower, corn, soy, nuts, seeds, grains, beans and legumes.
Optimal food sources for aromatic amino acids
  • Fish
  • Meat
  • Tofu
  • Legumes
  • Nuts and Seeds

One 4 ounce serving of beans, tofu, fish or chicken will exceed daily nutrient requirements for tryptophan.

Other Essential Amino Acids

Aid in production of antibodies to maintain essential immune system functions, protect from tissue damage and promote wound healing .


Aids in production of antibodies, promotes collagen and protein synthesis, blocks absorption of argenine in herpes virus replication. Lysine is required in the formation of chromatin used to regulate genetic processes in cell nuclei.

  • Optimal herbivorous food source for lysine– soy, beans, legumes, watercress, parsley, avocados, nuts and seeds.

Aids in production of antibodies, digestion of fats, bone building and wound healing. Threonine is required in the formation of mucins used to protect intestinal linings, and for production of glycine and serine used in formation of muscle proteins collagen and elastin.

  • Optimal herbivorous food sources for threonine– soy, watercress, spirulina, pumpkin, leafy greens,avocados, dried fruit, grains, bean, legumes, nuts and seeds.
Optimal food sources for other essential amino acids
  • Legumes
  • Tofu
  • Dairy
  • Eggs
  • Nuts and Seeds
  • Fish and Chicken– one 4 ounce serving will exceed daily requirements for lysine

Conditionally Essential

Can only be synthesized in the human body under certain conditions, dietary supplementation generally required to maintain vital bodily functions.


Can be synthesized from disposable nutrient glutamic acid via proline and glutamine, but the process releases a lot of energy in the form of ATP that can be preserved by increasing dietary intake. Preterm and newborn babies cannot synthesize arginine internally, rendering it an essential nutrient in these stages of development, but a disposable amino acid for adults. Arginine stimulates the thymus gland, increasing production of t-cells in the immune system. In the liver, arginine is required for production of urea, allowing the body to excrete toxic ammonia through urination. Found in high concentrations in the skin, arginine helps process creatine to build and repair muscle tissue, and nitrogen for use in muscle metabolism. Nitric oxide, responsible for relaxing blood vessel contractions, requires arginine as a precursor. Arginine promotes production of insulin hormones in the pancreas, vasopressin hormones in the pituitary glands, and growth hormones in developing humans. Arginine deficiency is indicated in delayed sexual maturity and male sterility.

  • Optimal food sources for arginine– spirulina, coconut, dairy, soy, chocolate, meat, nuts, seeds, grains, wheat germ, gelatin, beans and legumes.

The most abundant amino acid in blood and muscle tissues. Glutamine promotes cell division serving as a crucial component in development of the immune system and synthesis of DNA and RNA. Glutamine can pass through the blood-brain barrier to regulate central nervous system functions. Inside the brain, glutamine can be converted into disposable amino acids GABA and glutamic acid. If glucose supply is insufficient, glutamine can be metabolized as an alternative energy source for the nervous system. In the liver, excess nitrogen bonds with glutamic acid to form glutamine instead of ammonia toxins. Glutamine protects the liver from drug and alcohol poisoning, and transports excess nitrogen throughout the body as needed. By replenishing nitrogen and glycogen supplies in muscle tissues, glutamine prevents muscle degradation after strenuous activity.

  • Optimal food sources for glutamine– beef, chicken, fish, dairy, eggs, beans, beets, carrots, parsley, wheat, papaya, celery and raw leafy greens. Glutamine is easily deteriorated by cooking.

Can be synthesized from disposable nutrient glutamic acid. Proline works with lysine to form collagen, essential in building and repairing skin, cartilage, muscle and connective tissues. If blood glucose levels are insufficient to sustain prolonged activity, the body will burn muscle mass for energy. To prevent muscle loss, increase dietary proline intake if highly active or recovering from traumatic tissue damage.

  • Optimal food sources for proline– meat, dairy, eggs, fish, soy, brewer’s yeast, cabbage, spinach, watercress, asparagus, avocado, cucumber, sea vegetables, sprouts, nuts, seeds, grains, beans and legumes.

Can be synthesized from serine under certain conditions in the body. Glycine aids in protein synthesis for muscle growth, conversion of glucose into energy, construction of DNA and RNA, and maintenance of nervous and digestive systems. Found in skin, muscle and connective tissue, glycine is a major component in the structural protein collagen. Glycine prevents muscle loss by promoting creatine production, regulates blood sugar by promoting absorption of glucose into muscle tissue, protects from free radical damage via antioxidant properties, acts as a neurotransmitter in the central nervous system, and synthesizes gastric bile acids for use in digestion.

  • Optimal food sources for glycine– fish, beans, dairy, meat, soy, spinach, kale, cabbage, cauliflower, pumpkin, cucumber, kiwi and banana.