Protein
Histidine
Responsible for: growth, red blood cell production, tissue repair, histamine production, maintenance of myelin sheath
Deficiency can cause: anemia
Sources: poultry, fish, nuts, seeds
Responsible for: wound healing, immunity, blood sugar regulation, hormone production
Deficiency can cause: muscle wasting & shaking
Isoleucine
Sources: fish, poultry, eggs, cheese, lentils, seeds nuts
Responsible for: blood sugar regulation, muscle & bone repair, growth hormone production
Deficiency can cause: skin rash, hair loss, fatigue
Leucine
Sources: dairy, soy, beans, legumes
Responsible for: health of hair & nails, proper absorption of selenium & zinc
Deficiency can cause: reduction in T cell population
Methionine
Sources: eggs, grain, nuts, seeds
Responsible for: creation of other amino acids, proteins, and enzymes
Deficiency can cause: eczema, fatigue, memory problems
phenylalanine
Sources: dairy, meat, poultry, soy, fish, beans, nuts
Responsible for: health of skin & teeth, helpful in fat metabolism & digestion
Deficiency can cause: possible neurological dysfunction
Threonine
Sources: cottage cheese, wheat germ
Responsible for: production of serotonin and melanin
Deficiency can cause: possible dementia, skin rashes, digestive issues
Tryptophan
Sources: wheat germ, cottage cheese, chicken, turkey
Responsible for: mental focus, muscle coordination, tissue repair
Deficiency can cause: insomnia, reduced cognitive function
Valine
Sources: soy, cheese, peanuts, mushrooms, vegetables
Responsible for: muscle building, bone strength, injury recovery, regulation of hormones
Deficiency can cause: possible anxiety
Lysine
Sources: meat, eggs, soy, blackbeans, quinoa
Hover over each box to learn about what the amino acid is responsible for, effects of deficiency in that amino acid, and where it can be found.
The average person needs about 7 grams of protein every day for every 20 pounds of body weight. Getting enough protein is extremely important as it necessary for the building and maintenance of bones, muscles, cartilage, and skin. Additionally, it is needed for tissue repair, digestion, hormone regulation, and catalysis of many other essential reactions in the body.
What are proteins made of?
Proteins are complex structures made of units called amino acids. The general chemical structure for an amino acid can be seen in the figure on the right. There are 20 different amino acids. All of them have an amino group and a carboxyl group at the end. What differentiates each amino acid is its R group (or side chain). The atoms that make up the R group affect its polarity and charge.
Polarity refers to the degree of difference in charge within a molecule due to the unequal sharing of electrons between atoms in the molecule (to learn more about atoms, charge, and bonding, see "Elements, Atoms & Ions"). Polar structures are attracted to other polar substances, like water, while nonpolar substances interact with nonpolar. Keep in mind that nonpolar and polar substances do not like to interact with each other. One example of a nonpolar substance is oil, which separates from water.
When amino acids bond together and fold, they create a protein. The degree of polarity of the R group is what determines the way each amino acid interacts with each other, which affects the way the protein folds. So a difference of even one amino acid or even a change in the sequence of amino acids can create a huge impact on the shape of the protein. And the shape determines the functionality of the protein. This is why a deficiency in even one amino acid can result in a reduction in certain proteins or enzymes and the body may be unable to carry out some essential processes. For example, a prolonged lack of amino acid valine can cause growth failure and loss of muscle mass. The deficiency of amino acid tryptophan can lead to low serotonin levels, resulting in mood disorders, anxiety, and depression.
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Amino Acids
The amino acids fall under 3 different categories: essential, nonessential, and conditional. Essential amino acids cannot be made by the body, so they must come from food. Nonessential amino acids are synthesized by the body. Lastly, conditional amino acids are needed in times of illness. The 20 amino acids are categorized in the table to the left. Now we are going to look at the 9 essential amino acids, what they do, and where to get them.
Greek Yogurt- 10 g (100 g)
Lentils - 9 g
(100 g, boiled)
Chicken - 27 g (100 g)
Kidney beans - 9 g
(100 g, boiled)
Peas - 5 g
(100 g)
Salmon - 20 g
(100 g)
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