Proteins & Amino Acids

Proteins and amino acids are essential for building and repairing tissues, enzymes, and muscles. Here, we explain how they work and why they are important for health. Discover which foods provide the protein your body needs.

Proteins are essential molecules your body uses to build muscles, organs, enzymes, hormones, and even parts of your immune system. Proteins are made of amino acids, which are like the “letters” that form the “words” (proteins) your body needs.

Some amino acids must come from your diet (essential), some are only needed in special situations (conditionally essential), and others your body can make on its own (non-essential).

Essential Amino Acids → Must be eaten because the body can’t make them

Histidine

Role: Helps make proteins, supports growth, repair, and immune function.
Too little: Poor growth in children, anemia, fatigue.
Too much: Rarely an issue in normal diet.
Example: Meat, fish, dairy, soy, quinoa.

Isoleucine

Role: Supports energy, muscle repair, and blood sugar regulation.
Too little: Weakness, low energy, poor recovery from exercise.
Too much: May cause stomach upset if taken in huge supplement doses.
Example: Eggs, chicken, lentils, almonds.

Leucine

Role: Critical for muscle building, regulates blood sugar, supports healing.
Too little: Muscle wasting, slow recovery from illness or exercise.
Too much: Usually safe in food; high supplement doses can strain kidneys.
Example: Beef, soy, whey protein, seeds.

Lysine

Role: Helps make collagen, supports immune function, helps absorb calcium.
Too little: Slow growth, fatigue, poor immunity.
Too much: Generally safe in foods.
Example: Meat, cheese, beans, lentils.

Methionine

Role: Supports detoxification, liver health, and antioxidant production.
Too little: Poor liver function, hair and skin problems.
Too much: May increase risk of heart issues in very high supplement doses.
Example: Eggs, fish, sesame seeds, Brazil nuts.

Phenylalanine

Role: Precursor to important brain chemicals like dopamine and norepinephrine.
Too little: Low mood, cognitive issues.
Too much: Dangerous for people with phenylketonuria (PKU).
Example: Meat, soy, dairy, nuts.

Threonine

Role: Supports proteins, collagen, elastin, and fat metabolism in the liver.
Too little: Fatty liver, digestive issues, poor skin or hair.
Example: Cottage cheese, beans, seeds, poultry.

Tryptophan

Role: Precursor for serotonin and melatonin, helps regulate mood and sleep.
Too little: Mood swings, insomnia, low appetite.
Too much: Rare from food; supplements may cause drowsiness.
Example: Turkey, milk, oats, pumpkin seeds.

Valine

Role: Supports energy, muscle growth, and tissue repair.
Too little: Weakness, poor recovery, fatigue.
Example: Meat, dairy, soy, peanuts.

Conditionally Essential Amino Acids → Needed during stress, illness, or growth

Arginine

Role: Supports wound healing, immune system, and blood vessel health.
Too little: Slower healing, immune deficiencies.
Example: Meat, nuts, seeds, whole grains.

Cysteine

Role: Important for detox, antioxidant glutathione production, and hair/skin health.
Too little: Poor detox, weak nails/hair, oxidative stress.
Example: Eggs, poultry, garlic, onions.

Glutamine

Role: Fuels gut cells, supports immune system, and helps recovery after stress.
Too little: Gut issues, weak immunity, slower recovery.
Example: Meat, dairy, cabbage, beans.

Glycine

Role: Supports collagen, brain function, and detoxification.
Too little: Poor joint and skin health, sleep issues.
Example: Gelatin, meat, fish, legumes.

Proline

Role: Essential for collagen production, skin, and connective tissue repair.
Too little: Weak connective tissues, poor wound healing.
Example: Gelatin, meat, dairy.

Tyrosine