9 Essential Amino Acids: Everything You Need to Know

Amino acids are essential — so essential that scientists are finding these organic little molecular structures in — wait for it — outer space.
Yes, you read that right.
Scientists have confirmed that a meteorite that fell near Murchison, Victoria, Australia, in 1969, contained amino acids — primarily glycine. They also confirmed that this particular amino acid originated outside the Earth. Glycine has even been spotted in the atmosphere of a comet.
Clearly, amino acids are more than just the building blocks of proteins — these findings tell us that amino acids could be the building blocks of life in the far reaches of the universe.
So, what’s so ‘essential’ about these acids? Read on to find out everything you need to know about essential amino acids on a plane much closer to home — your body!
What Are Essential Amino Acids?
As a group, these organic molecules are called ‘acids’ because of their chemical structure. This includes a carboxyl group (carbon, oxygen, and hydrogen) bonded to an amino group (two hydrogens and nitrogen).
Where they differ is the ‘side chain’ that’s attached to the central carbon atom. The side chain is how we differentiate between the 20 amino acids that make up the more complex protein structures.

To be clear, all 20 amino acids are vital for your body. We call nine of them ‘essential’ for our health, but we can’t actually produce them within the body. So it’s essential that we get them through diet and nutrition.
The 9 Essential Amino Acids
The nine essential amino acids are not just for weightlifting gym rats. They play key roles in your metabolism, the creation of energy through ATP synthesis, and muscle recovery.
The nine essential amino acids include leucine, isoleucine, lysine, methionine, phenylalanine, threonine, tryptophan, valine, and histidine.
Let’s take a look at the role of each.

1) Leucine
If you’ve ever seen leucine advertised as a supplement for bodybuilding, then you can already guess its main function. Like valine and isoleucine, leucine is one of the branched-chain amino acids (BCAAs). Its natural form is ‘L-leucine.’
Leucine’s primary benefits include:
• Providing energy during exercise to skeletal muscle
• Potentially increasing muscle growth and lean body mass
• Increasing the production of human growth hormone (HGH)
• Helping to control and regulate blood sugar
Sources of leucine
• Meats (such as fish, chicken, and turkey)
• Dairy products (such as yoghurt and cheese)
• Eggs and fruit (though to a lesser extent)
• Plant-based sources of protein such as quinoa, seeds, nuts, corn, wheat germ, brown rice, and spirulina

2) Isoleucine
Another branched-chain amino acid is isoleucine. Research shows that it plays a role in the production of haemoglobin, which is the oxygen-carrying pigment that colours red blood cells.
Besides this, some of isoleucine’s benefits include:
• Helping to control blood sugar
• Boosting energy and endurance
• Speeding up the healing of injured or fatigued muscles
• Supporting muscle development and the maintenance of lean body mass
• Detoxifying the body of nitrogenous waste products such as ammonia
Sources of isoleucine
• Meat-based foods such as beef and seafood like tuna, cod, and haddock
• Yoghurt
• Plant-based foods such as oats, lentils, sunflower seeds, and seaweed

3) Lysine
Also known as ‘L-lysine,’ it plays a key role in body tissue growth and recovery from damage. If you’ve ever experienced an outbreak of the herpes virus, you may have also been advised to take a lysine supplement. Some studies show that lysine supplements can, at the very least, help reduce the frequency and severity of cold sore outbreaks.
Lysine brings a host of health and immunity benefits, which include:
• Helping the body absorb calcium, iron, and zinc
• Contributing to the production of collagen, which is very important in the formation of ligaments, tendons, hair, skin, and cartilage
• Helping to reduce high blood pressure
Sources of lysine
• Red meat such as beef, lamb, and pork
• Plant-based sources such as lima beans, avocados, potatoes, peppers, beets, and leeks

4) Methionine
Some essential amino acids, like leucine, help in muscle development. Others address the production of important compounds such as haemoglobin and collagen. Methionine, however, contributes primarily to detoxification. The key is sulphur, which protects cells from free radical damage and removes heavy metals like lead and mercury.
Methionine brings other benefits such as:
• Improving wound healing speed
• Breaking down and preventing fatty deposits in the liver
• Liver detoxification
• Staving off the effects of copper accumulation in the body
Sources of methionine
• Besides the usual suspects (animal sources like tuna, salmon, shrimp, and beef), a significant source of methionine is Brazil nuts.
• You can also get methionine from soybeans, tofu, beans, lentils, and wheat germ.
5) Phenylalanine
Researchers are still studying how and why phenylalanine works in the body. So far, we know that it aids in the production of other amino acids (tyrosine), hormones, and neurotransmitters such as dopamine and norepinephrine.
Currently, medical research is looking into phenylalanine’s potential to address issues like:
• Helping with pain relief in some instances
• Partially alleviating the symptoms of alcohol withdrawal
• Regulating thyroid and adrenal gland hormones
Sources of phenylalanine
• Eggs and meat-based sources, including red meat and yoghurt
• Plant-based sources, including pumpkin seeds, peanuts, wheat germ, quinoa, and tofu

6) Threonine
You may recognise threonine better as glycine — yes, the same glycine that scientists found on the Murchison meteorite. Glycine contributes to the production of collagen and elastin, which means that threonine aids in maintaining healthy skin. It also plays a role in dental health. Besides this, threonine can help to prevent liver failure.
Sources of threonine
• Beef, lamb, pork, collagen supplements, gelatine, and cheese
• Nuts such as cashews, almonds, and pistachios
• Roasted soybeans
• Seeds like sunflower seeds and flax seeds
• Wheat germ
7) Tryptophan
Your body greatly depends on tryptophan to control a number of functions crucial to the central nervous system. From regulating serotonin levels in the brain to melatonin levels for sleep cycles, tryptophan also contributes to the production of the B-vitamin known as niacin.
Sources of tryptophan
• Squash and pumpkin seeds
• Dark chocolate
• Turkey, red meats, eggs, and fish
• Milk and cheese
• Chickpeas, pepitas, peanuts
• Bananas
• Spirulina

8) Valine
Valine is the third of the branched-chain amino acids group or BCAAs. As such, it’s primarily used to:
• Stimulate muscle growth
• Produce energy and maintain physical stamina
• Supports the central nervous system in times of stress
Sources of valine
• Mushrooms
• Peanuts
• Red meats
• Dairy products
• Soy products

9) Histidine
If ‘histidine’ reminds you of ‘antihistamine,’ you’re very close. Actually, histidine gets converted into histamine, a neurotransmitter that stimulates the body’s response to inflammation and allergens. That means it’s crucial to overall immune function.
Histidine specifically:
• Aids in digestion, libido, and sleep-wake cycles
• Protects and supports the coating around nerve cells known as the myelin sheath
Sources of histidine
• Fruits such as apples and pomegranates
• Veggies such as beets, carrots, celery, cucumber, radish, and spinach
Whey Protein as a Source of Essential Amino Acids
Whey protein is the liquid you get when you process milk into cheese. This is how we get whey protein concentrate. The good news is that whey protein isolate has 90% protein, which is obtained through a special process that reduces fat and lactose levels to less than 1%.
What’s more, whey protein concentrates and whey protein isolates have high levels of essential amino acids. So, if you’re primarily a plant-based protein consumer, you can use whey protein isolate to boost your essential amino acid profile.

Studies show that:
• More than 50% of the amino acids in whey proteins are essential.
• Whey proteins provide a surplus of EAAs and BCAAs.
In fact, whey protein is so effective for EAAs that it outperformed even WHO recommendations for daily recommended intake in 2007.

This means that a person could reduce their other forms of protein intake and substitute whey protein without worrying about being deficient in amino acids.
Amino Acids: Daily Recommended Intake
Over the years, guidelines have changed regarding how much of each of the nine essential amino acids your body needs. The daily recommended intake also depends on the age and weight of the individual.
But generally speaking, everything starts with your protein intake. You should get about 0.8 grams of protein of your body weight. So, if you weigh 150 pounds, your protein intake would be 120 grams.
Your protein intake can be broken down further for amino acid intake. For each gram of protein, you need:
• 18 mg of histidine
• 25 mg of isoleucine
• 25 mg of methionine (and cystine)
• 55 mg of leucine
• 51 mg of lysine
• 47 mg of phenylalanine (and tyrosine)
• 27 mg of threonine
• 7 mg of tryptophan
• 32 mg of valine

If this sounds like a lot, don’t stress. Remember that many of the foods (meat-based and plant-based) overlap. And you’re probably already including these sources right now in your diet.
Since proteins are the building blocks of the body, amino acids are the building blocks of protein. However, amino acids are only as good as what you consume — which are the building blocks of your body and its intricate processes.

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