Essential amino acids are a specific group of amino acids that the human body cannot synthesise on its own and must be obtained through the diet.
These amino acids are vital for various physiological processes, including protein synthesis, metabolism and overall health. While most whole-food sources contain a mixture of amino acids, certain foods are particularly rich in essential amino acids.
Animal-based protein sources like meat, poultry, fish, eggs and dairy products, provide all the essential amino acids in adequate quantities. Plant-based protein sources such as legumes, soy products, quinoa, chia seeds and hemp seeds, also offer essential amino acids, although some plant sources may be low in one or more of these amino acids.
Having a balanced diet that includes a variety of protein sources can ensure an adequate intake of essential amino acids. However, in some cases, such as certain dietary restrictions or specific health conditions, a doctor or nutritionist may recommend amino acid supplements to meet the body’s needs.
The role of the nine
Each of the nine essential amino acids plays a distinct role in the body. Here’s a brief overview of the functions of each essential amino acid:
- Histidine This amino acid is involved in various physiological processes, including the growth and repair of tissues, the production of red and white blood cells, and the synthesis of histamine, which is important for immune response and digestion.
- Isoleucine This amino acid is involved in muscle metabolism, energy regulation, and immune function. It also plays a role in hemoglobin synthesis and the regulation of blood sugar levels.
- Leucine This is a key amino acid for muscle protein synthesis, making it important for muscle growth, repair and maintenance. It also regulates blood sugar levels and contributes to the production of energy and growth hormones.
- Lysine This amino acid is crucial for protein synthesis, collagen formation and the absorption of calcium. It is also involved in the production of enzymes, hormones and antibodies, as well as supporting immune function.
- Methionine This amino acid is essential for the synthesis of proteins and other important molecules in the body. It is involved in metabolism, detoxification processes, and the production of sulphur-containing compounds, such as glutathione.
- Phenylalanine This amino acid is a precursor for various neurotransmitters, including dopamine, noradrenaline and adrenaline. It is also involved in protein synthesis, thyroid hormone production, and the synthesis of other important molecules like melanin.
- Threonine This amino acid is important for the synthesis of proteins and the production of antibodies and enzymes. It also plays a role in supporting healthy connective tissues and maintaining the balance of proteins in the body.
- Tryptophan This amino acid is a precursor for serotonin, a neurotransmitter involved in regulating mood, sleep and appetite. It is also involved in the synthesis of niacin (vitamin B3) and supports immune function.
- Valine This amino acid is essential for muscle metabolism and repair.It works together with isoleucine and leucine to promote muscle growth and recovery.Valine also contributes to energy production and helps maintain the nitrogen balance in the body.
These amino acids all have diverse functions and are necessary for overall health, growth, tissue repair, hormone production, immune function and various metabolic processes in the body.
From non-essential to essential
On occasion, your body may also need what is known as conditionally-essential amino acids. These are amino acids that are normally non-essential, meaning the body can synthesize them on its own under normal circumstances.
However, in certain situations or conditions, the body may not be able to produce adequate amounts of these amino acids, making them “conditionally essential”.
Various factors can contribute to the conditionally-essential status of these amino acids, including illness, stress, trauma, growth stages, certain genetic disorders, or insufficient intake of precursors required for their synthesis. Some examples of conditionally essential amino acids include:
- Arginine – essential for periods of rapid growth, severe stress or critical illness.
- Cysteine – needed in situations where methionine intake or metabolism is impaired.
- Glutamine – essential during critical illness, trauma or intense physical stress.
- Tyrosine – needed in individuals with phenylketonuria (PKU), a genetic disorder that impairs phenylalanine metabolism.
These conditionally-essential amino acids may need to be obtained from the diet or through supplementation in specific situations to meet the increased demand or when the body’s ability to synthesise them is compromised.
How much you need
According to the World Health Organization (WHO), here are the daily required intakes for the essential amino acids. These are for adults per one kilogramme of body weight:
- Histidine: 10 milligrammes
- Isoleucine: 20mg
- Leucine: 39mg
- Lysine: 30mg
- Methionine: 10.4mg
- Phenylalanine, combined with the non-essential amino acid tyrosine: 25mg
- Threonine: 15mg
- Tryptophan: 4mg
- Valine: 26mg
Essential amino acid supplements can offer several health benefits when used appropriately and in the context of an overall balanced diet. Here are some potential benefits of taking essential amino acid supplements:
> Muscle growth and repair
Essential amino acids are the building blocks of proteins, and they play a crucial role in muscle growth, repair and maintenance. Supplementing with essential amino acids, especially in combination with resistance exercise, can support muscle protein synthesis, enhance muscle recovery and promote muscle growth.
> Athletic performance and endurance
Essential amino acid supplements have been shown to improve exercise performance and endurance. They can help reduce muscle fatigue, improve muscle recovery, and support energy production during intense physical activity.
> Metabolism and weight management
Essential amino acids play a role in regulating metabolism and can support healthy weight management. They help promote satiety, regulate appetite, and support the preservation of lean muscle mass while promoting fat loss.
> Nutritional support during certain conditions
Essential amino acid supplements may be beneficial for individuals with specific health conditions or situations that require additional protein or have increased protein needs. This includes situations such as recovery from surgery or injury, certain illnesses, chronic diseases, or during periods of restricted food intake.
> Cognitive function and mood
Essential amino acids, particularly tryptophan, play a role in the synthesis of neurotransmitters involved in mood regulation and cognitive function. Adequate intake of essential amino acids can support brain health, enhance cognitive performance, and promote a positive mood.
From your diet
Meanwhile, here are some examples of foods that provide significant amounts of essential amino acids:
> Meat and poultry
Beef, chicken, turkey, pork and other types of meat are excellent sources of all the essential amino acids. They are particularly rich in leucine, isoleucine, lysine and valine.
> Fish and seafood
Salmon, tuna, trout and sardines are high in essential amino acids, especially lysine, methionine and tryptophan. Shellfish like shrimp, crab and mussels are also good sources.
> Eggs
They are considered a complete protein, as eggs contain all essential amino acids in good proportions. They are particularly rich in leucine, lysine and methionine.
> Dairy products
Milk, yoghurt, cheese and other dairy products provide a good balance of essential amino acids. They are especially rich in leucine, isoleucine, lysine and valine.
> Legumes
Lentils, chickpeas, black beans, kidney beans and soybeans are excellent plant-based sources of essential amino acids. While they may be lower in methionine, they are typically higher in lysine and tryptophan.
> Quinoa
This is a unique plant-based protein source that contains all the essential amino acids. It is particularly rich in lysine and methionine.
> Nuts and seeds
Almonds, walnuts and cashews, as well as seeds like chia seeds, hemp seeds and pumpkin seeds, provide a good profile of essential amino acids. They are higher in certain amino acids like arginine, phenylalanine and tryptophan.
> Whole grains
Brown rice, oats and whole wheat are not as high in essential amino acids as animal-based proteins, but they still contribute to overall amino acid intake. Combining them with legumes or other protein sources can help create a more complete amino acid profile.
It’s important to note that the amino acid composition of different foods can vary, so having a diverse diet that includes a variety of protein sources is key to obtaining all the essential amino acids. For individuals following vegetarian or vegan diets, combining different plant-based protein sources can help ensure a complete amino acid profile.
By Datuk Dr Nor Ashikin Mokhtar
Published in Star Newspaper, 17 Jul 2023
