Amino acids explained

Advice Sam Rider
7 May 2014
supplement pills

Amino acids are the building blocks of muscle-building protein but what are the best sources for them and are you getting enough?

The word protein is derived from the Greek word 'proteos', meaning 'primary'. They amount for 20% of our bodyweight and are crucial for building muscle yet lately high-protein diets have come under scrutiny for denying you a balanced diet.

But in the background the proteins in your body are working tirelessly to keep your immune system functioning, maintain healthy skin, hair and nails and help your body produce vital enzymes and hormones, including insulin and glucagon that help regulate blood sugar and stop you storing excess fat.

Am I missing out on amino acids?

There are two types of amino acids: essential and non-essential. Essential amino acids cannot be synthesised by our body on its own so must be obtained from our diet. The eight essential amino acids are isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan and valine. Non-essential amino acids can be synthesised by our body and are not necessary to obtain from our diet. These include glutamate, alanine, aspartate, glutamine, arginine, proline, serine, tyrosine, cysteine, taurine and glycine. Got that? Well done.

Before you show off your recall skills to your friends, a couple of caveats need explaining. Firstly, histidine is debated as the ninth essential amino acid because the body occasionally struggles to make sufficient amounts. Secondly, the definition of non-essential amino acids is over simplified. The body has the potential to manufacture them but environmental factors, such as being exposed to large quantities of toxins and pollutants, can inhibit the body's ability to produce them. Therefore, it's wise to consider all the amino acids as equally important and worth finding space for in your diet.

Below we've explained the supplements and food sources that will help you keep your amino acid levels up.

Whey protein

Will supplements help?

Most whey protein shakes will include several of the 21 amino acids mentioned above but three are especially worth remembering when physically training. Leucine, isoleucine and valine are the only ones defined as BCAA (branched-chain amino acid).

Crucially, they are the only ones that are oxidised for energy during exercise, nullifying their highly anabolic (muscle-building) qualities. That's why taking BCAA supplements when training can have such positive effects. Together, these three essential amino acids can comprise up to one-third of your total muscle protein.

What do BCAAs do?

The theory is that they can help prevent the breakdown of muscle tissue during intense exercise. They also increase the release of human growth hormone.

Who should take them?

‘BCAAs should be taken by anyone who weight trains,’ says strength coach Gregg Marsh, ‘preferably in capsule form rather than tablet or liquid.’ There's little evidence that BCAAs will improve performance among endurance athletes, though, and unless you’re training seriously hard it’s possible you can get enough BCAAs from a recovery drink to make a separate supplement unnecessary.

How much should I take?

‘Anything less than 20 capsules per workout is a waste of time,’ says Marsh. ‘Many professional rugby and football clubs have seen huge improvements in performance, using 40 caps of BCAAs every workout.’ Nutrition expert Anita Bean is more conservative: 'Doses of 6-15g may help improve your recovery during hard training periods.'

man flexing muscles back

When should I take them?

‘They have positive benefits before, during and after a workout,’ says Marsh. ‘Studies have shown that taking BCAA supplements during and after exercise can reduce muscle breakdown, while taking them before resistance training reduces delayed onset muscle soreness [DOMS].’ They might also be beneficial if taken last thing at night - but the evidence here is sketchier.

Taking BCAAs before exercise causes the breakdown of leucine, isoleucine and valine in the liver, directing it to your muscles for muscle protein synthesis. Just make sure you don’t train on an empty stomach or you may experience some discomfort. The best combination is to ingest BCAAs before and during exercise, followed by whey protein after the gym session.

Will they help me recover quicker?

Potentially. Japanese researchers carried out a study that investigated whether the use of BCAA supplements could reduce muscle soreness after intense activity. Their findings revealed that 5g of BCAAs consumed prior to resistance workouts decreases muscle soreness and fatigue for several days after exercise, supporting the use of BCAAs in improving recovery.

Will they help me get stronger?

A separate study carried out by Australian researchers at Victoria University, Monash University, Macquarie University, and 
the Australian Institute of Sport discovered that when athletes drank a formula containing BCAAs (13.5g leucine, 8g isoleucine and 9g valine) three hours before strenuous exercise, their performance improved by 10%.

Do they have any side effects?

BCAAs are fairly safe, since you’d normally find them in dietary protein sources anyway. Excessive intake might reduce the absorption of other amino acids, but that's about it.

One problem with amino acids is that they quickly deteriorate. Amino acids are not stored by your body in the same way as it stores starch and protein as fat, but they can be replaced.

Your body can’t make them, but that doesn't mean you have to take BCAA supplements. These vital muscle-builders are also found in certain foods.

poached egg on smoked salmon and asparagus

5 natural sources of amino acids

Eggs offer a full range of essential amino acids as well as plenty of liver-protecting choline.

Salmon provides essential amino acids and a dose of healthy polyunsaturated fats.

Soy beans are a rare plant-based source of essential amino acids and also provide heart-healthy monounsaturated 

Beef is a complete protein source that has all the essential amino acids as well as a dose of muscle-boosting creatine.

Turkey provides all the essential amino acids plus high levels of immunity-boosting selenium.

Click on the links below to find out all you could possibly want to know about the other major supplements:
Protein Creatine Amino acids Antioxidants Fat burners Lesser known supplements Supplement FAQs

Getting all your essential amino acids on a vegetarian diet

Most food we eat contains some form of amino acids, but not all contain whole proteins. Any animal-based foods such as dairy, eggs and meat are rich in whole proteins, which is why a lot of people tend to assume they're the best/only worthwhile source of the nutrient. Plant-based foods do actually contain a great deal of high quality amino acids that the body can use to create proteins itself. Yes, the human body is that amazing.

A bad habit that some people who train fall into is getting overly comfortable with certain foods and eating them over and over again. This is especially true with vegetarians as the options for getting enough protein and amino acids are fewer. While there may not be many sources of amino acids to choose from on a vegetarian diet it's important to keep them as varied as possible to ensure you’re getting all the necessary amino acids. Covering all the bases in this way gives the body much-needed amino fuel to synthesise the proteins that it needs in order to function and aid muscle recovery.

Try to eat from as many of these categories as possible each day:

-       Grains: Wheat, oats, brown rice and bulgur wheat.

-       Nuts and seeds: Almonds, cashews, flax seeds and chia seeds.

-       Soy: Tofu, soymilk, soy cheese and meat substitutes.

-       Dairy: Milk, cheese, natural yoghurts.

-       Beans and legumes: Lentils, chickpeas, edamame and kidney beans.

All of those are excellent sources of amino acids for vegetarians. Some, such as soy, provide proteins of equal quality to that provided by meats, so you don’t need to be missing out on your amino acid quota just because you’re skipping the steak. Proteins that have been synthesised by the body from the essential amino acids that are found in the above selection of food are also of a high quality, easily replacing meat in your diet.

It’s not strictly necessary to combine plant-based proteins in every meal that you have, but do endeavour to get a good variety of plant-based proteins throughout the day, this way you will be assured of the sufficient amount of amino acids to keep your body happy. 

These are the experts who filled us in on amino acids:

Anita Bean is the author of The Complete Guide To Sports Nutrition (£15.99, A&C Black Publishers). For more visit
Dr. Lonnie Lowery is an exercise physiologist, nutrition expert and former competitive bodybuilder. He is also a licensed dietician specialising in sports nutrition.
Nikhil Rao is a trainee doctor, avid weightlifter and regular contributor to the US bodybuilding site He has been using creatine for six years.
Gregg Marsh is a strength and conditioning coach, personal trainer and nutrition consultant. He has more than eight years of experience in nutrition. For more visit

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