Essential Amino Acid Food Sources
Complete Proteins and Essential Amino Acids
There are 20 commonly known amino acids 8 of which must come from the food you eat as your body cannot produce them and are needed to help build muscle.
As an adult the amino acids we need to get from our food are isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine. They are used to grow and repair hair, skin, organs and muscle.
Best Source of Complete Proteins
Meat and Eggs are amino acid rich foods that contain all of the essential amino acids your body needs for maintenance and repair. Lean cuts of pork and beef, chicken and turkey, fish and shellfish are all excellent sources of high quality proteins.
Eggs also rank alongside meat with high levels of vitamins and minerals. Egg white has no fat although the yellow yolk contains high amounts of cholesterol. Consuming egg cholesterol does not raise LDL (bad cholesterol) levels in your body for most people so are safe to eat.
Contrary to popular belief in the UK there is no recommended limit on how many eggs you can eat. General consensus seems to point to 3 eggs a day as part of a healthy diet.
Best Source of Complete Proteins for Vegetarians and Vegans
White beans, soy products, peas, quorn, lentils, quinoa, wheat germ, tofu, grains to name a few along with many processed products directly aimed at those on a vegetarian diet. As far a package, process foods many tend to have high levels of fat so it is essential you check the food labelling.
Whereas meat contains all of the essential amino acids for most plant based foods you would need to combine different plant based foods in a single meal in order to get all the essential amino acids as previously mentioned. So combining baked beans with wheat toast would be one way of doing this.
Quinoa and soya beans are the only plant foods to contain all essential amino acids.
RDA of Essential Amino Acids for Adults
The World Health Organization gives some figures for the recommended daily amount of the essential amino acids an adult needs to consume daily. Various sources cite varying levels as there seems to be some disagreement as to the exact requirements.
Children need higher levels due to their growing bodies plus other amino acids that they cannot produce in high enough quantities themselves until they become adults.
- 20 mg/kg/day of isoleucine
- 39 mg/kg/day of leucine
- 30 mg/kg/day of lysine
- 10.4 mg/kg/day of methionine + cysteine 4.1mg/kg/day
- 25 mg/kg/day of phenylalanine + tyrosine
- 15 mg/kg/day of threonine
- 4 mg/kg/day of tryptophan
- 26 mg/kg/day of valine
Most healthy people eating a balanced diet are unlikely to be deficient or overdose. Bodybuilders can consume many times the RDA for long periods of time due to a diet high in protein and there isn't a problem in the bodybuilding world.
I've listed the essential amino acids with some example amino acid rich food sources and some known benefits and side effects. However for most people concentrating on a sensible and healthy diet consuming quality foods with high levels of protein you should not need to overly worry about amino acid content.
Fruits, vegetables and high fibre foods reduce your risk of cancer whilst red and processed meats and salt, increase the risk of developing cancer.
Leucine Rich Foods
Leucine is an essential amino acids found in some protein sources that is thought to stimulate muscle growth and reduce age related muscle loss. Foods containing leucine include red meat, fish, chicken, soy, beans, nuts and seeds and dairy products such as milk.
The most leucine rich foods include dried egg white and soy protein isolate which contain more than 6 g (6,000 mg) per 100 g weight. Tofu and seafood, particularly mollusks also have a high leucine content.
Leucine Side Effects
It is unlikely that you would exceed the 39 grams a day suggested in the 2012 study published in the Journal of Nutrition without taking supplements. The stated high doses interfere with the bodies absorption of vitamin B-3 (niacin) and B-6 (pyridoxine) leading to deficiencies which may increase your risk of Alzheimer's disease.
Use dietary sources of leucine rather than supplements to get your daily recommended 42 mg and stay well under the 39,000 mg dose stated in the study.
Methionine Rich Foods
Methionine along with cysteine are the two sulphur containing amino acids. It stimulates the formation of cartilage, has anti-inflammatory and pain relieving properties and strengthens hair and nails.
Eggs, brazil nuts, soy, meat and fish, wheat germ and oats are all good sources. However if you eat a typical meat heavy western diet you are probably getting more than the recomended 19mg/kg/day of methionine and cysteine.
Methionine Side Effects
Too much methionine is thought to be related to cancer growth in high meat diets according to several studies. Conversely it is thought lower levels such as those found in vegan diets prolongs life.
Arginine Rich Foods
Soy protein isolate has 6.67 grams per 100 grams but is also high in other amino acids plus it is one of the cheapest protein powders you can buy. Only sesame and cottonseed flour has more per 100g at 7.44g and 6.73g.
It can be found in red meats, nuts and grains. Pumpkin, squash and watermelon seed kernels as well as mollusks and whelks. Cod, walnuts, peanuts (including peanut butter) and Tofu are also some of the best arginine rich foods you can buy off the supermarket shelf.
Arginine is thought to improve blood flow, reduce the the risk of vascular and heart diseases, a reduction in erectile dysfunction and show an improvement in immune response and inhibition of gastric hyperacidity.
Arginine Side Effects
Many people worry about the reoccurence of a virus such as Herpes or Shingles where foods high in arginine and low in lysine (a poor lysine arginine ratio) seem to promote these conditions.
The cocoa in chocolate contains arginine but the levels are much lower, up to 7 times lower compared to the foods mentioned above. Dark chocolate has more than other types.
If you are worried about a virus then dairy foods generally have the best lysine to arginine ratio meaning they have the highest levels of lysine with the lowest levels of arginine.
Lysine Rich Foods
A high lysine intake in your diet through food or supplements is thought to help alleviate herpes outbreaks. Conversely you need low arginine to lysine ratio as the former is thought to promote some viral conditions such as herpes.
Soy protein isolate (5.33g or 5,330mg in every 100g of food) and dried egg white have very high levels of L-Lysine. They are however also very high is L-Arginine so if you are looking for foods that are low in arginine and high in lysine you will find dairy products are a better option.
Parmesan cheese has 3.843g (3,843mg) of lysine and 1.531g (1,531mg) of arginine per 100 grams of cheese. Cheese however is high in saturated fat so not a food you can eat in any quantity.
Quark on the other hand not only has about 12 grams of protein per 100 grams but is low in sugar and very low in fat and salt with 552 mg of lysine to 217 mg of arginine.
Lysine Side Effects
Lysine can increase calcium absorption so be wary if taking calcium supplements. You should be OK with amounts consumed from your diet but excessive doses may be thought to cause gallstones.
Isoleucine Rich Foods
One of the branched chain amino acids along with valine and leucine are thought to be important for muscle recovery. Soy 4.25g (4,250mg) particularly in its concentrated protein isolate form (powder) has concentrated levels of many of the beneficial amino acids. It is the best vegan and vegetarian source having the highest levels, twice that of Tofu the next best option.
Meats and fish (seafood) will have the highest levels of Isoleucine and lower levels can be found in dairy products.
Isoleucine Side Effects
It is taken by athletes to reduce muscle breakdown and given to bedridden patients to reduce muscle wasting. There are not thought to be any serious side effects from taking Isoleucine.
Phenylalanine Rich Foods
You may recognise this amino acid from food labeling on sugar free food and drinks. We need to get phenylalanine from our diet from foods such as dairy, fish and meat which have high levels. Soy protein isolate has 4.59g (4,590mg) per 100 grams, dried egg white and tofu also have very high levels.
Phenylalanine Side Effects
For most of us it is safe but in high doses can cause anxiety, headaches and hypertension plus it has a laxative effect.
Threonine Rich Foods
The essential amino acid threonine supports your immune system, liver, nervous system, bones and tooth enamel. It is thought to speed up recovery from injury and wound healing.
Like all other essential amino acids it is found in meat and fish, seafood, eggs nuts, seeds and beans. Soya protein is particularly rich in threonine along with egg white powder and spirulina (seaweed).
Threonine Side Effects
A deficiency in threonine can lead to confusion and agitation, digestive problems and lead to a fatty liver. Too high a level of threonine can cause cold like symptoms including headache and nausea as well as stomach problems including diarrhea.
Tryptophan Rich Foods
Tryptophan is thought to improve sleep, lift your mood, reduce headaches and migraines and help maintain a healthy weight.
Red and lean meat including chicken, tofu, cheese, seeds, nuts and eggs all contain tryptophan. As with other amino acids foods particularly rich in tryptophan are the powdered supplements including soy, spirulina and egg white.
Tryptophan side effects
High levels of tryptophan can cause similar side effects to threonine which include stomach problems and heartburn. Additionally people can suffer from lightheadedness and drowsiness.
Valine Rich Foods
Valine regulates blood sugar, repairs tissue and stimulates the nervous system. It helps prevent the breakdown of muscle tissue and transports nitrogen to other tissues in the body.
Meat, fish, dairy, beans, nuts and seeds and even mushrooms contain valine. High levels can be found in powdered soy protein isolate, egg white and spirulina.
Valine Side Effects
Valine deficiency can lead to motor and cognitive function problems. In high doses it can lead to fatigue but is thought to be safe. Its an essential acid after all and cannot be stored by the body.
Eating up to twice the current RNI for protein is generally thought to be safe.
All information provided on this website is well researched or based on my own experience or my personal opinions and is not intended to constitute medical advice. The overall aim of this site is to encourage people to lead a healthier lifestyle by including healthy sources of protein rich in vitamins and nutrients in their diets as a part of a diverse and well balanced diet.
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