Amino Acids In protein - Complementary protein sources

When eating a vegetarian diet, it is important to get the protein right.

Usually the protein content of various food is labelled in grams, but not all protein is equal. The combination of amino acids that make up the protein does matter.

For example, a person could get (for example) 10g protein from 100g wholewheat bread. However the human body would be unable to utilise all that protein, as wheat protein does not contain all the essential amino acids (the amino acids that the body has to be fed, as it can not make them itself). A food that contains all the essential amino acids is called a "complete protein". Vegetarian sources are dairy products, quinoa, soya. A food that contains protein but not all the essential amino acids is called an incomplete protein. An incomplete protein has some amino acids that limit it, these are called "limiting amino acids". In wheat (and most grain) protein for example, the limiting amino acid is lysine. As the body uses amino acids together to do stuff, in a ratio, it can therefor only process as much protein as the limiting amino acid allows.

So that is why it is necessary to complement vegetarian protein sources sometimes. For example mixing wheat or rice protein, with a legume protein (rice and dal, beans on toast, tortilla and refreid beans), results in all essential amino acids being present. As although wheat and rice lack lysine,it has plenty of methionine and tryptophan. Legumes are high in lysine, but low in methionine and tryptophan. Together they form a complementary protein.

I found a good utility online to check the amino acid profile of foods (from the USDA database)
Amino Acid Check

This can help to choose a variety of foods over a course of a day that will complement each other, so providing enough of all the essential amino acids.

I was surprised to see that most green vegetables, spinach, broccoli etc, in fact have excellent amino acid profiles, with all the essential amino acids contained. Obviously you would have to eat alot of greens to get the rda of protein, but I have read that our ancestors, in paleolithic times, might have eaten several carrier bag fulls of green leafy veg a day.

An interesting fact for weight watchers, is that 600g of broccoli, contains nearly 20g protein and under 150 calories. Weight watchers usually like to eat food that keeps them nice and full up without having too many cals. The equivalent calorie amount of rice, would be just around 35g, and would only provide about 3g protein. If hungry, I know which choice i would go for to keep me full for longer!

As a side note, recent reports state that eating broccoli along with something spicy such as mustard or horseradish, boosts it anto cancer properties. Vegetables have so many wonderful properties, that are only just being discovered.

I once used the USDA database to analyse my daily food intake and discovered that by eating 5 portions of fruit and veg a day, I was not achieveing the rda of all the nutrients. In fact to do so a person has to eat a really wide range of fruit and veg and in quite large quantities. Americas 7 a day advice is better, but still, it depends on what you choose. It is a complicated science really.

This post is about amino acids in protein though, it is a huge subject, but really important for vegetarians to get to grips with, as amino acids are the building blocks of life. Every part of the human bodily system requires amino acids to function and renew. From blood, skin and cartilage, to muscles and bones, hormones and enzymes. It is all very well taking a multi vitamin, but without amino acids, the vitamins and minerals will have nothing to act with.

Personally as a vegetarian for many years, I now have a couple of scoops of whey protein powder daily, to be certain that my body always has a good supply of these treasures. It also saves me having to think too much about combining other protein sources and I do like to keep my life simple!




Essential Amino Acids Important Functions In The Body:

Isoleucine (Ile) - for muscle production, maintenance and recovery after workout. Involved in hemoglobin formation, blood sugar levels, blood clot formation and energy.
Leucine (Leu) - growth hormone production, tissue production and repair, prevents muscle wasting, used in treating conditions such as Parkinson’s disease.
Lysine (Lys) - calcium absorption, bone development, nitrogen maintenance, tissue repair, hormone production, antibody production.
Methionine (Met) - fat emulsification, digestion, antioxidant (cancer prevention), arterial plaque prevention (heart health), and heavy metal removal.
Phenylalanine (Phe) - tyrosine synthesis and the neurochemicals dopamine and norepinephrine. Supports learning and memory, brain processes and mood elevation.
Threonine (Thr) monitors bodily proteins for maintaining or recycling processes.
Tryptophan (Trp) - niacin production, serotonin production, pain management, sleep and mood regulation.
Valine (Val) helps muscle production, recovery, energy, endurance; balances nitrogen levels; used in treatment of alcohol related brain damage.
Histidine (His) - the 'growth amino' essential for young children. Lack of histidine is associated with impaired speech and growth. Abundant in spirulina, seaweed, sesame, soy, rice and legumes.

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