I have been a vegetarian (lately an "aquatarian" as I occasionally eat fish and seafood) since I was in my early teens and there really was no end to people telling me I would not grow properly.
I did though, and there is much evidence that cutting down on meat is one of the best thing we can do for our health.
However, there seems to be a lot of concern regarding protein and a vegetarian diet and in this post I will attempt to break this down – into amino acids (pun intended).
Amino acids (“aminoes”) are organic compounds that consist of at least one amino group (-NH2) and one carboxyl group (-COOH).
In our human bodies we make use of 20 amino acids to build proteins and these aminoes are therefore named proteinogens. There exists about additional 500 amino acids overall which do not form proteins, but they form other things such as sugars.
We need all of the proteinogens and we can synthesise some in the body while others must be supplied by our diet.
The ones we cannot make ourselves are named essential amino acids and they are called isoleucine, histidine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan and valine, which makes a total of nine essential amino acids.
When essential amino acids were first classified it was thought that histidine was indispensable only during infancy, but it has later been reclassified as an essential amino acid as it is essential throughout the entire lifespan.
For children one additional amino acid is categorised as essential.
It is called arginine and is referred to as a semi-essential amino acid as it can be synthesised in the body, but is crucial for body growth and the body cannot synthesise enough on its own during a growth-period.
A healthy human body can produce the remaining proteinogens itself. They are alanine, asparagine, aspartic acid, cysteine, glutamine, glutamic acid, glycine, proline, serine and tyrosine.
Lack of sufficient amino acids can lead to a number of health hazards and as the body is unable to store amino acids it is important to have them in the diet.
If there are not enough amino acids available the body will begin to break down muscle tissue in order to access amino acids there to use them elsewhere.
This is why muscle waste is the first sign of lack of aminoes.
As proteins supports functions such as hormone production, cell-to-cell communication and immune health, these are other areas in which lack of protein will show.
There is an ongoing debate on whether or not it is safe to eat a vegetarian/vegan diet because of the “protein argument”: that one cannot get sufficient protein/sufficient range of amino acids through a plant based diet alone.
Some even say it is irresponsible not to feed children meat.
There is much research to contradict this.
A study conducted by the American Dietetic Society and Dieticians of Canada concluded that “Well-planned vegan and other types of vegetarian diets are appropriate for all stages of the life cycle, including during pregnancy, lactation, infancy, childhood, and adolescence.
Vegetarian diets offer a number of nutritional benefits, including lower levels of saturated fat (although saturated fat, as we know, is not necessarily a bad thing), cholesterol and animal protein as well as higher levels of carbohydrates, fibre, magnesium, potassium, folate and antioxidants such as vitamins C and E and phytochemicals.
Vegetarians have been reported to have lower body mass indices than nonvegetarians, as well as lower rates of death from ischemic heart disease; vegetarians also show lower blood cholesterol levels; lower blood pressure; and lower rates of hypertension, type 2 diabetes, and prostate and colon cancer.” (1)
Another study conducted on children eating a plant-based diet in India (2) concluded that
"The adequacy of plant-based diets in developed and developing countries as sources of protein and amino acids for human subjects of all ages is examined. Protein quantity is shown not to be an issue. (…) Inadequate amino acid supply is not an issue with most cereal-based diets.” (3)
In other words we do not need to aim for one amino-acid “hit” in every meal, but we may sample amino acids from various plant based sources throughout the day.
Take for instance the amino acid lysine, which comes up time and time gain as an amino acid vegetarians “are sure to be deficient of”.
Tofu, tempeh and lentils all contain a lot of lysine.
Quinoa, amaranth, pistachios and pumpkin seeds are also decent sources of lysine.
Sometimes the argument is that there are aminoes found in meat exclusively, but this is simply not true.
There is a dipeptide (a molecule consisting of two amino acids joined by a peptide bond) called carnosine which is only found in animal flesh as it is synthesised in animal tissues.
Carnosine consists of histidine, one of the essential amino acids, and an amino acid called beta-Alanine.
Some research (4) has shown that carnosine in the diet may help prevent Alzheimer’s and Parkinson’s disease, but the studies on this are still in infancy (the earliest one was conducted in 2007) and today carnosine is not considered essential for optimum health.
When you eat a protein-rich food the body breaks the protein down to single amino acids. Then the amino acids are transported throughout the body and assimilated by the cells who pick aminoes out of this “pool” to create new proteins to build the body.
Think of it as a lego set that comes in the shape of a truck (the original protein), but can be disassembled into individual lego bricks (amino acids), mixed with lego bricks from other lego sets (other proteins) to build an entirely new lego construction from the mix of pieces, such as a lego house (muscle tissue), lego tractor (blood cells) or lego lion (hormones).
(Maybe not an easier explanation, but a more fun one)
Therefore, it is important to mix and match your protein intake so as to get a wide a range of different amino acids to choose from as possible. This is the problem with getting one’s protein from meat exclusively: the amino acid source is not very varied.
A food that falls under the category protein and contains all the essential amino acids is called a “complete protein”.
Meat is a complete protein, but there are many vegetarian complete proteins too: peanuts, tempeh, chick peas, buckwheat, quinoa, almonds, brown rice, butter beans, red lentils, amaranth, hemp seed, chia seed and spirulina, to mention a few.
As Christmas is approaching I am sure that other plant-based humans such as myself are bracing themselves for being questioned at every Christmas family dinner when they refuse the traditionally meaty holiday dishes.
Hopefully this little bit of ammunition will make dinner party season feel a little less daunting – and make conversation at the table a lot more interesting!
2: A digression: in India there have been whole societies living to ripe old ages, prospering and creating a unique and innovative culture while being entirely vegetarian for innumerable generations. How can we then say that meat is essential for life and growth?