My favourite (cheeky) answer is: ‘To which amino acid do you refer?’ (I must thank Isa Chandra Moskowitz in the magnificent Veganomicon for that one.)
Proteins are composed of amino acids; these are our cellular building blocks. There are twenty standard amino acids taken up by the body through the food we eat. Nine of these cannot be synthesised by the body itself and must be obtained from food; these are known as the ‘essential’ amino acids. Requirements are a little different for children, as a further five of the twenty standard amino acids are required for normal growth. The main vegan sources of protein are nuts, grains, and legumes, although there are smaller proportions in many other plant foods.There has been much written on the importance of ‘protein combining’. This theory, first made popular in 1971 in Francis Moore Lappé’s Diet for a Small Planet, is an approach to eating that aims to ensure that all the essential amino acids are combined in each meal by mixing foods (for instance, beans and rice) that have some of each. Although popular for some time, this theory has been largely discredited; it was even repudiated by Moore Lappé herself in 1981.
But this is not to say that ‘complete proteins’ are not hugely important in a vegan or vegetarian diet.
What is a compete protein? Simply put, one that contains all of the essential amino acids. An example is quinoa (pronounced ‘keen-wa’), wonder grain of the Andes. This is fantastically quick and easy to prepare. So versatile and efficient that it has been singled out by NASA as one of the key crops for long-term space missions, each grain looks like a tiny, edible Saturn and it comes in standard issue beige or exotic red. Here in Auckland it is fairly readily available in supermarkets and whole food stores.
Nutritional hair-splitting aside, although the amount of protein you need is dependent upon age, height, weight, gender, and activity level, the fact is that if you are consuming enough calories you are almost certainly getting enough protein. The only times this will be a concern at all is if you are undertaking some kind of strenuous physical training. Even then, there are ample supplies of protein in many vegan staples and nutritionists recommend that an athlete’s diet be comprised of between twelve and fifteen percent protein. Tofu and chickpeas are two of the best sources and there’s nary a vegan who does not consume more than enough of these. Beans are also an abundant supply of protein and can be worked into any type of cooking.
To put things in their proper perspective, let’s look at how much protein a person actually needs per day. An average adult male needs about fifty six grams a day, and an average adult female needs about forty six. A 250 gram serving of red meat (that is, a standard New Zealand steak, or a few sausages) contains eighty five to ninety grams of protein. That is just one meal. Considering that meat-eaters tend to consume more than one serving of meat per day and that protein will be absorbed from other sources, it is likely that the meat-eater will get three times (possibly more) protein than his or her body actually needs.
But surely, there’s no harm in getting too much of a good thing? Unfortunately, there is. There is a substantial body of scientific evidence showing that an excessive consumption of protein can cause deterioration of the nephrons, the kidney’s filtering system and also increases the risk of kidney stones. Other health conditions that may result from an overabundance of protein (particularly animal protein) include excessive calcium leaching from the bones causing osteoporosis, acid reflux, obesity, plaque build-up in the arteries, high blood pressure, pain from arthritis, high cholesterol, bad breath from sulfur-containing amino acids, and increased risk of cancer, especially colon cancer. None of this takes into account the high cholestorol content of animal proteins.
This is not the place to go into detail about exactly which plant foods contain the most protein; for your edification, some of the more comprehensive lists and tables available on the internet can be found here, here, and here.
Since the advent of large-scale industrialised farming post-World War Two, Western societies have been assailed with messages about the Herculean quantities of animal protein that are supposedly required for human survival. In a dairy-producing country like New Zealand this is doubly so and at least a modicum of scepticism seems reasonable when we consider just how much money is lavished by agricultural companies and statutorily created marketing boards on promoting this idea. Even GPs (who have only a few lectures on nutrition at medical school) will counsel their patients that it is impossible to be healthy without eating meat despite heart disease and obesity being two of our major killers.