The current focus on "plant-based" eating creates concern and confusion about protein in the diet. Can a plant-based diet offer enough protein? After all, protein is vital for many bodily processes, especially to form the structure of our bodies (like our skeletons).
While some plants may have a lower percentage of certain amino acids, as compared to animal-source foods, a plant-based diet will provide all the essential amino acids that combine together to form protein molecules.
There are 21 amino acids. Nine are essential because we can’t produce them. We must obtain them from our diet. The remaining 12 are non-essential because our bodies are able to produce them. Amino acids form together in various ways for several different functions
in the body.
The body digests the amino acids from our foods (both plant and animal source) and combines them to create protein molecules. Protein is necessary for many vital functions. Most notably, it's important for growth and repair of our body tissues. Protein basically “constructs” us; our bones, hair, teeth, fingernails, etc. And protein is necessary to create several components vital for our bodies to function, like antibodies, enzymes, and hormones.
Regarding our diet, there are two types of protein; complete and incomplete. Meat and other animal sources of food are considered complete proteins, as they offer all nine essential amino acids in proper proportions. Incomplete proteins are foods of plant origin. This is because some plants may be missing one of the essential amino acids or may not offer adequate amounts of certain amino acids. However, that doesn't mean plants can't provide enough of the essential amino acids we need to meet our protein needs. A diet of a wide variety of plant foods can easily ensure this. Only those who stick to eating the same limited choice of foods every day – with very little variety – will risk a deficiency in an amino acid (and other nutrients as well).
In the past, those eating little or no "meat" believed in combining plant foods at each meal to create a complete protein. This was referred to as “complementing proteins”.
For example, rice was combined with beans, or seeds with legumes, or grains were combined with leafy vegetables. Meal ideas included “Chili” made with various legumes and vegetables, or a quinoa and mixed-bean salad. Vegetable or fruit salads were combined with nuts, seeds, chickpeas or mixed beans. Split pea or bean soup could be made with cooked whole grains or a variety of vegetables added. Lentils or another legume replaced the meat in a stir-fry.
However, it’s not necessary to consume complimentary protein foods at each meal. This practice was "debunked" many years ago after it was found that throughout the entire day, your total plant food consumption eventually combines to create the protein your body requires. Therefore, it's more important to consume a wide variety of foods every day rather than worry about combining your foods at each meal. However, the importance of eating a wide variety of foods must never be overlooked. This ensures we are getting all the nutrients we need – including all the amino acids. Therefore, there is nothing wrong with "protein combining" at each meal if you are just starting to improve your diet: For a short time, it can be a helpful and convenient reminder to ensure you are including a diversity of plants in your diet.
About being a "smart" vegetarian . . .
Plant-based eating isn't necessarily the same as being a vegetarian. Most plant-based eaters simply put a greater focus on eating plant foods (they may still eat animal sources of food).
However, if you want to call yourself a "vegetarian" here's some common sense information for you . . .
Becoming a vegetarian isn’t only about omitting meat. And it’s not simply a matter of replacing meat with bread. Plant foods like legumes, whole grains, as well as nuts and seeds should be considered as protein source alternatives.
Vegetarians must choose from as wide a wide variety as possible of fresh fruits and vegetables. Limiting their choices to only a few will severely limit the many nutrients needed to sustain life (including the essential amino acids).
There are many variations of a vegetarian diet: A vegan avoids all animal-derived products including eggs, dairy products, and even honey (bees are considered animals).
An ovo-vegetarian eats eggs. A lacto-vegetarian eats dairy products. An ovo-lacto-vegetarian consumes both dairy and eggs. A pescetarian is a vegetarian who eats fish and shellfish. A pesco-pollo vegetarian eats fish, shellfish and chicken. Flexitarians predominantly consume plant foods, but will occasionally have a meat or dairy source (this is also called a “plant based” diet).
Vegetarian diets – especially strict vegan diets – may be relatively low in certain nutrients, most notably vitamin B 12, which can only be found in animal source foods. Other nutrients some vegetarians may be low in include omega 3 fatty acids (these are richest in animal products, especially fish), iron (the non-heme iron in plants is not as bioavailable as from meat sources), and calcium may also be a concern if the vegetarian is not consuming enough legumes or dark-green vegetables (collard greens, kale, broccoli), which are good calcium sources. Vitamin D, iodine and zinc could also be concerns. Supplementation can be considered or perhaps switch to following other versions of the diet.
Vegetarians vs. meat eaters has been a long, on-going debate. Sometimes it's a very heated one! But there is no one diet for everyone. Some of us function well on a meat-based diet, while others do better consuming more plants. If you decide to go "vegetarian" or want to focus more on plant-based eating, discuss your concerns with a Registered Dietitian (RD).
For 40 years, Eve Lees has been a Nutrition Coach, a Health Speaker, and a Health Writer for several publications. For more health articles by Eve visit her website.