Just like everybody else, vegetarians and vegans need complete protein to get all the essential amino acids, so their bodies don't fall into a negative protein balance - otherwise known as starvation.
Fortunately, it's easy to get more than enough protein in a vegetarian or vegan diet. If you've heard otherwise, it's simply not true.
The USDA recommends 56 grams of protein a day for a man age 40 weighing 160 lb, and 46 grams of protein for women - based on a 40 yr old woman who weighs 140 lb. That's about 0.36 grams of protein for every pound of body weight.
But protein needs vary depending on age, size, growth, health, physical activity, body type, pregnancy and lactation. For more information on this point, read How Much Protein and Calories Do We Really Need?.
Protein is essential for health, along with carbohydrates and fats. We use amino acids as building blocks, to make protein, for every part of our bodies: blood, skin, cartilage, muscles and bones, hormones and enzymes.
Our bodies can synthesize 16 of the 23 amino acids that we need. That leaves 8 essential amino acids (9 for children), which must come from the foods we eat.
ALL plant based foods have varying amounts of protein (plus carbohydrates, fats and other good things), and the body will combine proteins from all sources, to make 'complete protein'. That's true for everybody, veg or non-veg.
The term 'complete protein' means that all eight essential amino acids are present in the correct proportion.
Foods from animal sources have complete proteins Some foods from the plant kingdom, such as soy and quinoa, have complete protein.
The term 'incomplete protein' refers to foods which have all the essential amino acids, but are low in one or more of them. That's called the 'limiting amino acid'.
Most plant foods have one or more limiting amino acids which limit the availability of all the other amino acids in the food. That's why these foods are called 'incomplete proteins'.
For example, the limiting amino acid in grains is usually lysine (Lys); in legumes it can be methionine (Met) and tryptophan (Trp). So, the low level of Lys in grains is complemented by a higher level in legumes, and vice versa, to make 'complete protein'.
However, vegetarians and vegans don't need to worry about complete and incomplete protein. It is NOT NECESSARY for vegetarians and vegans to combine specific protein foods at one sitting to make complete protein.
Scientists used to think that vegetarians, and especially vegans, would develop protein deficiency if they didn't get eight or nine essential amino acids all together in proper amounts at every meal.
Frances Moore Lappé, author of 'Diet For A Small Planet', is well known for the theory of combining complementary proteins at each meal. In the 20th Anniversary Edition of her book, she has altered her views in light of new knowledge about amino acid storage.
Whenever we eat, our body deposits amino acids into a storage bank, and then withdraws them whenever we need them. So, it's no longer considered necessary to eat complementary proteins together at one sitting, to make complete protein. Your body does that automatically, from all the foods that you eat over the course of a day or so.
We still need a healthy variety of good protein building foods, so the body can make enough complete proteins to be happy, even though you don't need to worry about how and when you combine them.
Each plant food has its own unique amino acid profile, from green leafy veggies to tubers, from barley to quinoa, from lentils to tofu, from macadamias to brazil nuts. By eating a variety of plant foods with 'incomplete proteins' throughout the day, we can easily get enough 'complete protein.' For lacto and ovo-lacto vegetarians, any food can be complemented by the high quality proteins in dairy products or eggs, but it isn't at all necessary to include animal foods to get enough protein in your diet.
Your body puts together amino acids from plant foods to give you complete protein throughout the day. For instance, the amino acids in beans & lentils are balanced by those in grains, nuts and seeds, and vice versa.
Vegetables and fruits also contribute significant amounts of protein. A one cup serving of avocado, for example, has 3 grams of protein, and a medium potato with skin has 4 grams.
Vegans and vegetarians can't help getting all the essential amino acids, through eating different combinations of grains, legumes, nuts & seeds, vegetables & fruit several times throughout the day.
Eating for complete protein isn't a scientific system of food combining, where you have to keep track and analyze everything you eat. It's a natural traditional way of eating, which most human beings have thrived on, for thousands of years. Food is a sensual pleasure, and complete protein is a side benefit.
As a rough guide, the chart below shows some examples of foods which go together well. This chart is very limited, in reality the possibilities could fill several pages, and you don't need to rely on precise combinations of food for complete protein.
Protein amounts, serving sizes, and calories are shown in our Protein Chart, to help you put together balanced healthy vegetarian meals.
Complete Protein Sample Menus gives suggestions for two days vegan meals and snacks, which will give your body the raw materials to make plenty of "complete protein" . The menus include some of Savvy Vegetarian's favorite recipes - easy, family tested, and delicious - along with nutritional values.
Author Dr. Linda Posch MS SLP ND, is a natural health care consultant, who helps her patients to achieve a healthy body balance through proper nutrition. She holds degrees in organic chemistry, psychology and a Masters in Communication Sciences and Disorders. Dr. Posch's professional background includes acute care & senior neuro-rehab, special education, autism support & therapy, spinal cord injuries, and oncology family support services.
"You may have heard that vegetable sources of protein are incomplete and become complete only when correctly combined. Research has discredited that notion so you don't have to worry that you won't get enough usable protein if you don't put together some magical combination of foods at each meal." - Andrew Weil, M.D.
"Complementing proteins is not necessary with vegetable proteins. The myth that vegetable source proteins need to be complemented is similar to the myths that persist about sugar making one's blood glucose go up faster than starch does. These myths have great staying power despite their being no evidence to support them and plenty to refute them." - Dennis Gordon, M.Ed, R.D.
"It is very easy for a vegan diet to meet the recommendations for protein, as long as calorie intake is adequate. Strict protein combining is not necessary; it is more important to eat a varied diet throughout the day." - Reed Mangels, Ph.D., R.D.; Vegetarian Resource Group, VRG.org
"All proteins are made up of the same amino acids. All. No exceptions. The difference between animal and vegetable proteins is in the content of certain amino acids. If vegetable proteins are mixed, the differences get made up. Even if they aren't mixed, all you need to do to get the right amount of low amino acids is to eat more of that food. There is no 'need' for animal proteins at all." - Dr. Marion Nestle, Professor, Department of Nutrition, Food Studies, and Public Health, New York University
"Some Americans are obsessed with protein. Vegans are bombarded with questions about where they get their protein. Athletes used to eat thick steaks before competition because they thought it would improve their performance. Protein supplements are sold at health food stores. This concern about protein is misplaced.
Although protein is certainly an essential nutrient which plays many key roles in the way our bodies function, we do not need huge quantities of it. In reality, we need small amounts of protein. Only one calorie out of every ten we take in needs to come from protein. Athletes do not need much more protein than the general public. Protein supplements are expensive, unnecessary, and even harmful for some people." - Reed Mangels, Ph.D., R.D., Protein in the Vegan Diet, Vegetarian Resource Group, VRG.org