Protein in the Vegan Diet
Summary: 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.
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 (1). Athletic performance is actually improved by a high carbohydrate diet, not a high protein diet (2). Protein supplements are expensive, unnecessary, and even harmful for some people.
How much protein do we need? The RDA recommends that we take in 8/10ths of a gram of protein for every kilogram which we weigh (or about 0.36 grams of protein per pound that you weigh) (1). This recommendation includes a generous safety factor for most people. When we make a few adjustments to account for some plant proteins being digested somewhat differently from animal proteins and for the amino acid mix in some plant proteins, we arrive at a level of 1 gram of protein per kilogram body weight (0.45 grams of protein per pound that you weigh). Since vegans eat a variety of plant protein sources, somewhere between 0.8 and 1 gram of protein per kilogram would be a protein recommendation for vegans. If we do a few calculations we see that the protein recommendation for vegans amounts to close to 10% of calories coming from protein [For example, a 79 kg vegan male aged 25 to 50 years. His RDA for calories is 2900 calories per day. His protein needs might be as high as 79 kg x 1 gram/kg = 79 grams of protein. 79 grams of protein x 4 calories/gram of protein = 316 calories from protein per day. 316 calories from protein divided by 2900 calories = 10.1% of calories from protein]. If we look at what vegans are eating, we find that between 10-12% of calories come from protein (3). This contrasts with the protein intake of non-vegetarians which is close to 15-17% of calories.
So, in the US it appears that vegan diets are commonly lower in protein than standard American diets. Remember, though, with protein, more (than the RDA) is not necessarily better. There do not appear to be health advantages to consuming a high protein diet. Diets which are high in protein may even increase the risk of osteoporosis (4) and kidney disease (5).
Written by Reed Mangels, Ph.D., R.D.