This is without a doubt the most common question asked about plant-based diets….and no wonder. Protein bars and drinks are available everywhere, advertised to provide boosts in protein that are touted to prevent fatigue and provide energy for exercise, to help recover from a workout and rebuild damaged muscle fibers. The disquieting thing is that all this hype is completely unfounded.
The basic truth is that, in most cases, if you’re eating enough calories from a variety of whole plants to feel satisfied and maintain your desired weight, you’ll be eating more than enough protein for good health. On the other hand, if you’re eating the standard Western diet or a high-protein diet, you’re getting too much protein. Yes, you really can get too much protein.
First of all, just because you are eating a plant-based diet does not mean you’ll have trouble getting your protein. All plants contain protein. Protein in humans is made from various combinations of twenty amino acid building blocks. Our bodies can produce eleven of these. The other nine are called “essential” amino acids, meaning we must get them from the food we eat. This, however, is not a big deal at all. All amino acids, including the essential ones, are easily available from plant-based foods (2).
Protein as a food component has an interesting history. A century ago it was thought that protein deficiency was a worldwide problem and everyone was advised to eat 100 gm of protein daily for good health (1). There was no evidence for this at all and by the 1970s this theory had been debunked, new calculations were performed and a much lower protein intake was recommended. But the confusion didn’t end here. Some plants are relatively low in certain amino acids, a fact which launched the myth of protein combining; that we need to eat complementary proteins at the same time to allow our body to make up complete proteins. Once again, there is no basis to this theory. Our body constantly recycles protein by regularly breaking down body proteins, adding the resulting amino acids to the constantly renewing amino acid pool and reassembling them into new ones. Our body performs all the amino acid combining that is necessary (2,3). Yet another erroneous concept arose when studies on rats found that they did not grow as well when eating plants as they did when eating meat. Does this mean that plant protein is inferior to animal protein? Of course not. What was not taken into consideration was that rats grow eleven times faster than humans, reaching their adult size in only five months. Another theory disproven.
In direct contrast to past ideas, it is becoming clear that plant protein is actually healthier than animal protein. Animal protein is associated with increased cardiovascular mortality. Plant protein is associated with lower cardiovascular and all-cause mortality (12). Cancer is affected by protein source. Studies have found that increasing protein from plants by a mere 2% can cut the rate of bladder cancer by 23% and a 3% increase in animal protein consumption raises risk of bladder cancer by 15% (38).
What might be surprising to many people is that protein excess is a greater problem than protein deficiency (4,5,6). Long-term high protein diets cause disorders of the kidney (30) and liver, diabetes (10,11), increased risk of cancer (7,31) and worsening coronary artery disease (8,9,32). It is illuminating to look at human breast milk, unarguably the perfect food for a new human being. Is it high in protein? No. In fact it is one of the lowest-protein milks among mammals – less than 1% of protein by weight, supplying about 5% of the calories in breast milk (13,27).
So how much protein do we actually need? Canadian recommendations for adults are for 0.8 gm of protein per kilogram of ideal body weight per day. If you prefer to think in pounds, you can calculate 0.36 gm of protein per pound of ideal body weight. NOTE: Ideal weight means the healthy weight for your height, not your current weight which may not be optimal. For example, if you are a man whose ideal body weight is 160 pounds, you would require 58 gm of protein daily. A woman with an ideal body weight of 130 pounds would require 47 gm of protein a day (14). All nutrient recommendations are calculated to cover 98% of the population. This means there is quite a large built-in safety margin and the actual protein requirement for most people is less than the stated recommendations.
Do people eating plants get enough protein? They sure do. A huge study of 30,000 non-vegetarians compared to 25,000 vegetarians, vegans, flexitarians and pesco-vegetarians concluded that vegetarians and vegans actually eat 70% more protein than they need every day (15). Other studies agree that more prudent diets, including vegetarian, semi-vegetarian and pesco-vegetarian diets, are generally higher in nutrition than omnivorous diets. Plant-based diets score the highest on the Healthy Eating Index while omnivorous diets score the lowest (16).
The amount of protein we need does vary. Athletes often require extra protein. Protein recommendations for endurance and strength athletes range from 1.2 to 1.7 gm per kg of ideal body weight (0.5 gm to 0.75 gm protein per pound of ideal body weight) (35). This is usually taken care of naturally by the extra calories also required (33,35). For example, a 150 pound male doing regular activities requires around 2500 calories a day. A plant-based diet supplies, at the bare minimum, 10% of calories from protein. So our regular 150 pound male eating 2500 calories will acquire at least 10% of these (250 calories) from protein. Since protein supplies 4 calories of energy per gram he would be getting around 64 gm of protein a day. The athlete on the other hand will increase his calorie intake to fuel the extra activity. A person training hard might be taking in 4000 calories. 10% of 4000 calories is 400 calories or 100 gm of protein. This is within the desired protein intake for this athlete (28). According to the American Dietetic Association, Dietitians of Canada, and the American College of Sports Medicine, extra protein needs for athletes can be generally met through diet alone with no need for protein or amino acid supplements (35). It is wise to always check the diet first (34,35)! If still more protein is needed over what the diet is contributing, the best way to obtain it is through an extra daily serving or two of beans, lentils or peas (34).
Others who might require some extra protein are women who are pregnant or breastfeeding. Once again, look at actual protein coming from the diet before adding supplements. Seniors, especially if they are sedentary and not eating enough calories, are another group who need to look at their protein intake. People over the age of 65 who are not active lose about 1% of their muscle mass every year. Those who are ill and spend much time in bed can lose muscle mass six times faster than a younger person. Additionally, seniors often have a reduced ability to absorb and use protein. Due to these factors some seniors may need to increase their protein to between 1 gm and 1.2 gm per kg of ideal body weight per day (0.45 mg to 0.55 mg protein per pound of ideal body weight) to avoid loss of lean muscle mass (28,36,37). Once again, look at the diet first. Active seniors with good appetites usually ingest enough protein through their diets. Remember also that physical activity is an additional way to combat muscle loss from aging (29).
Now back to the query that started all this. Where do I get my protein? Whenever I hear this question I feel like asking one back. Where do you get your fiber? If you are concentrating on protein you are likely to be low in fiber. There is no fiber at all in meat, dairy or eggs and very little, if any, in processed foods. Fiber comes only from plants. Fiber is one of the most important nutrients you can eat for health. It has been found to protect against diabetes, metabolic syndrome, high cholesterol, high blood pressure, cardiovascular disease, obesity and various cancers (17,18,19,20,21,22,23,24). Fiber is the preferred food for the “good” bacteria in our gut (25,26). Average fiber intake in North America is 15 grams per day. The minimum recommended daily requirement is 32 gm daily but more is better. There is no upper limit. Many of the healthiest populations in the world eat four times that amount.
Let’s do our own little study here. I have recorded everything I ate yesterday and looked up the amount of protein and fiber incIuded in my food using Health Canada nutrition data (27). The only unusual aspect of this day was that we had Black Bean Brownies for dessert. We don’t usually eat desserts per se. A satisfying end to supper can be a piece of fruit or, for a special treat, a chocolate or strawberry smoothie, both of which can contribute to protein and fiber intake. Black Bean Brownies are delicious and, as you can see, no slouches in the nutritious food department either. We include beans, lentils or chickpeas in our meals every day along with whole grains, fruits and vegetables. Most days we actually eat a much wider variety of vegetables than on this particular day. We are also fairy active, cycling or hiking on most days. The recipes for the “Good Morning Smoothie” and the “Sweet Black Beans and Rice” can be found on this website.
Results of our “study”; Check out the chart below. Yesterday I ate 75 gm of protein and 79 gm of fiber just by eating plants. No need to worry about where I get my protein or my fiber or any other nutrient for that matter – just another one of the benefits of a whole-food plant-based diet.
|Total gm protein|
|Total gm fiber|
|Good Morning Smoothie||1 tbsp chia seeds||1.8||3.7||105|
|1 tbsp flax seeds||2||3||57|
|1/2 cup blueberries||0.4||2.6||42|
|1/2 cup strawberries||0.5||1.8||41|
|1 cup kale /spinach||3||1.7||147|
|1/4 cup soy milk||3.4||0.3||43|
|Home-made granola||1/2 cup oatmeal, PB, maple syrup||7||5||98|
|Prunes - 6 pieces||1.2||4.2||20.6||24.8||210|
|Toasted sandwich||3 slices whole-wheat bread||9||6||240|
|2 tbsp peanut butter||7.5||2.5||184|
|Sweet Black Beans & Rice||1 1/2 cups cooked rice||7.7||4.6||344|
|1 cup black beans||16||16.2||254|
|3/4 cup green peas||6.5||5.6||107|
|1/4 sweet onion||0.6||0.8||26|
|1 clove garlic||0.2||0.1||4|
|Dessert||2 black bean brownies||5||5.8||36||33.1||150|
|TOTALS FOR THE DAY||PROTEIN||FIBER||CALORIES|
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