Of all the macronutrients we consume (protein, carbohydrates, and fats), proteins, which are made up of amino acids, are the only macronutrients that contain nitrogen. We can measure nitrogen loss, which tells us how much protein our bodies eliminate every day. At a minimum, we need to replace the amount of protein that our bodies eliminate every day, which experimentally is about 0.5-0.6 grams (g) of protein per kilogram (kg) of body weight per day. This is the Estimated Average Requirement (EAR).
Because the EAR was determined for a only small portion of the population, the Recommended Dietary Allowance (RDA) increased this amount by two standard deviations to 0.8 g of protein per kg of body weight per day to represent 98% of the population. In other words, for most of us, 0.8 g of protein per kg of body weight per day is more protein than we actually need.
Since the RDA has been adjusted upward from the minimum requirement, the RDA is not at all the minimum requirement, as many believe. If you’re consuming the RDA for protein, you are getting plenty of protein and don’t need to increase that amount!
In terms of calories, 0.8 g of protein per kg body weight per day is equivalent to about 8-10% of total dietary calories. This amount is readily provided by all plants!
To confirm this, I went to the USDA National Database and looked up the calories and protein (in grams) for 60 different plant-based foods, including vegetables, fruits, whole grains, beans, lentils, nuts, and seeds. Knowing that every gram of protein has four calories, I converted grams of protein into calories, and used that to calculate the percent of protein in each of the 60 plant-based foods that I looked up. Here’s what I found in order from highest to lowest percentage of protein:
- White mushrooms – 56.2% protein
- Spinach – 49.7% protein
- Bok choy – 46.2% protein
- Mustard greens – 42.4% protein
- Mung beans, sprouted – 40.5% protein
- Portabella mushrooms – 38.4% protein
- Swiss chard – 37.9% protein
- Collard greens – 37.8% protein
- Kale – 34.9% protein
- Broccoli – 33.2% protein
- Lentils – 31.1% protein
- Cauliflower – 30.7% protein
- Romaine lettuce – 28.9% protein
- Zucchini squash – 28.5% protein
- Kidney beans – 27.3% protein
- Black beans – 26.8% protein
- Pinto beans – 25.2% protein
- Pumpkin seeds – 21.6% protein
- Summer squash – 21.3% protein
- Cabbage – 20.5% protein
- Multigrain bread – 20.2% protein
- Tomatoes – 19.6% protein
- Peanuts – 18.7% protein
- Cucumber – 17.3% protein
- Celery – 17.3% protein
- Garlic – 17.1% protein
- Radishes – 17.0% protein
- Eggplant – 15.7% protein
- Pumpkin – 15.4% protein
- Sweet, yellow corn – 15.2% protein
- Buckwheat flour, groats - 15.1% protein
- Beets – 15.0% protein
- Quinoa, cooked - 14.7% protein
- Buckwheat groats, cooked - 14.7% protein
- Almonds – 14.6% protein
- Cooked oats – 14.3% protein
- Sunflower seeds – 14.2% protein
- Hulled barley – 14.1% protein
- Cashews – 13.2% protein
- Blackberries – 12.9% protein
- Red bell peppers – 12.8% protein
- Jalapenos – 12.6% protein
- Sesame seeds – 12.4% protein
- Millet, cooked (porridge) - 11.8% protein
- Onions – 11.0% protein
- Baked potato – 10.8% protein
- Walnuts – 9.3% protein
- Raspberries – 9.2% protein
- Carrots – 9.1% protein
- Baked sweet potato – 8.9% protein
- Butternut squash – 8.9% protein
- Strawberries – 8.4% protein
- Brown rice, medium-grain, cooked – 8.3% protein
- Kiwifruit – 7.5% protein
- Oranges – 7.4% protein
- Pearled barley – 7.3% protein
- Mango – 5.5% protein
- Blueberries – 5.2% protein
- Bananas – 4.9% protein
- Avocados – 4.7% protein
- Pineapple – 4.3% protein
- Persimmons – 2.5% protein
- Apples – 2.0% protein
As you can see from this list, consuming a whole, plant-based diet is how vegans get more than enough protein!