Can plants provide adequate protein?
About 11 percent of Americans get their daily fiber intake, less than 5 percent meet their daily potassium, vitamin A, C, D, iron, and calcium needs (Illinois), and one in three adults are obese. At the same time, America is the second greatest consumer per capita of meat in the world and is estimated to be less than one percent vegan. If the majority of Americans have micro-nutritional deficiencies and the vast majority of Americans consume animal products, then dietary scrutiny should probably not be limited to the vegan diet, which is subject to a fair amount of controversy. Protein is one of the most troubling components of the vegan diet to the general public because animal products are more protein dense per ounce than many plant products. As a former cross country athlete who ran 50 miles a week, and the sister of a nationally-ranked high school runner, I was skeptical that our vegan diet was not providing us with the protein we needed. To explore this skepticism, I looked closely at the nutritional values of lentils and tofu, which I eat regularly, and compared them to chicken and beef. By looking at the raw data, I was able to assess their value without my bias or the bias of others influencing the results. I found that when you consider protein density per calorie the values are comparable and plant-based proteins tend to be more nutritionally holistic.
You won't have trouble getting your protein
Figure 1: Protein quantity per 100 calories by food type and the requirements for 70kg moderately active person and a 70 kg bodybuilder
Figure one breaks down the protein content in grams per 100 calories of the following foods: tofu, lentils, chicken, and lean beef. Based on the nutritional data, chicken contains the most protein, followed by tofu, beef, and lentils. Chicken contains far and away more protein than the rest, but tofu, lentils, and beef are nearly equal. Alongside that data is the per 100 calorie protein requirement for a 70 kg (154 lb), moderately active person consuming 2500 calories and the requirement for a serious athlete consuming the same number of calories. The recommended amount of protein consumption is about 0.8-1.3 grams per kg of body weight; 1 gram of protein/kg for a moderately active person was used for means of comparison. Under a 2500 calorie diet, this individual would need to consume 70 grams of protein. This comes out to 2.8 grams of protein/100 calories. Many bodybuilders recommend 1 gram of protein per pound of body weight, so at 154 grams of protein and 2500 calories a day, it comes out to 6.16 grams/100 calories. This information brings me to my first conclusion: chicken may be more protein dense, but even a body builder would be able to achieve their protein intake with plant-based proteins.
You will get your essential amino acids
Figure 2: Essential amino acids per food type and requirements for 70 kg person on 2500 calories/day
Another popular concern is that you will be deficient in various essential amino acids such as lysine, methionine, tryptophan, and phenylanine. In Plant Foods have a Complete Amino Acid Composition, published by the American Heart Association Inc., Dr. McDougall (renowned physician and nutrition expert) determined that "By calculating the amount of each essential amino acid provided by unprocessed complex carbohydrates (starches and vegetables)...the results show that any single one or combination of these plant foods provides amino acid intakes in excess of the recommended requirements". I performed some simple math, using lentils, chicken and lean beef, and arrived at the same conclusion. Once again, I had calculated the quantity per 100 calories and compared it to daily recommendations of each type of amino acid from the FAO for a 70kg person consuming 2500 calories a day. I also found that there might be an added benefit to consuming lesser quantities of certain amino acids, such as methionine PubMed). Decreased methionine consumption results in aging retardant effects such as the suppression of mitochondrial superoxide production. This correlation might support increased mean and maximal longevity of followers of a plant-based diet, given a healthy diet and lifestyle.
And you'll get other important nutrients too
Figure 3: Micro-nutrients in food types per 100 calories
The truth is that protein deficiency is rare in the USA and other developed/developing nations, despite how widely is is discussed. On the other hand, fiber, potassium, vitamin A, C, D, calcium, and iron deficiencies are widespread. As shown in figures 3 and 4, lentils are the richest in these nutrients with the exception of vitamin A. However, it still out-competes beef and provides a good serving of vitamin A, whose daily requirement can be met in 50 calories of carrots. Vitamin D is absent from all three foods, but is often fortified in foods and can easily be achieved with simple sunlight exposure. The beauty of plant-based proteins is that they often contain higher quantities of these other micro-nutrients, but still meet the protein needs of humans. They also tend to provide fiber and exclude saturated fat, as is the case with lentils.
Figure 4: Micro-nutrients in food types per 100 calories
Figure 5: Macro-nutrients in food types and the rcommended amount of fiber per 100 calories
In Conclusion: Keep eating those beans and greens!
Based on all the data I have collected and analyzed and the sources I have researched, there is no reason to believe that you cannot get adequate or even abundant protein with plant-based foods while getting other important nutrients too. If you are interested in consuming meat, chicken is far superior to lean beef in terms of protein content and nutritional value, as well as a better choice for the environment.
All data was collected from the NutritionData.com database, which gets it's data from the USDA's National Nutrient Database for Standard Reference.
All graphs were created by myself.
Annalise