Kidney Beans

Getting Protein From Plants

What are plant proteins?

Proteins are generally referred to as the building blocks of life as they are required for the growth, development, and repair of body tissues. As a matter of fact, every human cell contains proteins. Like every other nutrient, we get proteins from the foods we consume, either plants or animals. Animal based protein sources include meat, milk, eggs, poultry, fish, and diary. On the other hand, plant-based protein sources include beans (e.g., kidney beans, mung beans, chickpeas), soyabeans (including edamame, tofu, and tempeh) nuts (e.g., cashew nuts, walnuts, almond nuts), peanuts, seeds (e.g., flaxseeds, chia seeds) and cereal grains (e.g., wheat, rice, corn, quinoa) (1, 2).

While most people get their proteins from both plants and animals, others get more of their proteins from plant sources and some others exclusively from plant sources (vegans). Though a good variety of plants do contain a modest to high percentage of protein, plant proteins are said to be inferior to animal proteins because plant proteins are not complete. Soyabean is the only plant with a complete protein profile. Proteins are made up of smaller units called amino acids, which are 20 in number. The human body can make 11 of them (also called non-essential amino acids) and relies on the foods we eat to supply the remaining 9 (also called essential amino acids). Thus, a complete protein is one that contains all the 9 essential amino acids (histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine) and an incomplete protein is one that lacks any other the 9 essential amino acids (3).


For decades now the world has seen a surge in consumer demand for plant-based protein foods/products, a demand which is projected to grow significantly in the next decades. Factors that have favored this increase in demand include increased awareness of the health benefits of a plant-based diet (reduced risk of chronic diseases), environmental sustainability issues (growing plants being more environmentally sustainable than animals), and ethical issues with regards to raising and killings animals (4). The following are some benefits of getting proteins from plants.

  1. Reduces risk for cardiovascular diseases. Consuming more plant proteins is associated with lower levels of low-density lipoprotein (LDL) cholesterol in the blood, which is a risk factor for cardiovascular disease like heart disease (5).

  2. Reduces risk for diabetes and improves diabetic control. Research studies have reported that consuming more plant proteins like soyabean protein, is linked to a reduced risk of type 2 diabetes, as they reduce postprandial glucose response (6). One study reported improvements in fasting blood glucose and fasting insulin levels with the consumption of a meal where at least 35% of its protein came from plant sources (7).

  3. Reduces over all mortality. Consuming more plant proteins have been reported to show a significant inverse relationship with both case specific and all-cause mortality arising from cardiovascular diseases and stroke (8). Replacing as little as 3% of one’s protein intake with plant protein reduces overall mortality by 10% in both males and females (9).

The Recommended Dietary Allowance (RDA) for protein is 0.8 grams of protein per kilogram of body weight. An adult man requires about 56g of protein per day and adult woman requires about 46g (and 71g for pregnant and breastfeeding women) (10). Getting your proteins from plants can be very rewarding health wise and affordable. Though plant proteins are incomplete, if planned properly, it does not make a person disadvantaged. If you are going for more plant proteins, do ensure to consume a variety of plants to get the missing amino acids in each category. Beans and peas for example tend to contain less amounts of the amino acids cysteine and methionine. On the other hand, cereal grains, nuts, and seeds tend to contain low amounts of the amino acid lysine (11).



  1. Protein in diet. (n.d.). Retrieved September 24, 2022, from website:

  2. Villines, Z. (2021, September 10). Top 15 sources of plant-based protein. Retrieved September 24, 2022, from website:

  3. The difference between complete and incomplete proteins. (n.d.). Retrieved September 24, 2022, from WebMD website:

  4. Hertzler, S. R., Lieblein-Boff, J. C., Weiler, M., & Allgeier, C. (2020). Plant proteins: Assessing their nutritional quality and effects on health and physical function. Nutrients, 12(12), 3704. doi:10.3390/nu12123704

  5. Li, S. S., Blanco Mejia, S., Lytvyn, L., Stewart, S. E., Viguiliouk, E., Ha, V., … Sievenpiper, J. L. (2017). Effect of plant protein on blood lipids: A systematic review and meta-analysis of randomized controlled trials. Journal of the American Heart Association, 6(12). doi:10.1161/JAHA.117.006659

  6. König, D., Muser, K., Berg, A., & Deibert, P. (2012). Fuel selection and appetite-regulating hormones after intake of a soy protein-based meal replacement. Nutrition (Burbank, Los Angeles County, Calif.), 28(1), 35–39. doi:10.1016/j.nut.2011.02.008

  7. Viguiliouk, E., Stewart, S. E., Jayalath, V. H., Ng, A. P., Mirrahimi, A., de Souza, R. J., … Sievenpiper, J. L. (2015). Effect of replacing animal protein with plant protein on glycemic control in diabetes: A systematic review and meta-analysis of randomized controlled trials. Nutrients, 7(12), 9804–9824. doi:10.3390/nu7125509

  8. Huang, J., Liao, L. M., Weinstein, S. J., Sinha, R., Graubard, B. I., & Albanes, D. (2020). Association between plant and animal protein intake and overall and cause-specific mortality. JAMA Internal Medicine, 180(9), 1173–1184. doi:10.1001/jamainternmed.2020.2790

  9. Naghshi, S., Sadeghi, O., Willett, W. C., & Esmaillzadeh, A. (2020). Dietary intake of total, animal, and plant proteins and risk of all cause, cardiovascular, and cancer mortality: systematic review and dose-response meta-analysis of prospective cohort studies. BMJ (Clinical Research Ed.), 370, m2412. doi:10.1136/bmj.m2412

  10. The basics: Protein. (2016).

  11. Lopez, M. J., & Mohiuddin, S. S. (2022). Biochemistry, Essential Amino Acids. In StatPearls [Internet]. StatPearls Publishing.


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