Soybean (Glycine max) is a particular legume, part of the plant family which includes peas and lentils. Whilst it originated in Asia hundreds of years ago, it is amazing how popular this ordinary-looking bush has become in recent years around the world.  Let’s have a closer look at this humble plant that’s often hailed as “a miracle crop”.

The story of soybeans started long ago in Asia, but in the 18^th and 19^th century, it began to be cultivated in different countries around the world (1, 2); today, soybeans can also be grown in parts of Europe. The first farmers who grew soybeans used them as animal feed and when they started to rotate their original crops with soy, a miracle happened. The farmers noticed that their original crops had started to grow better!

This is because soy is a nitrogen-fixing crop and when it comes to farming, nitrogen is a key nutrient. Other crops remove nitrogen from the soil, but soybeans put it back into the soil with the help of bacteria that sit among their roots (3, 4). Soy is renowned for its many positive traits, including its sustainability. When compared to dairy and meat proteins, the carbon footprint, land and water use of soy protein isolate, is among the smallest of all (5). Animal meat, per gram of protein, needs 6 times as much water as legumes like soy (6) and ruminant meat, like beef, leads to a 50 times greater greenhouse gas emission per gram in comparison to soybean (7).

However, the tale of soy wouldn’t be complete without mentioning one particular nutrient - protein. Although extraction of protein from soy was first described in 1911, it took years to master its production. In 1937, the first commercial soy protein isolate became available, but it took another 20 years to discover its nutritive potential;  edible soy protein isolate first became available in 1959 (4).

Soy is a well-known source of protein and raw soybeans contain 30-46% protein (8). Soy protein isolate is a uniquely high purified form of protein. It contains more than 90% protein and due to its neutral flavour, it can be used in many ways. Most plant proteins are not regarded as high-quality proteins, as they lack different essential amino acids, but soy protein is an exception. Therefore, the protein within soy can contribute to the daily protein requirements of up to 30% of the daily energy intake (9). Some examples of nutritional food that has soy in it is Tofu, Tempeh, Soy Bean Dairy and Edamame.

A number of sports performance research studies have explored the nutritional power of soy protein.  These pieces of research have shown that soy protein can support our body’s processes as effectively as animal protein. It appeared that soy protein can stimulate muscle protein synthesis, in the same way that whey protein can (10, 11). Consuming soy protein also has the same benefits that are associated with protein in general, such as its effect on weight management, support of tissue maintenance and growth, satiety and thermogenesis (12-16). In addition to this, several meta-analyses have linked the consumption of soy protein to a decreased level of total and low-density lipoprotein (LDL) cholesterol, or the “bad” type; features that are associated with improved cardiovascular health (17-19).

Soy protein can provide many benefits in terms of health, cultivation and sustainability. American scientists from NASA even have started to look at the possibility of growing soybeans in space (20, 21). Who knows what the future may hold! 

References

1. Lee G-A, Crawford GW, Liu L, Sasaki Y, Chen X. Archaeological Soybean (Glycine max) in East Asia: Does Size Matter? PLOS ONE. 2011;6(11):e26720.
2. Chaplin JE. An Anxious Pursuit: agricultural innovation and modernity in the Lower South, 1730-1815: UNC Press Books; 2012.
3. Roth M. Magic Bean: The Rise of Soy in America: University Press of Kansas; 2018.
4. Shurtleff W, Aoyagi A. History of modern soy protein ingredients-isolates, concentrates, and textured soy protein products (1911-2016): Extensively annotated bibliography and sourcebook: Soyinfo Center; 2016.
5. Nadathur S, Wanasundara JP, Scanlin L. Sustainable protein sources: Academic Press; 2016.
6. Mekonnen M, Hoekstra A. The green, blue and grey water footprint of farm animals and animal production. Volume 1: Main Report. Value of Water. Research Report Series; 2010.
7. Clune S, Crossin E, Verghese K. Systematic review of greenhouse gas emissions for different fresh food categories. Journal of Cleaner Production. 2017;140:766-83.
8. Huang S, Yu J, Li Y, Wang J, Wang X, Qi H, et al. Identification of Soybean Genes Related to Soybean Seed Protein Content Based on Quantitative Trait Loci Collinearity Analysis. Journal of agricultural and food chemistry. 2019;67(1):258-74.
9. IOM. Dietary Reference Intakes for Energy, Carbohydrate, Fiber, Fat, Fatty Acids, Cholesterol, Protein, and Amino Acids. Board FaN, editor. Washington (DC): National Academy Press; 2005.
10. Churchward-Venne, Pinckaers PJM, Smeets JSJ, Peeters WM, Zorenc AH, Schierbeek H, et al. Myofibrillar and Mitochondrial Protein Synthesis Rates Do Not Differ in Young Men Following the Ingestion of Carbohydrate with Whey, Soy, or Leucine-Enriched Soy Protein after Concurrent Resistance- and Endurance-Type Exercise. J Nutr. 2019;149(2):210-20.
11. Tang, Moore DR, Kujbida GW, Tarnopolsky MA, Phillips SM. Ingestion of whey hydrolysate, casein, or soy protein isolate: effects on mixed muscle protein synthesis at rest and following resistance exercise in young men. J Appl Physiol (1985). 2009;107(3):987-92.
12. Dhillon J, Craig BA, Leidy HJ, Amankwaah AF, Anguah KO-B, Jacobs A, et al. The effects of increased protein intake on fullness: A meta-analysis and its limitations. Journal of the Academy of Nutrition and Dietetics. 2016;116(6):968-83.
13. Westerterp-Plantenga M, Nieuwenhuizen A, Tome D, Soenen S, Westerterp K. Dietary protein, weight loss, and weight maintenance. Annual review of nutrition. 2009;29:21-41.
14. Yang D, Liu Z, Yang H, Jue Y. Acute effects of high-protein versus normal-protein isocaloric meals on satiety and ghrelin. Eur J Nutr. 2014;53(2):493-500.
15. Leidy HJ, Clifton PM, Astrup A, Wycherley TP, Westerterp-Plantenga MS, Luscombe-Marsh ND, et al. The role of protein in weight loss and maintenance. The American journal of clinical nutrition. 2015;101(6):1320S-9S.
16. Pasiakos SM, Lieberman HR, Fulgoni III VL. Higher-protein diets are associated with higher HDL cholesterol and lower BMI and waist circumference in US adults. The Journal of nutrition. 2015;145(3):605-14.
17. Blanco Mejia S, Messina M, Li SS, Viguiliouk E, Chiavaroli L, Khan TA, et al. A meta-analysis of 46 studies identified by the FDA demonstrates that soy protein decreases circulating LDL and total cholesterol concentrations in adults. The Journal of nutrition. 2019;149(6):968-81.
18. Reynolds K, Chin A, Lees KA, Nguyen A, Bujnowski D, He J. A meta-analysis of the effect of soy protein supplementation on serum lipids. Am J Cardiol. 2006;98(5):633-40.
19. Gaudichon C, Azzout-Marniche D, Chalvon-Demersay T, Tomé D, Arfsten J, Karagounis LG, et al. A Systematic Review of the Effects of Plant Compared with Animal Protein Sources on Features of Metabolic Syndrome. The Journal of nutrition. 2017;147(3):281-92.
20. Wheeler RM. Agriculture for space: people and places paving the way. Open agriculture. 2017;2(1):14-32.
21. Chapter 15: “Soybeans - they’re not just for breakfast anymore!”: nasa.gov; 2005 [Available from: https://www.nasa.gov/centers/johnson/astronauts/journals_anderson_ch15.html.