Talkin' About Tofu

With the rise of plant-based diets, tofu (as one of the most popular meat substitutes) has become a staple in the vegetarian kitchen. This soy derived product has been known in Asia for over a thousand years, yet tofu didn't make it to stores in the USA until the 1970s (Messina, 2015). 

What exactly is tofu?

Tofu is made in a similar process as cheese. The soy milk is curdled, processed into a block and cooled (Burch , 2020). There are a few types of tofu you can find in stores: silken, soft, firm, extra firm and super firm. The difference between them is the amount of water pressed out of the tofu (Han, 2014). There are also black, fermented, and sprouted types of tofu (Messina, 2015). The nutrition content of tofu varies according to the way tofu is made; as a rule, firmer tofu will have more calories, protein and fat than the softer versions. Tofu is an excellent source of protein and contains all nine essential amino acids.

According to the USDA one-quarter cup of firm tofu (81g) contains (Frey, 2020):

117 kcal

7g of fat, mostly polyunsaturated and monounsaturated 

11mg sodium 

2.2g carbohydrates

1.9g fiber

14g of protein 

553mg calcium 

2.5mg iron 

What does the research say?

The various ways in which soy is studied have reached differing conclusions about soy. However, recent research done suggests either beneficial or neutral effects on human health (Harvard T.H. Chan School of Public Health, n.d.). Research focusing on soy as a whole food versus research on isolated nutrients from soy can be contributed to contradicting results (Webster, 2017).

Tofu as a soy food, contains a high amount of isoflavones; 100g of tofu provides about 25 mg of isoflavones (Messina M. , 2016). Isoflavones are a class of flavonoids that belong to phytoestrogens, compounds that naturally occur in plants. In plants, phytoestrogens have antibacterial, antiviral and antioxidant functions (Křížová, Dadáková, Kašparovská, & Kašparovský, 2019). Isoflavones are similar molecules to the hormone estrogen, and this similarity has brought concerns that soy may influence the risk of estrogen related cancers. In fact, isoflavones differ from estrogen by binding weakly to estrogen receptors as compared to  estrogen (Messina M. , Impact of Soy Foods on the Development of Breast Cancer and the Prognosis of Breast Cancer Patients, 2016).  Because of the isoflavones and its estrogenic and anti-estrogenic effects on the body, soy has been widely studied. 

What do we mean by estrogenic and anti-estrogenic effect? It means that estrogen has both positive and negative effects. High levels of estrogen can be good for bone health but can also increase the risk of breast cancer. Soy’s isoflavones, by use of selective estrogen receptor modulators have an anti-estrogenic effect by lowering the risk of breast cancer and they also have a pro-estrogenic effect by helping to reduce menopausal symptoms (Greger, 2015).  During menopause the levels of estrogen decline and when consuming soy-based food the phytoestrogen in soy may slightly increase estrogen levels which helps to ease symptoms of menopause such as hot flashes (Lewin , 2019).

Tofu exhibits antioxidant and anti-inflammatory properties protecting blood vessels from oxidative stress and inflammation. Furthermore, the latest research suggests that consumption of soy- based products helps in the prevention of breast cancer, as mentioned above, but also prevents osteoporosis (Pal, Devrani, & Ayele, 2019) and prostate cancer(Applegate, Rowles III, Ranard, Jeon, & Erdman Jr., 2018). One of the latest findings about soy revealed that isoflavones in soy help to lower blood glucose levels and lower the risk of type 2 diabetes (Ramdath, Padhi, Sarfaraz, Renwick, & Duncan, 2017). Another well-researched claim is that soy foods help to reduce the risk of cardiovascular disease(Ramdath, Padhi, Sarfaraz, Renwick, & Duncan, 2017). Tofu and soy products are naturally free of cholesterol, and consumption of soy- based foods will lower the intake of saturated fat and will increase the intake of monounsaturated fats as compared to the consumption of meat (Lopez-Jimenez, 2020). There is also research, though limited, done on soy and obesity which suggests that soy may decrease lipase activity and improve insulin resistance. Some research also proposes that soy may be good for the kidneys and cognitive functions (Rizzo & Baroni, 2018). 

There are a few things to remember when we talk about the health benefits of soy products. Tofu contains a high number of proteins and has a low-fat content which makes for a great meat substitute, but we need to take into consideration that soy is one of the main food allergens and that conventional tofu is made from genetically modified soybeans (The George Mateljan Foundation , n.d.). To include soy-products in our diets, we should have a personalized approach where the benefits outweigh the risks. I, personally, am a huge fan of tofu and I find it to be a great addition to a balanced diet based on plant foods.

Edited by PreRD intern, Lauren Gatto

Written by Aneta Palmer: I completed my bachelor's degree in dietetics and nutrition at Queens College in December 2020. I have been accepted to the MS+DI program, also at Queens College. This is a new program in which I will complete most of my master courses in the year prior to beginning the dietetic internship. I am interested in healthy aging, plant based nutrition and sports nutrition. I am looking forward to my internship and everything that follows. I also enjoy running, biking, developing new recipes and learning Spanish!

References:

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Burch , K. (2020, November 5). Insider. Retrieved from Tofu: Health benefits, downsides, and misconceptions, according to a registered dietitian: https://www.insider.com/is-tofu-bad-for-you

Frey, M. (2020, July 27). Tofu Nutrition Facts. Retrieved from Very Well Fit : https://www.verywellfit.com/tofu-nutrition-facts-calories-and-health-benefits-4113988

Greger, M. (2015). How not to die: discoer the foods scientifically proven to prevent and reverse disease? New York : Flatiron Books.

Han, E. (2014, March 28). What’s the Difference Between All the Types of Tofu? Retrieved from kitchn: https://www.thekitchn.com/tofu-varieties-whats-the-difference-201345

Harvard T.H. Chan School of Public Health. (n.d.). The Nutrtition Source Straight Talk about Soy. Retrieved March 2021, from harvard.edu: https://www.hsph.harvard.edu/nutritionsource/soy/

Křížová, L., Dadáková, K., Kašparovská, J., & Kašparovský, T. (2019, March). Isoflavones. Molecules, 24(6), 1076 10.3390/molecules24061076.

Lewin , J. (2019, November 4). The health benefits of tofu. Retrieved from BBC Good Food: https://www.bbcgoodfood.com/howto/guide/ingredient-focus-tofu#:~:text=Nutritional%20highlights,copper%2C%20zinc%20and%20vitamin%20B1.

Lopez-Jimenez, F. (2020, February 7). Soy: Does it reduce cholesterol? Retrieved from Mayo Clinic: https://www.mayoclinic.org/diseases-conditions/high-blood-cholesterol/expert-answers/soy/faq-20057758

Messina, M. (2016, April 12). Impact of Soy Foods on the Development of Breast Cancer and the Prognosis of Breast Cancer Patients. Forschende Komplementärmedizin / Research in Complementary Medicine, 23(2), 75-80 10.1159/000444735.

Messina, M. (2016, December). Soy and Health Update: Evaluation of the Clinical and Epidemiologic Literature. Nutrients, 8(12), 754 10.3390/nu8120754.

Messina, V. (2015, April). Tofu's many faces. Today's Dietitian, 17(4), 22.

Pal, M., Devrani, M., & Ayele, Y. (2019, April 11). Tofu: A Popular Food with High Nutritional and Health Benefits. Food & Beverages Processing, 5, 54-55 .

Ramdath, D. D., Padhi, E. M., Sarfaraz, S., Renwick, S., & Duncan, A. M. (2017, April). Beyond the Cholesterol-Lowering Effect of Soy Protein: A Review of the Effects of Dietary Soy and Its Constituents on Risk Factors for Cardiovascular Disease. Nutrients, 9(4), 324 10.3390/nu9040324.

Rizzo, G., & Baroni, L. (2018, January 5). Soy, Soy Foods and Their Role in Vegetarian Diets. Nutrients, 10(1), 43 10.3390/nu10010043.

The George Mateljan Foundation . (n.d.). Tofu. Retrieved from The world's healthiest foods: http://www.whfoods.com/genpage.php?tname=foodspice&dbid=111Webster, A. (2017, December 5). Sound Science: History of Soy and Health. Retrieved from Food Insight : https://foodinsight.org/sound-science-history-of-soy-and-health/