Soy and IBD: A Comprehensive Review

The common question of, “is soy bad for IBD?” comes up a lot in our practice. We understand that tofu can come with concerns like hormonal imbalances and even how much should be consumed overall.  We wanted to address the most common concerns regarding soy and IBD, while placing emphasis on its health benefits with IBD!   

Soy and IBD: A Comprehensive Review

What do we know?

Although the reason for the development of IBD is very individual and widely unknown still, current research suggests that certain dietary patterns can contribute to an IBD diagnosis.  

Consuming a diet that is high in sugar, ultra-processed, and low in fruits and vegetables can increase a person’s risk of developing IBD (4).  Furthermore, consuming animal protein frequently can also increase a person’s risk of IBD whilst showing a strong association with the risk of relapse in patients with ulcerative colitis (5).  

While some research has shown how certain foods can be problematic for people with IBD, other research has shown how certain foods, including soy and tofu, can provide beneficial properties for patients with IBD.  

Are soy and tofu the same thing?

There are many soy products on the market, such as soy milk, edamame, tofu, tempeh, miso, natto, soy nuts, sprouts, and soy sauce. Since tofu is often recommended and we talk a lot about tofu, we will be highlighting it as an ingredient, however the aforementioned soy products listed above still contain the same properties we will discuss in this article.  

So, what’s tofu all about?  We see it on the menu, and we keep hearing that it’s a plant-based protein.  But, what is it? 

Tofu is an unfermented soy food that is made from condensed soy milk. The soy milk is made from soybeans (a type of legume that is native to East Asia), which is then coagulated and pressed into the blocks we all know and love. It’s easy to consume due to its texture, it’s nutritious, and delicious!  

Tofu is a complete protein since it contains all 9 essential amino acids that our bodies are unable to make on their own.  Tofu makes a great meat alternative and is easily prepared using different cooking methods.  This soybean is an inexpensive way to include a high-quality protein source into your diet! 

According to the U.S. Food & Drug Administration (FDA), 25 grams of soy protein per day along with a decreased intake of saturated fat can decrease a person’s risk of heart disease.  Furthermore, having up to 50 grams of soy protein is both clinically safe and nutritious.  

How do you cook tofu?

Let’s look at some of the ways tofu can be prepared.

Ways to cook tofu

• Baked
• Grilled
• Steamed
• Stir-fried
• Blended (for smoothies)
• Scrambled
• Pan-fried (without deep frying)
• Boiled

With its large variety and adaptability as an ingredient, it’s easy to incorporate in your daily diet! 

Is soy bad for IBD?

As practitioners, we shy away from labeling foods as good and bad because we want to encourage a curious and open-minded perspective about food. We want to preserve your enjoyment and trust with food and your body as much as possible. 

But many question whether or not soy is a good option for those with IBD. To help us answer that question, we need to take a closer look at the changes IBD makes to our bodies and consider the consequences. 

IBD consequences and soy’s role

When IBD is active or even recovering, many of our nutrients are being utilized to “save the day” which can lead us into a malnourished state.  Even once the flare has been treated, nutrient requirements continue to be increased due to any damage that the inflammation may have caused.  This is part of the reason why IBD patients tend to have higher needs for specific nutrients compared to non-IBD patients.  

Properties of soy

For example, during an active IBD flare some nutrients can become lower due to inflammation and from medications. Nutrients including folic acid, calcium, vitamin D, zinc, iron, B12, and vitamin A E K can become low. 

Fortunately, there are many foods that contain some of these nutrients, including tofu!  In fact, tofu provides us with many nutrients including fiber, potassium, calcium, B vitamins, and magnesium.  

Research has shown that soy is not only a substitute for animal-based protein but also contains anti-inflammatory components including isoflavones which have been shown to alleviate gut inflammation (6).  

It is also important to not confuse soy products like tofu with highly processed soy products like soybean oil. Soybean oil is higher in omega-6 fatty acids compared to omega-3 fatty acids which can drive inflammation and lack the antioxidant isoflavones that are naturally found in tofu and other plant-based foods.  

Want to know one more super exciting, nerdy fact about tofu? Nuclear factor kappa B (NF-κB), a transcription protein that participates in activating inflammation , is suppressed by the activity of soyasaponin, a soy-derived compound found in tofu (7). What this tells us is that soy-derived products, including tofu, can help mitigate inflammatory pathways that are prevalent with inflammatory diseases such as IBD. Furthermore, Lunasin, a peptide that is found in soybeans, has also been shown to suppress inflammation and its pathways that can contribute to inflammation (8).  

Common concerns about soy

Fluctuations in hormones, the risk of breast cancer, and the uncertainty of this legume are all common concerns that people have regarding the consumption of tofu.  So, let’s talk about it!

Selective Estrogen Receptor Modulators and Phytoestrogens in soy

Selective estrogen receptor modulators (SERMs) are synthetic non-steroidal agents that bind to estrogen receptors to produce a change in the mechanism of the tissue, depending on the type (10). Similarly, phytoestrogens are the plant-derivatives of SERMs and also bind to estrogen receptors and enact a biological change. Their structure (pictured below) mimics estrogen and therefore can play both agonist and antagonist roles with estrogen receptors. 

Take a look at this great picture breakdown of the different forms and much how they look alike!

Researchers often refer to phytoestrogens as natural SERMs and the literature surrounding breast cancer, for example, is growing in its understanding of using phytoestrogens as a potential cancer preventative agent because of its protective effects. 

Interestingly, phytoestrogens are also found in a wide variety of foods! Because phytoestrogens have been further identified into subgroups, including flavonoids, isoflavones (a subgroup of flavonoids), lignans, coumestans and stilbenes, you can imagine the wide variety of foods represented within each category.

Examples include: 

• Green beans
• Flaxseeds
• Whole grains
• Soy, tofu, tempeh
• Sesame seeds 
• Lentils 
• Carrots 
• And so many more!

Phytoestrogens seem to play a role in suppressing tumor growth, suppress alpha-type estrogen receptors common in breast and uterine cancers,  as well as being anti-inflammatory in nature. So time will tell if phytoestrogens can definitively be used as a chemopreventive agent! 

Breast cancer and soy

One of the largest prospective studies, the Japan Collaborative Cohort (JACC), found that there was no increase in breast cancer from tofu consumption. In fact, studies have shown the isoflavones that are found in soy foods have a protective mechanism against certain cancers (1).  

Another study suggested that there are lower rates of breast cancer in Asia due to the higher consumption of tofu (2).  Additionally, one research article took a compilation of published data to determine a possible association between tofu and the risk of breast cancer.  In fact, multiple published meta-analyses reported the soy isoflavones (found in tofu) actually decreased the risk of developing breast cancer. This association was made in areas where soy is commonly consumed (2).  

Heart health and soy

Finally, in reference to heart health, one study suggested that 80 milligrams (mg) of isoflavones per day for 12 weeks can decrease the risk of a stroke and overall improve blood flow (3). All in all, soy is anti-inflammatory and plays a protective role in cancer risk rather than the common myth of potentially causing it. 

What a relief! 

Key Takeaways

Nutritional needs, including protein, are increased during active IBD and are crucial in the prevention of malnutrition and decreased risk of hospitalization.  Isoflavones, which are found in soybeans, have anti-inflammatory properties, and also provide antioxidant components to those with colitis.  We also know how animal protein sources can become pro-inflammatory in this population and even cause a relapse in disease (9).  

Overall, tofu is a nutritious legume that can be conveniently incorporated into the diet and is well tolerated in our IBD community.  In addition, the literature tells us that soybean protein intake in IBD provides anti-inflammatory properties and supports muscle mass maintenance.

While more research is needed in human studies, it is still promising to know how incorporating tofu into the diet can be both nutritious and anti-inflammatory.  Furthermore, tofu’s soft texture is easily tolerated in patients with IBD and can be prepared in numerous ways! 

For more in depth reviews and more personalized nutrition strategies, check out all the ways you can work with us.

We have several different levels of support that we offer the IBD community and would be honored to partner with you!

References:

1. Zhone, XS., Ge, J., Chen, SW., Xiong, YQ., Ma, SJ., Chen, Q. (2018). Association between Dietary Isoflavones in Soy and Legumes and Endometrial Cancer: A Systematic Review and Meta-Analysis. Journal of the Academy of Nutrition and Dietetics. Apr;118(4):637-651. https://doi.org/10.1016/j.jand.2016.09.036.
2. Wang, Q., Liu, X., Ren, S. (2020). Tofu intake is inversely associated with risk of breast cancer: A meta-analysis of observational studies. PloS one. 15(1):e0226745. https://doi.org/10.1371/journal.pone.0226745.
3. Chan, YP., Lau, KK., Yiu, KH., Li, SW., Chan, HT., Fong, DYT., Tam, S., Lau, CP., Tse, HF. (2008). Reduction of C-reactive protein with isoflavone supplement reverses endothelial dysfunction in patients with ischaemic stroke. European Heart Journal. Nov;29(22):2800-7. https://doi.org/10.1093/eurheartj/ehn409
4. Campmans-Kuijpers, MJE., Dijkstra, G. (2021). Food and Food Groups in Inflammatory Bowel Disease (IBD): The Design of the Groningen Anti-Inflammatory Diet (GrAID). Nutrients. Apr;13(4):1067. https://doi.org/10.3390/nu13041067.
5. Mentella, MC., Scaldaferri, F., Pizzoferrato, M. Gasbarrini, A., and Miggiano, GAD. (2020). Nutrition, IBD, and Gut Microbiota: A Review. Nutrients. Apr;12(4):944. https://doi.org/10.3390/nu12040944.
6. Metzger, CE., Narayanan, SA., Zawieja, DC., Bloomfield, SA. (2018). A moderately elevated soy protein diet mitigates inflammatory changes in gut and in bone turnover during chronic TNBS-induced inflammatory bowel disease. Applied Physiology, Nutrition, and Metabolism. 44(6):595-605. https://doi.org/10.1139/apnm-2018-0514.
7. Basson, AR., Ahmed, S., Almutairi, R. Seo, B., Cominelli, F. (2021). Regulation of Intestinal Inflammation by Soybean and Soy-derived Compounds. Foods. 10(4):774. https://doi.org/10.3390/foods10040774.
8. Suzuki, R., Kohno, H., Sugie, S., Nakagama, H., Tanaka, T. (2006). Strain differences in the susceptibility to azoxymethane and dextran sodium sulfate-induced colon carcinogenesis in mice. Carcinogenesis. 27(1):162-169. https://doi.org/10.1093/carcin/bgi205.
9. Andersen, V., Olsen, A., Carbonnel, F., Tjonneland, A., Vogel, U. (2012). Diet and risk of inflammatory bowel disease. Digestive and Liver Disease. 44(3):185-194. https://doi.org/10.1016/j.dld.2011.10.001.
10. Oseni T, Patel R, Pyle J, Jordan VC. Selective estrogen receptor modulators and phytoestrogens. Planta Med. 2008 Oct;74(13):1656-65. doi: 10.1055/s-0028-1088304. Epub 2008 Oct 8. PMID: 18843590; PMCID: PMC2587438.