By Dietetic Intern Wareesha Nadeem, MHSc(c) and Julie Hutter, RD, CDE
People with chronic kidney disease are advised to be mindful of their daily protein intake and to follow a low-protein diet, as it promotes kidney health. In addition to the amounts of protein consumed daily, the types of protein, whether animal based, or vegetable based, can affect our kidney health.
A recent study by Milovanova et al. 2 showed that eating a low-protein diet and incorporating soy protein, can preserve the kidneys’ function more than animal-based protein diets. Of note, this study also found that utilizing ketoanalogues, a form of amino acid (the building blocks of protein) supplement, in addition to low-protein diets was advantageous! Overall, this study reinforces the benefits of replacing animal protein with soy protein, in delaying the progression of kidney disease, and protecting heart function.
So, what is soy protein?
Soy protein is a type of vegetable protein found in soy products, such as tofu and soy milk. Like animal-based protein, protein derived from soy is of high quality, meaning it has nutrients (called amino acids) which our bodies cannot produce on their own. Soy protein is also cholesterol-free, and a great source of fibre, calcium, iron, magnesium, and zinc.
Soy protein is especially beneficial for people with stages 3 and 4 CKD. A new study published in the Journal of Renal Nutrition found that over a year’s time, replacing animal protein with soy protein within a low-protein diet can:
- Protect kidney health (eGFR)
- Reduce levels of phosphorus, cholesterol, and urea in the blood
- Lower blood pressure
- Slow the loss of muscle mass
These findings suggest that people with chronic kidney disease should incorporate more soy protein into their diet. The results of this dietary shift can slow the progression of kidney disease and may delay the need for dialysis or a kidney transplant. Other benefits of consuming more soy proteinare an improved heart health, a decrease in cholesterol levels, as well asbetter blood sugar control, all of which can further support kidney health.
But, before adding soy protein to your diet, there are few things you must keep in mind. For instance, you should stay away from soy products if you have a soy allergy. Additionally, some soy products can have high potassium, phosphorus, and sodium levels. Since large amounts of these nutrients can be harmful for people with kidney disease, we encourage you to carefully read food labels to learn the nutrient content in soy products. It is also important to be mindful of kidney-friendly portion sizes for protein of any source.
Below are some examples of soy protein sources and their recommended portions for a kidney-friendly diet:
- ¼ cup of firm or extra firm tofu
- ½ cup of soft tofu
- ½ cup of soy milk
- ½ cup of cooked edamame
- ¼ cups of texturized soy protein (used as a meat substitute in plant-based products like veggie burgers)
Try these delicious tofu-based recipes:
Vegetable and Tofu Stir-Fry recipe
Spicy Pina Colada Smoothie – Kidney Community Kitchen
Additional examples of soy protein sources can be found in our Plant-based Protein Options handout.
Consult with your renal dietitian to learn how you can safely add more soy protein into your diet, and with your kidney team about the availability of ketoanalogues in your area.
References
- Harvard Medical School. (2021, September 30). Confused about eating soy? Harvard Health Publishing. Retrieved from https://www.health.harvard.edu/staying-healthy/confused-about-eating-soy
- Milovanova, L. Y., Taranova, M.V., Volkov, A.V., Milovanova, S.Y. & Nezhdanov, K.S. (2022). Soy protein as a part of a low-protein diet is a new direction in cardio- and nephroprotection in patients with 3b-4 stages of chronic kidney disease. Journal of Renal Nutrition, doi: https:// doi.org/10.1053/j.jrn.2022.10.008.
- Otun, J., Sahebkar, A., Ostlundh, L., Atkin, S. L. & Sathyapalan, T. (2019). Systematic review and meta-analysis on the effect of soy on thyroid function. Scientific Reports, 9(3946), doi: https://doi.org/10.1038/s41598-019-40647-x
- Rafienian-Kopaei, M., Beigrezaei, S., Nasri, H. & Kafeshani, M. (2017). Soy protein and chronic kidney disease: An update review. International Journal of Preventative Medicine, 8(105). doi: 10.4103/ijpvm.IJPVM_244_17