soybeans

Soy: An Overlooked Tool In Our Cholesterol-Lowering Toolbox

ByCheryl

Note from Cheryl: This is a guest post about soy written by Julianna Bennett, a dietetic student at Unity Health Toronto, with support from her supervisor, Andrea Glenn, MSc, RD, PhD, Postdoctoral Fellow. I also reviewed and edited it.

I welcome students, other healthcare professionals, and people living with heart disease to guest post. If you’d like to submit something, click here to find out how.

​​Soy foods are a true staple in my diet as they are versatile and easy to cook. They’re made from soybeans and include foods as varied as tofu, edamame, tempeh, texturized vegetable protein (TVP), soy milk and soy-based meat alternatives.tofu dish

There is an abundance of evidence demonstrating the effectiveness of soy protein for lowering cholesterol, which is why it is a main component of the cholesterol-lowering Portfolio Diet.

In addition, soybeans are an all-star plant protein choice, as their protein contains all nine essential amino acids, which are the building blocks for protein, making them a complete protein source. Soy protein is also an excellent alternative to meat as it does not contain dietary cholesterol or saturated fat that can impact your LDL (or bad) cholesterol levels.

Is consuming soy safe?

You may have heard that soy can lead to feminization in men or breast cancer in women, due to isoflavones, which are a type of plant estrogen. However, the effect of plant estrogens is different from human estrogen, and clinical evidence shows that eating soy has no effect on either estrogen levels or feminization in men. 

While animal studies have suggested a linkage between soy and breast cancer, some studies actually show the opposite in humans, with soy being protective against breast cancer in some populations, with other studies showing no association between soy and breast cancer. (See this meta-analysis for more).

Soy intake has also been raised as a possible risk factor in the development of uterine fibroids in women. Some studies find an increase in fibroids in women who consume more soy, while others do not. This recent review concluded that there is overall “no significant association.”

How much soy protein should I eat?

If your goal is lower cholesterol, several studies showed that roughly 25g of soy protein per day resulted in a 4% reduction in LDL cholesterol. While this may seem small, LDL drops by 8-10% when that soy protein replaces foods high in saturated fat, such as red and processed meat. In combination with other cholesterol-lowering foods, such as nuts, plant sterols, other legumes and soluble-fibre rich foods, you may be able to bring your LDL down as much as about 30%, as shown in the Portfolio Diet trials. 

For those not familiar with soy products, consuming 25g of soy protein may be challenging at first. You can always start with small changes where possible, such as replacing some meat in your diet with soy protein foods. For example, the following foods each contain about 10 grams of soy protein: 

  • ½ cup of tofu or edamame 
  • ¼ cup of tempeh 
  • 1 ½ cups of soy milk.

What are ways to include soy protein in your diet? salad with edamame

If you try one of these each week, you might be surprised how easy it is to get more soy on your plate!

  • Cube tofu and mix in with stir frys 
  • Replace ground beef with crumbled tempeh or soy-based ground round
  • Add edamame to salads, stir fries or rice
  • Add silken tofu to smoothies or pureed soups
  • Replace dairy milk with soy milk in coffee, oatmeal or baked goods
  • Scramble tofu in a pan and add it to pastas, wraps or eat it on its own

Recipe ideas:

The internet is packed with soy protein recipe ideas. Some of my favourite dishes to make are:

Where can I buy soy foods?

Soy foods have become very accessible and easy to find in most grocery stores. Some larger stores will even have a section dedicated to meat replacement foods and many unique soy protein products can be found there like hot dogs, ground meat, and dessert tofu. (Read the labels – some of these will have more sodium and sugar than others.) 

Soy milk will often be stored in the dairy section, while tofu is more likely to be found in the produce section of most grocery stores. TVP is a slightly more difficult product to find, but most health food stores carry it. 

Note from Cheryl: We drink soy milk here primarily and cook our porridge in it. We often add a few shelled edamame (soybeans) to pasta, salads, and wraps, and we make something with tofu about once a week. I actually find it much easier to use than messing with cooking chicken or meat! I’m excited to try some of these recipes Julianna has shared with us.

How about you? Do you incorporate soy foods into your diet?  Join us in the Sweet Spot Heart-Healthy Cooking Club to discuss and swap recipes.

Sources:

Jenkins DJ, Mirrahimi A, Srichaikul K, et al. Soy protein reduces serum cholesterol by both intrinsic and food displacement mechanisms. J Nutr. 2010;140(12):2302S-2311S.

Lovati MR, Manzoni C, Gianazza E, et al. Soy protein peptides regulate cholesterol homeostasis in Hep G2 cells. J Nutr. 2000;130(10):2543-2549.

Blanco Mejia S, Messina M, Li SS, 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. J Nutr. 2019;149(6):968-981.

Food Directorate Health Products and Food Branch HC. Summary of Health Canada’s assessment of a health claim about soy protein and cholesterol lowering. https://www.canada.ca/en/health-canada/services/food-nutrition/food-labelling/healthclaims/assessments/summary-assessment-health-claim-about-protein-cholesterollowering.html. Published 2015. 

Maskarinec G, Ju D, Morimoto Y, Franke AA, Stanczyk FZ. Soy Food Intake and Biomarkers of Breast Cancer Risk: Possible Difference in Asian Women?. Nutrition and cancer. 2017 Jan 2;69(1):146-53.

Messina M. Soybean isoflavone exposure does not have feminizing effects on men: a critical examination of the clinical evidence. Fertil Steril. 2010 May 1;93(7):2095-104. doi: 10.1016/j.fertnstert.2010.03.002. Epub 2010 Apr 8. PMID: 20378106.

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