The Joy of Soy...Isoflavones!
The month of April is National Soy Foods Month
The soybean has been a part of Asian cuisine for thousands of years. A member of the legume family, it was first cultivated in China over 7000 years ago. Edamame, the immature soybean that dates back to 1275 in on the record for having medicinal purposes and snack food. It wasn't until 1923, with the book "The Soya Bean, by C.V. Pipe and Joseph Morse did the U.S. public realize the hard shelling bean being harvested by farmers could be eaten out of the shell. This legume is the size of a lima bean with a starchy texture and mild flavor.
Whats the Score on Soy?
Soybeans are not a vegetable, but a legume like green peas, snap peas and snow peas. Utilized in various forms, they are a standard nutrition solution for vegetarians and vegans alike. Due to their high protein content and high bioavailability, and versatility, they have produced several products- meat analogs, milk substitutes, and protein supplements. Soybeans may also be found frozen as edamame [immature soybeans], canned, or dried [mature soybeans]. Soybeans are good source of unsaturated fats, fiber, iron, zing, calcium, B vitamins and bioactive compounds called isoflavones. [1,2,3]
Photo courtesy of Marcovector
Sizing Up Soy...Nutritionally
Here are a few of the major nutrients found in 1/2 c of soy beans:
[Courtesy USDA Food Data Base]
Soy has gotten a bad rap over the years; most are misconceptions based on soyfoods containing isoflavones. The main isoflavones contained in soybeans are genistein, daidzein, and glucitein, a mouthful I know. Soy isoflavones have similar chemical makeup as estrogen; they can bind to receptors in the body, producing a weak estrogen-like effect. Most of the research findings which pop up to the surface on websites cite animal studies and not human. Here are some of the benefits of isoflavones:
A 2011 study reported daily consumption of up to 65g per day reduced LDL [bad cholesterol] 4.2-5.5%, increased HDL [good cholesterol] 3.2%. It was also shown to reduced triglycerides by 10.7%, all of which were beneficial in cardiovascular disease management. Whole soy items such as soymilk and soy nuts having the most significant effect over processed soy products.
The symptoms of menopause-hot flashes, vaginal dryness, weight gain, insomnia and body pain are a result in the fall of estrogen hormone products levels. Women are often prescribed HRT [hormone replacement therapy]. HRT is now being abandoned as it has shown to increase a woman's risk of breast cancer and cardiovascular disease. A 2010 study showed increase isoflavone intake of just 15g per day reduced symptoms by 34%
High Blood Pressure
Meta-analysis suggests soy protein may have modest effects in lowering blood pressure. Soybeans have several bio-nutrients which may be involved; fiber, isoflavones, and unsaturated fats. It may also slow clogged artery progression, although further epidemiological studies are needed to strengthen these claims. [3,4]
The anticancer effects of soy have been associated with a reduced risk of breast cancer in Asian populations for years due to long-term consumption. A recent review of 143 studies on the link between soy intake and cancer risk revealed a reduced risk of breast, lung, and stomach cancers.[1,3]
Seeking out the Benefits of Soy
To obtain the health benefits of isoflavones you need to get 30-50mg each day, but how? The number of isoflavones in soyfoods varies dramatically due to processing. Traditional soy foods [tofu, soymilk, tempeh] have more beneficial benefits—Second-generation or processed soy foods [texture vegetable protein, meat analogs].
Here are examples of popular soyfoods and the average isoflavone content:
1/2 c Edamame 40 - 75 mg
1 c Soy Milk 15 - 60 mg
115g Tofu 13 - 43 mg
110g Tempeh 41 mg
1 teaspoon Soy Sauce 0.4 - 2.2 mg
Tips for Inserting Soy Isoflavones Into Your Diet
Read ingredients list to be sure the soy foods you purchase are made with soy beans and not soy isolates
Be sure products such as cereals contain soy protein and not just added isoflavone
If you haven't tried cooking with tofu, tempeh, or edamame, well its time to grab and apron and get cookin'! Add them to salads, sandwiches and more!
Mapo Tofu Serious Eats Kenji Lopez
Marinated Peanut Tempeh Minimalist Baker Dana Shultz
Here's one of my favorite tempeh recipes- Creole-style tempeh cakes. These crispy, crunchy cakes are reminiscent of the Louisiana favorite, crab cakes with remoulade sauce. In our house, we have made them with or without dried seaweed or dulse flakes. This ingredient is optional due to the fact it can be hard to find and expensive.
1.Nogueira-de-Almeida CA, Ferraz IS, Ued F da V, Almeida ACF, Ciampo LAD. Impact of soy consumption on human health: integrative review. Brazilian Journal of Food Technology. 2020;23. doi:10.1590/1981-6723.12919
2.Dennett, MPH, RDN, CD C. Soy Antinutrients - Today’s Dietitian Magazine. www.todaysdietitian.com. Published April 2021. Accessed April 3, 2021. https://www.todaysdietitian.com/newarchives/0421p22.shtml
3.Rizzo G, Baroni L. Soy, Soy Foods and Their Role in Vegetarian Diets. Nutrients. 2018;10(1):43. doi:10.3390/nu10010043
4.Magee E, MPH, RD. The Joy of Soy. WebMD. Published 2003. Accessed April 6, 2021. https://www.webmd.com/diet/features/the-joy-of-soy#2
5.Magee MPH, RD E. SOY: Overview, Uses, Side Effects, Precautions, Interactions, Dosing and Reviews. www.webmd.com. Published 2003. Accessed April 10, 2021. https://www.webmd.com/vitamins/ai/ingredientmono-975/soy#:~:text=Kidney%20failure%3A%20Soy%20contains%20a