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Can Soy Lower Your Blood Pressure?

By +Carolyn Richardson on Apr 17, 2012 10:00 AM in Healthy Eating

According to the Centers for Disease Control and Prevention, one in three adults in the U.S. has high blood pressure. That’s an estimated 68 million people, and another 30% are pre-hypertensive, that is, their blood pressure numbers are higher than the normal 120 over 80. Although 70% of those with high blood pressure take medications to treat the condition, dietary changes could also help lower blood pressure. In addition to a low-sodium diet with lots of potassium from fruits, vegetables, and legumes, and other lean proteins, new research presented at the American College of Cardiology's 61st Annual Scientific Session reveals a compound found in soy may significantly help reduce blood pressure. 

The Study

A study called the Coronary Artery Risk Development in Young Adults was analyzed for the development of cardiovascular disease in its 5,115 subjects between the ages of 18-30. The 20th year of the study was the first that collected extensive dietary information. Researchers evaluated the relation between daily isoflavone intake and systolic blood pressure. After controlling for age, sex, BMI, smoking, alcohol, physical activity, and total caloric intake, a significant relationship was found between daily isoflavone intake(more than 2.5 mg) and lower systolic blood pressure. A 10 mmHg dop in systolic blood pressure was observed in pre-hypertensive participants. Lead investigator, Safiya Richardson, had this to say of their findings, “Any dietary or lifestyle modification people can easily make that doesn't require a daily medication is exciting, especially considering recent figures estimating that only about a third of American hypertensives have their blood pressure under control.” It may be worth incorporating more foods with isoflavones in your diet.

What are Isoflavones?

Isoflavones are a subclass of flavonoids, which may reduce the risk of chronic diseases. There are three major isoflavones found in soybeans: daidzin, genistin, and glycitin. According to a report in Immunologic Research, they exhibit chemopreventive and anti-imflammatory properties. They are also known as phytoestrogens for their ability to bind to estrogen receptors. They work by increasing the production of enzymes that create nitric oxide, which helps to widen blood vessels, resulting in a reduction of the pressure created by blood against the vessel walls. The concentration of isoflavones varies widely and depends on the processing techniques used during production. 

Isoflavone Content in Soy Foods

While small amounts are found in other food items, isoflavones are found in abundance in soybeans and soy products. Stick to minimally processed sources of soy to get the highest isoflavone content. The USDA’s database for the isoflavone content lists over 550 foods by mg per 100 grams. The highest content of isoflavones in the list is found in raw soybeans. Additional soy products that will help you reach the 2.5 mg per day that acted as a benchmark for the aforementioned study includes a soy flour, soy milk, tempeh, textured tofu, or soy yogurt. Supplements may not have the same effect, A study of the quality of commercially available soy supplements suggests that less than 25% of products contain within 90% of labeled isoflavone content.  

Natural Ways to Lower Blood Pressure

In addition to eating a healthy diet, regular exercise, reducing stress, and not smoking will help lower your blood pressure. You might also find losing pounds will help, a loss of just 10 pounds could reduce your blood pressure. Limit your alcohol intake as well. While small amounts of alcohol have been shown to reduce blood pressure, more than one drink a day for women and two for men could spell trouble. Caffeine intake should also be kept in check. Lastly, monitor your blood pressure regularly to be sure yours is under control. Work with your physician to come up with a plan to get or keep your blood pressure in the normal range.

Your thoughts…

What soy products do you eat or are interested in trying but haven’t?

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i LOVE soy milk w/ all the flavors BUT i found out i am allergic to it!!  couldn't figure out why my lips were red and swollen.  it was the soy.  plus now no matter what i eat - mainly acidic foods - instead of itching :), it shows up on my lips.  quite annoying.  soy and i just don't get along.  didn't know it helped BP. 

Soy Isoflavone lowers BP.   I have been thinking of incorporating more tofu into my diet.   Looks like a glass of soy milk a day should also do the trick.

I want to offer a word of caution regarding blanket praise for foods made from soy.  Tofu is great.  Other soy foods should be consumed sparingly.  Two months ago, after the Nagatoro fire festival, a friend's mother showed me how she makes miso every year to serve with breakfast and dinner for her family, and I learned something about Japan's traditional foods: to this day they are preserved with excessive amounts of sodium.  1Tbsp of soy sauce contains almost 40% of your daily sodium intake.  1 bowl of miso soup contains almost 50%.  Back in the U.S. I remember having both at the same meal when going to Japanese restaurants.  Each of these food items is great, but after checking the nutrition info, I now spread them out as additions to different meals throughout the week.  For those of you living where such a thing is abundant, also try low-sodium soy sauce on your tofu or with your sushi, but use it sparingly too, as 1Tbsp is still 25% of your suggested sodium intake for the day.

I've talked to my students about this.  They didn't know that every food in the cafeteria exceeds the recommended sodium amount, containing 300% or more.  One said he didn't know soy sauce was even an ingredient in the egg-topped rice dishes.

@ bioluminescent - thank you for educating others w/ regard to sodium content in food!  i stopped using soy sauce years ago and later hoisin sauce along w/ many other sauces/foods!  my salt shaker has mold on it.  :)  there are so many other ways to season food.

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