Do Soy Products Help Lower Blood Pressure?

Soy products are a regularly discussed and widely debated subject. If you haven't already tried them, you may be wondering if they really are beneficial. So, what exactly are soy products?

Soy is a complete source of protein containing essential amino acids. They also contain high levels of polyunsaturated fats, fibre, vitamins, and minerals, antioxidants, and low levels of saturated fat.

In the mid 1990s, the cholesterol lowering effect of soy and its role in heart disease was widely believed to be true by health conscious individuals. However, future studies failed to show a particularly strong link to its cholesterol lowering effect.

Based on recent studies, the American Heart Association (AHA) no longer recommends eating soy to lower cholesterol. However, since soy products contain many other beneficial components, the AHA still consider them a healthy replacement for meats and other foods high in fat.

Evidence linking soy to blood pressure lowering

According to a study published in the journal, Archives of Internal Medicine, the effect of soy on blood pressure is comparable to that of blood pressure lowering medication.

Researchers looked at 60 healthy post-menopausal women between the ages of 48 and 65 years, over a period of 16 weeks. The two diets were:

1. Therapeutic Lifestyle Changes (TLC) diet, consisting of 30% calories from fat (7% or less from saturated fat), 15% from protein, and 55% from carbohydrates; 1,200 milligrams of calcium per day; two meals of fatty fish per week; and less than 200 milligrams of cholesterol per day.
2. A diet having the same calorie, fat and protein content, but replacing 25 grams of protein with one-half cup of unsalted soy nuts.

Study results

Compared with the TLC diet alone, the TLC diet plus soy protein significantly reduced systolic (10%) and diastolic (7%) blood pressure in women with high blood pressure; and in women with normal blood pressure the reductions were 5% and 3% respectively.

Another beneficial pattern noted was that in women with high blood pressure, the soy diet also decreased levels of LDL (bad) cholesterol by an average of 11%, and levels of apoliprotein B (particle that carries LDL cholesterol) by an average of 8%. Cholesterol levels remained the same in women with normal blood pressure.

The authors concluded that, "Dietary soy may be a practical, safe and inexpensive modality to reduce blood pressure. If the findings are repeated in a larger group they may have important implications for reducing cardiovascular risk in postmenopausal women on a population basis."

What we see from this study is that soy can be a healthy addition to a balanced diet. Whilst it may not lower cholesterol to the extent we had originally thought, it does appear to have a beneficial effect on blood pressure, and it certainly does not harm our health!

Available soy products include:

• Calcium fortified soy milk
• Edamame
• Soy beans
• Soy cheese
• Soy miso
• Soy nuts
• Soy yogurt
• Tempeh
• Textured vegetable protein (TVP)
• Tofu
• Miso