Soy for Cardiovascular Disease and Diabetes

Some of the uses of soy include preventing hyperlipidemia, type 2 diabetes, cardiovascular disease, prostate cancer, osteoporosis, and menopausal symptoms. The medicinal parts are the soya lechithin extracted from the soya bean, the soya oil, and the soya seed. Soybeans are legumes that contain up to 50% protein; 24% carbohydrates; and 25% oil. The active constituents of soybeans are the phytoestrogens, known as isoflavones and lignans, and phytosterols. Soybeans are also rich in calcium, iron, potassium, amino acids, vitamins, and fiber. Soybeans and soy foods are the most significant dietary source of isoflavones, which are a class of organic compounds and biomolecules related to the flavonoids (2). Isoflavones are phytoestrogens (chemicals that act like estrogen in humans and animals), and have strong antioxidant activity (6).

Several studies have found positive results in incorporating soy into the diet of people with diabetes. In one study of postmenopausal women with type 2 diabetes, treatment with a soy product containing 30 grams of soy protein and 132 mg isoflavones daily for 12 weeks seemed to lower fasting insulin levels, insulin resistance, and low-density lipoprotein (LDL) cholesterol (5)

Research suggests that soy protein can lower total cholesterol up to 7% and LDL up to 27%. A review published in the Scientific Journal Advances in Therapy found that consumption of new soy products containing high, fixed levels of isoflavones, cotyledon soy fiber, and soy phospholipids significantly reduced the LDL: HDL ratio by up to 27%. The authors concluded that new soy-based supplements might play an important role in reducing cardiovascular risk (4).

Another recent study examined the use of soy isoflavones’ anti-inflammatory properties. The researchers concluded that soy isoflavones may lower the negative effects of chronic inflammation on bone and cardiovascular health. The authors noted that additional research is needed to examine the mechanisms that led to the anti-inflammatory properties (1).

Although there are many promising studies outlining the advantages of soy, some research has suggested that high isoflavone levels in the body might increase cancer risk. However, the results are inconclusive, and not all studies have found similar effects This is a concern with isolated substances from soy protein, not the intact soy protein. Some scientific data on rats also suggests that a component of soy protein, genestin, may cause breast growth in males (3).

References

1. Droke et al. (2007). Soy isoflavones avert chronic inflammation-induced bone loss and vascular disease. J Infamm (Lond); 4(1):17 [Epub ahead of print].
2. Fleming, Thomas (ed.) PDR for Herbal Medicines. Montvale (NJ): Medical Economics Company Inc.;1998.
3. Henkel (2000). Soy: Health Claims for Soy Protein, Questions About Other Components. U.S. Food and Drug Administration (online). Available from http://www.fda.gov/Fdac/features/2000/300_soy.html [Cited Sept.13, 2007].
4. Hermansen et al. (2003). Effects of soy and other natural products on LDL:HDL ratio and other lipid parameters: a literature review. Adv Ther; 20(1): 50-78.
5. Luckaczer et al. (2006). Effect of a low glycemic index diet with soy protein and phytosterols on CVD risk factors in postmenopausal women. Nutrition; 22(2): 104-13.
6. Wikipedia (2007). Isoflavone. Available online from http://en.wikipedia.org/wiki/Isoflavone [Cited Sept.13, 2007].