ABSTRACT

1. ABSTRACT Whether you’re a vegan, vegetarian, or omnivore, soy is a common ingredient in the average person’s daily diet. There have been various scientific studies conducted to evaluate different health issues related to soy: lowering blood pressure, decreasing women’s hot flashes during menopause, reducing blood LDL cholesterol, preventing/affecting several types of cancers, as well as many other issues. I evaluated several scientific documents stating the pros and cons of soy food consumption. This is important because soy plays a significant role in the average person’s daily intake. There are various benefits and disadvantages of soy to consider, but based on my review, I would like to conclude that a daily intake of at least 25 g of soy protein would be beneficial for overall health. This intake level can be reached by having 4 servings of soy milk, or 1-2 servings of tofu. INTRODUCTION Soy is a common ingredient in the average person’s daily diet. Soy has been used in Asian for over 5,000 years, and various health benefits have been scientifically proven based on the culture’s consumption of soy such as lower rates of cancers, osteoporosis, and menopausal issues. There have been claims that soy phytochemicals can contribute to heart protection, however, soy is high in polyunsaturated fatty acid, fibers, minerals, vitamins, proteins, and is low in saturated fat, so it is very likely that heart protection could be caused by these factors instead of soy phytochemicals (1). The same is true for low cancer rates, osteoporosis, and menopausal issues. The studies I have read all state that soy can have many nutritional benefits, but there have been speculations as to what those benefits are and to what extent. What information should people trust about soy? I hypothesize that soy consumption can be beneficial to one’s overall health if eaten in a well-balanced diet. RESULTS Phytoestrogens: Soy contains phytoestrogens, which are plant-estrogens related to the flavonoid family (1). Phytoestrogens can be very beneficial to one’s health. Some studies suggest that phytoestrogens can help the brain after a brain injury; however, further studies are necessary to make a permanent claim. Studies also suggest that phytoestrogens may reduce the risk of estrogen-type cancers such as breast, colon, prostate, and ovarian cancer, however, further study is needed (1). Cholesterol: Soy contains no cholesterol. Because of this, the FDA states that 25 grams of soy proteins in a daily intake may lower heart disease risks (5). A large serving of soy protein could lower LDL cholesterol when the soy protein is consumed instead of dairy or animal protein (2). Although it takes much less dairy and animal protein to achieve the daily protein intake, soy is better for overall cholesterol. Omega-3 Fatty Acids: Soy contains omega-3 fatty acids. Because of this, soy contains alpha-linolenic acid, which studies claim may be nutritionally beneficial. However, eicosapentaenoic acid and docosahexaenoic acid, which are found in fish oil, are much more nutritionally beneficial; EPA and DHA can help prevent future blood clots, but there is no scientific evidence that proves alpha-linolenic acid to prevent future blood clots as well (5). However, omega-3s from soy do reduce inflammation, which is important because the modern diet is seriously deficient in omega-3s (8). Isoflavones: There are 12 total soybean isoflavones, but the primary ones are daidzin and genistein (3). Studies have suggested that isoflavones can prevent cancers, decrease cardiovascular disease risks, and contribute to bone strengthening. Claims have been made that isoflavones can possibly prevent cancers (specifically breast, colon, and prostate cancer), but there is conflicting data and not enough information to validate this claim. Phytic Acid: Soybeans are high in phytic acid, which has several benefits: it can be an antioxidant and a chelating agent and can reduce cancer risks, reduce diabetes risks, and reduce inflammation. However, phytic acid can sometimes reduce mineral levels because of the chelating agent, which is a disadvantage, especially for those who use soy as a main source of protein such as vegans and vegetarians (5). Usage and Production: Soybeans provide more protein per acre than dairy cows, various types of vegetables and crops, and animals used for consumption (4). Textured soy protein has no cholesterol and less saturated fat than meat, which is better for overall health (4). Soy Usage in Asia: Asians have lower rates of osteoporosis, cancers (breast, colon, prostate), and heart disease than Westerners do. This is not a racial or genetic issue; when Asians take on Western diets, these issues arise for them as well (1). Because soy is such a prominent component in Asian food, these health benefits are often times link to soy products. Asian women who live in Asia have far fewer menopausal symptoms, although there isn’t direct information verifying that phytoestrogens specifically reduce these symptoms such as hot flashes (1). Other studies have reviewed the CVD and diet of Asian countries and linked soy products to blood cholesterol levels (2). These studies are difficult to conduct because of the numerous differences in culture and lifestyle between Asian and Western societies. METHOD In order to break down the wide-spread information about soy products, I read different types of scientific literature: sections of text books, scientific journals, and information from scientific committees. When I put all of my notes together, the information started to make a little more sense. What I really wanted to know was whether or not soy was ultimately good for one’s health, and the information I found seemed to give me a good answer. From the studies, I was able to find the health benefits that soy can possibly contribute. The Potential Benefits of Soy ConsumptionHannah Ice-CookBiochemistry Program, Beloit College, Beloit, WI Figure 1: Diagram of Isoflavone In soybeans, the main isoflavones are genistein and daidzin. Genistein 5-OH, 7-OH, 4’-OH. Daidzen 7-OH, 4’-OH CONCLUSION In my research, I have looked at many studies suggesting the potential benefits of soy consumption. It is important to remember that many of the studies only suggest these concepts, and that further research is necessary to draw a clear conclusion about some of these issues, especially those discussing and linking soy products to preventing or causing various types of cancers. However, many of these studies would agree with my hypothesis; as long as soy is consumed in a balanced diet and eaten in normal amounts, soy can provide many nutritional benefits: it has no cholesterol, is low in fat, and is a good source of protein. It is important that we monitor whether or not soy can prevent breast, colon, prostate, and other estrogen related cancers, as well as other suggested nutritional benefits to soy. REFERENCES 1. Frances Sizer, Ellie Whitney. "Nutrition Concepts and Controversies." Frances Sizer, Ellie Whitney. Nutrition Concepts and Controversies. Belmont: Wadsworth, 2008, 2006. 62-63, 215, 416. 2. Frank M. Sacks, Alice Lichtenstein, Linda Van Horn, William Harris, Penny Kris-Etherton, Mary Winston. "Circulation." January 17 2006. American Heart Association. 4 October 2010 <http://circ.ahajournals.org/cgi/content/full/113/7/1034#SEC5>. 3. Mark J. Messina, Charles L. Loprinzi. "Soy for Breast Cancer Survivors: A Critical Review of the Literature." November 2001. LabDiet. 4 October 2010 <http://jn.nutrition.org/cgi/content/full/131/11/3095S>. 4. "Soy Benefits." n.d. National Soybean Research Laboratory. 25 October 2010 <http://www.nsrl.uiuc.edu/soy_benefits.html>. 5. Wikipedia. 24 October 2010. 4 October 2010 http://en.wikipedia.org/wiki/Soybeans. 6. My Health Driver. 2008. 27 October 2010 <http://myhealthdriver.com/product/enerflex-plus/fulfilling-needs.html>. 7. Indian-Commodity. 2010. 4 October 2010 <http://www.indian-commodity.com/commodities/Soybean-Likely-To-Fall-In-Brazil-Output.aspx>. 8. Paolo Fanti, Reto Asmis, Tammy J. Stephenson, B. Peter Sawaya, Adrian A. Franke. "Nephrology Dialysis Transplantation." 15 March 2006. Oxford Journals. 4 11 2010 <http://ndt.oxfordjournals.org/content/21/8/2239.full>.