Today’s soy featured blog post is written by Lauren Landgrebe, Food Scientist & Sodexo Dietetic Intern.
Soy, oh Boy!
Soy intake was previously thought to cause cancer, yet more recently studies are finding soy ingestion can have a benefit regarding certain types of cancers.1 A lot of the confusion between soy and cancer lies in the naturally occurring phytochemical isoflavones: genistein and daidzein. These isoflavones are considered phytoestrogens, which are known as plant sourced estrogen and can mimic the effects of the hormone estrogen. 2
Studies have found that a long-term, increased exposure to estrogen shows an increased risk of cancer such as breast, uterine, and prostate, so the alarm and confusion is understandable. However, long-term exposure to phytoestrogens in the presence of increased estrogen may help combat this risk by blocking the hormone receptors found in the body and thus protecting from developing cancer.
The difference between estrogen and phytoestrogens is the plant sources weakly mimic the real hormone, and incorporating soy products into a balanced diet should not be cause for concern in healthy and cancer patients.2
The American Institute of Cancer Research (AICR) and Dana Farber Cancer Institute suggest 1-2 servings per day of un-processed soy products are safe for not only the general public but cancer patients as well.3, 4, 5
There are many benefits from the ingestion of soy due to its many phytochemicals that are thought to protect the body with cell growth, cholesterol reduction as well as anti-cancer properties.3 Soy is also an excellent source of calcium, fiber, omega-3, B vitamins, and protein. The bean contains all 9 essential amino acids making it an excellent complete protein source for vegetarians and vegans.3
Soy can be consumed via several different forms including miso, edamame beans, tofu, soy milk, and tempeh. Whole unprocessed soy has benefits, not only in cancer patients but the general public as well.3, 4
The important message is that a moderate amount of soy can be beneficial.
An intake of processed foods including soy products are not beneficial to human health. Similar to many other ingredients, the extraction method changes the nature of the soy and can cause unknown harm. Ingredients derived from natural sources can be extracted using chemicals which can cause harm in long-term consumption.6 Dana Farber suggest to avoid soy protein isolates due to the possible concentrated amounts of isoflavones present and having unknown effects on human health.4 An excessive intake of any one protein source is something to be cautious with, so following the AICR’s suggestion of 1-2 servings a day of soy along with a combined healthy balanced diet rich in a variety of plant sources would be a good guide to follow.3
References/Websites:1) Messina M. Impact of Soy Foods on the Development of Breast Cancer and the Prognosis of Breast Cancer Patients. Forschende Komplementärmedizin / Research in Complementary Medicine. 2016;23(2):75-80. doi:10.1159/000444735.
2) National Institutes of Health. National Institutes of Health. https://www.niehs.nih.gov/health/topics/agents/endocrine/. Accessed February 4, 2017.
3) AICR's Foods That Fight Cancer™. American Institute for Cancer Research. http://www.aicr.org/foods-that-fight-cancer/soy.html. Accessed February 4, 2017.
4) Estrogen-Sensitive Tumors and Nutrition - Dana-Farber Cancer Institute, Boston, MA. http://www.dana-farber.org/Health-Library/Estrogen-Sensitive-Tumors-and-Nutrition.aspx. Accessed February 4, 2017.
5) Die MDV, Bone KM, Williams SG, Pirotta MV. Soy and soy isoflavones in prostate cancer: a systematic review and meta-analysis of randomized controlled trials. BJU International. 2014;113(5b). doi:10.1111/bju.12435.
6) Manuhara GJ, Praseptiangga D, Riyanto RA. Extraction and Characterization of Refined K-carrageenan of Red Algae [Kappaphycus Alvarezii (Doty ex P.C. Silva, 1996)] Originated from Karimun Jawa Islands. Aquatic Procedia. 2016;7:106-111. doi:10.1016/j.aqpro.2016.07.014.