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Celebrate Soyfoods Month in April by Getting the Facts and the Flavor
Learn the facts about soyfoods and your health during Soyfoods Month in April. “Myth-information” may be preventing you from getting the news—and the benefits—associated with eating soyfoods.
Myth #1: Anybody who has had breast cancer should avoid traditional soyfoods such as tofu and soymilk.
Actuality: In fact, new research studies offer evidence that breast cancer patients who consume soyfoods after their diagnosis actually fare better than patients who do not consume soyfoods. The American Cancer Society says that breast cancer patients can safely consume up to three servings of traditional soyfoods per day.
Myth #2: People in Japan and other Asian countries consume only small amounts of soyfoods and use them primarily as condiments.
Actuality: The results from large surveys—often involving tens of thousands of people—indicate that on average, Japanese adults and older adults in Shanghai consume 1½ servings of soyfoods per day. But those who consume a bit more tend to have better health—so shoot for about two servings per day.
Myth #3: Soyfoods cause mineral deficiencies or imbalances.
Actuality: This myth probably got started because soyfoods contain phytate and another plant chemical, oxalate (also found in spinach), which inhibit calcium absorption. However, the evidence unequivocally shows that calcium absorption from soymilk and cow’s milk are similar. And new research indicates iron absorption from soy is excellent. Nor surprisingly, there is no evidence that soyfoods cause mineral deficiencies or imbalances.
Myth #4: Soyfoods contain estrogen and men who eat them may experience feminization or even impair their fertility.
Actuality: Soyfoods do not contain estrogen, and the clinical evidence indicates that soyfoods do not feminize men—soy doesn’t lower testosterone levels or lower sperm concentration. The myth may have its roots in the fact that naturally present isoflavones in soyfoods are commonly referred to as plant estrogens, or phytoestrogens. The good news is that soyfoods may offer several health benefits for men. For example, evidence suggests soyfoods are protective against prostate cancer.
Myth #5: Soyfoods should be avoided because they are harmful to the thyroid.
Actuality: More than 20 clinical studies have shown that neither eating soyfoods nor using soybean extracts cause thyroid problems. This myth is based on the results from studies in which the effects of isolated soybean components (not soyfoods) on individual thyroid cells in test tubes have been evaluated.
Irritable bowel syndrome (IBS) is a common disorder that affects the large intestine. IBS affects about one of out every 10 persons in the world although rates vary from region to region. Some research suggests that about 14% of Americans have IBS although the vast majority are undiagnosed.
Signs and symptoms of IBS include cramping, abdominal pain, bloating, gas, and diarrhea or constipation, or both. Some people can control their symptoms by managing diet, lifestyle and stress.
The role of food allergy or intolerance in IBS isn’t fully understood but science-based evidence indicates that the Low FODMAP Diet can help manage the gastrointestinal symptoms associated with IBS. And soyfoods can be part of the Low FODMAP Diet.
FODMAP is an acronym that stands for: Fermentable – meaning they are broken down (fermented) by bacteria in the large bowel, Oligosaccharides – “oligo” means “few” and “saccharide” means sugar. These molecules made up of individual sugars joined together in a chain. Disaccharides – “di” means two. This is a double sugar molecule. Monosaccharides – “mono” means single. This is a single-sugar molecule. And Polyols – these are sugar alcohols (however don’t lead to intoxication!).
When consumed in foods and/or drinks, FODMAPs can be poorly absorbed in the small intestine and pass through to the large intestine, where two major events happen:
- The FODMAPs are readily fermented by bacteria in the large bowel, contributing to the production of gas.
- The FODMAPs are also highly osmotic, meaning that they attract water into the large bowel, which can alter how quickly the bowels move.
These two processes can then trigger symptoms including excess wind, abdominal bloating and distension, abdominal pain, constipation or diarrhea, or a combination of both.
Many soyfoods, although not all, can be part of the Low FODMAP Diet. If you have IBS, good choices are firm tofu (as opposed to silken tofu), soymilk made using isolated soy protein, soy cheese and tempeh. Tempeh is made by fermenting whole soybeans. It has an excellent texture and is highly nutritious and may help to promote the growth of friendly bacteria, which could lead to an assortment of health benefits.
Should You Sip Soymilk to Improve Your Skin Health?
Ankeny, Iowa, January 9, 2018— A new clinical study from Japan draws attention to one of the lesser-known potential health effects of consuming soyfoods: the benefits of soy for skin health. Results of this study are consistent with previously published research. For this latest study, postmenopausal women consumed one cup of soymilk a day for eight weeks. The women filled out facial skin questionnaires three times—at the beginning of the study, eight weeks after consuming the soymilk, and four weeks after they were no longer consuming soy—answering questions about the condition of their facial skin. Questions covered dryness, elasticity, moisture, coarseness, pigmentation, and overall satisfaction.
At the beginning and end of the study, samples were also taken of skin underneath the forearm from each study participant. After eight weeks of drinking soymilk, the results showed that for all six questions, the condition of the skin significantly improved. Furthermore, the skin samples taken from underneath the forearm also were consistent with the improvements reported by the women themselves. With possible skin scores ranging from a low of 2 to a high of 10, at the beginning of the study, the skin score was approximately 4, whereas at the study’s conclusion, it was approximately 8. After four weeks of abstaining from soymilk, questionnaires indicated that most of the benefits were lost. That is, the condition of the skin approached the condition at the beginning of the study.
An important strength of this study is that the changes in skin health were determined both subjectively (questionnaires) and objectively (skin biopsies). Also noteworthy is that just one serving of soy per day led to such pronounced benefits.
In addition to offering potential benefits for skin health, eating soyfoods may also reduce the risk of developing heart disease and some forms of cancer, including breast cancer. One serving of soy offers approximately 7 to 15 grams of high-quality protein but not the large amount of saturated fat that typically comes with animal sources of protein.
For more research about the health benefits of soyfoods and recipe ideas for incorporating more soyfoods into your diet, visit the Soyfoods Council website at www.thesoyfoodscouncil.com. You’ll also find nutrition information and cooking tips.
About the Soyfoods Council: The Soyfoods Council is a non-profit organization, created and funded by Iowa soybean farmers, providing a complete resource to increase awareness of soyfoods, educate and inform media, healthcare professionals, consumers and the retail and foodservice market about the many benefits of soyfoods. Iowa is the country’s number one grower of soybeans and is the Soyfoods Capital of the world.
About the Role of Soyfoods in a Healthful Diet: Soyfoods have played an important role in Asian cuisines for centuries. In recent years they have become popular in Western countries because of their nutrition and health properties. Soyfoods are excellent sources of high-quality protein and provide a healthy mix of polyunsaturated fat. In addition, independent of their nutrient content, there is very intriguing evidence indicating soyfoods reduce risk of several chronic diseases including coronary heart disease, osteoporosis and certain forms of cancer. All individuals are well advised to eat a couple of servings of soyfoods every day.
Ever since the US National Cancer Institute first expressed interest 30 years ago in exploring the role of soy in cancer prevention, this topic has been rigorously investigated. Much of the focus has been specifically on cancer of the breast. That is understandable given that compared to the West, breast cancer mortality rates in soyfood-consuming countries are extremely low. But the rates of prostate cancer in soyfood-consuming countries are just as low. And new research suggests soyfoods could very well be one of the reasons.
To better understand the relationship between soy and prostate cancer a team of researchers from the University of Illinois analyzed 30 observational or epidemiologic studies. Observational studies examine how exposure to a particular factor, such as soy, among a given population, affects risk of developing a particular outcome, such as prostate cancer. When all studies were included in the analysis, those men consuming the most soy were 29% less likely to develop prostate cancer in comparison to men infrequently consuming soy. The results were similar when looking at either Asian or North American studies. However, whereas the consumption of unfermented soyfoods, such as tofu and soymilk, was very protective, no such protective effects were found for fermented soyfoods such as miso. Exactly why fermented foods weren’t protective isn’t clear.
Why is soy protective against prostate cancer? The answer appears to be because soyfoods are such rich sources of isoflavones. Isoflavones are naturally-occurring compounds found in very high amounts in soybeans. The results showed that among the Asian studies, the intake of genistein and daidzein, the two primary isoflavones in soybeans, was inversely related to risk. That is, the more isoflavones consumed, the less likely men were to develop prostate cancer.
In Asian studies, men in the highest intake group, consume about two servings of soyfoods per day. That amount is easy to incorporate into the diet given that a serving is one cup of soymilk, one-half cup of tofu or an ounce of soynuts. It isn’t clear why the isoflavones in soy are protective against prostate cancer, but it isn’t because they lower testosterone levels. Studies show quite clearly that consuming even very high amounts of isoflavone-rich soy doesn’t lower blood testosterone.
Applegate CC, Rowles JL, Ranard KM et al. (2018) Soy consumption and the risk of prostate cancer: An updated systematic review and meta-analysis. Nutrients 10.
Do soyfoods help or hurt breast cancer patients? That question has been hotly debated over the past 20 years. Although older animal studies raised some initial concerns, extensive human research not only suggests soyfoods are safe for women with breast cancer but potentially beneficial. Population studies show that consuming 1-2 servings of soyfoods per day after a diagnosis of breast cancer reduces recurrence and improves survival. Now, research published in Breast Cancer Research and Treatment that was conducted by investigators from several US universities suggests that breast cancer patients who consume soyfoods are less likely to suffer from menopausal symptoms and fatigue.
Women involved in this study were recruited from two California cancer registries. All women had completed primary treatment for breast cancer. In total, there were 192 Chinese-Americans and 173 Non-Hispanic Whites. Information on dietary intake and symptoms was obtained through a 1-hour-long survey administered via telephone. The dietary questionnaire included four questions specifically about soyfoods. Women were divided into three soyfood intake groups: none, low and high intake.
In addition to obtaining information on dietary intake, all women in the study were asked if they experienced any of 34 possible treatment-related symptoms and its severity within the past 12 months prior to the interview date. Symptoms were assessed using a five-level scale, from “not at all” to “very much.”
When all women were included in the analysis, the findings showed that high-soy-consuming patients were less than half as likely to report having menopausal symptoms in comparison to women who didn’t consume soyfoods. Symptoms included hot flashes or night/cold sweats, vaginal dryness/pain with intercourse and vaginal discharge. Similarly, high-soy-consumers were also about half as likely to suffer from fatigue.
The experimental design of this study doesn’t allow for definitive conclusions about the benefits of soyfoods to be made. However, given that other research shows that soyfoods may improve the prognosis of breast cancer patients and that soyfoods are excellent sources of protein and healthy fat, adding soyfoods to the diet makes sense for women with breast cancer. The results of the current study suggest that about two servings per day are sufficient to derive benefit. One serving is a cup of soymilk, one-half cup of tofu or edamame, or one ounce of soynuts.