Soy & Health Research

Many soyfoods are good choices for those with IBS

March 15, 2018 By JL Fields

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.

Source

Population studies show soy intake is protective against prostate cancer

January 15, 2018 By JL Fields

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.

Soyfoods benefit breast cancer patients by reducing menopausal symptoms and fatigue

December 13, 2017 By JL Fields

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.

Soy isoflavones linked with protection against breast cancer

October 23, 2017 By admin

Much of the early excitement about the potential role of soyfoods in reducing risk of breast cancer was based on the knowledge that soyfood-consuming countries such as China and Japan have had historically very low rates of this disease. However, as these countries have experienced Westernization of their cultures, including a change in diet, breast cancer rates have dramatically increased.

For example, since 2003, breast cancer has become the most common type of cancer among women in Taiwan and the fourth leading cause of female cancer deaths. In fact, the incidence of breast cancer has doubled within just two decades. The good news is that new research from Taiwan indicates that greater soyfood consumption could help stem this unwelcomed tide.

This suggestion comes from a study of 233 breast cancer patients and 236 women similar in age but without breast cancer. To determine dietary intake, each study participant filled out a questionnaire that included questions about the intake of 28 frequently-consumed food items. The women also indicated whether they were a vegetarian.

From the questionnaire, the researchers were able to identify 5 different dietary patterns: 1) high meat 2) high processed meat 3) high fruits and vegetables and soyfoods 4) high consumption of desserts and sugar and 5) high consumption of fermented food. The results indicated that the high meat and high processed meat dietary patterns were associated with an increased breast cancer risk. Conversely, a vegetarian diet was protective against breast cancer.

To determine the impact of soyfood intake on risk of breast cancer the investigators estimated the amount of isoflavones the women in this study consumed. Isoflavones, which are purported to be anti-cancer agents, are found in uniquely rich amounts in soyfoods. Women with breast cancer consumed significantly lower amounts of isoflavones than women without breast cancer. And most importantly, women who consumed more than 22 milligrams of isoflavones per day were 63% less likely to develop breast cancer in comparison to women who consumed fewer than 22 milligrams daily.

Twenty-two milligrams is the amount of isoflavones found in one serving of a traditional soyfood, such as one cup of soymilk or ½ cup of tofu or edamame. These results from Taiwan strongly indicate that consuming a more plant-based diet and as little as one serving of soy daily is protective against breast cancer.

Linoleic acid protective against diabetes

October 17, 2017 By admin

The primary fatty acid in soybean oil is protective against diabetes

Linoleic acid is an essential omega-6 polyunsaturated fat. It is the primary omega-6 fat in the diet and the primary fatty acid in soybeans. New evidence indicates consuming linoleic acid is protective against diabetes

Health authorities recognize that linoleic acid lowers blood cholesterol levels and as a result, risk of coronary heart disease. The cholesterol-lowering effect of linoleic acid is acknowledged by the American Heart Association and the 2015-2020 Dietary Guidelines. Furthermore, soybean oil was recently awarded a health claim for coronary heart disease based on its ability to lower blood cholesterol levels.

Less is known about the role that linoleic acid may have in protecting against other chronic diseases such as diabetes. The incidence of diabetes has increased dramatically over the past 20 years in large part because of the skyrocketing rates of obesity. Most people with diabetes, about 90%, over overweight.

To gain insight into the relationship between linoleic acid and diabetes an international team of researchers conducted a comprehensive statistical analysis of 20 different population studies from ten countries.¹ This analysis involved nearly 40,000 participants. All of the participants were free of diabetes at enrollment. During the period the participants were followed, 4,347 individuals developed diabetes.

When the investigators looked at levels of linoleic acid in the body, such as in adipose tissue, it was found that those with the highest levels were 35% less likely to develop diabetes. These findings strongly suggest consuming linoleic acid will protect against this disease.

This new analysis is especially noteworthy not only because of its size but because the researchers relied upon levels of linoleic acid in the body as the primary metric, rather than the amount of linoleic acid the study participants reported eating. Accurately assessing dietary intake is very difficult.

This new research indicates that dietary sources of linoleic acid, such as soybean oil, will not only lower risk of coronary heart disease but will protect against diabetes as well.

Wu JHY, Marklund M, Imamura F, et al. Omega-6 fatty acid biomarkers and incident type 2 diabetes: pooled analysis of individual-level data for 39 740 adults from 20 prospective cohort studies. Lancet Diabetes Endocrinology. 2017.

Soy protein may lower blood pressure

October 11, 2017 By admin

“If you’re worried about high blood pressure, a new systematic review of scientific evidence has good news: Changing your diet really can make a difference,” according to a recent article in the Tufts Health & Nutrition Letter.

Soy protein is best known for its ability to lower elevated blood levels of cholesterol. In recognition of this ability in 1999, the FDA awarded soyfoods a health claim for reducing risk of coronary heart disease. Less well known is that soy protein may also lower blood pressure. Blood pressure is a major risk factor for coronary heart disease.

More than a decade ago a commentary in the Canadian Medical Association Journal suggested soy protein could be the next “anti-hypertensive” agent. This commentary was written in response to a clinical study that found soy protein lowered systolic blood pressure (top number) by more than 4 points and diastolic blood pressure by almost 3 points. Since that study was published several statistical analyses of the clinical studies have been published all of which confirm that indeed soy protein lowers blood pressure. The largest analysis included 27 clinical trials. In theory, over time the reduction in blood pressure in response to soy protein could reduce of stroke, heart attack and overall mortality by 4 to 10%.

Of course, although to dramatically lower blood pressure by making dietary changes requires adopting a comprehensive approach but the evidence is clear that soy protein should be part of that overall mix. In addition to soy protein, that mix should include lots of fruits and vegetables and foods that are low in sodium. Fortunately, soy protein is easy to incorporate into the diet. Foods such as tofu, soynuts, edamame and soy burgers are all rich sources of soy protein.

Soy protein promotes strength in postmenopausal women

July 21, 2017 By admin

Maintaining strength is an important key to preventing age-related functional decline. Research out of Brazil shows one way to do that is to engage in a resistance exercise program and to supplement the diet with soy protein.

For this study, 32 postmenopausal women began resistance exercise training 2-3 times per week. Half of the women were asked to consume a cup of milk after exercise and the other half were asked to consume milk but to which had been added 25 grams of soy protein. At the 16 week study period, both groups of women experienced increases in muscle mass and strength. However, women who consumed soy protein had significantly greater gains in strength for bench press and knee extension and for all 8 exercises combined.

The amount of soy protein added to the diet – 25 grams per day – is notable because research suggests that at this intake level, soy protein will lower both cholesterol and blood pressure. These benefits make adding soyfoods and soy protein to the diet an especially good choice for women wanting to become stronger.

Typically, soyfoods provide anywhere from 6 to 15 grams of protein per serving. So it is relatively easy to add 25 grams of soy protein to the diet. For those not wanting to eat soyfoods, two scoops of soy powder (isolated soy protein) provide about 25 grams of protein.