Researchers Dr. Pamela J. Magee from the University of Ulster and Dr. Ian Rowland from the University of Reading (United Kingdom) extensively reviewed the evidence related to soyfood consumption and breast cancer risk (2). They looked at studies focusing on prevention as well as prognosis in women who have had breast cancer….
Nearly 300 million people worldwide have asthma, a chronic inflammatory lung disease that causes wheezing, coughing, chest tightness, and shortness of breath. Asthma is caused by a combination of genetic and environmental factors. Although symptoms can be prevented by avoiding triggers such as allergens and irritants, the prevalence of asthma has increased significantly since the 1970s.
Diet is increasingly recognized as an important risk factor for asthma. Foods that are rich in antioxidants, such as fruits and vegetables might be protective against this disease since decreased consumption of these foods is associated with an increased prevalence of asthma. There is also growing interest in the effects of soyfoods. Their isoflavone content may make them a protective food as well, which could be part of the explanation for the lower rates of asthma in Japan.
Researchers from the Johns Hopkins University School of Medicine compared the isoflavone intake of 300 patients with poorly controlled asthma. They measured isoflavone intake with a questionnaire that assessed intake of soyfoods, which are the only foods that provide relevant amounts of isoflavones. Patients with the lowest isoflavone consumption had worse asthma symptoms. For example, on a test that measured the amount of air that patients could expel from their lungs, those with the lowest isoflavone intake had a reduced capacity that was equivalent to 6 to 7 years of age-related lung function decline. Also, a higher proportion of patients in the low isoflavone group reported an episode of poor asthma control. While more research is needed to confirm the relationship, it’s possible that including soyfoods in your diet could aid in asthma control.
Bime C, Wei CY, Holbrook J, Smith LJ, Wise RA. Association of dietary soy genistein intake with lung function and asthma control: a post-hoc analysis of patients enrolled in a prospective multicentre clinical trial. Primary care respiratory journal : journal of the General Practice Airways Group 2012.
While they are relatively new to western menus, tofu and the fermented soybean paste miso have been on the menu throughout Asia for centuries. Today, soyfoods are finding their way onto more American tables than ever. Packed with high quality protein, these foods also provide healthy fats and beneficial phytochemicals like isoflavones. Research suggests that isoflavones lower risk for heart disease and certain cancers.
Recently, their relationship to thyroid function has become an active area of research. The thyroid gland, found at the front of your neck, regulates metabolism and energy use through production of two thyroid hormones, T3 and T4. Synthesis of these hormones requires the mineral iodine, which attaches to tyrosine, an amino acid.
In animal studies, iodine can also attach to the soy isoflavone genistein, which has a similar chemical structure to tyrosine. That’s raised concerns that eating too much soy could lead to a reduction in active thyroid hormone. But until now, it wasn’t known whether this happens in humans. However, a new study from the Czeck Republic has allayed concerns about the effects of genistein on thyroid hormone production.
The researchers provided subjects with about 80 milligrams of isoflavones—the amount in about three servings of soyfoods—to men and women for 3 months. All of the subjects were consuming adequate amounts of iodine. At the end of the trial, thyroid hormone levels were essentially unchanged. The research did find that some iodine attached to genistein, but the amount was insignificant, representing less than 1% of the total iodine consumed. Based on these findings, the authors concluded that soyfoods have no impact on thyroid function as long as iodine intake is adequate.
Sosvorova L, Miksatkova P, Bicikova M, Kanova N, Lapcik O. The presence of monoiodinated derivates of daidzein and genistein in human urine and its effect on thyroid gland function. Food Chem Toxicol 2012.
Anyone who has ever stubbed a toe knows what inflammation feels like. The redness and swelling that follow an injury are part of a normal healthy response of the immune system, which is aimed at healing and protecting damaged tissues. As healing occurs, inflammation disappears. In some people, however, the immune system goes into overdrive, leading to production of compounds that promote low-level chronic inflammation. Chronic inflammation is thought to contribute to an increased risk of heart disease, diabetes, rheumatoid arthritis, and cancer….
The effect of soyfoods on cognition has been a topic of some controversy. Because soybeans contain isoflavones, which are phytoestrogens, some researchers have theorized that they could prevent cognitive decline that occurs with aging as estrogen is believed to do. However, the results from a Hawaiian population study published in the year 2000 linked soy consumption with greater risk of cognitive impairment.
A number of studies since then have challenged the findings from Hawaii. Recently, an expert panel organized by the North American Menopause Society recently concluded that clinical research suggests soy could favorably impact cognition in women younger than 65, with little effect in older women. The panel also emphasized the need for further research, and especially for larger and longer studies.
That call has been answered with a study by investigators from Stanford University and the University of Southern California Keck School of Medicine. In this three-year study, 350 healthy postmenopausal women received either 25 grams of soy protein or 25 grams of milk protein daily. The soy protein provided 91 mg of isoflavones, the amount found in about 3 to 4 servings of traditional soyfoods. At the end of the study, women who had consumed soy protein showed more improvement in tests of visual memory—the ability to recall pictures. Generally, however, there were no differences between the groups in terms of global cognitive function.
The study is important because of its size and duration. These findings refute concerns that soyfoods could be harmful for cognitive function although they don’t support the theory that they are protective. However, the study did show heart health benefits for younger postmenopausal women in that their progression of subclinical atherosclerosis, an indicator of stroke and heart disease risk, was markedly reduced in response to soy intake.
Henderson VW, St John JA, Hodis HN, et al. (2012) Long-term soy isoflavone supplementation and cognition in women: A randomized, controlled trial. Neurology 78:1841-8.
Hodis HN, Mack WJ, Kono N, et al. (2011) Isoflavone soy protein supplementation and atherosclerosis progression in healthy postmenopausal women: a randomized controlled trial. Stroke 42:3168-75.
Tommy Fello doesn’t just celebrate National Soyfoods Month in April. He lives it, all year long. The owner of the 125-seat Tommy’s Restaurant in the Coventry Road neighborhood of Cleveland Heights, OH, has been in business since 1972, and offers soyfoods on the menu seven days a week. It’s a broad menu, little unchanged from the restaurant’s early years, where meat items continue to coexist with vegan and vegetarian options.
Tommy Fello estimates, “About 75% of our sales are vegan or vegetarian items.” He explains that one goal of the restaurant is for people to come in as a family and have each person get something they want. “We fell into a niche where we could grow and prosper. We have our customers to thank for it.”…
Ankeny, Iowa, April 19, 2012— Today’s consumers are increasingly interested in broadening their culinary experience with more global ingredients and healthful choices. That goes for school kids, too, who are acquiring more educated palates thanks to school food service programs. Beginning April 24, students in grades K-12 in the Ankeny Community School District will be introduced to Edamame (fresh green soybeans) as a vegetable choice on their school menus. Edamame, steamed in the pod or shelled, are a traditional Japanese snack. The recipe that will be offered to students in the Ankeny Schools is Edamame Succotash, a colorful side dish featuring corn and bell peppers….