News Posted in December

New Breast Cancer Research Supports Soy, December 2009

A recent study published in the Journal of the American Medical Association (JAMA) shows evidence that a diet containing several daily servings of soy may have special benefits for breast cancer patients and survivors. Researchers concluded that a diet with moderate soy intake can be associated with a 29% decrease in mortality, and a 32% decrease in the risk of recurrence among those diagnosed with breast cancer.

This is the largest population-based study ever to examine soy intake and breast cancer outcomes. Scientists followed the diet and health status of more than 5,000 breast cancer patients over the course of several years, with ongoing research still underway.

The new research has been acknowledged as a significant soy science development by JAMA and experts from the National Cancer Institute and the Cancer Research Center. The findings offer encouraging confirmation that minimally processed foods made from whole soybeans are a safe choice for women with a history of breast cancer; a position long supported by the American Cancer Society.

Even more important are the findings suggesting that soy consumption may actually provide specific health benefits relevant to breast cancer patients. In the words of one specialist commenting on the study: “Clinicians can advise their patients with breast cancer that soyfoods are safe to eat, and that these foods may offer some protective benefit for long-term health.”

This exciting study adds strong positive data to a large body of research examining the value of soy in the diet of breast cancer patients. We at Silk are encouraged by the study, and look forward to additional research that may help advance science in this area. Breast cancer patients or those known to be at high risk for the disease should always work closely with a doctor to determine the healthiest dietary choices.

Read the press release from the Journal of the American Medical Association.

Consumption of Soy Food Among Women With Breast Cancer Associated With Decreased Risk of Death, Cancer Recurrence

INFORMATION CONTAINED IN THESE NEWS RELEASES IS PROTECTED BY COPYRIGHT. JOURNAL ATTRIBUTION IS REQUIRED.

EMBARGOED FOR RELEASE: 3 P.M. (CT) TUESDAY, DECEMBER 8, 2009

Media Advisory: To contact Xiao Ou Shu, M.D., Ph.D., call Craig Boerner at 615-322-4747 or email craig.boerner@Vanderbilt.Edu. To contact editorial co-author Rachel Ballard-Barbash, M.D., M.P.H., call the NCI Press Office at 301-496-6641 or email ncipressofficers@mail.nih.gov.

Consumption of Soy Food Among Women With Breast Cancer Associated With Decreased Risk of Death, Cancer Recurrence

CHICAGO – Although there is a concern regarding the safety of soy food consumption among breast cancer survivors, researchers have found that women in China who had breast cancer and a higher intake of soy food had an associated lower risk of death and breast cancer recurrence, according to a study in the December 9 issue of JAMA.

"Soy foods are rich in isoflavones, a major group of phytoestrogens that have been hypothesized to reduce the risk of breast cancer. However, the estrogen-like effect of isoflavones and the potential interaction between isoflavones and tamoxifen have led to concern about soy food consumption among breast cancer patients," the authors write.

Xiao Ou Shu, M.D., Ph.D., of Vanderbilt University Medical Center, Nashville, Tenn., and colleagues examined the association between soy isoflavone intake with breast cancer recurrence and survival. The researchers analyzed data from the Shanghai Breast Cancer Survival Study, a large, population-based study of 5,042 female breast cancer survivors in China. Women ages 20 to 75 years with diagnoses of breast cancer between March 2002 and April 2006 were recruited and followed up through June 2009. Information on cancer diagnosis and treatment, lifestyle exposures after cancer diagnosis, and disease progression was collected at approximately 6 months after cancer diagnosis and was reassessed at three follow-up interviews conducted at 18, 36, and 60 months after diagnosis. A Shanghai Vital Statistics Registry database was used to obtain survival information for participants who were lost to follow-up.

After a median (midpoint) follow-up of 3.9 years, 444 total deaths and 534 recurrences or breast cancer-related deaths were documented among the group of 5,033 surgically-treated breast cancer patients. Soy food intake, as measured by either soy protein or soy isoflavone intake, was inversely associated with mortality and recurrence. Patients in the group with the highest intake of soy protein had a 29 percent lower risk of death during the study period, and a 32 percent lower risk of breast cancer recurrence compared to patients with the lowest intake of soy protein. The adjusted 4-year mortality rates were 10.3 percent and 7.4 percent and the 4-year recurrence rates were 11.2 percent and 8.0 percent, respectively, for women with the lowest and highest groups of soy protein intake.

"The inverse association was evident among women with either estrogen receptor–positive or –negative breast cancer and was present in both users and nonusers of tamoxifen," the researchers write.

"In summary, in this population-based prospective study, we found that soy food intake is safe and was associated with lower mortality and recurrence among breast cancer patients. The association of soy food intake with mortality and recurrence appears to follow a linear dose-response pattern until soy food intake reached 11 grams/day of soy protein; no additional benefits on mortality and recurrence were observed with higher intakes of soy food. This study suggests that moderate soy food intake is safe and potentially beneficial for women with breast cancer."

(JAMA. 2009;302[22]:2437-2443. Available pre-embargo to the media at www.jamamedia.org)

Editor's Note: Please see the article for additional information, including other authors, author contributions and affiliations, financial disclosures, funding and support, etc.

Editorial: Challenges in Design and Interpretation of Observational Research on Health Behaviors and Cancer Survival

Rachel Ballard-Barbash, M.D., M.P.H., of the National Cancer Institute, Bethesda, Md., and Marian L. Neuhouser, Ph.D., of the Fred Hutchinson Cancer Research Center, Seattle, write in an accompanying editorial that while this study provides important information, there are several concerns, including differences in the quality, type and quantity of soy food intake between China and the U.S. (47 mg/d vs. 1 to 6 mg/d, respectively, average isoflavone intake). Also, they point out the relatively short median follow-up time of the study (4 years); that there likely are differences in screening rates in China compared with the U.S.; and a number of factors may make it difficult to compare stage- and treatment-specific results in China with outcomes in the U.S.

"Even though the findings by Shu et al suggest that consumption of soy foods among breast cancer patients is probably safe, studies in larger cohorts are required to understand the effects of these foods among diverse clinical subgroups of breast cancer patients and survivors. In the meantime, clinicians can advise their patients with breast cancer that soy foods are safe to eat and that these foods may offer some protective benefit for long-term health. Moreover, the potential benefits are confined to soy foods, and inferences should not be made about the risks or benefits of soy-containing dietary supplements. Patients with breast cancer can be assured that enjoying a soy latte or indulging in pad thai with tofu causes no harm and, when consumed in plentiful amounts, may reduce risk of disease recurrence."

(JAMA. 2009;302[22]:2483-2484. Available pre-embargo to the media at www.jamamedia.org)

Editor's Note: Please see the article for additional information, including financial disclosures, funding and support, etc.

Other News

2009

February | January

2008

February

Soy, plant foods, and PSA levels, February 2009
Carmody J, Olendzki B, Reed G, Andersen V, Rosenzweig P. A dietary intervention for recurrent prostate cancer after definitive primary treatment: results of a randomized pilot trial. Urology 2008;72:1324-8.

This is an interesting study that was designed to determine the effect of a plant-based diet on PSA levels in prostate cancer patients. The experimental diet group was instructed to consume a diet that emphasized plant-based foods and fish, and included a wide variety of fruits, vegetables (with an emphasis on cruciferous varieties), whole grains, and soyfoods, with avoidance of meat, poultry and dairy products. The PSA doubling time increased substantially in the intervention group compared with that in the controls. Doubling time is a legitimate measure of PSA change and suggests the plant-based diet may delay tumor recurrence.

The investigators reported that the phytoestrogen intake of the subjects was 19 mg/d, which suggests the subjects were consuming the equivalent of about one serving of a traditional soyfood per day. Several published studies have found soy intake reduces the rise in PSA levels in prostate cancer patients. This study adds to the growing body of evidence suggesting that soy may play a role in prostate cancer. More...

Isoflavones and Prostate Tissue, February 2009
Gardner CD, Oelrich B, Liu JP, Feldman D, Franke AA, Brooks JD. Prostatic soy isoflavone concentrations exceed serum levels after dietary supplementation. Prostate 2009.

This is an important study because it is one of the few that measured the isoflavone content of prostate tissue and also compared that to serum isoflavone content. It shows that isoflavones are concentrated in prostate tissue and that in response to the ingestion of 82 mg isoflavones (~3 serving of traditional soyfoods) from supplements, prostate tissue concentrations reached ~2 uM, which is quite high. This study indicates that isoflavones are concentrated in the prostate relative to serum making it even more likely that isoflavones exert physiological effects in that organ. More...

Omega-6 Fatty Acids and CHD Risk, February 2009
Harris WS, Mozaffarian D, Rimm E, et al. Omega-6 Fatty Acids and Risk for Cardiovascular Disease. A Science Advisory From the American Heart Association Nutrition Subcommittee of the Council on Nutrition, Physical Activity, and Metabolism; Council on Cardiovascular Nursing; and Council on Epidemiology and Prevention. Circulation 2009.

This AHA science advisory provides important guidance on fatty acid intakes for CHD reduction. In recent years, many have called for lower the ratio of dietary omega-6 to omega-3 fatty acids. Full-fat soyfoods are loaded with naturally omega-6 fatty acids and are sometimes criticized for this reason, despite also providing linolenic acid, an essential omega-3 fatty acid. Although increasing omega-3 intake is associated with reducing the risk for CHD, it does not follow that decreasing omega-6 levels would do the same. In fact, the evidence in this paper suggests that lowering omega-6 intake could have the opposite effect. The AHA supports an omega-6 fatty acid intake of at least 5-10% of total energy. Soyfoods are naturally rich in omega-6 fatty acids and are low in saturated fat, making them a good way to meet this recommendation. More...

January

Soy and colorectal cancer risk, January 2009
Yang G, Shu XO, Li H, Chow WH, Cai H, Zhang X, Gao YT, Zheng W. Prospective cohort study of soy food intake and colorectal cancer risk in women. Am J Clin Nutr 2008.

In this study, higher soy intake was associated with about a one-third reduction in risk of colorectal cancer. Plus, there was a graded response which adds to the validity of the findings. Although these findings are quite impressive, there are two important caveats to consider. First, the Shanghai Women's Health Study, almost without exception, has produced results that are very supportive of the benefits of soy. It is always preferable to see these types of findings replicated in different cohorts. Second, these findings are inconsistent with other recent results showing that soy intake did not have a significant effect on markers of colon cancer. So although these epidemiologic findings are intriguing, it is premature at this time to state that soy reduces colorectal cancer risk. Further research is indicated to clarify the relationship between soy intake and colorectal cancer risk. More...

Food matrix, isoflavone bioavailabilty, and equol production among different Nationalities, January 2009
Food matrix and isoflavones bioavailability in early post menopausal women: An European clinical study. Brigitte Chanteranne, Francesco Branca, A Kaardinal, K Wahala, Véronique Braesco, Philippe Ladroite, Fred Brouns, Véronique Coxam. Clinical Interventions Aging 3 (4) 1-8, 2008

This study compared isoflavone bioavailability between two different soy isoflavone-enriched foods. Bioavailability was similar whether the isoflavone vehicle was cereal bars or biscuits but what was especially intriguing from this study was as shown in the table below - the higher percentage of equol producers in France compared to the Netherlands and Italy. Although the sample size was relatively small, this is an interesting finding since it is thought that equol producers may have a more pronounced response to isoflavone consumption.

Click to enlarge

More...

December

Isoflavones and prostate cancer risk, December 2008
Kurahashi N, Iwasaki M, Inoue M, Sasazuki S, Tsugane S. Plasma Isoflavones and Subsequent Risk of Prostate Cancer in a Nested Case-Control Study: The Japan Public Health Center. J Clin Oncol 2008.

In this prospective study, plasma isoflavone levels, especially genistein and equol, were significantly inversely related to risk of developing prostate cancer, especially localized cancer, among Japanese men. The strengths of this study include the long follow up period – 12.8 years, and the study size, 14,000 men. This study is consistent with several other recently published studies suggesting soy is protective against prostate cancer. More...

Isoflavones and Memory, December 2008
Islam F, Sparkes C, Roodenrys S, Astheimer L. Short-term changes in endogenous estrogen levels and consumption of soy isoflavones affect working and verbal memory in young adult females. Nutr Neurosci 2008;11:251-62.

This is a potentially important study because isoflavones led to cognitive benefits (improved verbal memory) in premenopausal women not taking oral contraceptives. Most research has been conducted in postmenopausal women so any study showing potential benefits in younger women is important. The premise of the study was that estrogen affects cognition and that isoflavones might be able to mitigate the effects of low estrogen levels during certain periods of the menstrual cycle. Subjects consumed 120 mg/day of isoflavones. A limitation of the study is that soy germ was used as the supplement. Since soy germ is high in glycitein and low in genistein the results can't be necessarily extrapolated to soyfoods in general, which are high in genistein. Also, the intervention period was only 3 days. Still, as a pilot study, the results are very intriguing. More...

Isoflavones and lipids, December 2008
Chedraui P, San Miguel G, Hidalgo L, Morocho N, Ross S. Effect of Trifolium pratense-derived isoflavones on the lipid profile of postmenopausal women with increased body mass index. Gynecol Endocrinol 2008;24: 620-4.

Important study because of the finding that isoflavones favorably affected lipids levels in postmenopausal women. This study utilized a cross-over design and women consumed 80 mg/d isoflavones. The lipid effects, which were quite dramatic in regard to both lipoprotein A (LpA) and LDL cholesterol, were only apparent in women with a BMI ≥ 25 kg/m2 and not in thinner women. Whether the effects were apparent in high-BMI women because the baseline lipid levels were much higher than in thinner women or because of some physiological difference between thin and overweight women is unclear. But clearly future studies should examine the effects of soy in heavier women. One caveat is that the isoflavones were derived from Trifolium pretense, which has a different isoflavone profile than soy; however, in vivo the isoflavones in red clover are metabolized into the isoflavones present in soy. More...

November

Isoflavones and Breast Tissue Density, November 2008
Verheus M, van Gils CH, Kreijkamp-Kaspers S, et al. Soy protein containing isoflavones and mammographic density in a randomized controlled trial in postmenopausal women. Cancer Epidemiol Biomarkers Prev 2008;17:2632-8.

These study results are derived from a 1-year study that was first published in 2004. The current publication focuses on the impact of the intake of 25 g isolated soy protein containing 99 mg isoflavones on breast tissue density. Breast tissue density is considered to be a marker of breast cancer risk although there is some uncertainty about whether greater density is causally related to risk. It is known that exposure to HRT increases both density and risk whereas exposure to tamoxifen decreases risk and density. In the current study, isoflavone exposure had no effect on breast tissue density, a finding which is consistent with the literature overall. This finding provides reassurance about the safety of isoflavone-rich isolated soy protein. However, the study did have some limitations, the most important of which is the long time period (>3 months) between the end of the study (end of exposure to soy) and the taking of the second mammogram. During this time, it is possible that any effects of soy on density would have disappeared. More...

Antioxidant potential of soybeans, November 2008
Xu B, Chang SK. Characterization of phenolic substances and antioxidant properties of food soybeans grown in the North Dakota-Minnesota region. J Agric Food Chem 2008; 56:9102-13.

The study serves as a good reference for the antioxidant activity of different varieties of soybeans and for isoflavone content separated into the different isoflavone isomers. While all soybeans exhibited antioxidant properties, superior antioxidant activity was measured in black soybeans in comparison to yellow soybeans. This adds credence to a recent similar paper by this research group demonstrating the superiority of black soybeans. More...

October

Bone and Bone Mineral Density and Breast Safety, October 2008
Marini H, Bitto A, Altavilla D, et al. Breast Safety and Efficacy of Genistein Aglycone for Post-Menopausal Bone Loss: A Follow-up Study. J Clin Endocrinol Metab 2008.

The results described in the abstract are from the third year of a two-year study involving osteopenic, post-menopausal women. The study was planned for 2 years but a subset of the participants (n=138) agreed to continue for a third year. Consequently, the sample size was reduced by half but the results continue to show remarkable improvements in bone mineral density in response to 54 mg/day genistein. In fact, by the third year there was a 9% increase in bone mineral density the genistein group and an 11% decrease in the placebo group. Additionally, there was no effect of genistein on breast tissue density and unexpectedly, BRCA1 and BRCA2 levels were maintained in the genistein group but decreased in the placebo group. The BRCA1 and BRCA2 genes breast control cell proliferation. When there is a mutation in these genes such that their normal function is impaired, breast cancer risk increases dramatically. Thus, the results suggest that genistein potentially reduced breast cancer risk in this population, although breast tissue was not directly assessed. More...

Isoflavones Improve Endothelial Function in Stroke Patients, October 2008
Chan YH, Lau KK, Yiu KH, et al. Reduction of C-reactive protein with isoflavone supplement reverses endothelial dysfunction in patients with ischaemic stroke. Eur Heart J 2008.

This study has received worldwide attention. It shows that in patients with prior stroke, isoflavones (80 mg/day) increase flow mediated dilation (FMD), a marker of endothelial function, by approximately 1% on an absolute basis and by 50% on a relative basis, (i.e., FMD increased from 2 to 3% after 12 weeks of isoflavones). The authors estimated that this improvement would decrease risk of coronary events by 12%. Interestingly, efficacy was noted only in past or current smokes and in non-diabetics and was inversely related to baseline FDM. The latter observation suggests that the failure of some past studies to find isoflavones improve FDM may have been because the subjects were healthy and had normal endothelial function. The lack of efficacy in diabetics is not totally unexpected because prior work has shown diabetics have severe disruptions in endothelial function, perhaps preventing them from favorably responding to isoflavones. This is the second study within 2 months demonstrating isoflavones improve endothelial function, adding to the growing body of evidence in this area. More...

Soy Oil as a Source of Omega-3 Fatty Acids beyond Linolenic Acid, October 2008
Harris WS, Lemke SL, Hansen SN, et al. Stearidonic Acid-enriched soybean oil increased the omega-3 index, an emerging cardiovascular risk marker. Lipids 2008;43:805-11.

A soybean oil has been developed that is rich (20%) in stearidonic acid (SDA), an omega-3 fatty acid (18:4, n-3) that has one more double bond than linolenic acid at the 6th carbon, thereby avoiding the need for delta-6 desaturase, the rate-limiting enzyme in the conversion of linolenic acid to EPA. This study in fact shows that there was good conversion of SDA to EPA as assessed by red blood cell (RBC) EPA content; although relative to the direct consumption of EPA the conversion rate was only 17%. However, this is much better conversion than is typically reported for the conversion of ALA to EPA. Thus, stearidonic-rich soybean oil appears to represent a vegetarian approach to increasing EPA content. However, RBC DHA content was not increased so it would be necessary to combine DHA with SDA to fully duplicate the effects of fish and fish oil supplements. More...

September

Isolated soy protein and lipids, September 2008
Appt SE, Tormala R, Franke AA, et al. Soy-tibolone combination-Effect on lipids in postmenopausal monkeys and women. Maturitas 2008.

The study involved both monkeys and women. In women, all of whom were taking tibolone, a steroid that is being studied as a possible alternative to convention HRT, soy protein lowered LDL cholesterol by 10%. Obviously, this is a very significant decrease. However, there was also a decrease in the control group of about 4%, so the net decrease in LDL-C was about 6%. Of course, since all women were on tibolone it is not clear that the results can be extrapolated to the general population. The authors also found a statistically significant reduction in LDL in equol producers but not non-producers. However, when looking at net differences (taking into consideration the decrease in the control) in response, there does not appear to be differences between subjects according to equol status. More...

Effects of genistein on bones, August 2008
Bitto A, Burnett BP, Polito F, et al. Effects of genistein aglycone in osteoporotic, ovariectomized rats: a comparison with alendronate, raloxifene and oestradiol. Br J Pharmacol 2008.

Although this is an animal study, it is unique in that the rats used were older ovariectomized rats, which is a better model than young ovariectomized rats, which are usually used. Second, the study compared genistein with both estrogen (known to be efficacious) and alendronate, a bis-phosphonate, and raloxifene, both of which are used in clinical practice to treat osteoporosis. Genistein was as effective at improving bone mineral density, improving bone quality, and increasing bone breaking strength as the other treatments. More...

August

Soy and blood pressure, August 2008
Hooper L, Kroon PA, Rimm EB, et al. Flavonoids, flavonoid-rich foods, and cardiovascular risk: a meta-analysis of randomized controlled trials. Am J Clin Nutr 2008;88:38-50.

This systematic review and meta-analysis confirmed the cholesterol-lowering effects of soy protein but was unable to conclude that isoflavones improve endothelial function as measured by flow mediated dilation. However, the analysis did find that soy protein resulted in statistically significant decreases in blood pressure. For isolated soy protein (ISP) and soyfoods, the decreases in systolic and diastolic blood pressure were 1.60 and 1.99 and 5.76 and 4.04 mm Hg, respectively. However, only the decrease in diastolic blood pressure in response to ISP was statistically significant although the other values nearly reached significance. This study is importance because it is the first meta-analysis to look at the blood pressure-lowering effects of soy and because it highlights the possibility that soyfoods are more hypotensive than ISP although there were only 5 soyfood studies. More...

Soy and breast cancer protection, August 2008
Suzuki T, Matsuo K, Tsunoda N, et al. Effect of soybean on breast cancer according to receptor status: A case-control study in Japan. Int J Cancer 2008: Oct 1;123(7):1674-80.

More than 20 epidemiologic studies have examined the relationship between soy and breast cancer, so this study is certainly not unique in this regard. However, this is essentially the only study to examine the relationship between soy intake and breast cancer risk according to receptor status. Specifically, patients were assessed as to whether they were positive for estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor 2 (HER2). The study included a total of 678 cases and 3990 controls. Soyfood intake was associated with a 27% reduced risk of breast cancer but only among patients that were ER+/PR+/HER2-. Approximately 20% of women are HER+. Since HER2+ cases are unresponsive to tamoxifen HER2 over-expression appears to be associated with hormone independence. In contrast to HER2+, at least initially, most postmenopausal women breast cancer patients are ER+. That the protective effect of soy was restricted to ER+/PR+/HER2- cases suggests soy is working through an anti-estrogenic mechanism. Past epidemiologic studies failing to find protective effects of soy against breast cancer may have done so because the results were not sub-analyzed according to receptor status. More...

Soyfoods and prostate cancer, August 2008
Li XM, Li J, Tsuji I, Nakaya N, Nishino Y, Zhao XJ. Mass screening-based case-control study of diet and prostate cancer in Changchun, China. Asian J Androl 2008;10:551-60.

Very interesting study showing that soy consumption is associated with a decreased risk of prostate cancer. Small number of cases (n=28) but cases (diagnosed with prostate cancer) were matched 1:10 with controls (with normal PSA values). There was a dose response relationship between soy intake and risk, which serves to reinforce the general finding. Plus, maximum risk reduction was associated with the consumption of only about 1 serving of soy foods daily, thus, modest amounts of soy were protective. More...

July

Isoflavones and endothelial function, July 2008
Hall WL, Formanuik NL, Harnpanich D, et al. A meal enriched with soy isoflavones increases nitric oxide-mediated vasodilation in healthy postmenopausal women. J Nutr 2008;138:1288-92.

As many as 20 studies have examined the effects of isoflavone-rich soy products on endothelial function as assessed by changes in flow mediated dilation (FMD). This is done by measuring the change in the diameter of the brachial artery after blood has been temporarily occluded. Perhaps one-third of these studies have shown isoflavones enhance endothelial function (suggestive of a protective effect against coronary heart disease). To date, the reason for the inconsistent results has not been identified. The current study offers a possible explanation. In this acute study, isoflavones (80 mg/day) were shown to increase FMD when tested 6 hours after isoflavone exposure but not 4 hours after exposure. The improvement correlates with peak serum isoflavone levels, the reason the second test was done at that time. The implications of these findings may be that FMD is improved only when isoflavones reach a fairly high serum level. If in fact this is the case, it may be that the inconsistent FMD results from previous studies is because these studies tested FMD at varying times in relation to peak isoflavones levels. Peak isoflavone levels reached 1.5 uM in this study and at 4 hours post ingestion they were less than half this amount. Thus, it may be necessary for isoflavones to be at least 1.0 uM for benefits to result. More...

Isoflavones and breast cancer risk, July 2008
Imhof M, Molzer S. Effects of soy isoflavones on 17beta-estradiol-induced proliferation of MCF-7 breast cancer cells. Toxicol In Vitro 2008.

This study is potentially one of the most important to be conducted even though it utilized an in vitro and ex vivo design. It shows that isoflavones stimulate breast cell proliferation in vitro only in a low estrogen environment, an environment that doesn't exist in either pre- or postmenopausal women. This argument has been made before and studied to some extent, but this paper is the first to approach this issue in a more systematic manner. Also, the study found that blood taken from women supplemented with isoflavones for two weeks had more anti-proliferative effects than unmetabolized isoflavones. These findings help to cast doubt upon the findings from animal models showing that genistein stimulates mammary tumor growth. More...

Soy, lifestyle, and prostate cancer risk, July 2008
Ornish D, Magbanua MJ, Weidner G, et al. Changes in prostate gene expression in men undergoing an intensive nutrition and lifestyle intervention. Proc Natl Acad Sci U S A 2008;105:8369-74.

The results suggest the intensive nutrition and lifestyle intervention led to a significant number of changes in prostate tissue gene expression. Many of the genes were involved in cell growth and regulation, suggesting the intervention holds the potential to modulate prostate tumor growth. The intervention included the consumption of 1 daily serving of tofu and 58 g of a fortified soy protein powdered beverage. Thus, soy and isoflavone exposure was a big part of the intervention. Understanding the prostate molecular response to comprehensive lifestyle changes may strengthen efforts to develop effective prevention and treatment. Larger clinical trials are warranted to confirm the results of this pilot study. More...

Soy protein and cholesterol reduction meta-analysis, July 2008
Harland JI, Haffner TA. Systematic review, meta-analysis and regression of randomised controlled trials reporting an association between an intake of circa 25g soya protein per day and blood cholesterol. Atherosclerosis 2008.

This meta-analysis of thirty studies included only studies that utilized no more than 40 g soy protein (mean amount 26.9 g/day) for the intervention. Thus, one intention was to show that achievable daily intakes of soy protein can lower cholesterol. The 6% reduction found in this analysis is larger than all other recently published analyses. However, it is not clear if this reduction represents the reduction from baseline or the reduction in comparison to the change in the control group. The study adds to the body of evidence indicating that adults with elevated cholesterol experience significant reductions in total and LDL cholesterol when incorporating 25 g day of soy protein into the diet. More...

June

Soy and prostate cancer, June 2008
Pendleton JM, Tan WW, Anai S, et al.: Phase II Trial of Isoflavone in prostate specific antigen recurrent prostate cancer after previous local therapy. BMC Cancer, 8, 132, 2008

There is some suggestion of modest benefit of isoflavones in this pilot study. This was a single-group study with no control group. In the year before the study PSA increased 56% whereas during the year-long intervention, PSA increased only about 20%. The change was statistically significant. More specifically, the slope of PSA after study entry was significantly lower than that before study entry in 6 patients and the slope of PSA after study entry was significantly higher than before study entry in 2 patients. For the remaining 12 patients, the change in slope was statistically insignificant. Nearly two thirds of the patients were noted to have significant levels of free equol in their serum while on therapy, which is about twice the usual rate. More...

May

Soy and tomatoes for prostate cancer prevention, May 2008
Grainger EM, Schwartz SJ, Wang S, et al.
Nutr Cancer 60:(2), 145-54 (2008).

These findings suggest the combination of soy and tomato products may be helpful for prostate cancer patients. There were no effects on testosterone levels but there appeared to be a decrease in the rise in PSA levels and a decrease in serum vascular endothelial growth factor in the subjects. Although these are pilot data, the results are encouraging and are consistent with the findings of previous research examining the effects of this combination in the treatment of prostate cancer. Future studies are warranted to further investigate the efficacy of the combination of soy isoflavones and tomatoes/tomato extracts in prostate cancer prevention and management. More...

Soy protein not associated with peanut allergy, May 2008
Koplin J, Dharmage SC, Gurrin L, et al.
J Allergy Clin Immunol (2008).

This is an interesting finding because it helps to dispel the previously reported notion that exposure to soy protein increases risk of developing peanut allergy. This study is a classic illustration of the importance of controlling for confounding variables, as what appeared to be a correlation was actually just a result of parents providing soy milk more often in infants with prior history or family history of allergies. More...

March

Isoflavone Absorption from Fermented versus Non-Fermented Soy, March 2008
Maskarinec G, Watts K, Kagihara J, Hebshi SM, Franke AA.
Br J Nutr

Although only urine and not blood was analyzed, the study provides very important information about isoflavone absorption. In this study, total isoflavone absorption was similar after consuming miso or soymilk. Thus, fermentation, which results in the hydrolysis of isoflavones, does not increase total isoflavone absorption although other data indicate that fermentation and the resulting conversion of glycosides to aglycones results in faster isoflavone absorption. Thus, the results do not support claims that fermented soyfoods are superior to those of unfermented soyfoods because isoflavones are absorbed to a greater extent in the former. More...

February

Hypocholesterolemic Effects of Soy Protein in Young People, February 2008
Weghuber D, Widhalm K.
Br J Nutr

This is one of the few cholesterol-lowering studies to include children and is therefore noteworthy. The reduction in total and LDL-cholesterol was quite significant and above and beyond that seen with a standard cholesterol-lowering diet. Unfortunately, it is not possible to tell from the study how much soy protein was consumed because it is based on body weight, and only BMI is presented. Substituting soy protein for animal protein in cholesterol-lowering diets may provide additional benefit in the prevention of early vascular disease in this high-risk population. More...

January

Soy and Premenopausal Bone Mineral Density, January 15, 2008
Yoon Ju Song, Hee Young Paik, Hyojee Joung.
Nutrition Research

This is a relatively small study — it involved only 34 subjects, it was observational in nature and isoflavone intake among the Korean pre-menopausal women was only 8 mg/day. However, the authors cite two intervention trials (published in Korean) that, along with the current study, make the case that isoflavones may exert beneficial effects of the skeletal system of young women if in fact, they are underweight and, presumably, somewhat estrogen-deficient. Past research suggests (although it is not 100 percent consistent) that isoflavones will exert bone benefits only in post-menopausal women, because estrogen levels are low and bone loss is occurring. Thus, isoflavone-containing soy products may be of specific benefit to U.S. women who are consuming calorie-restricted diets or are overly thin. More...

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