Soy Foods, Pumpkin Seeds and Sunflower Seeds Reduce Breast Cancer Risk






 

A new study links the consumption of soy foods, pumpkins seeds, and sunflower seeds with a decreased risk of breast cancer.


 

 

SOY FOODS, PUMPKIN SEEDS AND SUNFLOWER SEEDS REDUCE BREAST CANCER RISK

As I discuss in my bestselling book, A Cancer Prevention Guide for the Human Race, phytoestrogens are substances found in plant-based foods that have weak estrogen-like effects in the body.  As estrogen is a known risk factor for breast cancer, there has been understandable concern that phytoestrogens, if consumed regularly, may lead to an increased risk of breast cancer over time.  While the data supporting this hypothesis has been both weak and contradictory thus far, some of the strongest available data regarding phytoestrogen intake and breast cancer risk has, counterintuitively, linked certain phytoestrogen-rich foods, and especially soy foods like tofu, with a decreased lifetime risk of breast cancer, particularly when consumed before and during the onset of puberty, as I discuss in my book.

Now, a newly published German study further suggests that the regular consumption of at least some phytoestrogen-rich foods may significantly decrease breast cancer risk, particularly later in life, after menopause.  In this public health study, 2,884 postmenopausal women diagnosed with breast cancer and 5,509 age-matched “controls” without breast cancer underwent detailed assessments of their dietary habits.  In addition to using a scientifically validated food-frequency questionnaire, additional specific questions regarding the consumption of phytoestrogen-rich foods were asked of all of the 8,393 women who participated in this case-control clinical study.  Importantly, the volunteers’ individual risk factors for breast cancer were assessed and accounted for when the study’s researchers analyzed their data.  This public health study appears in the current issue of the journal Nutrition and Cancer.

Among all foods known to contain phytoestrogens, three foods were found to be significantly associated with a lower risk of breast cancer among postmenopausal women.  Specifically, the regular consumption of soy foods was linked to a 17 percent reduction in breast cancer risk, while the routine intake of sunflower and pumpkin seeds was associated with a 34 percent reduction in breast cancer risk.  At the same time, the consumption of flaxseed, which contains very high levels of phytoestrogens, did not appear to be linked with a decrease in breast cancer risk in this study.

The results of this study add further evidence that at least some forms of phytoestrogens may actually decrease the risk of breast cancer, even though they are able to weakly stimulate the same hormonal receptors that estrogen normally stimulates.  While this finding may at first seem contradictory, recent research has shown that these plant-derived nutritional substances actually have rather complex effects on estrogen receptors within breast cells and other hormone-sensitive cells.  In fact, in many cases, phytoestrogens may actually block the effects of estrogen on estrogen receptors within breast cells, thus acting more like medications that are regularly used to reduce the risk of breast cancer recurrence in patients with estrogen-sensitive tumors, including tamoxifen and raloxifene.

I will end my review of this new public health study by reminding readers that studies such as this one rely upon relatively weak research methods, and the findings of these types of public health studies are less compelling, in general, than “gold standard” prospective, randomized, blinded, placebo-controlled clinical research studies.  Unfortunately, the overwhelming majority of cancer prevention research data published to date has been derived from relatively less powerful public health studies like this particular study.  However, given the enormous expense and resources necessary to perform large prospective, randomized, blinded, placebo-controlled clinical studies, and the extended period of time that is required to arrive at meaningful observations within such studies, we are left primarily with questionnaire-based public health studies such as this one in an effort to better understand potential links between diet and cancer risk.  For a much more detailed evidence-based discussion of the impact of diet and other lifestyle factors on cancer risk, purchase your copy of A Cancer Prevention Guide for the Human Race from your favorite bookstore (available in both print and e-book formats).


At this time, more than 8 percent of Americans are unemployed.  According to the Bureau of Labor Statistics, however, the unemployment rate for veterans who served on active duty between September 2001 and December 2011 is now more than 12 percent.  A new website, Veterans in Healthcare, seeks to connect veterans with potential employers.  If you are a veteran who works in the healthcare field, or if you are an employer who is looking for physicians, advanced practice professionals, nurses, corpsmen/medics, or other healthcare professionals, then please take a look at Veterans in Healthcare. As a retired veteran of the U.S. Army, I would also like to personally urge you to hire a veteran whenever possible.

 

For a groundbreaking overview of cancer risks, and evidence-based strategies to reduce your risk of developing cancer, order your copy of my bestselling book, “A Cancer Prevention Guide for the Human Race,” from AmazonBarnes & NobleBooks-A-MillionVroman’s Bookstore, and other fine bookstores!

Within one week of publication, A Cancer Prevention Guide for the Human Race was ranked #6 among all cancer-related books on the Amazon.com “Top 100 Bestseller’s List” for Kindle e-books. Within three months of publication, A Cancer Prevention Guide for the Human Race was the #1 book on the Amazon.comTop 100 New Book Releases in Cancer” list.




Disclaimer:  As always, my advice to readers is to seek the advice of your physician before making any significant changes in medications, diet, or level of physical activity


 

Dr. Wascher is an oncologic surgeon, professor of surgery, cancer researcher, oncology consultant, and a widely published author


 

I and the staff of Weekly Health Update would again like to take this opportunity to thank the more than 100,000 health-conscious people from around the world who visit this premier global health information website every month.  (More than 1.3 million pages of high-quality medical research findings were served to the worldwide audience of health-conscious people who visited Weekly Health Update in 2011!)  As always, we enjoy receiving your stimulating feedback and questions, and I will continue to try and personally answer as many of your inquiries as I possibly can.


 






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Soy (Isoflavones), Osteoporosis, and the Symptoms of Menopause


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A new placebo-controlled, double-blinded research study showed no benefit from soy supplements in reducing osteoporosis or the symptoms of menopause.



SOY (ISOFLAVONES), OSTEOPOROSIS, AND THE SYMPTOMS OF MENOPAUSE

As I discuss in detail in my recent book, A Cancer Prevention Guide for the Human Race, combination hormone replacement therapy (HRT) for the symptoms of menopause have been clearly linked to an increased risk of breast cancer.  (This important topic is also the subject of my next book, which will be published in 2012.)  Since the preliminary findings of the landmark Women’s Health Initiative study were released in 2002, proving the link between HRT and breast cancer, many women and their physicians have been searching for safer alternatives to HRT in an effort to relieve the symptoms of menopause, and to reduce the risk of thinning of the bones (osteoporosis).

There have been several public health research studies that have suggested a role for soy foods in the prevention of both osteoporosis (“thin bones”) and menopausal symptoms. Indeed, the findings of these studies make scientific sense, as soy isoflavones, which are present in many soy food products (and especially in tofu), act as a weak form of estrogen. (It is the loss of estrogen production in the ovaries, after menopause, that leads to both osteoporosis and the unpleasant symptoms of menopause in postmenopausal women.) However, as with the vast majority of disease prevention research in general, the available research data linking soy isoflavones to improvements in bone density and menopausal symptoms has been in the form of survey-based studies, and other relatively unreliable types of research studies. Now, a newly published prospective, randomized, placebo-controlled, doubled-blinded clinical research study takes a closer (and more accurate) look at the impact of soy isoflavone supplements on osteoporosis and menopausal symptoms. This clinical research study appears in the current issue of the Archives of Internal Medicine.

In this study, 122 postmenopausal women were randomized to receive a daily soy isoflavone supplement pill (200 mg), while 126 postmenopausal women were randomized to receive a placebo (sugar) pill that was identical in appearance to the soy isoflavone pills. Neither the research study volunteers nor the research staff knew which patient volunteers received the soy isoflavone tablets and which volunteers received the placebo pills until the research study was completed. These patient volunteers were all followed for an average of 2 years. Bone density measurements were performed at the beginning of the study, and then again 2 years later. Common menopausal symptoms were also tracked throughout the duration of this study.

After 2 years of observation, there was no significant difference in bone density measurements between the two groups of women who participated in this clinical research study (in both groups of women, there was an average bone density loss of about 2 percent over the 2-year period of this study). Moreover, the women in the soy isoflavone group actually reported ahigher incidence of hot flashes and constipation than the women in the placebo group.

In this well-controlled prospective, randomized, doubled-blinded, placebo-controlled clinical research study, a daily supplement of 200 mg of soy isoflavones neither improved postmenopausal bone density loss nor improved the most troublesome symptoms of menopause.  (Whether or not higher doses of soy isoflavones, or natural soy foods instead of soy isoflavone supplements, might have shown some beneficial effect on bone density loss or menopausal symptoms in postmenopausal women cannot be answered by this study.)  Therefore, this study convincingly shows that even relatively large daily doses of purified soy isoflavones have no beneficial effect on either bone density loss or menopausal symptoms in postmenopausal women.  Based upon the results of this study, if you are currently taking soy isoflavone supplements in an effort to reduce your risk of osteoporosis, or the symptoms of menopause, this high-level clinical research study indicates that you are probably wasting your time and money on such supplements.  (However, as I discuss in A Cancer Prevention Guide for the Human Race, soy foods may actually reduce a woman’s lifetime risk of developing breast cancer, particularly if consumed during early adolescence and early adulthood, and soy products may also decrease a man’s lifetime risk of developing prostate cancer.)

 

For a comprehensive guide to living an evidence-based cancer prevention lifestyle, order your copy of my new book, A Cancer Prevention Guide for the Human Race.  For the price of a cheeseburger, fries, and a shake, you can purchase this landmark new book, in both paperback and e-book formats, and begin living an evidence-based cancer prevention lifestyle today!

For a groundbreaking overview of cancer risks, and evidence-based strategies to reduce your risk of developing cancer, order your copy of my new book, A Cancer Prevention Guide for the Human Race,” from Amazon, Barnes & Noble, Books-A-Million,Vroman’s Bookstore, and other fine bookstores!

On Thanksgiving Day, 2010, A Cancer Prevention Guide for the Human Race was ranked #6 among all cancer-related books on the Amazon.com “Top 100 Bestseller’s List” for Kindle e-books! On Christmas Day, 2010, A Cancer Prevention Guide for the Human Race was the #1 book on the Amazon.comTop 100 New Book Releases in Cancer” list!


Disclaimer:  As always, my advice to readers is to seek the advice of your physician before making any significant changes in medications, diet, or level of physical activity



Dr. Wascher is an oncologic surgeon, professor of surgery, cancer researcher, oncology consultant, and a widely published author



For a different perspective on Dr. Wascher, please click on the following YouTube link:

Texas Blues Jam



I and the staff of Weekly Health Update would again like to take this opportunity to thank the more than 100,000 health-conscious people, from around the world, who visit this premier global health information website every month. (More than 1.2 million health-conscious people visited Weekly Health Update in 2010!) As always, we enjoy receiving your stimulating feedback and questions, and I will continue to try and personally answer as many of your inquiries as I possibly can.





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Hesperidin in Orange Juice Improves Hypertension and Arterial Function

 

Welcome to Weekly Health Update


“A critical weekly review of important new research findings for health-conscious readers”


HESPERIDIN IN ORANGE JUICE IMPROVES

HYPERTENSION AND ARTERIAL FUNCTION

 

Polyphenols are chemical compounds that are found in most of the plant-based foods that we commonly eat.  As I discuss in detail in my new book, A Cancer Prevention Guide for the Human Race, some polyphenolic compounds, such as green tea flavonoids, soy-based isoflavones, quercetin, curcumin, and resveratrol, among other polyphenols, may possess important cancer prevention properties.  There is also abundant research data suggesting that diets rich in certain natural dietary polyphenols may be associated with a decreased risk of cardiovascular disease, as well.

Hesperidin, which is a flavonoid polyphenol, is found in a variety of plant-based foods, including oranges, orange juice, and other citrus fruits.  A newly published prospective, randomized, blinded clinical research study, which appears in the current issue of the American Journal of Clinical Nutrition, offers intriguing evidence that hesperidin may actually decrease the risk of cardiovascular disease in high-risk patients.

In this pilot study, 24 overweight (but otherwise healthy) men, ages 50 to 65 years, were subjected to 4-week intervals in each of three experimental groups.  The first group was assigned to drink 500 ml (17 ounces) of orange juice per day.  The second experimental group drank a “control drink” that appeared similar to orange juice, but which did not contain any actual orange juice.  However, this “sham orange juice” was fortified with hesperidin.  The third group was also assigned to drink the fake orange juice, and to which was added a supplement portrayed (to the study volunteers, and to the research nurses who administered the beverages to these research volunteers) as hesperidin, but which, in fact, was an inert placebo that contained no hesperidin or other polyphenols.

Physical examinations and blood tests were performed before and after the men rotated through each of these three experimental groups.

The findings of this small but high quality clinical research study were quite interesting.  When compared to the control group that consumed the fake orange juice and fake hesperidin supplement, the men in the other two experimental groups experienced a significant reduction in their blood pressure measurements.  Specifically, the diastolic blood pressure was significantly reduced, which suggests that these men experienced an improvement in the elasticity, or compliance, of their arteries, as a direct result of the hesperidin contained in both orange juice and in the non-juice beverage supplemented with hesperidin.  This observation was again confirmed through additional testing that revealed improved vascular compliance associated with hesperidin intake.  Moreover, this significant improvement in arterial compliance was observed only after the ingestion of hesperidin, and disappeared when these same men were retested after undergoing an overnight fast.  (Improved arterial compliance is associated with a reduced risk of cardiovascular disease, including high blood pressure, coronary artery disease, and stroke.)

To summarize the findings of this study, hesperidin, when taken in the form of either orange juice or as a supplement, appeared to significantly improve arterial elasticity, and lower diastolic blood pressure, in middle-aged overweight men.  While this brief study cannot prove that these observed and transient improvements in arterial compliance subsequently reduced the incidence of cardiovascular disease in these high-risk men, there is abundant data from other research studies linking improved arterial compliance with a reduced incidence of cardiovascular disease.  A much larger version of this small pilot study should now be repeated, and the volunteers in this larger study need to be followed for a much longer duration of time, before we can say, with certainty, that hesperidin significantly reduces the risk of cardiovascular disease.  That being said, the findings of this small but well-conducted, and elegant, randomized, controlled, prospective clinical research study are still quite compelling.

   

HAPPY HOLIDAYS TO OUR MANY HEALTH-CONSCIOUS

WEEKLY HEALTH UPDATE” READERS AROUND THE WORLD!

 

PEACE, LOVE, AND GOOD HEALTH TO ALL OF YOU!

 

For a complete discussion of the role of dietary flavonoids and polyphenols in cancer prevention, and other important evidence-based approaches to cancer prevention, order your copy of my new book, A Cancer Prevention Guide for the Human Race, now!  For the price of a cheeseburger, fries, and a shake, you can purchase this landmark new book, in both paperback and e-book formats, and begin living an evidence-based cancer prevention lifestyle today!

 

GIVE  THE  GIFT  OF  HEALTH  THIS  HOLIDAY  SEASON!  For a groundbreaking overview of cancer risks, and evidence-based strategies to reduce your risk of developing cancer, order your copy of my new book, A Cancer Prevention Guide for the Human Race,” from Amazon, Barnes & Noble, Books-A-Million, Vroman’s Bookstore, and other fine bookstores! 

On Thanksgiving Day, A Cancer Prevention Guide for the Human Race was ranked #6 among all cancer-related books on the Amazon.com Top 100 Bestseller’s List for Kindle e-books!  On Christmas Day, 2010, A Cancer Prevention Guide for the Human Race was the #1 book on the Amazon.comTop 100 New Book Releases in Cancer” list!



Disclaimer: As always, my advice to readers is to seek the advice of your physician before making any significant changes in medications, diet, or level of physical activity


Dr. Wascher is an oncologic surgeon, a professor of surgery, a cancer researcher, an oncology consultant, and a widely published author


For a different perspective on Dr. Wascher, please click on the following YouTube link: 

Texas Blues Jam


I and the staff of Weekly Health Update would again like to take this opportunity to thank the more than 100,000 health-conscious people, from around the world, who visit this premier global health information website every month.  (As of 9/16/2010, more than 1,000,000 health-conscious people have logged onto Weekly Health Update so far this year!)  As always, I enjoy receiving your stimulating feedback and questions, and I will continue to try and personally answer as many of your inquiries as I possibly can.



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Soy, Curcumin & Prostate Cancer Risk

 

Welcome to Weekly Health Update


“A critical weekly review of important new research findings for health-conscious readers”



SOY, CURCUMIN & PROSTATE CANCER RISK

Because chronic inflammation within the prostate gland is through to be an important risk factor for prostate cancer, anti-inflammatory dietary supplements and medications may be able to reduce the risk of prostate cancer by reducing inflammation.

Isoflavones from soy-based foods are known to act as a weak form of estrogen (the dominant female sex hormone).  Based upon this estrogen-like behavior, as well as potential anti-inflammatory properties, soy isoflavones are being studied as possible prevention and treatment agents for prostate cancer, and other types of cancer. 

Curcumin, which is present in the Indian curry spice turmeric, is also known to have potent anti-inflammatory properties, and has also been the subject of considerable cancer prevention and cancer treatment research.

A newly published prospective, randomized, blinded, placebo-controlled research study, published in the current issue of the journal Prostate, suggests that the combination of soy isoflavones and curcumin may have important potential prostate cancer prevention properties.

In the first part of this study, human prostate cancer cells were treated with a combination of soy isoflavones and curcumin.  Treatment of these human cancer cells with soy isoflavones and curcumin resulted in a significant reduction of prostate-specific antigen (PSA) production by these malignant cells (PSA is a marker of both prostate gland inflammation and prostate gland cancer).

As regular readers of this column are already aware, treatments performed in the laboratory that have beneficial effects on cancer cells, or on mice or rats, do not always have the same positive effects on living, breathing human beings.  Therefore, the findings of the second part of this study are of particular interest.  A total of 85 men with elevated PSA levels, but without prostate cancer (as confirmed by prostate biopsy), were enrolled in the second phase of this intriguing small study.  These 85 men were divided into two groups, and one group received daily supplements containing both soy isoflavones and curcumin, while the second (control) group of men received placebo (sugar) pills that were identical in appearance to the supplement pills (neither the 85 men, nor the nurses who dispensed the supplement pills and placebo pills, were aware of which pills each study volunteer was receiving until after the research study had been completed).

PSA blood levels were tested at the beginning of the clinical portion of this study, and once again 6 months later.  As was observed in the prostate cancer cells during the first part of this study, men with a PSA level of 10, or higher, experienced a significant reduction in their blood PSA levels 6 months after starting daily supplementation with soy isoflavones and curcumin.

Although this brief study cannot definitively confirm that soy isoflavone and curcumin supplements reduce the risk of prostate cancer, their ability to reduce elevated PSA levels in men with chronic prostate inflammation, but without evidence of prostate cancer, at least suggests a potential role in the prevention of prostate cancer (presumably through a reduction in prostate gland inflammation).

While there are multiple human research studies underway that are evaluating the effectiveness of soy isoflavones as cancer prevention agents, currently, there are no major human studies looking at the effects of curcumin on prostate cancer risk.  Based upon the findings of this small, interesting study of soy isoflavones and curcumin, which suggest a potential additive effect on PSA reduction when both of these dietary supplements are taken together, human research trials should be developed to look at the long-term impact, if any, of combined soy isoflavone and curcumin supplementation on prostate cancer risk.

 

For additional research information on soy isoflavones and curcumin in cancer prevention and cancer treatment, please review the following previous columns:

Soy Foods & Stomach Cancer Risk

Cruciferous Vegetables, Soy & Breast Cancer Risk

Soy Isoflavones & Recurrent Prostate Cancer

Soy Isoflavones Decrease Breast Cancer Recurrence Risk

Genistein (Soy Isoflavone) & Prostate Cancer

Diet, Soy & Breast Cancer Risk

Viagra & Sexual Function in Women; Patient-Reported Adverse Hospital Events; Curcumin & Pancreatic Cancer



To learn more about the role of soy isoflavones and curcumin in the prevention of cancer, look for the publication of my new landmark book, “A Cancer Prevention Guide for the Human Race,” in the summer of this year.  


Disclaimer: As always, my advice to readers is to seek the advice of your physician before making any significant changes in medications, diet, or level of physical activity


Dr. Wascher is an oncologic surgeon, a professor of surgery, a cancer researcher, an oncology consultant, and a widely published author  


For a different perspective on Dr. Wascher, please click on the following YouTube link: 


http://www.youtube.com/watch?v=7-Tdv7XW0qg



I and the staff of Weekly Health Update would like to take this opportunity to thank the more than 100,000 new and returning readers who visit our premier global health information website every month.  As always, we enjoy receiving your stimulating feedback and questions, and I will continue to try and personally answer as many of your inquiries as I possibly can.



 

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Soy Isoflavones Reduce Breast Cancer Recurrence Risk

Welcome to Weekly Health Update



 

“A critical weekly review of important new research findings for health-conscious readers”


SOY ISOFLAVONES REDUCE BREAST CANCER

RECURRENCE RISK

 

 

Regular readers of this column are already aware of the controversy surrounding soy isoflavone intake and breast cancer risk.  As happens frequently in clinical research (unfortunately), contradictory research findings have made it difficult to understand the true relationship between dietary soy intake and breast cancer risk (if one exists).  There is, for example, both laboratory and clinical data suggesting that a diet rich in soybean-derived products may be associated with a lower risk of developing breast cancer.  At the same time, because genistein and other dietary isoflavones are known to weakly mimic the effects of estrogen, there has been some concern that a diet rich in isoflavone “phytoestrogens” may increase both the risk of developing a new breast cancer and the risk of developing a recurrence of a previous breast cancer.  (In fact, there is data from laboratory research studies showing that genistein can indeed fuel the growth of human breast cancer cells growing in culture dishes, when exposed to high concentrations of this soy-derived isoflavone.)

 

A growing body of public health research, primarily from Asian countries where tofu and other soy-based foods are frequently consumed, appears to link increased soy consumption with a decreased lifetime breast cancer risk, particularly when soy-based foods are consumed during adolescence, during the time when development of the female breast is most active (Soy & Breast Cancer Risk).  (Interestingly, there is also recent research suggesting that soy products might also reduce the risk of prostate cancer, which is another hormonally driven cancer:   Genistein & Prostate Cancer Cells, Dietary Soy & Prostate Cancer Risk.)

 

Although epidemiological research is, increasingly, suggesting that a diet rich in soybean-derived foods might lower a woman’s lifetime risk of developing breast cancer, many breast cancer experts have remained apprehensive regarding dietary isoflavone intake in women with a prior history of breast cancer, in view of the estrogen-like effects of these “phytoestrogens.”  As I have already noted, there is considerable research data available to suggest that soy-derived isoflavones can, at least under certain laboratory conditions, stimulate estrogen-sensitive breast cancer cells to grow and divide.  These research findings have left many oncologists feeling uncomfortable in recommending soy-based foods to their breast cancer patients.  Now, a newly publish public health study in the Journal of the American Medical Association suggests that soy-based foods may actually reduce the risk of breast cancer recurrence, and death due to any cause, in women who have previously been diagnosed with this very common form of cancer.

 

In this study, which was performed in Shanghai, China, 5,042 female breast cancer survivors (ages 20 to 75 years) were followed for an average of almost 4 years.  All of these patient volunteers underwent detailed surveys regarding their lifestyle habits, including their diets.  These patients, who were originally diagnosed with breast cancer between 2002 and 2006, were surveyed at 6, 18, 36 and 60 months following their original diagnosis with breast cancer.  

 

The results of this study indicate that the breast cancer survivors who consumed the greatest amount of soy-based foods in their daily diets were 32 percent less likely to experience a recurrence of their breast cancer when compared to the women who consumed the least amount of soy-based isoflavones.  Moreover, the women who consumed the greatest amount of soy were also 29 percent less likely to die, from any cause, when compared to the women who consumed the least amount of soy-derived foods.

 

A particularly interesting and unexpected finding of this study was that both women with estrogen sensitive breast cancers and women with tumors that were not sensitive to estrogen appeared to experience a significantly decreased risk of breast cancer recurrence if they frequently consumed soy products.  Another important finding of this study was that women who were taking the estrogen-blocking cancer treatment drug tamoxifen also appeared to enjoy a reduced risk of breast cancer recurrence with higher levels of dietary soy intake.  Additionally, the researchers noted that high levels of soy intake appeared to be about as effective in reducing the risk of breast cancer recurrence as the breast cancer prevention drug tamoxifen, alone.

 

The results of this very important study mirror the findings of the only other prospective clinical study that has looked at the impact of soy-based foods on breast cancer recurrence (the “Life After Cancer Epidemiology,” or “LACE,” study).  The LACE study, which was performed in the United States, followed nearly 2,000 breast cancer survivors for, on average, more than 6 years.  In the LACE study, women who were taking tamoxifen, and who also consumed the highest amount of soy-based dietary isoflavones, were 50 percent less likely to develop a recurrence of their breast cancer when compared to women who reported the lowest consumption of soy-derived foods.

 

As I have pointed out previously, epidemiological research studies based upon dietary surveys are susceptible to several types of bias which, in turn, can cause researchers to draw the wrong conclusions.  In this case, however, there are now two large prospective cohort studies that have reached essentially the same conclusions (albeit with a rather limited duration of patient follow-up).  Both studies strongly suggest that high levels of soy-based isoflavones in the diet may be able to significantly reduce the risk of breast cancer recurrence.  Based upon the findings of this large Chinese study, the apparent cancer risk reduction effect associated with high levels of soy intake also appears to benefit premenopausal and postmenopausal women, as well as women who are taking the estrogen-blocking drug tamoxifen, women with estrogen-sensitive tumors, and women with (counter-intuitively) estrogen-resistant tumors.

 

In view of the limited duration of patient follow-up in both of these clinical breast cancer studies, as well as the limitations of survey-based epidemiological research in general, I would like to see updated data from both of these studies after at least 10 years of patient observation before I would be willing to tell my breast cancer patients that they should significantly increase their dietary soy intake.  On the other hand, the rather compelling data presented by both of these clinical research studies will also make me less anxious when any of my breast cancer patients decide, of their own accord, to increase their intake of soy-derived isoflavones.

 

 

Note:  Weekly Health Update is currently undergoing an extensive upgrade to better serve its tens of thousands of health-conscious readers around the world.  Beginning in January 2010, newly archived columns will be available by selecting the “Archives” tab on the right side of your screen (all archived columns prior to January 2010 will continue to be available by selecting the “Archives 2007-2009” tab at the top of the screen.)


 


Disclaimer: As always, my advice to readers is to seek the advice of your physician before making any significant changes in medications, diet, or level of physical activity


Dr. Wascher is an oncologic surgeon, a professor of surgery, a cancer researcher, an oncology consultant, and a widely published author

 

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