New research presented recently at ENDO 2001, the 83rd Annual Meeting of The Endocrine Society, in Denver, Colorado, shows a link between postmenopausal health and dietary phytoestrogens. A panels of researchers presented three new studies, which demonstrate that phytoestrogens -- a compound found in legumes such as soybeans, soybean sprouts, and soy products such as tofu and soymilk -- may benefit the health and, specifically, bones of postmenopausal women.
In a study out of China, researchers studied 357 postmenopausal Chinese women to determine whether a link exists between dietary phytoestrogen intake and bone mineral density. Among the subjects, the average phytoestrogen intake was 21 mg/day -- a number that is seven times higher than the phytoestrogen intake of the Western population. The study showed a link between high phytoestrogen intake and increases in bone mineral density.
We found that women who ate 60 milligrams of phytoestrogens per day, which is the equivalent of two pieces of tofu or 3 cups of soy milk, had stronger bones said Dr. Annie Kung, Professor at the University of Hong Kong, Queen Mary Hospital, who presented the study at the press conference. These results suggest that phytoestrogens might help protect women's bones as they go through menopause.
Another study, which was presented by Dr. Trent Lund, an endocrinologist and researcher at Colorado State University, found a link between a diet high in phytoestrogens and decreases in body fat, body weight, prostate weight and blood pressure as well as alterations in insulin and leptin levels in adults. In the study, which was conducted by researchers at Colorado State University and Bringham Young University, male and female rats were fed either a phytoestrogen-rich diet or a phytoestrogen-free diet. The research showed that leptin levels significantly increased in both male and female rats that were fed phytoestrogen-rich diets compared with rats who received phytoestrogen-free diets. According to Dr. Lund, the insulin levels in female rats who were fed phytoestrogen-rich diets were also significantly increased compared with females fed the phytoestrogen free diet.
Finally, Dr. Lee-Jane Lu, an investigator in nutrition research, and her colleagues-Drs. Manubai Nagamani and Karl E. Anderson-at the University of Texas Medical Branch in Galveston, presented a study conducted in the university's General Clinical Research Center that examined whether soy consumption alters bone metabolism in postmenopausal women. The researchers studied the markers that reflect bone turnover in 12 healthy, postmenopausal women not on hormone replacement therapy. The women were studied before, during and after they ate a soy diet containing 112 mg of isoflavones for 16 weeks.
Our findings suggest that soy consumption may stimulate bone turnover or formation, said Dr. Lee-Jane Lu. Additional studies are now needed to determine whether soy diets have a long term beneficial effect on bone and a direct impact on fracture rates in women.
***********************
The popular Reader's Digest recommends soy products such as tofu as one of the top foods that are most needed for good health.
Writing in the July issue, author Maureen Callahan reports on Five Foods Men and Women Need Most,'' and says that foods high in soy protein are among the foods recommended particularly for women.
Foods high in soy protein can lower cholesterol and may minimize menopausal hot flashes and strengthen bone,'' the Reader's Digest article says. The reason is that soy foods contain isoflavones, the plant chemicals found at their highest level in soybeans.
The article cites one study on human consumption of soy that found that 90 milligrams of isoflavones daily was beneficial to bone, specifically the spine.''
Two other studies suggest that 50 to 76 milligrams of isoflavones a day may offer some relief from hot flashes,'' the Reader's Digest said. Half a cup of tofu contains about 25 to 35 milligrams of isoflavones, the article pointed out.
***********************
Results of a new University of California study show that men who are at risk of prostate cancer can include more soy products such as tofu and soy milk in their diets.
Dr. Ralph deVere White, director of the University of California at Davis Cancer Center, presented the study at a meeting of the American Urological Association here and said that, although the initial tests were conducted on mice and need to be replicated on humans, we are encouraged by these results.
The soy compound genistein, an isoflavone, slowed prostate growth in the test mice and caused prostate cancer cells to die.
We've identified the mechanisms by which genistein may work in prostate cancer, Dr. White said. While we are encouraged by these results, we need to test genistein in patients with prostate cancer to be certain of its effectiveness.
Prostate cancer is estimated to kill more than 40,000 men in the United States each year. The American Cancer Society anticipates 334,500 new cases of prostate cancer in the U.S. this year.
Dr. White and a team of researchers now are evaluating the effects of genistein in men who have been diagnosed with slow-growing prostate cancer. The University of California at Davis Cancer Center will enroll 70 men in a pilot study to determine whether genistein can lower prostate specific antigen (PSA), a tumor marker widely used to find prostate cancer. Results of the further study are expected to be known next year.
Dr. White said it is unlikely that genistein alone can be used as a singular treatment for prostate cancer, which is the most common cancer among American men, but that he hopes genistein can be used with conventional anti-cancer therapy or preventive drug to combat prostate cancer.
***********************
Permission is granted to reprint this information, as long as credit is given to Soyfoods USA
