Phyllis A. Balch, CNC
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 Once considered a wonder food, soy-based infant formulas are now under attack from some scientists and physicians who predict that infants may develop hormonal imbalances due to the presence of soy isoflavones, which act as phytoestrogens (plant-based estrogens). However, many other scientists have stated the opposite. Still, since there are so many alternatives for babies who have problems with milk-based formulas, it might be wiser to stay away from soy-based infant formula. Also, soymilk should not be substituted for soy formula. |
Steven G. Pratt, M.D. and Kathy Matthews
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 Moreover, it's not clear if soy isoflavones behave exactly the way they do when they arrive in our bodies via the whole food. My recommendation is to avoid them.
Kitchen Tofu Tip
Many people are unaware that tofu, like milk or meat, is perishable. It won't last forever in the fridge. Pay attention to the expiration date on the package when you buy it (look for the latest date as you would on milk), keep it refrigerated at all times, and change the water in the package daily. Moreover, remember that tofu, like meat, can host unfriendly bacteria like salmonella. |
Phyllis A. Balch, CNC
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| One group of phytochemicals unique to soybeans is soy isoflavones. On the molecular level, they are similar to the female hormone estrogen, yet different enough to be called weak estrogens. They are also antioxidants. Genistein and daidzein are the two primary isoflavones in soybeans. Extensive studies have shown that these isoflavones can help to guard against various cancers, prevent bone loss, and lower cholesterol. |
| A 1998 study concluded that the regular consumption of soy isoflavones might reduce total cholesterol levels by up to 10 percent. Sources of soy protein are soymilk, tempeh, tofu, and textured soy protein.
Fish
Research has shown over and over that people who often eat omega-3-rich fish have a lower risk of heart disease than those who don't eat it as often. In addition to lowering triglyceride levels, research suggests that omega-3s make the blood more slippery and less likely to clot. The American Heart Association recommends eating fish two or three times a week. |
the Editors of FC&A Medical Publishing
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 Be sure you know the amount of soy isoflavones you consume each day, and avoid soy supplements and soy-enriched foods (like some nutritional bars) until more research is done.
The following chart will help you determine the isoflavone content of some common soy products.
How many soy isoflavones do you consume each day?
Food
Milligrams of isoflavones*
Serving size (approximate)
Bacon, meatless
1.9
2 strips (1/2 ounce)
Granola bar (hard, plain)
.1
3.5 ounces
Harvest Burger,
(all vegetable protein patty)
8. |
The Life Extension Editorial Staff
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 For example, some soy isoflavones (a type of phytoestrogen) benefit bone but do not affect the kidney. In drug lingo, this is called a selective estrogen receptor modulator (SERM). A compound in soy, genistein, is a natural SERM. Tamoxifen and Ralox-ifen are chemical SERMs (Setchell et al. 1999).
The latest science available suggests that the reason that different estrogens have different effects on different tissues is because there is more than one type of estrogen receptot. So far, three variations on the estrogen receptor have been found: alpha and two betas. |
Kaayla T. Daniel, PhD, CCN
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 Conceivably scientists could breed and cultivate plants to achieve the most beneficial mix but no one has yet determined what that mix might be.10
Isoflavones in the soybean exist primarily in the glucoside forms of genistein, daidzein and glycitein, but must be converted to the aglucone forms of genistin, daidzin and glycitin to be absorbed. The fact that the glucoside forms have not been found in plasma indicates that they cannot be transported intact across the gut mucosa. To be absorbed, an enzyme known as beta-glycosidase must first chip off a sugar. |
volker schulz and Rudolf Hansel
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 All other potentially beneficial effects of soy isoflavones are less well documented. At this time, it is still impossible to state definitively whether the compounds can reduce the risk of breast or prostate cancer, osteoporosis, or hot flashes. However, this is a very fast-moving research field, and many present conclusions will almost certainly be subject to change as additional data become available. |
Earl Mindell
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 Since estrogen replacement began in the 1960s, it has been linked to a 35 percent increase in uterine cancer. soy isoflavones, particularly genistein and daidzein, are estrogen-like compounds that can not only help relieve the symptoms of menopause, such as hot flashes, irritabiUty, and vaginal dryness, they can help protect against cancer as well. In fact, the combination of soy isoflavones, plus calcium, magnesium, vitamin D, and boron, has also been found helpful in preventing osteoporosis!
Getting Well and Staying That Way
253. |
The Life Extension Editorial Staff
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| V PRODUCT AVAILABILITY
Acetyl-L-camitine, alpha-lipoic acid, NAC, ptegnenolone, DHEA, Life Extension Mix, Creatine NGH Powdet, pregnenolone, petilla and borage oils, coenzyme Qiq, branched-chain amino acids, Sports Ginseng, CLA, TMG, vinpocetine, methylcobalamin, SAMe, zinc lozenges, glutathione, selenium, L-cysteine, DMG, soy isoflavones, melatonin, beta carotene, and magnesium are available by calling (800) 544-4440 ot otdeting online at www.lef.org. Hydergine is available by prescription in the United States or from overseas pharmacies. |
Kaayla T. Daniel, PhD, CCN
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| In addition, the modern industrial soy processing techniques used to make soy protein isolate, textured vegetable protein and other modern soy products create toxic and carcinogenic residues (see Chapters 11 and 22-23). Finally, soybeans naturally contain goitrogens, allergens, protease inhibitors and other antinutrients and toxins that damage the digestive, immune and neuroendocrine systems, putting consumers at increased risk for many health problems, including cancer (see Chapters 16-20, 24-25 and 27). |
volker schulz and Rudolf Hansel
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| Because Chinese man have a relatively low incidence of prostate disease, these findings tend to support the conclusion that high concentrations of soy isoflavones in the prostatic fluid may have a protective role (Morton et al., 1997).
A recent randomized placebo-controlled open clinical trial tested the influence of daily doses of mixtures of isoflavones from red clover (Trifolium pratense) on arterial compliance, an index of the elasticity of large arteries, in 17 (14 active, 3 placebo) menopausal women. |
| Four of the groups consumed daily for 9 weeks a beverage containing 25 g of soy protein and various levels (trace, 25 mg, 42 mg, and 58 mg) of soy isoflavones. The fifth group consumed a placebo consisting of casein.
The soy protein containing 58 mg of isoflavones reduced both total (8 %) and LDL (10 %) cholesterol levels in persons with initially high baseline LDL (>i6o mg/dl). Effects were decremental with decreasing isoflavones (Crouse et al., 1998). |
The Life Extension Editorial Staff
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| Children's Hospital and Medical Center in Cincinnati, Ohio confirmed the estrogenic activity of the principal soy isoflavones daidzein, genistein, and glycitein (Setchell et al. 2001)- Setchell conducted research on the chemical structure and metabolism of soy phytoestrogens and concluded that consuming modest amounts of soy protein results in relatively high blood concentrations of phytoestrogens, and that this could have a significant hormonal effect in many individuals (Setchel 1998). |
Heather Boon, BScPhm, PhD and Michael Smith, BPharm, MRPharmS, ND
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 A randomized, placebo-controlled trial (n=49) found that a phytoestrogen combination containing 60 mg soy isoflavones, 100 mg dong quai and 50 mg black cohosh significantly decreased the frequency of menstrual migraine attacks as well as significantly decreasing the frequency of all migraines, headache severity, doses of triptans and doses of analgesics compared to the placebo group when ingested for 24 weeks.17 The clinical contributions of the dong quai in this product cannot be determined from this study. |
| Another randomized, placebo-controlled trial (n=49) found that a phytoestrogen combination containing 60 mg soy isoflavones, 100 mg dong quai and 50 mg black cohosh significantly decreased the frequency of menstrual migraine attacks as well as significantly decreasing the frequency of all migraines, headache severity, doses of triptans and doses of analgesics compared to the placebo group when ingested for 24 weeks.24 The clinical contributions of the black cohosh in this product cannot be determined from this study. |
The Life Extension Editorial Staff
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| Researchers who have investigated the effects of soy isoflavones on estrogen metabolism report that genistein causes cancet cells to metabolize estradiol to "estrogenically weaker or inactive metabolites" (Brueggemeier et al. 2001).
The big news on soy is the discovery of a new estrogen receptor that soy phytoesttogens naturally activate. The receptor, known as ERb, appears to suppress the activation of ERa, which allows growth-promoting estradiol into cancet cells (Pettersson et al. 2000). |
Henry Pasternak, D.V.M., C.V.A.
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 The soy isoflavones and other chemicals inhibit thyroid peroxidase, a key thyroid enzyme.
If you are thinking that this might be a good treatment for feline hyperthyroidism, it is unlikely that cats will ingest enough soy protein to be of benefit; however, research in this area might prove interesting. Unfortunately, the inhibition of thyroid per-oxidase-catalyzed reactions results in decreased levels of circulating thyroid hormones, which lead to increased secretion of TSH by the anterior pituitary. |
Laurie Deutsch Mozian, M.S., R.D.
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 You begin to include in your diet about 100 milligrams of soy isoflavones daily. You soon notice that your night sweats and hot flashes diminish in frequency and severity. You now have evidence that the phytochemicals are working. The amount of time it takes to experience relief from a certain condition will vary from person to person and disease to disease. Some women have reported almost immediate results from symptoms of menopause with the addition of soy products to their diets, but it will take longer, say, to affect cholesterol levels with the same soy intake. |
| About 45 milligrams of soy isoflavones may begin to offer relief from symptoms of menopause.
When it comes to the long-range consequences of decreased estrogen on women's health, the data on the value of soy foods are favorable. More than thirty years of research has shown that the inclusion of soy protein in the diet can lower serum cholesterol significantly. Intakes of 25 to 50 grams of soy protein daily can result in a 10-percent drop in heart-damaging low-density-lipoprotein cholesterol levels. |
| One animal study and three short-term studies on postmenopausal women show that soy isoflavones help to reduce bone loss.
You may find that the research on isoflavones found in legumes is dominated by references to soy foods. Soybeans are slightly higher in total isoflavone content than other beans, but I would be remiss if I did not point out that most legumes, including black beans, kidney beans, pinto beans, lentils, and lima beans all are rich sources of isoflavones and can promote a healthy menopause.
Flaxseeds
Flaxseeds contain lignans, which are rich sources of phytoestrogens. |
| Those who received 40 grams of soy protein containing 80 milligrams of soy isoflavones a day experienced an increase in bone mineral density. Studies that examine bone density over at least a two-year period are needed to confirm the apparent findings. Some studies suggest that genistein inhibits bone breakdown, and others show that isoflavones stimulate bone formation. Animal studies show that soymilk accelerates intestinal calcium absorption. If you are depending on tofu as a source of calcium, check the label to ensure that calcium is added. |
Textbook of Natural Medicine 2nd Edition Volume 1Michael T. Murray, ND
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| After examining plasma, fecal and urinary concentrations of isoflavones in healthy volunteers, Xu et al6 concluded that the bioavailability of soy isoflavones is influenced by an intact, healthy gut, with microflora capable of converting these isoflavones to their active forms. Wheat fiber appears to decrease the bioavailability of genistein. A small cross-over study of seven healthy women found that a more fiber-rich diet resulted in 55% less plasma genistein 24 hours after soy intake and a 20% reduction in total urinary genistein. |
| Reprinted with permission from Alternative Medicine Review 1997; 2: 433^50
Introduction 953
Chemical composition 954
Isoflavones 954
Other soy constituents 955
Pharmacology 956
Hormonal effects 957
Mechanism of action of soy isoflavones 959
Clinical applications 959
Cancer 959
Cardiovascular disease 962
Other potential therapeutic benefits 962
Genistein
OH o
Diadzein
O ^ -OH
Figure 112.1 Structure of genistein and diadzein. |
Donald R. Yance, j r.,C.N., M.H., A.H.G., with Arlene Valentine
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 Genistein and other soy isoflavones also have an antiangiogenesis effect on tumors. As noted in chapter 2, angiogenesis is the process that generates new capillary blood vessels, a critical step in the growth and proliferation of solid tumors. Genistein inhibits angiogenesis by neutralizing vascular endothelial growth factor (VEGF), a substance put out by tumors to encourage blood vessel nourishment.
Isoflavones also exert a mild estrogenic effect that may help relieve or eliminate the symptoms of menopause. |
National Women's Health Network
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 Each 600 mg tablet contained 50 mg of soy isoflavones. Total intake of isoflavones was thus 150 mg per day. One hundred forty-nine women completed the study. The trial was nine weeks long. The first week was to establish a baseline, then women received four weeks of either the treatment or the placebo. After that, the subjects crossed over to the other substance.21
Percentages of patients reporting reductions in hot flashes were similar between the two groups. |
Textbook of Natural Medicine 2nd Edition Volume 1Michael T. Murray, ND
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| Although millions of Asians have consumed large quantities of soy foods for hundreds of years without any apparent health risk and seemingly with health benefits, long-term studies are needed to clarify the safety of using soy-based infant formulas and to assess the potential beneficial or adverse effects of consuming phytoestrogens in the form of soy isoflavones early in life.
Adults
Plant lignan and isoflavonoid glycosides are converted by gut bacteria in the intestines to compounds with molecular weights and structures similar to steroid hormones (see Fig. 112.3). |
Robert S. McCaleb, Evelyn Leigh, and Krista Morien
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 Another plausible theory is that soy isoflavones lower levels of lipoprotein(a) [Lp(a)], a cholesterol-carrying particle in the blood that is structurally similar to LDL cholesterol. Lp(a) is a more recently discovered risk factor for heart disease, and one that does not respond to standard dietary, lifestyle, or pharmacological approaches.
The only treatment that has been found to lower Lp(a) is estrogen therapy, an approach that carries serious health risks of its own. |
Donald R. Yance, j r.,C.N., M.H., A.H.G., with Arlene Valentine
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| They also happen to be the best source of genistein and other soy isoflavones, which have a particularly beneficial effect on hormonal receptor-type cancers as well as an antian-giogenesis effect on tumors of any kind.
Although soy foods are relatively unfamiliar in American diets, I recommend including them at least three to four times each week. The recipes included here are easy to prepare and are good examples of the diverse ways you can incorporate this important food group into your diet. |
Textbook of Natural Medicine 2nd Edition Volume 1Michael T. Murray, ND
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| Further studies on the use of soy isoflavones for the prevention and treatment of osteoporosis are warranted.
Eye disorders
Neovascularization complicates many eye disorders, such as proliferative diabetic retinopathy, and is responsible for corneal transplant rejection. Substances which exhibit the capacity to inhibit angiogenesis could play an important role in preventing this vascularization. An animal study demonstrated that genistein, when injected subconjunctivally, inhibited corneal neovascularization. |
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