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Soy Found To Reduce the Risk of Breast Cancer December 9, 2009

Posted by feminestra in Breast Cancer, Health, Menopause, Natural Menopause Relief, Prevention, Uncategorized.
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In a report published in the December 9 issue of the Journal of the American Medical Association (JAMA)1, researchers in China found that breast cancer survivors who had higher intake levels of soy foods were at a lower risk of breast cancer recurrence and death. The authors of this study explained that, “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.”1

The study analyzed data from the Shanghai Breast Cancer Survival Study which was a population-based study using over 5,000 female breast cancer survivors aged 20-75. The women were diagnosed between March 2002 and April 2006 and were studied through June 2009. The study collected data about the cancer diagnosis and treatment, lifestyle after diagnosis, and cancer progression roughly six months after the initial diagnosis. The patients were reassessed after 18, 36, and 60 months after initial diagnosis.

After a follow up of 4 years there were a documented 444 deaths and 534 cancer recurrences or breast cancer-related deaths among the 5,033 patients who where surgically treated for breast cancer. The patients who had the highest intake of soy protein had a 29 percent lower risk of death and a 32 percent lower risk of breast cancer recurrence. The researchers explained in their study that, “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.”1

Soy has also been found to help with many other conditions such as menopausal symptoms and osteoporosis. Soy can be found in a number of things from chocolate bars (soy lecithin) to potato chips as well as many vegetarian food products.

2

Uses based on scientific evidence Grade*
Dietary source of protein

Soy products, such as tofu, are high in protein and are an acceptable source of dietary protein.

A
High cholesterol

Numerous human studies report that adding soy protein to the diet can moderately decrease blood levels of total cholesterol and low-density lipoprotein (“bad” cholesterol). Small reductions in triglycerides may also occur, while high-density lipoprotein (“good” cholesterol) is altered in some, but not all, studies. Some scientists have proposed that specific components of soybean, such as the isoflavones genistein and daidzein, may be responsible for the cholesterol-lowering properties of soy. However, this has not been clearly demonstrated in research and remains controversial. It is not known if products containing isolated soy isoflavones have the same effects as regular dietary intake of soy protein. Dietary soy protein has not been proven to affect long-term cardiovascular outcomes, such as heart attack or stroke.

A
Diarrhea (acute) in infants and young children

Numerous studies report that infants and young children (2-36 months old) with diarrhea who are fed soy formulas experience fewer daily bowel movements and fewer days of diarrhea. This research suggests that soy has benefits over other types of formula, including cow milk-based solutions. The addition of soy fiber to soy formula may increase the effectiveness. Better quality research is needed before a strong recommendation can be made.Parents are advised to speak with qualified healthcare providers if their infants experience prolonged diarrhea, become dehydrated, develop signs of infections (such as fever), or have blood in the stool. A healthcare provider should be consulted for current breastfeeding recommendations and to suggest long-term formulas that provide enough nutrition.

B
Allergies (prevention of food allergies)

Soy formulas are commonly used by infants with sensitivities to milk-based formulas. There is currently little evidence to support the use of soy formulas for preventing food allergies. Further research is needed in this field.

C
Antioxidant

There is some evidence in support of soy increasing antioxidant status in humans. In general, diets high in plant foods may offer antioxidant benefits. Further research is required in this field before recommendations can be made.

C
Bowel/intestinal disorders

The effect of soy on erosive-ulcer lesions of the alimentary tract has been examined in limited study. Overall, the effects of soy products appear beneficial. Further study is required before recommendations can be made.

C
Cancer (prevention and treatment)

Several large population studies have asked people about their eating habits and reported that higher soy intake (such as dietary tofu) is associated with a decreased risk of developing various types of cancers, including breast, prostate, and colon cancer. However, other research suggests that soy does not have this effect. Until better research is available, it remains unclear if dietary soy or soy isoflavone supplements increase or decrease the risk of these cancers.

C
Cardiovascular disease

Dietary soy protein has not been shown to affect long-term cardiovascular outcomes, such as heart attack or stroke. Research does suggest cholesterol-lowering effects of dietary soy, which in theory, may reduce the risk of heart problems. Soy has also been studied for blood pressure-lowering and blood sugar-reducing properties in people with type 2 diabetes, although the evidence is not definitive in these areas. In women with suspected cardiac ischemia, high levels of the soy isoflavone genistein have been associated with blood vessel problems. Further investigation is needed before a strong recommendation can be made.

C
Cognitive function

It is unclear if soy isoflavone supplementation in postmenopausal women can improve cognitive function. Results from studies are mixed.

C
Crohn’s disease

Due to limited human research, there is not enough evidence to recommend for or against the use of soy as a way to prevent Crohn’s disease. Further research is needed before a recommendation can be made.

C
Cyclical breast pain

It has been theorized that the “phytoestrogens” (plant-based compounds with weak estrogen-like properties) in soy may be beneficial to premenopausal women with cyclical breast pain. However, due to limited human research, there is not enough evidence to recommend for or against the use of dietary soy protein as a therapy for this condition.

C
Diabetes

Several small studies have examined the effects of soy products on blood sugar levels in people with type 2 (“adult-onset”) diabetes. Results are mixed, with some research reporting decreased blood glucose levels and other trials noting no effects. Overall, research in this area is not well designed or reported and better information is needed.

C
Exercise performance enhancement

Soy protein has been investigated as a source of protein with potential for benefit in exercise performance. In general, research findings suggest soy protein is better than no protein but is unlikely to be superior to other sources of protein. Further research is required in this field.

C
Gallstones (cholelithiasis)

Due to limited human research, there is not enough evidence to recommend for or against the use of soy as a therapy in cholelithiasis. Further research is needed before a strong recommendation can be made.

C
Gastrointestinal motility

In limited available studies, the addition of soy polysaccharide to non-regular diets increased the moisture content of stool and decreased the number of liquid stools. It is not clear if soy polysaccharide would be superior to other fiber sources in this regard.

C
High blood pressure

There is limited human research on the effects of dietary soy on blood pressure. Some research suggests that substituting soy nuts for non-soy protein may help improve blood pressure. Further research is needed before a firm recommendation can be made.

C
Infantile colic

There is currently a lack of scientific evidence to recommend for or against the use of soy formula for fussiness and gas in infants with cow’s milk allergy over a partially hydrolyzed cow’s milk protein formula.

C
Inflammation

There is currently a lack of scientific evidence to recommend for or against the use of soy protein on inflammation associated with hemodialysis (removal of waste products from the blood).

C
Iron deficiency anemia

There is currently a lack of sufficient evidence to recommend for or against the use of soy-based formula in the treatment of iron deficiency anemia in children.

C
Kidney disease (chronic renal failure, nephrotic syndrome, proteinuria)

Due to limited human study, there is not enough evidence to recommend for or against the use of soy in the treatment of kidney diseases, such as nephrotic syndrome. People with kidney disease should speak with their healthcare providers about the recommended amounts of dietary protein because soy is a high-protein food.

C
Menopausal symptoms

Overall, evidence suggests that soy products containing isoflavones may help reduce menopausal symptoms, such as hot flashes. More study is needed to confirm this use.

C
Menstrual migraine

A phytoestrogen combination may help prevent menstrual migraine attacks. Further research is needed before a strong recommendation can be made.

C
Metabolic syndrome

Treatment with soy protein and soy nuts was evaluated in patients with metabolic syndrome and benefits were found in terms of plasma lipids in patients consuming soy nuts as part of the DASH (Dietary Approaches to Stop Hypertension) diet. Further research is required in this field in terms of soy protein supplementation.

C
Obesity/weight reduction

Some research suggests that soy might be as effective as skim milk and more effective than a low-calorie diet alone in reducing weight. Other research has reported conflicting results. Further research is needed before a strong recommendation can be made.

C
Osteoarthritis

Osteoarthritis is a form of arthritis caused by the breakdown of cartilage. Early research suggests that intake of soy protein may be associated with reduced symptoms of osteoarthritis.

C
Osteoporosis

It has been theorized that “phytoestrogens in soy” (such as isoflavones) may increase bone mineral density in post-menopausal women and reduce the risk of fractures. However, more research is needed before a conclusion can be made.

C
Quality of life

The effect of soy on quality of life has been investigated in limited study. Further study is required before recommendations can be made.

C
Rheumatoid arthritis

There is currently insufficient evidence to recommend for or against the use of soy as a treatment for rheumatoid arthritis.

C
Skin aging

It is unclear if aglycones, a form of soy isoflavone, can improve aged skin in middle-aged women when it is taken by mouth. More research is needed.

C
Skin damage caused by the sun

A soy moisturizing cream may help improve signs of sun damage, including discoloration, blotchiness, dullness, fine lines, and overall texture. Because the cream contained other ingredients besides soy, more research with soy alone is needed.

C
Spinal cord injury

Whey protein has traditionally been used as a protein source to increase body strength. Limited available study investigated whether soy protein could be used to increase ambulation performance in patients with incomplete spinal cord injury. There is currently not enough evidence to recommend for or against the use of soy as a treatment for increased endurance in individuals with spinal cord injury.

C
Thyroid disorders

Early research suggests that soy supplements do not affect thyroid function. More research is needed.

C
Tuberculosis

It has been suggested that soy may be beneficial for tuberculosis when taken with standard medications. According to early research, soy may improve the process of detoxification, have positive effects on the liver, reduce cell damage, and decrease inflammation. Therefore, soy supplements may allow patients to safely take higher doses of antimicrobial drugs that are used to treat tuberculosis.

C
Weight gain (infants)

In limited study, weaning infants with cow’s milk allergy to soy based formula resulted in reduced weight for age as compared with formulas containing hydrolyzed proteins (broken down). Further research is required in this field.

C

*Key to grades

A: Strong scientific evidence for this use;

B: Good scientific evidence for this use;

C: Unclear scientific evidence for this use;

D: Fair scientific evidence against this use;

F: Strong scientific evidence against this use.

Learn more about Soy

Creative Commons License
Soy Found To Reduce the Risk of Breast Cancer by Feminestra is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 United States License.
Sources: 1Journal of the American Medical Association jama.ama-assn.org.
2MedlinePlus http://www.nlm.nih.gov

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