Another in the ongoing soy thread.."Why soy is so good!"

[kuso]

Why soy is so good!

February 13, 2003


A recent Japanese study found soy has the potential to reduce the risks of postmenopausal osteoporosis and cardiovascular disease in women.
Postmenopausal osteoporosis is associated with oestrogen deficiency. Oestrogens are known to have effects not only on bone metabolism, but also on cholesterol metabolism and blood pressure. Oestrogen replacement therapy is often considered for reducing bone loss and other symptoms in women who have been through menopause.

However such therapy may have serious side-effects. Another option to be considered is the use of weak oestrogen-like compounds. Isoflavones, have an oestrogenic effect and are known as phytoestrogens or plant oestrogens. Soybean has a high isoflavone content and is widely consumed in many Asian countries.

This study examined the possibility that supplemental isoflavone intake would both decrease bone turnover and alter blood lipids in postmenopausal Japanese women who already have high daily dietary intakes of soybean products. Thus, the isoflavone intake during the study was in addition to the common dietary intake among Japanese.

23 healthy Japanese women age 40 - 62 years took part in the study and were randomly assigned to either isoflavone or placebo. 12 women received daily capsules of soy isoflavone extract (61.8mg of isoflavones) and 11 women received placebo capsules for 4 weeks.

The 23 subjects documented their food intake for the trial period. Based on these records, daily isoflavone intakes were calculated for each subject. The results of this study found :


Total and LDL cholesterol decreased significantly in the isoflavone group
Excretion of bone resorption markers was reduced significantly in the isoflavone group thus indicating a reduction in the rate of bone loss
Isoflavone supplementation did not affect liver function
No side effects were detected
The researchers conclude that, "our data confirms isoflavones had beneficial effects on bone and lipid metabolisms, suggesting they may be useful for preventing both osteoporosis and coronary heart diseases."


REFERENCES
Uesugi T et al. Beneficial effects of soybean isoflavone supplementation on bone metabolism and serum lipids in postmenopausal Japanese women: a four-week study. J Am coll Nutr. 2002;21(2):97-102




Other links

http://www.ironmagazineforums.com/showthread.php?s=&threadid=16776

http://www.ironmagazineforums.com/showthread.php?s=&threadid=16689

http://www.ironmagazineforums.com/showthread.php?s=&threadid=16800

 

[kuso]

Plant Hormones

March 1, 1998


The 'menopause' category is one of the largest sectors of the supplement market. Products based on plant hormones are the fastest growing segment of this menopause category. There are two distinct groups of plant hormone products - those based on plant oestrogens, and those based supposedly on plant progesterones.
This news release contains an update on the current state of research with plant oestrogens, followed by a critical look at so-called 'plant progesterones' from the Mexican wild yam.


Phytoestrogen Research Update
Phytoestrogens are natural plant oestrogens that occur in a variety of foods, particularly soy, and have a mild oestrogenic activity. Most of the evidence that natural plant oestrogens (such as the isoflavones) provide protection against a number of chronic diseases has come from observation of populations consuming different diets. These population studies clearly demonstrate that a higher incidence of common cancers (such as colon, breast and prostate cancers) and of coronary heart disease is related to lower amounts of soy phytoestrogens in the diet. On top of this epidemiologic evidence, recent clinical research has shown that phytoestrogens have potential not only in hormone-sensitive conditions but also in conditions, where the effect is independent of their hormonal effects - for example anti-tumour, antioxidant and vascular effects.
Most of the clinical research on phytoestrogens has been with soy foods and supplements containing known levels of isoflavones such as daidzein and genistein. Following is an update on the major areas of research.


Heart Disease
Controlled clinical trials have shown that, when soy is substituted for animal protein, there is a reduction of about 10-20% in total cholesterol, LDL, and the cholesterol : HDL ratio. The lipid-lowering effect is particularly beneficial where the cholesterol is raised to begin with.

Menopause
Pilot studies have indicated that phytoestrogens may reduce the severity of symptoms in women suffering oestrogen-responsive menopausal disorders.
In January this year a significant study was published. Italian researchers carried out a double-blind clinical trial with 104 postmenopausal women; half the group took 60 grams of soy protein daily for 12 weeks, while the other half were given a placebo. By the end of the twelfth week patients taking soy had a 45% reduction in daily hot flushes compared with only a 30% for those on placebo.


Osteoporosis
Studies have shown that soy foods may prevent postmenopausal bone loss and osteoporosis in women. The isoflavones help to both decrease loss of calcium and to increase bone density.

Cancer
There are a number of controlled trials being carried out in subjects who are at high risk for colon, breast and prostate cancer. In a study recently published in the Lancet, Australian researchers found a significant reduction in the risk of breast cancer among women with a high phytoestrogen intake.

Kidney disease
Some clinical studies have demonstrated enhanced renal function when soy is substituted for animal protein in patients suffering nephrotic syndrome and renal failure.

Wild Yam Creams - Fact or scam??
Wild yam (Dioscorea villosa) has been used traditionally as an internal herbal remedy for the treatment of colic and diverticulitis, for rheumatism, and for female problems including both premenstrual and menopausal symptoms. In the 1940s it was discovered that Mexican wild yam contained a substance called diosgenin which had a molecular structure similar to the hormone progesterone; in fact, scientists were able to isolate diosgenin from wild yam in a laboratory and from it synthesise progesterone for use commercially as a drug. As a drug, when taken orally, progesterone has been used as part of hormone replacement therapy for the treatment of menopausal symptoms. However, there is no evidence that diosgenin, as a component of wild yam preparations taken internally or applied to the skin, is converted by the body to progesterone. If wild yam creams are effective in the treatment of menopausal symptoms it is not because of a progesterone hormone effect.
There is no published clinical evidence to date to show that a cream containing only wild yam is effective. The Therapeutic Goods Administration's laboratory in Canberra has recently been analysing wild yam creams and unfortunately it has been revealed that at least one manufacturer has been 'spiking' product with synthesised progesterone, and has had to recall its product.

To summarise:

??? wild yam contains diosgenin

??? diosgenin can be converted in a laboratory to progesterone

??? diosgenin is not converted in the body to progesterone

??? wild yam doesn't contain progesterone

??? wild yam creams do not contain progesterone unless it is added. If it is added, it should be declared on the label and the product would be classified as AUST R (registered) and would have to go through a full evaluation by the government's Medicines Evaluation Committee - no wild yam product has been through this process.


REFERENCES
Ingram D et al, Case-control study of phytoestrogens and breast cancer. The Lancet 1997 Oct 4; 350 (9083): 990-4.
Phytoestrogens: the clinical guide. Blackmores Professional Services. 1997

Brandi ML, Natural and synthetic isoflavones in the prevention and treatment of chronic diseases. Calc. Tissue Int. 1997; 61 Suppl 1: 55-8

British Herbal Pharmacopoeia, 1991

Townsend Letter for Doctors, November 1995

Albertazzi P et al. The effect of dietary soy supplementation on hot flushes. Obstetrics & Gynecology January 1988; Vol 91, No 1: 6-11

 

[kuso]

Phytoestrogens and Isoflavones: Food Nutrients with Significant Health Benefits

October 1, 1997

Phytoestrogens = Phyto - Oestrogens = Plant Hormones
Phytoestrogens are chemical compounds that occur in a variety of plant foods:
??? They have a chemical structure similar to that of the body's own oestrogen. ??? There are four classes of phytoestrogens found in plants - isoflavones, lignans, coumestans and resorcylic acid lactones. ??? The most important dietary phytoestrogens are the isoflavones and, to a lesser extent, the lignans, both of which are found in soya beans. Legumes, particularly soya beans, are the major dietary sources of isoflavones. ??? The isoflavones with the most important biological role are daidzein and genistein. ??? Legumes such as soya beans are the major dietary sources of daidzein and genistein.


How do they work?
Isoflavones are classified as 'weak' oestrogens and have an activity that is between 1,000 and 100,000 less than that of the body's own oestrogen. It seems that weak oestrogens in the diet can have an antioestrogen effect by competing with the body's oestrogens for binding to the sites where oestrogens attach - high levels of oestrogen in the blood are thought to increase the risk of hormone-related cancers. Around the menopause, when oestrogen production by the ovaries decreases, isoflavones are able to compensate for the body's lack of oestrogen. Isoflavones therefore have a balancing effect on oestrogen levels, which explains why they are of benefit over the whole of a woman's reproductive life - pre-menstrual, peri-menopausal and post-menopausal. Isoflavones also act as antioxidants.

Dietary Source of Isoflavones
Phytoestrogens are found in a wide variety of grains, legumes, fruits, vegetables and grasses. The isoflavones, however, appear to be restricted mainly to legumes, where they play a role in nitrogen fixing and form part of the plant's defence mechanism.
The isoflavones have a greater oestrogenic activity than other phytoestrogens, and they are found at higher concentrations - they may be present at up to 0.3% of the dried weight of plant part.


The Soy Connection
Researchers have noted in the past that populations consuming diets rich in legumes enjoy significant health benefits, in particular a decreased incidence of the diseases prevalent in Western societies - cancer, cardiovascular, reproductive and bone diseases. These diseases are now known to be diet-related, and isoflavone intake is one of the key nutrient factors in controlling them. In Oriental diets, soy products such as tofu, tempeh and miso are the major sources of isoflavones. The typical Oriental diet contains 20-60mg of isoflavones, which is at least ten times that of the average Western diet (2-5mg).
Studies comparing the health of Oriental and Western populations show that Asians consuming a soyfood-rich diet have less hormone-related cancers, bone fractures and menopausal symptoms. Analysis of population food consumption and health statistics provides conclusive evidence for the protective effects of a diet high in soy products.


Health Benefits of Phytoestrogens
Isoflavone-rich foods such as soy are receiving a lot of attention, particularly for conditions affecting women. Although modern medicine focuses on the symptomatic relief of menopausal symptoms, it is the longer term effects of oestrogen depletion that are most devastating. Low oestrogen levels can lead to crippling osteoporosis. Studies comparing animal versus soy protein diets show that soy protein has much less of a calcium depleting effect; significantly the soy isoflavones, genistein and daidzein, both appear to inhibit the re-absorption of bone. The calcium in soy is as bioavailable as milk calcium - some soy supplements are also fortified with calcium.
Low oestrogen levels are also implicated in cardiovascular disease. There have been thirty-eight studies into the effects of soy foods on serum cholesterol levels; an analysis of results from these studies reveals an average decrease in undesirable LDL cholesterol of 12.9% - this represents a 40% decrease in risk of heart disease. Research is now showing that soy foods also inhibit the oxidation of cholesterol, and that genistein inhibits platelet aggregation, which reduces the tendency to form blood clots.

Genistein is also the focus of research into cancer where, under laboratory conditions, it has been shown to inhibit the growth of both oestrogen and non-oestrogen dependent breast cancer cells. This supports the population studies which show that in Japan, where soyfood and isoflavone consumption are high, the death rate from breast cancer is 75% less than that of the USA. Other hormone-related cancers such as endometrial, ovarian and colon cancer are less in populations consuming soy-rich diets.


Men can Benefit too
Population studies show a link between the consumption of a high isoflavone diet and a reduced incidence of prostate cancer. This protective effect has been observed with vegetarian Seventh Day Adventist men consuming beans, peas and lentils, as well as with native Japanese and Hawaiian Japanese men who eat soy and rice. A low fat intake in these populations may also be significant. The isoflavones are thought to bind to sex hormone receptor sites, leading to lower plasma levels of the hormone testosterone, which stimulates the growth of prostatic cancers.

Soy - How Much is Enough?
Soy is the most important source of dietary isoflavones and soya beans also contain other beneficial nutrients, such as lecithin and vitamin E.
Experts now recommend a diet containing an average intake of 40-60mg isoflavones on a daily basis. As noted there are a number of excellent foods, including soy and other legumes, available as sources of isoflavones. The following food quantities provide 40mg isoflavones:


soy milk 1.3 litres
tofu (soy bean curd) 120g
soy flour 35g
For those unfamiliar with preparation and cooking of soya beans and soy products, concentrated soy supplements are also available, providing 40mg isoflavones in convenient tablet or powder form.

Isoflavone Supplements
Both soy and clover are used to make isoflavone supplements. Fresh clover contains a greater amount of isoflavones than fresh soy beans - however, when they are processed to extract or concentrate the isoflavones, the amount of active ingredient in the finished product ends up the same on a daily dose basis - around 40-60mg.

Clover is not a normal part of the diet, and some of the isoflavones found in clovers are not found in typical isoflavone-rich foods (although they may be converted to the active form if the intestinal microflora are adequate). Soy has the added benefit of containing other beneficial dietary phytonutrients, such as lignans and vitamin E.


REFERENCES
Messina M. The role of soyfoods in preventing and treating chronic disease.
Knight D, Eden J. Phytoestrogens - a short review. Maturitas 1995; 22:167-175.

Stanton R. Nutrition Column. Australian Doctor 1995 Sep 22.

Beckham N. Natural therapies for menopause and osteoporosis - a practitioner guide. 1997 Apr.

Reinli K, Block G. Phytoestrogen content of foods - a compendium of literature values. Nutrition & Cancer 1996; 26(2):124-148.

Lee H, et al. Dietary effects on breast-cancer risk in Singapore. Lancet 1991; 337: 1197-1200.

 

[kuso]

Soy Isoflavones Strengthens Bone Mass

February 1, 2000


Bone loss was significantly reduced in Chinese women taking part in a 3 year study. Dr Suzanne C Ho and colleagues at the Chinese University of Hong Kong, studied 134 women aged 31-40 and found that their bones were strengthened after a dietary intake of soy foods containing isoflavones.
Previous studies found that bone mass was consolidated in pre-menopausal women aged in their early 30fs, but more research was required especially in Asian women.

The researchers called for further study into the effects of phytoestrogens like soy isoflavones and bone fitness. "This study shows that soy intake reduces bone loss and is a significant dietary factor", reported Dr Ho and colleagues. They also found that the protective effect of soy isoflavones still remained in the participants after adjustments for bone area, weight-bearing exercise and other factors.

This article also mentions that this study was also reported at a meeting of the American Society for Bone and Mineral Research, where a conference report on the study stated: "In a study conducted among Chinese women, the amount of soy protein in the diet appeared to relate to the rate of bone loss. Soy, which provides a source of phytoestrogens, appears to slow bone loss in pre-menopausal Chinese women in Hong Kong. Some data suggest that similar findings may be seen in Caucasian women, but the appropriate dosage requirements of this source of phytoestrogens needs to be determined.

In addition, we still do not know whether soy intake is associated with reduction in fracture risk. Given the high prevalence of soy intake in the United States, this is encouraging news for reduction in fracture load in the future.".


REFERENCES
(Reuters/Foods for the future/PRNewswire)

 

[w8lifter]

Kuso...now why didn't you just add this to one of the other threads

 

[kuso]

Originally posted by w8lifter
Kuso...now why didn't you just add this to one of the other threads

I was just following what has become the obvious standard here.

Besides which, at least I was smart enough to include links to the other threads so as not to "bias" here solely influence others, or to make it sound like soy is "all" good.