In 1991, two bird breeders in New Zealand, Richard and Valerie James, changed the feed they gave to their birds.
The new feed was based on soy protein.
They soon started to notice changes.
Some of their birds developed fully-coloured plumage within just a few months instead of the normal one-and-a-half to two years.
The Jameses were concerned but the feed manufacturers said it was a good thing.
Over the next few years, the birds developed fertility problems.
Many baby birds were stillborn, or they matured too early and had deformed or stunted offspring.
Beak and bone deformities, thyroid abnormalities and aggressive behaviour became common.
The Jameses knew something was wrong, and suspected the soy feed.
They stopped using it and their business eventually returned to normal.
A Crusade Begins But now seriously worried about soy products, Richard and Valerie feared for their children, who had been raised on a soy-based infant formula.
There were marked similarities between their children's developmental problems and those of their birds.
The Jameses asked an expert in toxicology - the study of poisons and their effects on health - to look into the possibility of toxins in soy foods.
His report made them start a crusade to warn the world.
In the early 1990s the current popularity of soy as a health food was just getting started.
Books and articles extolled it as an excellent vegetarian source of protein, and pointed out that in the Far East, where it has been a traditional food for hundreds of years, there are lower rates of breast and prostate cancer, heart disease and menopausal problems.
The rich and powerful soy industry widely publicised this research.
But until the Jameses came on the scene there were no champions for the other side of the story.
In fact soy products are not necessarily the reason for these lower disease figures.
Asian and oriental diets differ from western diets in many ways, and average soy consumption in China and Japan is only about nine grams (less than two teaspoons) a day.
The Other Side Of Soy Consuming large amounts of soy products could be damaging for babies and young children, due to the presence of natural hormone-disrupting chemicals and "anti-nutrients" (substances which hinder our absorption or utilisation of vitamins, minerals and other nutrients).
Since 1995 there have been many reports in the scientific literature, warning against "the other side of soy".
In 1999, this culminated in an open letter from two United States government scientists, Daniel Sheehan PhD and Daniel Doerge PhD, to their bosses at the Food and Drug Administration, giving detailed reasons why they disagreed with the FDA's decision to support health claims on soy product labels.
They had two main concerns about soy.
1.
Estrogenic Effects Substances known as genistein and daidzein (also referred to as "isoflavones") in soy products, can mimic the effects of estrogen.
In one study, pregnant Rhesus monkeys who were fed genistein developed up to double the normal levels of estrogen in their blood.
Their babies too showed abnormally high estrogen levels.
Until there is more research into the effects of this extra estrogen, say Sheehan and Doerge, we will not know whether it could be as damaging as taking artificial estrogens during pregnancy.
But, interestingly, research on human women given soy foods rather than concentrated soy extracts, reveals entirely different results.
A 1997 study from the Gifu University School of Medicine in Japan showed that the more tofu and miso Japanese women consumed, the lower were their estrogen levels, but only on days 11 and 22 of their menstrual cycle.
Research into breast cancer prevention also shows mixed results, with some studies showing a protective effect from soy products, and others showing that soya can cause chromosome breaks and other mildly pre-cancerous changes to cells.
The type of soy product may be significant here, since some feeding studies are carried out using soy protein isolate (SPI) - a highly processed concentrate which may have entirely different effects on the body from those of natural soy foods.
SPI is nowadays a very common ingredient in modern processed and fast foods, bakery products and diet beverages, and is used to make the "meat substitute" known as textured vegetable protein (TVP).
2.
Anti-Thyroid Effects Sheehan and Doerge also point out that we have known since 1933 that soy isoflavones can inhibit an enzyme which our bodies use to make thyroid hormone.
There are numerous reports of babies developing goitre after feeding with soy.
Children raised on soy-based infant formula are also twice as likely to develop a condition known as autoimmune thyroiditis, where the immune system attacks and destroys the cells of the thyroid gland.
Some researchers believe that feeding babies with soy formula gives them the estrogen equivalent of five contraceptive pills a day.
The dissident FDA scientists were also worried about findings from a long-term study on 7,000 Hawaiian men, which at the time was being carried out by the National Institute on Aging in the USA.
Those men with a history of consuming more than two servings of tofu per week were found to be nearly two-and-a-half times more likely than the rest to develop Alzheimer's disease and brain atrophy (shrinkage of the brain) in later life.
The undesirable "anti-nutrients" in soy products are known as phytic acid (or phytate) and protease inhibitors.
Phytic Acid This combines with minerals in our diet, and hinders their absorption.
Phytic acid is also found in raw grains such as muesli, and in unleavened wholemeal bread such as chappatis.
It causes dwarfism in parts of the world such as Iran where the soil is very poor in zinc.
Poor levels of zinc in the soil lead to poor levels in food.
If phytic acid then blocks the absorption of that zinc, children can fail to grow normally.
Combining soy and other phytic acid-rich foods with protein foods such as egg, meat and fish (which most orientals in fact do) helps to prevent the undesirable effects of phytic acid.
Taking extra minerals also helps, and manufacturers usually add them to soy-based baby formula feeds.
But vegetarians who eat no animal products may be vulnerable to mineral deficiencies from phytic acid, so all are advised to supplement daily with multiminerals.
Protease Inhibitors These are substances which inhibit protein digestion.
If we cannot digest our protein we cannot absorb vital amino acids.
Protease inhibitors also cause much stress to the pancreas (which produces protease, the protein-digesting enzyme) and have been linked with cancer of the pancreas.
Protease inhibitors occur in raw pulses, grains and seeds, and are normally broken down by cooking or partial germination.
For instance, there are large amounts of protease inhibitors in raw muesli which has not been soaked in liquid for at least a few hours.
The soy industry says that heat processing breaks down the protease inhibitors in soy products.
But Professor Irvin Leiner from the College of Biological Sciences, University of Minnesota, and one of the world's foremost experts on protease inhibitors, disagrees.
How Much Soy Is It Safe To Eat? Research is still scanty, so there's no real answer to this question.
Everything depends on how your body handles plant oestrogens.
We can expect to see more research over the next few years, but in the meantime it is probably sensible to avoid eating highly concentrated soy products every day.
The forms of soy which are not concentrated, are soy milk, tofu (or bean curd), soy yoghurt, miso, soy sauce, tamari sauce and tempeh.
All of these except soy milk and tofu contain very low levels of phytate, because they are fermented products.
Phytate is much reduced by the fermentation process.
Soy milk contains four times the amount of protease inhibitor found in tofu and more than 40 times the amount found in miso.
But I have known women who cured themselves of endometriosis by drinking half a litre of soya milk every day.
Like fibroids and most breast cancers, endometriosis is caused by an estrogen overload in the body.
The plant estrogens in soy can help to combat an estrogen overload because they attach themselves to estrogen receptors in the body, thus displacing stronger human estrogens such as estradiol.
The result is to normalize estrogen levels.
This property of soy could also be of benefit to men with gynecomastia - the development of breast tissue in the male as a result of excessive estrogen levels.
It does not take a lot of soy to normalize estrogen levels.
Half a litre of soy milk is about 16 fluid ounces or 32 tablespoons, but this probably does need to be consumed at least 5-6 times a week.
Concentrated Forms Of Soy On the other hand, the consumption of foods made from TVP and SPI should probably be strictly controlled.
Due to their heavy processing, they are highly concentrated sources of estrogenic isoflavones, containing up to 600 mg per 100 grams.
TVP and SPI are also found as ingredients in many processed and fast foods.
Similarly, it would be wise to be cautious about taking supplements of genistein and daidzein.
Some women who have taken them for hot flushes have developed thyroid abnormalities.
A Sensible Soy Intake For A Woman? On balance, as a woman, I would not hesitate to consume up to 2 litres of soy milk or yoghurt a week plus 2-3 portions of tofu and a little soy sauce.
As a nutritionist I am convinced by the science that this would actually bring me health benefits and is not enough to cause any problems as far as my thyroid gland or the phytate or protease inhibitor content are concerned.
My only concern is that many soy crops nowadays are genetically engineered.
Like many consumers, I am very much opposed to this so I would certainly go for organic brands.
Alternative Baby Milk Formula On the other hand I do feel that soy is risky for babies and should also be limited for children.
If you have a young baby who cannot be breast fed and is allergic to cow's milk formula, it's well worth considering a goat milk infant formula instead.
Further information on soy and health is available from www.
soyconference.
com Baby goat milk formulas can be obtained from Genesis Organics: www.
genesisorganics.
com and from Vitacare UK
The new feed was based on soy protein.
They soon started to notice changes.
Some of their birds developed fully-coloured plumage within just a few months instead of the normal one-and-a-half to two years.
The Jameses were concerned but the feed manufacturers said it was a good thing.
Over the next few years, the birds developed fertility problems.
Many baby birds were stillborn, or they matured too early and had deformed or stunted offspring.
Beak and bone deformities, thyroid abnormalities and aggressive behaviour became common.
The Jameses knew something was wrong, and suspected the soy feed.
They stopped using it and their business eventually returned to normal.
A Crusade Begins But now seriously worried about soy products, Richard and Valerie feared for their children, who had been raised on a soy-based infant formula.
There were marked similarities between their children's developmental problems and those of their birds.
The Jameses asked an expert in toxicology - the study of poisons and their effects on health - to look into the possibility of toxins in soy foods.
His report made them start a crusade to warn the world.
In the early 1990s the current popularity of soy as a health food was just getting started.
Books and articles extolled it as an excellent vegetarian source of protein, and pointed out that in the Far East, where it has been a traditional food for hundreds of years, there are lower rates of breast and prostate cancer, heart disease and menopausal problems.
The rich and powerful soy industry widely publicised this research.
But until the Jameses came on the scene there were no champions for the other side of the story.
In fact soy products are not necessarily the reason for these lower disease figures.
Asian and oriental diets differ from western diets in many ways, and average soy consumption in China and Japan is only about nine grams (less than two teaspoons) a day.
The Other Side Of Soy Consuming large amounts of soy products could be damaging for babies and young children, due to the presence of natural hormone-disrupting chemicals and "anti-nutrients" (substances which hinder our absorption or utilisation of vitamins, minerals and other nutrients).
Since 1995 there have been many reports in the scientific literature, warning against "the other side of soy".
In 1999, this culminated in an open letter from two United States government scientists, Daniel Sheehan PhD and Daniel Doerge PhD, to their bosses at the Food and Drug Administration, giving detailed reasons why they disagreed with the FDA's decision to support health claims on soy product labels.
They had two main concerns about soy.
1.
Estrogenic Effects Substances known as genistein and daidzein (also referred to as "isoflavones") in soy products, can mimic the effects of estrogen.
In one study, pregnant Rhesus monkeys who were fed genistein developed up to double the normal levels of estrogen in their blood.
Their babies too showed abnormally high estrogen levels.
Until there is more research into the effects of this extra estrogen, say Sheehan and Doerge, we will not know whether it could be as damaging as taking artificial estrogens during pregnancy.
But, interestingly, research on human women given soy foods rather than concentrated soy extracts, reveals entirely different results.
A 1997 study from the Gifu University School of Medicine in Japan showed that the more tofu and miso Japanese women consumed, the lower were their estrogen levels, but only on days 11 and 22 of their menstrual cycle.
Research into breast cancer prevention also shows mixed results, with some studies showing a protective effect from soy products, and others showing that soya can cause chromosome breaks and other mildly pre-cancerous changes to cells.
The type of soy product may be significant here, since some feeding studies are carried out using soy protein isolate (SPI) - a highly processed concentrate which may have entirely different effects on the body from those of natural soy foods.
SPI is nowadays a very common ingredient in modern processed and fast foods, bakery products and diet beverages, and is used to make the "meat substitute" known as textured vegetable protein (TVP).
2.
Anti-Thyroid Effects Sheehan and Doerge also point out that we have known since 1933 that soy isoflavones can inhibit an enzyme which our bodies use to make thyroid hormone.
There are numerous reports of babies developing goitre after feeding with soy.
Children raised on soy-based infant formula are also twice as likely to develop a condition known as autoimmune thyroiditis, where the immune system attacks and destroys the cells of the thyroid gland.
Some researchers believe that feeding babies with soy formula gives them the estrogen equivalent of five contraceptive pills a day.
The dissident FDA scientists were also worried about findings from a long-term study on 7,000 Hawaiian men, which at the time was being carried out by the National Institute on Aging in the USA.
Those men with a history of consuming more than two servings of tofu per week were found to be nearly two-and-a-half times more likely than the rest to develop Alzheimer's disease and brain atrophy (shrinkage of the brain) in later life.
The undesirable "anti-nutrients" in soy products are known as phytic acid (or phytate) and protease inhibitors.
Phytic Acid This combines with minerals in our diet, and hinders their absorption.
Phytic acid is also found in raw grains such as muesli, and in unleavened wholemeal bread such as chappatis.
It causes dwarfism in parts of the world such as Iran where the soil is very poor in zinc.
Poor levels of zinc in the soil lead to poor levels in food.
If phytic acid then blocks the absorption of that zinc, children can fail to grow normally.
Combining soy and other phytic acid-rich foods with protein foods such as egg, meat and fish (which most orientals in fact do) helps to prevent the undesirable effects of phytic acid.
Taking extra minerals also helps, and manufacturers usually add them to soy-based baby formula feeds.
But vegetarians who eat no animal products may be vulnerable to mineral deficiencies from phytic acid, so all are advised to supplement daily with multiminerals.
Protease Inhibitors These are substances which inhibit protein digestion.
If we cannot digest our protein we cannot absorb vital amino acids.
Protease inhibitors also cause much stress to the pancreas (which produces protease, the protein-digesting enzyme) and have been linked with cancer of the pancreas.
Protease inhibitors occur in raw pulses, grains and seeds, and are normally broken down by cooking or partial germination.
For instance, there are large amounts of protease inhibitors in raw muesli which has not been soaked in liquid for at least a few hours.
The soy industry says that heat processing breaks down the protease inhibitors in soy products.
But Professor Irvin Leiner from the College of Biological Sciences, University of Minnesota, and one of the world's foremost experts on protease inhibitors, disagrees.
How Much Soy Is It Safe To Eat? Research is still scanty, so there's no real answer to this question.
Everything depends on how your body handles plant oestrogens.
We can expect to see more research over the next few years, but in the meantime it is probably sensible to avoid eating highly concentrated soy products every day.
The forms of soy which are not concentrated, are soy milk, tofu (or bean curd), soy yoghurt, miso, soy sauce, tamari sauce and tempeh.
All of these except soy milk and tofu contain very low levels of phytate, because they are fermented products.
Phytate is much reduced by the fermentation process.
Soy milk contains four times the amount of protease inhibitor found in tofu and more than 40 times the amount found in miso.
But I have known women who cured themselves of endometriosis by drinking half a litre of soya milk every day.
Like fibroids and most breast cancers, endometriosis is caused by an estrogen overload in the body.
The plant estrogens in soy can help to combat an estrogen overload because they attach themselves to estrogen receptors in the body, thus displacing stronger human estrogens such as estradiol.
The result is to normalize estrogen levels.
This property of soy could also be of benefit to men with gynecomastia - the development of breast tissue in the male as a result of excessive estrogen levels.
It does not take a lot of soy to normalize estrogen levels.
Half a litre of soy milk is about 16 fluid ounces or 32 tablespoons, but this probably does need to be consumed at least 5-6 times a week.
Concentrated Forms Of Soy On the other hand, the consumption of foods made from TVP and SPI should probably be strictly controlled.
Due to their heavy processing, they are highly concentrated sources of estrogenic isoflavones, containing up to 600 mg per 100 grams.
TVP and SPI are also found as ingredients in many processed and fast foods.
Similarly, it would be wise to be cautious about taking supplements of genistein and daidzein.
Some women who have taken them for hot flushes have developed thyroid abnormalities.
A Sensible Soy Intake For A Woman? On balance, as a woman, I would not hesitate to consume up to 2 litres of soy milk or yoghurt a week plus 2-3 portions of tofu and a little soy sauce.
As a nutritionist I am convinced by the science that this would actually bring me health benefits and is not enough to cause any problems as far as my thyroid gland or the phytate or protease inhibitor content are concerned.
My only concern is that many soy crops nowadays are genetically engineered.
Like many consumers, I am very much opposed to this so I would certainly go for organic brands.
Alternative Baby Milk Formula On the other hand I do feel that soy is risky for babies and should also be limited for children.
If you have a young baby who cannot be breast fed and is allergic to cow's milk formula, it's well worth considering a goat milk infant formula instead.
Further information on soy and health is available from www.
soyconference.
com Baby goat milk formulas can be obtained from Genesis Organics: www.
genesisorganics.
com and from Vitacare UK
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