Soy Toxins / There's plenty yet that you didn't know about soy!

[Guest guest]

Soy Toxinshttp://www.soyonlineservice.co.nz/soytox.htm

 

 

 

Soy Toxins

There's plenty yet that you didn't know about soy!

 

Soy contains several naturally occurring compounds that are toxic to

humans and animals. The soy industry frequently refers to these toxins as

anti-nutrients, which implies that they somehow act to prevent the body getting

the complete nutrition it needs from a food. The soy toxins (such as phytic

acid) can certainly act in this manner, but they also have the ability to target

specific organs, cells and enzyme pathways and their effects can be devastating.

 

The soy toxins that Soy Online Service have concerns about are protease

inhibitors, phytic acid, soy lectins (or haemagglutins), nitrosamines, manganese

concentrations and the mysterious soyatoxin. Nitrosamines are not naturally

occurring in soybeans but form during the processing of products such as

isolated soy protein (ISP).

 

As with any toxin there will be a dose at which negative effects are not

observed. Soy Online Services have examined the scientific data on the soy

toxins and have uncovered several alarming truths:

 

There is no legislation to protect consumers from soy toxins in raw

soy products.

 

With the possible exception of soy lecithin, all soy products, no

matter how well treated, contain low to moderate levels of soy toxins;

processing cannot remove them all of any of them.

 

The soy industry has little in the way of quality control to protect

consumers from exposure to inadequately treated soy products.

 

 

Protease Inhibitors

 

Perhaps the best known of the soy toxins are the protease inhibitors (also

referred to as trypsin inhibitors) which, as the name suggests, are able to

inhibit the action of proteases (including trypsin) which are enzymes that are

involved in the process of dismantling proteins for use by the body.

 

In the rat, high levels of exposure to protease inhibitors (such as that

found in raw soy flour) cause pancreatic cancer whereas moderate levels cause

the rat pancreas to be more susceptible to cancer-causing agents. The validity

of the rat model to humans has been questioned and the USFDA have examined the

effects of protease inhibitors on the Cebus monkey (JP Harwood et al., Adv Exp

Med Biol 1986 199: 223-37).

 

The parameters of the Cebus Monkey study were as follows:

 

Group Number of monkeys Dietary Protein Trypsin Inhibitor (mg/g of

diet)

1 8 Lactalbumin 0.12

2 10 Soy Isolate 0.54

3 6 Casein 0.08

4 2 Soy Concentrate 2.41

 

After five years of chronic ingestion to low levels of trypsin inhibitors,

there was no discernible pancreatic damage effect in monkeys from groups 1-3.

However, one monkey in group 4 exhibited moderate diffuse acinar atrophy,

moderate diffuse interstitial fibrosis and moderate chronic pancreatitis in all

three sections of tissue examined. Minimal lymphoid hyperplasia was noted in

the other group 4 monkey.

 

Therefore, there is good reason to question claims that low levels of soy

protease inhibitors pose no threat to human health. Such a statement has even

been made by the USFDA in response to a health claim petition by Protein

Technologies. The USFDA reported that:

 

'Concerns have been raised in the past about exposure to trypsin

inhibitors contained in soybeans because these compounds had been found to

stimulate pancreatic hyperplasia and hypertrophy in animals. These concerns have

been allayed because heat treatment removes most of the activity of these

proteases. In addition, recent studies have questioned the applicability of the

animal models, which differ from humans in the type of diet, sensitivity of the

pancreas to trypsin inhibitors, and the anatomic sites of pancreatic cell

proliferation and have found low rates of cancer in populations with dietary

patterns that include soy foods' (FR 63, 217:62977-63015, 1998).

 

This statement brought an angry response from Professor Irvin Leiner, the

foremost expert on protease inhibitors. In his reply to the FDA Liener wrote:

 

'The impression one gets from reading this section is that that there is

little cause for concern as far as the human exposure to soybean trypsin

inhibitors is concerned.... In the interests of a balanced treatment of the

subject, I trust you will give due consideration to the opposing view that the

soybean trypsin inhibitors do in fact pose a potential risk to humans when soy

protein is incorporated into the diet.'

 

So, if there is valid concern about low levels of protease inhibitors in

soy foods, what about exposures to levels higher higher than those in the Cebus

monkey study? Is there any chance that such exposures could occur in human

diets?

 

Soy Online Service has noted that there is considerable variability in the

levels of protease inhibitors in commercially available foods and that there is

little to protect consumers from exposure to high levels of protease inhibitors.

For example, a study entitled 'Trypsin inhibitor levels in soy-based infant

formulas and commercial soy protein isolates and concentrates (RW Peace et al.,

1992, Food Res Int, 25: 137-141) found that trypsin inhibitor levels were as

high as 2.72 mg/g in ready to feed soy formulas and 7.30 mg/g in soy protein

concentrate.

 

Since there is no established acceptable levels of protease inhibitors in

foods and no protection from short-term high level (acute) exposures or long

term low level (chronic) exposures, Soy Online Service offer the following

advice:

 

Don't feed your baby or infant a soy formula; there are alternatives!

 

Avoid the direct consumption of raw or partially processed soy

products such as soy flour or soy protein concentrate. Traditionally fermented

soy foods are relatively free of protease inhibitors.

 

When preparing your own soy foods, such as boiled or roasted soybeans

or soy milk, ensure that they are adequately heated. The traditional Chinese

method for preparing soybeans was a time consuming job that was left to monks.

It involved soaking the beans first and then boiling them twice over 'the full

length of an incense'.

 

 

Phytates

 

The term phytate refers to several compounds that are based on phytic acid

(inositol hexaphosphate). It is the presence of multiple phosphates in phytates

that makes them effective chelating agents, i.e. they have the ability to bind

to certain metal ions. Obviously if metals are bound up in a phytate-complex,

they are less available to the body ( i.e. less bioavailable) for nutritive

purposes.

 

Phytates are particularly adept at binding metals in their so-called

divalent state, metal ions such as calcium (Ca2+), copper (Cu2+), iron (Fe2+),

manganese (Mn2+) and zinc (Zn2+).

 

Soybeans contain very high levels of phytate and their are numerous

reports of reduced bioavailablity of various metals from foods containing soy;

this has particular significance for vegetarians and infants fed soy-formulas.

 

Vegetarians, particularly young women vegetarians, need to be aware that

soy products affect their iron and zinc requirements and it has been recommended

that they utilise strategies that minimise the intake of dietary phytate.

 

The effects of phytate in soy-formulas are a great concern. The iron and

zinc requirements of developing infants are well documented, particularly those

that relate to cognitive function. There is no question that infants fed

soy-formulas are at greater risk of reduced uptake of various essential minerals

compared with breast-fed infants or infants fed other formulas.

 

Copper bioavailability is significantly lower in rhesus monkeys fed

low-phytate soy formula from 2 to 4 months.

Iron absorption in infants is approximately doubled by the removal of

phytate from soy formula; a similar effect is observed by doubling the ascorbic

acid content of a soy formula.

Manganese absorption is also doubled by the removal of phytate from

soy formula, but increasing the ascorbic acid content of a soy formula

containing the native amount of phytic acid did not improve manganese

absorption.

Zinc bioavailability from soy formulas is also reduced by phytate.

In rhesus monkeys, zinc absorption was 2.0 times greater from monkey milk

compared with soy formula, 2.2 times greater from whey-predominant formula

compared with soy formula and 1.7 times greater from casein-predominant formula

compared with soy formula. Zinc absorption from dephytinized soy formula was

approximately the same as that from casein-predominant formula.

 

Soy formulas are typically over-supplemented with minerals and vitamins to

account for the deficiencies caused by phytate, but it is evident that this does

not take care of the problems. Removal of phytate from soy formulas is

altogether a better solution but manufactures have not shown any inclination do

this. Why not? Phytate removal will cost $$$ and it seems to us that soy

formula manufacturers consider economics to be more important than the well

being of infants.

 

Manganese

 

The soybean plant has the ability to absorb manganese from the soil and

concentrate it to an extent that soy-based infant formulas can contain as much

as 200 times the level of manganese found in natural breast milk. In babies,

excess manganese that cannot be metabolised is stored in body organs. Around

eight percent of the excess manganese in the diet is stored in the brain in

close proximity to the dopamine-bearing neurons responsible, in part, for

adolescent neurological development.

 

The implications are that the one in eight infants raised on soy formula

during the first six months of life may be at risk of brain and behavioural

disorders that do not become evident until adolescence. The following two

links discuss the issue of manganese toxicity further.

 

Is soy-based infant formula brain damaging?

 

Press Release written by David Goodman, Ph.D.

 

" How safe is soy infant formula? " .

 

Soyatoxin

 

The soy industry funds millions of dollars of research each year; what

chance is there for the discoverers of soyatoxin to get funding to continue

their work?

 

 

 

Home Introduction History Phytoestrogens Soy Toxins Soy

Politics

SOS_Guidance Downloads Links Hot News Regulators Big Ugly Bull