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ETUDE SCIENTIFIQUE


A consulter le seul projet financé actuellement par l’Europe : http://www.nf-2000.org/secure/Fair/S911.htm

Les édulcorants sont dangereux !

Les édulcorants de synthèse, artificiels, ne sont pas aussi inoffensifs qu’il y parait.

L’OMS(organisation mondiale de la santé) pose des valeurs de dose quotidienne acceptable ADI(acceptable daily intake).

Ces valeurs indiquent la quantité d’édulcorant à ne pas dépasser par jour, par adulte et par kilo de poids.

Pour la saccharine, elle est de 5 mg, le cyclamate 11 mg,la néohespiridine 5 mg et l’aspartame 40 mg.

Un homme de 70 kg peut avaler 20 sucrettes de cyclamate ou de saccharine, ce qui est peu !

Mais des soupçons pèsent sur ces substances, qui seraient cancérigènes…

Quand la saccharine a été commercialisée en 1886,l’industrie sucrière a immédiatement lancé une campagne de dénigrement de ce produit, parce qu’il risquait de concurrencer le sucre .Aujourd’hui fabricants de sucre et d’édulcorants ont trouvé un compromis…

Pour l’instant,l’effet néfaste,provoquant le cancer n’a été prouvé que sur les animaux.,mais nous mourrons de plus en plus des cancers !

Mais aujourd’hui,de nombreux diététiciens américains et européens recommandent d’éviter la saccharine.Et le Japon, l’a interdite formellement.

Le cyclamate est cancérigène sur les animaux. De ce fait,il est interdit en Grande Bretagne,aux Etats-Unis et d’autres pays. En France, et en Allemagne il est autorisé !

Une réglementation européenne de 1994,interdit expressément l’utilisation d’édulcorants dans les produits tout prêts pour les bébés et les jeunes enfants. Ainsi,les sujets âgés, adultes sont censés pouvoir les consommer sans danger ?

Si vous voulez en savoir plus,consultez les sites suivants(en anglais)

http://www.tiac.net/users/mgold/aspartame/adverse.txt

http://www.healthy.net/asp/stores/sweetleaf/naturalsweetener.asp

 

Enfin ,la seule étude scientifique européenne,sérieuse du Professeur Geuns de Belgique 

SAFETY EVALUATION OF STEVIA AND STEVIOSIDE.

JAN M.C. GEUNS

Laboratory of Plant Physiology, KULeuven,

Kard. Mercierlaan 92, B 3001 Leuven

Tel.: +32-16-321510; Fax: +32-16-321509

e-mail: Jan.Geuns@bio.kuleuven.ac.be

ABSTRACT : The literature about Stevia and stevioside used as a sweetener is discussed. Injection experiments or perfusion experiments of organs are considered as not relevant for the use of Stevia or stevioside as food, and therefore these studies are not included in this safety evaluation.

The metabolism of stevioside is discussed in relation with the possible formation of steviol. Different mutagenicity studies as well as studies on carcinogenicity are discussed. Acute and subacute toxicity studies revealed a very low toxicity of Stevia and stevioside. A survey is given of calculated ADI's. Fertility and teratogenicity studies are discussed as well as the effects on the bio-availability of other nutrients in the diet.

The conclusion is that Stevia and stevioside are safe when used as a sweetener. It is suited for both diabetics, and PKU patients, as well as for obese persons intending to lose weight by avoiding sugar supplements in the diet. No allergic reactions to it seem to exist.

INTRODUCTION: STEVIA and STEVIOSIDE

Stevia rebaudiana Bertoni is a perennial shrub of the Asteraceae (Compositae) family native to certain regions of South America (Paraguay and Brazil). It is known to the Guarany people, native to these regions since time immemorial, by several names all of which refer to the sweet taste of the leaf, and especially to its use in “mate” tea (Ilex paraguariensis). It is often referred to as “the sweet herb of Paraguay”.

The Spanish Conquistadors of the Sixteenth Century sent back news to Spain that the indigenous population used Stevia to sweeten their herbal teas since ancient times, i.e. predating 1500 AD.

Stevia has been cultivated or is still cultivated in many countries: Paraguay, the USA, Mexico, Central America, Japan, China, Malaysia, South Korea, Spain, Italy, Belgium and the UK.

The main sweet component in the leaves of Stevia rebaudiana Bertoni is stevioside 3 (see Fig.(1)). Its content varies between 4 and 20 % of the dry weight of the leaves, and around 11% in many economical crop productions. Other compounds present but in much lower concentration are: dulcoside A 9 (± 0.5 %), steviolbioside 2 (trace), rebaudioside A 4 (±3 %), B 5 (trace), C 6 (± 1.5 %), D 7 and E 8 (traces) (See Fig.(1)).

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Compound name

R1

R2

1

steviol

H

H

2

steviolbioside

H

bGlc2-1bGlc

3

stevioside

bGlc

bGlc2-1bGlc

4

rebaudioside A

bGlc

bGlc2-1bGlc

3-1bGlc

5

rebaudioside B

H

bGlc2-1bGlc

3-1bGlc

6

rebaudioside C (dulcoside B)

bGlc

bGlc2-1aRha

3-1bGlc

7

rebaudioside D

bGlc2-1bGlc

bGlc2-1bGlc

3-1bGlc

8

rebaudioside E

bGlc2-1bGlc

bGlc2-1bGlc

9

dulcoside A

bGlc

bGlc2-1aRha

Fig. (1). Structures of stevioside and related compounds. In rebaudioside A, B, C, D and E an additional sugar moiety is added on carbon 3 of the first bGlc.

A typical composition on a dry weight basis of the most important components of the leaves is as follows:

- proteins: ± 6.2 %

- lipids: ± 5.6 %

- total carbohydrates (anthrone): ± 53 %

- stevioside: ± 11 %

- rebaudioside A: ± 2 %

- rebaudioside C: ± 2 %

Stevioside is a diterpene glycoside occurring in Stevia rebaudiana Bertoni leaves. It is a high intensity sweetener that is about 300 times sweeter than sucrose. In many countries it is used as a low calorie sweetener in a wide range of food products and beverages. Both the plant, its extracts, and stevioside have been used for several years as a sweetener in South America, Asia, Japan, China and even in the USA it is used as a dietary supplement since 1995.

Remarks to toxicological studies: Neither those scientific studies where Stevia extract or solution of pure stevioside were injected in animals, nor those studies employing perfusion experiments of organs, are considered relevant for the use of Stevia or stevioside as food and are not discussed in this review.

METABOLISM OF STEVIOSIDE

Compounds used as or added to food must be absolutely safe. This means that not only the added parent compound, but also its possible metabolites must be safe, for the possibility exists that compounds that themselves are not harmful can be taken up by the human body and be metabolised into products that may have some harmful effects. Therefore, the parent compounds as well as their metabolites should be thoroughly tested in toxicological studies. In one such study, steviol, the aglycone of stevioside, showed a weak mutagenic activity [1] and, although in later experiments these results could not be reproduced [2], this has led to a whole controversy in scientific literature.

It has been shown that stevioside is not taken up by the human body and none of the digestive enzymes from the gastro-intestinal tract of different animals and man are able to degrade stevioside into steviol 1, the aglycone of stevioside [3]. The lack of metabolism is due to the fact that the bonds in stevioside are b-glycosidic and we do not have the enzymes to split these b-glycosidic bonds. Stevioside was incubated with salivary a-amylase, pancreatic a-amylase, saliva, pepsin, gastric secretion, pancreatin and intestinal brush border membrane enzymes of mice, rats and hamsters. None of these enzymes digested stevioside. Nevertheless, in feeding experiments with rats and hamsters stevioside was metabolised to steviol by the bacterial flora of the caecum. After several hours steviol was found in the blood of the animals, the maximum concentration occurring after 8 hours [4]. In rodents coprophagy occurs (this means that rodents eat their own faeces and in this way they reabsorb nutrients set free by the bacteria of the caecum). In the cited studies, it was not indicated that coprophagy was prevented, so it is not clear if the steviol occurring in the blood was taken up directly from the colon or indirectly from the ingested faeces (after passing through the intestines again). Although bacteria isolated from the human colon are able to transform stevioside into steviol in vitro [3], it has never been proven that this is also the case in vivo nor that the steviol eventually formed is taken up directly from the colon. Moreover, studies with roosters [5] indicate that stevioside is rapidly eliminated from the body, largely untransformed. Roosters resemble humans as they too have a low functioning caecum.

Only the bacteria from the caecum or colon were able to degrade stevioside into steviol (caecum of mice, rats and hamsters; colon of man). The bacteria from the human colon also formed steviol epoxid in vitro, that was again metabolised to steviol. However, in vivo this epoxid formation probably will not occur due to the anaerobic conditions of the human colon. It was correctly concluded that steviol is the only possible metabolite [3]. Anyway, steviol epoxid has been tested in mutagenicity studies and showed to be inactive [1].

MUTAGENICITY STUDIES AND CARCINOGENICITY

Each new compound in the food chain has to be extensively tested to be sure that it is not carcinogenic. As studies with animals take several years and become expensive when many compounds need to be tested, so called mutagenicity tests were developed that are much faster and less expensive. In these tests compounds are evaluated to see if they provoke mutations or alterations of hereditary material. It should be emphasised that compounds giving a positive response in mutagenicity tests are not carcinogenic in se. Compounds having a positive score should be tested for carcinogenic activity, but not all mutations lead to cancer. This can be exemplified by the following examples. A point mutation in the gene that codes for the growth hormone receptor in chickens causes dwarf mutants (bantams). A dominant gene produces hairs on the mid-phalanx of the ring finger and its recessive mutation causes lack of hair. In a population about one fourth of the people have the recessive mutation (no hair) but this does not mean that they will have cancer because of this mutation.

Mutagenicity tests

In the Ames test or bacterial reverse mutation test, use is made of mutated bacteria that eg. cannot form an amino acid histidine (his-). Therefore, these bacteria are unable to grow on a medium lacking histidine. When these bacteria are grown on such a medium, most bacteria will die, but in some bacteria a natural reverse mutation occurs, i.e. the original mutation is repaired by a reverse mutation and these bacteria can again form histidine and can grow and form colonies on the medium without histidine. Mutagenic compounds will enhance the number of reverse mutations occurring. As many compounds are mutagenic only after metabolism in the body, the test is also done after adding a so-called metabolic activation system. This is a liver supernatant fraction (S9000g) of animals pretreated with known harmful substances (eg. poly-chlorinated biphenyls). This S9000g fraction will ensure the further metabolism of the compounds added in the Ames test.

In the forward mutation test, bacteria are added to a medium containing a harmful substance (eg. 8-azaguanine). Under these conditions m



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