English.pdf

Natural is not always innocuous
Vevy Europe Scientific Forum, Switzerland
Two Introductory Questions1, 2
Over recents years, interest in plant-derived products has increased proportionally to the withdrawal of
raw materials, functional or not, made from
substances of animal origin.
This is due to the growing popularity of various
movements, including those fighting for an end to
animal testing, which has led to the addition to the 6th
Modification of the EEC Directive of an article which
provides for raw materials tested on animals to be
banned as of 01.01.98, technical achievements
permitting.
We have in the past already had the possibility to
comment upon, and often even to challenge, the use of
the adjective “natural” as a synonym for “vegetable”
and consequently for “harmless” to influence the unaware consumer, the “victim” of advertising
statements which have little to do with the reality of the finished cosmetic product.
According to recent legal interpretations, which in any case highlight a certain legislative fuzziness
surrounding the use of this adjective, the term “natural” can be freely attributed to products derived
from vegetable, animal and mineral sources, provided that the process of extraction, refin ement,
purification, concentration, conservation, ethoxylation etc. has not transformed the original material
into something completely different.
Why should we take a closer look at the statement that natural plant substances are harmless
and respect the environment?
First of all, the exploitation of certain species of the world's flora leads to the exhaustion of sources
which are difficult to replace (as has already occured with certain precious woods), and consequently,
in certain cases, the purely “ecological” nature of this operations is, at the very least, questionable.
Many examples can be cited to reverse the established principle “vegetable is harmless”. To follow the
suggestion that we consume hemlock or Amanita would surely have a lethal effect, but eating products
deriving from “biological culture” increases the risk of introducing into the body carcinogenic
vegetable toxins, spontaneously present as a form of natural pesticide.
Nor should we forget the risk of toxicity linked to the use of botanical drugs, as the hepatotoxicity of
plant-derived substances containing pyrrolizidine alkaloids or safrole or pulegon; ginseng abuse
syndrome; the carcinogenicity of aristolochic acid; etc.
And finally another possible negative aspect of plant-derived substances: contamination by arsenic,
mercury, tin, lead, radionuclides, pesticides, etc. This can also be a danger if vegetable substances or
their non-purified extracts are applied to the skin.
1 Translation of the article published in Lexicon Vevy Europe 1993, 7:100-101. 2 See abstract published in Lexicon Vevy Europe 1992, 1:7-15(12-13) “Test alternativi alla sperimentazione animale”. English translation in Lexicon Vevy Europe 1992, 3: 65-67.
But should the slaughter of animals in order to use the properties of some of their by-products
not in any case be considered as an even more negative factor for our ecology?
The crude and irrefutable images we are shown of animals sacrificed for the sake of humanity must, for
the most part, be attributed to sectors other than the cosmetic industry (primarily the food industry); on
the contrary, the cosmetics industry has eliminated substances of animal origin, substituting them with
synthetic equivalents, for example, spermaceti and beeswax.
With the exception of vegetarians, who abhor the initial sacrifice of the animal and the consumption of
products of animal origin (e.g. butter, cheese, eggs), it is quite astonishing to consider the total lack of
sensitivity (on the part of producers, consumers and marketing operators) towards fish - they too
animals - which can be used to obtain alternative products such as collagen, without seeming to come
up against any objection whatsoever.
Remaining within the area of protein derivatives (collagen, fibronectin, elastin, etc.), it should be
pointed out that, by analogy with all the active principles concerning the use of animals in the cosmetic
industry, these are by-products of the food industry, which sacrifices different animals in order to fulfil
its own objectives. None are killed with the aim of producing cosmetics; on the contrary, the beauty
industry, by using the left-overs of others, is helping to reduce the problem of their disposal, thus
rendering animal derivatives substantially more ecological or green, in as much as the cosmetic
industry is in agreement with this easy way of recycling large amounts of waste produced by the food
industry.
Finally, attention should be drawn to the fact that through biotechnological processes it has always
been possible to obtain certain animal derivatives, by means of bacterial or other cellular cultures,
without having to use the animal itself as a primary source.
There are no preconceptions to indicate a priori those raw materials which are “better”or “more
ecologically sound” uniquely due to their origin. Only careful, scrupulous and safe reseach, be it
analytical, chemical, pharmacotoxicological or concerning its applications, can determine the worth of
an ingredient for local, topical use.
Generic promotional information, incomplete and eye-opening, is useless for the consumer or the
industry.
Carcinogenic Plant Life3
If a representative cross-section of the population were to be questioned on the various possible causes
of cancer, the majority of people interviewed and able to give an answer other than "I don't know"
would, almost without fail, cite - apart from cigarette smoke - exposure to man-made chemical
compounds. Indeed, ecologists have herewith managed to convince most people that nuclear power
stations, industrial pollution, car fumes, chromium, pesticides and other products of "civilisation" are
the main causes of disease in general and of cancer in particular, and that the human race can only be
saved by "going back to nature".
One of the possible reasons for this psychological eco-terrorism no doubt resides in the fact that, during
the second half of this century, toxicology specialists have concentrated on studying the harmful effects
of synthetic compounds, while paying little or no attention to those caused by natural substances. This
is particularly true in the case of carcinogenesis, and it is easy to affirm this by skimming through the
list of compounds examined by the WHO International Agency for Research on Cancer in its 49
3 "Cancerogeni vegetali". Lexicon Vevy Europe 1991, 9:193-197. "Monographs on the Carcinogenic Risk of Chemicals to Humans" published from 1972 to the present
day.4
It is Bruce Ames, the father of mutagenesis testing on bacteria, who has been attributed the distinction
of having been the first person to categorically declare that the food we eat, and a lot of vegetable
matter in particular, contains a great amount of toxic substances, mutagenic and carcinogenic
elements5,6 which, together with smoke, are probably the major cause of cancer development, and are
perhaps, to some extent at least, responsible for other pathologies such as atherosclerosis and aging.
The fact that plants contain toxic chemical substances, and sometimes in significant quantities, and that
some of them may constitute a carcin ogenic risk to man is not in the least surprising. These substances
are often synthesised as a means of defence against insects or other predators. Many of the most well
known and powerful poisons in the world today are of botanical origin. For the most part, they have
been known of for quite some time, seeing that their acute effects are easily recognisable, and
pharmacologists today show a very strong interest in these poisons given that, in small doses, they have
therapeutic effects. Morphine, atropine, scopolamine, eserine, ergometrine and digoxin are just a few
examples from a long list. Contrary to their carcinogenic activity, which, in order to be highlighted
requires periods of testing which are long (months or years) and extremely expensive, the functional
effects of these active ingredients can be identified, summarily at least, in just a few days. More
recently, the use of short-term tests for carcinogenesis, the first developed by Ames, which allow the
rapid evaluation of whether or not a substance is mutagenic for bacteria, has enabled the identification
of a number of potentially carcinogenic compounds present in the vegetable matter our diet contains.
For certain of them, their ability to cause cancer has been successively documented by long-term tests
carried out on rodents.
Some Examples
Certain mushrooms contain mutagenic and carcinogenic hydrazines.7 Ergotine,8 present to the extent of
0.4g/kg of fresh weight in Agaricus bisporus and also in a number of other species, is not carcinogenic
by itself, but one of the products of its hydrolysis causes pulmonary and blood vessels cancer to
develop in the mouse. Gyromitra esculenta contains various hydrazones, the most well known of which
is giromatrine (acetaldehyde-N-methyl-N-formylhydrazine), present in dried mushrooms in concen-
trations varying from 0.5 to 3g/kg. In the mouse, this provokes an increase in the occurrence of lung
and stomach tumors, as well as those of the foreskin in males and of the clitoris in females. One of its
metabolites, N-methyl-N-formylhydrazine causes tumors of the liver, the gall bladder, the bile duct and
the lung to appear, again in the mouse. Another metabolite, N-methylhydrazine, has proved to be
carcinogenic in the hamster, in which the occurrence of cancer of the caecum and of histiocytomes in
particular increases.9
Vegetables ad Drinks
4 International Agency for Research on Cancer. IARC Monographs on the Evaluation of the Carcinogenic Risk of Chemicals to Humans. 1972-1990, Vol. 1-49. IARC, Lyon, France. 5 Ames,B.N. Dietary carcinogens and anticarcinogens. Oxygen radicals and degenerative diseases. Science, 1983, 221: 1256-1264. 6 Ames,B.N. and Gold,L.S. Pesticides, risk, and applesauce. Science, 1989, 244:755-757. 7 Toth,B. Synthetic and naturally occurring hydrazines as possible cancer causative agents. Cancer Res., 1975, 35:3693-3697. 8 International Agency for Research on Cancer. IARC Monographs on the Evaluation of the Carcinogenic Risk of Chemicals to Humans. Vol. 3l, Some Food Additives, Feed Additives and Naturally Occurring Substances. IARC, Lyon, France, 1983, pp. 63-69. 9 Ibidem, pp. 163-170. A great number of edible plants - including, to name but the most common, onion (Allium cepa),
asparagus (Asparagus officinalis), chicory (Cichorium endivia), lettuce (Lactuca sativa ), apple (Pyrus
Malus), potato (Solanum tuberosum) and spinach (Spinacia oleracea) - contain quercetin, the most
extensively studied of the flavonoids.
The interest in the carcinogenicity of these compounds has been generated by their presence, in the
form of glucosides, in a number of beverages (tea, coffee, cocoa, fruit juice, red wine, vinegar and
beer) and, more particularly, by the fact that they are present in the fern Pteridium aquilinum which, it
has been shown, has a tumor-inducing ability in various animals. On the other hand, some flavonoids
have shown an anti-carcinogenic activity which can be attributed either to their being inducers of
detoxifying enzymatic systems, or to the inhibition of the carcinogenic nitrosation of precursors
containing amine groups.
Other Edible Vegetables
However, at least 27 aglycons of different flavonoids are mutagenic for Salmonella typhimurium, and
for one of these, quercetin, the results of tests carried out in the rat provide certain evidence of
tumorigenic activity.10 Another flavonoid present in a large number of plants, many of which are
edible, is campherol (kaempferol) or lutine. This, too, is mutagenic, not only in Salmonella , but also in
the cells of mammals, and it induces micronuclei in the polychromatic erythrocytes of the bone marrow
of mice; unfortunately, the data available is insufficient for it to be established whether or not it is also
carcinogenic in laboratory animals.11
Many essential oils contain saphrol; in particular, that of sassafras (up to 93%), but also, to a lesser
extent, (1-10%) those of nutmeg, ginger, cinnamon, black pepper and anise. In the same oils, very
small amounts of isosafrole and methyleugenol can also be found. Both safrole (3,4-methylenedioxy-1-
allyl benzene) and isosafrole (1,2 methylene-dioxy-4-propenyl benzene) generate the appearance of
liver tumors in the mouse and rat models.12
Cicasine, a methylazoxymethanol glucoside, has proved to be carcinogenic in various animals;13 it is
present in the seeds, leaves and roots of the Cycadaceae, which grows in tropical and subtropical
regions. The diet of certain populations uses a flour ground from the nut produced by these plants, and
in certain areas, they are also the source of well known local drugs. Various tests have shown that both
cicasine and its aglycon are genotoxic, and even relatively small doses produce cancer, particularly in
the liver. In the diet of the rat, for example, the presence of a mere 1-3% of flour from the nut of the
Cycadaceae is enough to cause hepatocarcinoma and/or kidney cancer to appear in all animals treated.
The Risks Associated with Herbalism
A particularly numerous and widespread category of vegetable matter with carcinogenic effect are
pyrrolizidine alkaloids.14 They are present in hundreds of plants, especially in the different varieties of
Senecio, but also in those of crotalaria, Heliotropium, Lappul, Symphytum, Petasites and Tussilago
farfara. A large number of these plants can be found in herbalist stores since they have a therapeutic
use; they may contaminate cereals used for human consumption, and honey; and they are used in the
preparation of certain beverages or even as foodstuffs. Extracts of Tussilago farfara are even
ingredients in certain shampoos and skin cleansers. Among the different pyrrolizidinic alkaloids which
have been identified, the most well known are senkirkine, hydroxysenkirkine, senephicilline, isatidine,
11 Ibidem, pp. 171-178. 12 International Agency for Research on Cancer. IARC Monographs on the Evaluation of the Carcinogenic Risk of Chemicals to Humans. Vol. 10. Some Naturally Occurring Substances. IARC, Lyon, France, 1976, pp. 231-244. 13 Ibidem, pp. 121-138. 14 Kingsbury,J.M. Poisonous Plants of the United States and Canada. Prentice-Hall, Englewood Cliffs, N.J., 1964. jacobine, lasiocarpine, monocrotaline, retrorsine, riddelline, petasitenine and symphitine.15,16 In
general, they are mutagenic, teratogenic and hepatotoxic, with the latter having also been highlighted in
man. In the rat, apart from certain pure alkaloids, only the products of plants which contain them have
proved to be carcinogenic, especially for the liver where they are transformed into pyrrole reactive
metabolites.
The case of Umbrelliferae
Plants belonging to the Umbelliferae family - such as celery and parsley - and also bergamot oil contain
linear furocoumarins, such as derivatives of psoralen which, activated by UV rays lead to an
acceleration in the tanning process, but also, either directly or indirectly, by producing free radicals
which harm DNA, to an increased occurrence in the appearance of skin cancer. A documented criticism
of the regulations which discipline the use of bergamot oil in tanning products was published in 1981
by Ashwood-Smith and Polton.17 This specified that the clastogenic effect of bergapten (5-
methoxypsoralen), which constitutes the melanogenic active ingredient, is proportional to the product
of its concentration in different preparations, varying from between 12 and 50 µg per ml per dose of
UV rays; consequently, it is sheer nonsense to impose limits in the concentration of furocoumarin,
since a small dose of this in combination with a high dose of UV can do similar damage to higher
concentrations combined with a small amount of radiation.
Some Very Powerful Poisons
For centuries it has been known that foodstuffs in storage can be damaged by moulds which sometimes
make necessary their destruction. A toxic syndrome, ergotism, caused by the fungus Claviceps
purpurea, which grows on rye (Secale cereale) and other graminaceae has been known, sadly, since the
Middle Ages. But it is only recently that certain mycotoxins have been found to have a very powerful
carcinogenic effect. Among them, the most important - since their cencerogenic action in man has now
been established - are the aflatoxins, produced by strains of fungi which are fairly common. In recent
years, epidemiological investigations18 have shown a distinct relationship between the consumption of
foodstuffs contaminated by aflatoxin and the increase in the incidence of hepatocellular carcinoma.
These investigations concern not only certain developing countries, such as Uganda, Kenya, Swaziland,
Mozambique or China, but also a number of Western nations, including the south-eastern region of the
United States of America; they indicate that a daily absorption of some tens of nanogrammes of these
mycotoxins is enough to determine a significant increase in the risk of hepatocancerogenesis.
Another mycotoxin, ocratoxin A,19 produced by fungi of the Aspergillus and Penicillum types, has been
found particularly in cereals and has been identified in the blood of animals which have consumed
contaminated food. This provokes a chronic tubulo -interstitial nephropathy, and in the Balkans, where
15 International Agency for Research on Cancer. IARC Monographs on the Evaluation of the Carcinogenic Risk of Chemicals to Humans. Vol. 10, Some Naturally Occurring Substances. IARC, Lyon, France, 1976, pp. 263-342. 16 International Agency for Research on Cancer. IARC Monographs on the Evaluation of the Carcinogenic Risk of Chemicals to Humans. Vol. 31, Some Food Additives, Feed additives and Naturally Occurring Substances. IARC, Lyon, France, 1983, pp. 207-212, 231-246. 17 Ashwood-Smith,M.J., Poulton,G.A. Inappropriate regulations governing the use of oil of bergamot in preparations. Mutat.Res., 1981, 85:389-390. 18 International Agency for Research on Cancer. IARC Monographs on the Evaluation of the Carcinogenic Risk of Chemicals to Humans. Supplement 7, Overall Evaluation of Carcinogenicity: An Updating of IARC Monographs Volumes 1 to 42. IARC, Lyon, France, 1987, pp. 83-87. 19 International Agency for Research on Cancer. IARC Monographs on the Evaluation of the Carcinogenic Risk of Chemicals to Humans. Vol. 10, Some Naturally Occurring Substances. IARC, Lyon, France, 1976, pp. 191-197. it is most commonly found, a definite increase in the frequency of cancer of the urinary tract has been
noted.20
Among the different fungi which grow on rice, the staple diet in many parts of Asia, the most well
researched is Penicillum islandicum. Two of the mycotoxins produced by this fungus, cyclochlorotine
and luteoskirine21 are the cause of benign and malignant tumors in mice; even though epidemiological
studies are not available, it is suspected that these may contribute to the high rate of primary liver
carcinoma which is characteristic in the Asiatic people.
Unfortunately, and apart from the lack of epidemiological studies, it is often the inadequacy of
carcinogenesis testing in rodents which currently prevents scientists from estimating the potential risk
to man of other mycotoxins such as patriline, penicillic acid, sterigmatocysteine and T2-tricotecene.
Genotoxics
With a vegetable diet, numerous quinones, or the phenols which are their precursors, are introduced
into the organism. The genotoxic effect of quinones can either be direct, or else due to their transformation into semi-quinonic radicals able to react with DNA and to give rise to the formation of
free radicals of oxygen by means of a redox cycle. These in turn activate the peroxydation of the fatty
acids present in the lipids of biomembranes, a process which, in its final stage generates a number of
aldehydes - alkanales, alkenales and hydroxyalkenales - capable of interfering with various enzymatic
systems and of provoking mutations.25 Methylglyoxal,26 present in various different foods and in coffee
in particular, is another genotoxic aldehyde; it is also normally produced be the enzymatic mechanisms
of the human organism.
The Case of Gossypol
A carcinogenic toxin called gossypol27 is found in the proportion of about 1% in cotton seed and of
about 0.1% in the unrefined oil which is extracted from it. This oil is used for cooking in certain
countries (e.g. Egypt) even though it has been known for quite some time that gossypol initiates and
promotes the growth of skin cancer in mice, and induces genetic damage in the rat. Moreover, this has
not prevented gossypol from being put forward and tested as an economical spermicide. With the aim
of reducing the risk, a new variety of cotton has been developed, the seed of which contains only a
small amount of gossypol, but in this particular case, the cure would appear to be worse than the
disease in so far as the new seed is even more liable to be attacked by Aspergillus flavus, a producer of
aflatoxins. Furthermore, cotton seed oil, like the meat and livestock fed on this seed, contains
20 Dirheimer,G., Creppy,E.E. Mechanisme d'action de l'ochratoxine A, une mycotoxine nephrotoxique et cancérìgéne. Atti
del Joint Meeting della Società Francese e Italiana di Tossicologia, Venezia, Novembre 1990, p. 31.
21 International Agency for Research on Cancer. IARC Monographs on the Evaluation of the Carcinogenic Risk of Chemicals to Humans. Vol. 10, Some Naturally Occurring Substances. IARC, Lyon, France, pp. 139-144, 163-169. 22 Brown,J.P., Dietrich,P.S. Mutagenicity of anthraquinone and benzanthrone derivatives in the Salmonella/microsome test: activation of anthraquinone glycosides by enzymic extracts of rat cecal bacteria. Mutat.Res, 1979, 66:9-24. 23 Stich,H.F., Rosin,M.P., Wu,C.H., Powrie,W.D. A comparative genotoxicity study of chlorogenic acid (3-o-caffeoylquinic acid). Mutat.Res., 1981, 90:201-212. 24 Bosch,R., Friederich,U., Lutz,W.K., Brocker,E., Bachmann,M., Schlatter,Ch. Investigation on DNA binding in rat liver and in Salmonella and on: mutagenicity in the Ames test by emodin, a natural anthraquinone. Mutat.Res., 1987, 188:161-168. 25 Brambilla,G., Martelli,A., Cajelli,E., Canonero,R., Marinari,U.M. Lipid peroxidation products and carcinogenesis: preliminary evidence of n-alkanal genotoxicity. In "Eicosanoids, Lipid Peroxidation and Cancer", Nigam et al. (eds.), Springer-Verlag,Berlin, 1988, pp. 243-251. 26 Cajelli,E., Canonero,R., Martelli,A., Brambilla,G. Methylglyoxal-induced mutation to 6-thioguanine resistance in V79 cells. Mutat.Res., 1987, 190:47-50. 27 Ames,B.N. Dietary carcinogens and anticarcinogens. Oxygen radicals and degenerative diseases. Science, 1983, 221: 1256-1264. cyclopropenoid fatty acids, sterculic acid and malvalic acid, which are easily oxydised into
peroxydes;28 it is perhaps to this mechanism to which we owe the great variety of toxic effects that
these acids perform, like, for example the carcinogenic effect which has been noted in trout.
Vegetables and Nitrosamines
In certain cases, the relationship between the ingestion of vegetable matter and the increase in the
carcinogenic risk has remained less direct, but probably no less dangerous; for example, the high level
of nitrates provided by certain vegetables (celery, lettuce, spinach, etc.). Within the organism, nitrate is
partly reduced to nitrite which, in the acid environment of the stomach, nitrosates the molecules
containing amine and amide groups transforming them into nitrosamines and nitrosamides
respectively.29 These nitroso compounds are generally genotoxic and carcinogenic, and a growing
number of epidemiological studies now show that cancer of the oesophagus and the stomach is higher
in populations whose diet is rich in nitrates.30 In this case, a valid remedy exists in the form of the
simultaneous absorption of ascorbic acid, which blocks nitrosation.
Apples
The list of vegetable carcinogenic substances listed here is far from complete, including only those for
which experimental and/or epidemiological evidence capable of allowing us to make, if not an
estimate, then at least an appreciation of the probable risks involved, is indispensable; however, it is
more than long enough to demonstrate that the picture of cancer that we have today, as being a by-
product of the industrial civilisation, should be profoundly reconsidered. Ames and Gold have recently
tackled this problem in a lecture published in "Science",31 by intervening in a violent debate on the
need or not to outlaw the use of Alar, a growth regulator which retards the ripening of apples and thus
prevents them from falling from the tree prematurely, or from ripening too quickly during storage.
Alar, in fact, decomposes, and one of the products it generates, UDMH, is carcinogenic, but the danger
of it leading to the appearance of cancer is less than that which derives from the consumption of
mushrooms containing carcinogenic hydrazine; to be precise, it is 59 times more likely that the
absorption of one mushroom per day will lead to the development of cancer than that of one glass of
apple juice per day, made from apples treated with Alar.
Pesticides
To consider the problem from a more general angle, Ames and Gold affirm that 99.99% of
the"pesticides" we consume every day are of natural origin. Only 0.01%, that is to say 10,000 times
less than this, are made up of man -made, synthesised compounds.The list of foodstuffs containing
natural pesticides which have proved carcinogenic in rodents is very long: apples, bananas, basil,
Brussels sprouts, broccoli, cabbage, cauliflower, carrots, mushrooms, mustard, orange juice, peaches,
pepper, pineapple, etc. Unfortunately, our knowledge on this subject is still rather limited; it is enough
to consider that the juice of the apple contains some 137 natural volatile compounds; only 5 have been
tested for possible carcinogenic effects, 3 of which have proved to be cancerogenic. The situation is
quite likely to worsen in the future, considering the effort that agricultural economists are putting into
the development of plants which are resistant to attack from insects, a situation which often leads to the
creation of varieties which contain even greater numbers of natural pesticides. Here are two cases in
28 Ames,B.N. Dietary carcinogens and anticarcinogens. Oxygen radicals and degenerative diseases. Science, 1983, 221: 1256-1264. 29 Mirvish,S.S. Formation of N-nitroso compounds: chemi stry, kinetics and in vivo occurrence. Toxicol.Appl.Pharmacol., 1975, 31:325-351. 30 Bartsch,H., Montesano,R. Relevance of nitrosamines to human cancer. Carcinogenesis, 1984, 5:1381-1393. 31 Ames,B.N., Gold,L.S. Pesticides, risk, and applesauce. Science, 1989, 244:755-757. point: the first concerns a new potato which is resistant to insects, and which has been taken off the
market because it has proved to be toxic owing to its high concentration of two teratogens, solanine and
caconine, normally only present in minute amounts; the second relates to a new strain of celery, also
resistant to insects, but which causes dermatitis in farmers because of the level of carcinogenic 8-
methoxypsoralen it contains. With this in mind, it is only natural for us to query the degree of
rationality behind the position of different Agencies which continue to issue ever more restrictive
norms regarding the use of synthetic pesticides, while paying no attention whatsoever to the dangers
posed by natural pesticides. In addition, it is our duty to question the fact that the major part of
available ressources continues to be devoted to study the toxicity of synthetic compounds, while the
study of natural substances is neglected.
Conclusion
To conclude, we would be wiser to consider that nature is not necessarily benign and that the
carcinogenic elements present in our diet - not only those of vegetable origin which have been
considered in this text, but also those which derive from the pyrolysis of proteins, which occurs during
cooking, for example - are the cause of a quantity of human neoplasia which is difficult to estimate but
which is no doubt significant. And to speak only of cancer is most certainly too restrictive, since the
degenerative illnesses associated with aging are at least partly due to damaged DNA. However, nature
also provides us with a remedy made up of a number of tiny molecules which are present in our diet
and which have an antioxydant and anticarcinogenic effect: vitamin E, which is the main protection the
lipids of biomembranes have against free radicals; beta-carotene, another molecule which protects fats
from oxydation; selenium, which is present where gluthatione peroxydase is active, and is an
indispensible element in the destruction of hydrogen peroxydes and lipidic hydroperoxydes;
gluthatione, one of the most efficient antimutagens; and ascorbic acid, which has an antioxydant effect
and which blocks reactions of nitrosation. It is quite probable that the several neoplasias which occur in
various geographical locations can be put down not only to levels of industrialisation, to lifestyle and to
the amount of carcinogenic elements absorbed from dietary sources, but also to a varying intake of
substances which are capable of inhibiting one or several phases of the carcinogenetic process.

Source: http://www.relata.eu/docs/Natural.PDF