February 8, 2005
Source: CORDIS News
Researchers in Denmark have confirmed that a chemical found
in raw carrots and other vegetables helps to prevent colon
cancer - although it is not the same substance that scientists
had previously thought responsible.
Experts used to believe that it was the beta carotene found in
carrots that had an inhibitory effect on cancer, but research
carried out at the University of
Southern Denmark shows that it is actually the plant
chemical falcarinol.
Falcarinol is also found in celery, parsley, parsnip and other
vegetables, but only when raw. Cooking destroys the cancer
preventing properties of falcarinol, the researchers say.
Morten Larsen, who headed the research, says: 'The discovery
makes it possible for us to authoritatively recommend which
vegetables should be eaten to protect against cancer. With more
research, we hope we can give more precise recommendations on
the amount of carrots and other vegetables a person should eat
daily.'
Dr Larsen conducted his research in collaboration with the
Danish Institute of
Agricultural Sciences, which is trying to develop methods
for growing carrots with higher levels of falcarinol, and
studying what happens to the chemical when vegetables are cooked
or frozen.
'We know the effect is greatest when carrots are eaten raw, and
we know that falcarinol is very sensitive to light and heat, so
cooking has a negative effect. It looks kike freezing will
preserve the cancer-preventive effect, so we can expect that
frozen carrots are also beneficial,' Dr Larsen added.
Colon cancer is the second most common cancer in the EU, and
there is currently no cure once it has become symptomatic, so
testing and early detection are crucial.
Related news release from
University of Newcastle upon Tyne:
Carrot component
reduces cancer risk
Scientists have given us another
reason to eat carrots - a compound found in the popular root
vegetable has been found to have an effect on the development of
cancer.
A team of researchers, from the
University
of Newcastle upon Tyne in England and Denmark, found
the natural pesticide falcarinol reduced the risk of cancer
developing in rats by one third.
Although experts have
recommended that people eat carrots for their anti-cancer
properties, it has not been known exactly what component of the
vegetable has this effect.
The study results, published
today in the Journal of Agricultural and Food Chemistry, are
significant as they could contribute to healthy eating advice
for consumers and recommendations for growers and may eventually
aid the development of anti-cancer drugs.
Falcarinol protects carrots
from fungal diseases, such as liquorice rot that causes black
spots on the roots during storage. The scientists investigated
the compound after a previous published study suggested it could
prevent the development of cancer.
The research team carried out
tests on 24 rats with pre-cancerous tumours in laboratory
conditions. They divided them into three groups and fed them
different diets.
The team found that, after 18
weeks, rats who ate carrots (the popular orange variety) along
with their ordinary feed and the group which consumed falcarinol
with their feed - in a quantity equal to that contained in the
carrots - were one third less likely to develop full-scale
tumours than the rats in the control group.
Dr Kirsten Brandt, a senior
lecturer with Newcastle University's School of Agriculture, Food
and Rural Development, carried out the research with the
University of Southern Denmark and the Danish Institute of
Agricultural Sciences. She said: "We already know that carrots
are good for us and can reduce the risk of cancer but until now
we have not known which element of the vegetable has these
special properties.
"Our research allows us to make
a more qualitative assessment of the vegetables we are eating,
rather than quantitative. We now need to take it a step further
by finding out how much falcarinol is needed to prevent the
development of cancer and if certain types of carrot are better
than others, as there are many varieties in existence, of
different shapes, colours and sizes.
"We could also expand our
research to include other vegetables. For consumers, it may soon
no longer be a case of advising them to eat five portions of
fruit and vegetables per day but to eat particular types of
these in certain quantities. The research could also lead to
more tailored advice for growers regarding the methods they
should use when growing vegetables."
The experiment was conducted
using raw carrots so researchers do not yet know if eating
boiled carrots or drinking carrot juice, for example, would have
the same effect.
Dr Brandt, who says she eats
"more carrots than most" and grows her own organic varieties,
recommended that consumers should eat one small carrot every
day, together with other vegetables and fruits, to benefit from
their health-giving properties.
Falcarinol is toxic in large
amounts but to obtain a lethal dose you would have to eat 400
kilograms of carrots at once. Researchers suspect it is
effective because it stimulates mechanisms in the body that
fight cancer, although they have yet to carry out a detailed
analysis in this respect.
The research was funded by
the Danish Agricultural and Veterinary Research Council and
participating institutions.
Journal ref. Inhibitory
effects of feeding with carrots or falcarinol on development of
azoxymethane-induced colon preneoplastic lesions in rats,
Kobaek-Larsen et al, Journal of Agricultural and Food Chemistry.
Related news release from
the Danish Institute of
Agricultural Sciences:
Gulerødder
hæmmer kræft
Det er cand.scient., ph.d.
Morten Kobæk Larsen fra Biomedicinsk Laboratorium på Syddansk
Universitet, som via en række dyreforsøg er nået frem til, at
plantestoffet falcarinol har en forebyggende effekt på
tarmkræft.
Hans opsigtsvækkende resultater
har allerede vakt interesse i udlandet, og de blev i går
offentliggjort i det ansete tidsskrift ”Journal of Agricultural
and Food Chemistry”.
- Vores opdagelse giver jo
nogle nye perspektiver. Nu kan vi gå ind og vejlede mere konkret
i, hvilke grøntsager vi skal spise for at forebygge kræft.
Desuden er det jo oplagt at forsøge at fremavle nogle gulerødder
med et højere indhold af falcarinol, siger Morten Kobæk Larsen.
Falcarinol-indholdet skal øges
Derfor er hans forskning også
foregået i samarbejde med blandt andet forskningsleder Lars
Porskjær Christensen fra Danmarks Jordbrugsforskning. Han har i
flere år forsket i gulerodens sundhedsgavnlige egenskaber og i,
hvordan man identificerer og isolerer de forskellige stoffer.
Målsætningen er i løbet af nogle år at øge indholdet af
falcarinol i gulerødder til et omfang, så det får optimal effekt
mod kræft.
Selv om forskerne i en årrække
har været enige om, at gulerødder er sunde, har de ikke vidst
specielt meget om de sundhedsgavnlige effekter i den
orangefarvede spise. I lang tid gik man ud fra, at det var
pigmentet beta-karoten, der havde gavnlig effekt mod kræft, men
undersøgelser har senere modbevist denne teori, og dermed var
forskerne lige vidt.
Kan det modvirke kræft?
Nu håber de altså på at have
fået et gennembrud, og dermed melder en række nye spørgsmål sig:
Hvor godt optages falcarinol for eksempel i kroppen, og hvordan
virker det? Og bliver der meget af det tilbage i gulerødderne,
efter at de er kogt, eller forsvinder stoffet i stedet hurtigere
på stegepanden? Og hvad med frosne gulerødder?
- Vi kender allerede nogle af
svarene, mens der forsat venter et stykke arbejde med at finde
resten. Hele tanken bag dette projekt er jo netop, at vi ikke
går efter et lægemiddel, men en grøntsag, siger Morten Kobæk
Larsen.
Med baggrund i de nuværende
resultater håber han at skaffe penge til at fortsætte sin
forskning i gulerøddernes betydning – han vil således gerne
undersøge om falcarinol ikke alene har en forebyggende
effekt mod kræft men også, om den rent faktisk kan modvirke
kræft, som allerede er i udbrud.
Falcarinol findes i gulerødder
samt i mindre omfang i beslægtede grøntsager og urter som for
eksempel knoldselleri, bladselleri, persille og pastinak samt i
medicinplanter som ginsengrødder. |