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ISIS Report 07/09/06
Organic Strawberries Stop Cancer Cells
Latest evidence on why organic foods are good for health. Prof.
Joe Cummins and Dr. Mae-Wan Ho
A fully referenced version
of this article is posted on ISIS members’ website. Details
here
Organic foods a cornucopia of health-promoting compounds
Scientific evidence has been accumulating on the health benefits of organic
foods (Are Organic Foods More Healthy? Organics for Health;
Organic Agriculture Helps Fight Cancer;
Food Quality? What's That? / Do
Animals Like Good Food?) (see Box).
Box 1
Why organic foods are healthy
Richer in essential minerals such as calcium, magnesium and ion, and
trace minerals such as copper [1-3]
Contain more vitamins and micronutrients [3]
Rich in antioxidants and other compounds that fight cancer and heart
disease (see main text)
Low in nitrates [4, 5]
Contain little or no harmful pesticide residues (see main text)
Grown without polluting pesticides and fertilizers and hence provide
a cleaner environment for health
Contain little or no antibiotics that harm beneficial natural gut bacteria
[6]
Contain no harmful artificial food additives such as
hydrogenated fats, phosphoric acid aspartame and monosodium glutamate
[7]
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One important thing about
organically grown foods is that they
are a cornucopia of health-promoting chemical compounds.
A new landmark study shows that organic strawberry
extracts inhibited the proliferation of cancer cells more effectively than
conventional strawberry extracts.
What is it about
organically grown plants that make them rich in secondary metabolites off
the main track, which are great for fighting diseases like cancer? Many of
these compounds are actually part and parcel of the plant’s own defence against
pests and disease.
Bengt Lundegardh and Anna Martensson [8] at the University of Agricultural
Sciences Uppsala Sweden believe that the benefits of organically grown foods
have a lot to with activating the plant’s defence mechanisms to synthesize its
own protective agents because synthetic pesticides are excluded. An active
soil where plants and microbes interact also facilitates the exchange of metabolic
compounds such as vitamins and cofactors. In addition, organically grown foods
have a richer mineral content, on account of a more balanced nutrient uptake
in the absence of artificial fertilizers, which would have provided excesses
of easily available nutrients such as nitrates.
Bioactive compounds in foods, especially the plant phenolic antioxidants, are
well known to prevent cancer and cardiovascular disease [9]. Phenolics are present
in many crops, particularly fruits, and it has become clear that organic foods
are richer in cancer fighting antioxidants [10, 11].
Organic strawberry extracts stop cancer cells
Strawberries have been studied extensively for their cancer fighting ability
and that is where the benefits
of organic fruit cultivation shine through. Swedish researchers at Swedish
University of Agricultural Sciences, Alnarp, and Lund University compared
extracts of five organic and conventional cultivars for their
ability to inhibit the proliferation of human colon and breast cancer cells.
They found that extracts from organically grown strawberries inhibited cell
proliferation more effectively than extracts from the conventionally grown
ones, and in both types of cancer cells [12].
The strawberry extracts
decreased cell proliferation in a dose-dependent manner between 0.025 to 0.5
percent dry weight of extract to volume of cell culture. At the highest concentration,
the organic extracts inhibited proliferation of colon cancer (HT29) cells
by 60 percent and breast cancer (MCF-7) cells by 53.1 percent; the corresponding
values for conventional strawberry extracts were 49.7 percent and 37.9 percent
respectively. The differences between conventional and organic were statistically
highly significant.
The most effective extracts at inhibiting cell proliferation contained 48 percent
more ascorbate and 5 times more dehydroascorbate. (Vitamin C is ascorbate plus
dehydroascorbate.) The organic strawberries also had more antioxidants and a
higher ratio of ascorbate to dehydroascorbate.
Compost as a soil supplement
increased the level of antioxidant compounds in strawberries [13]. The strawberry
extracts, rich in vitamin C and
antioxidants, were found to interfere with the mitogen-activated
protein kinase (MAPK) signaling cascade that leads to cell division, and to
suppress cancer cell proliferation and transformation [14].
These latest findings on
organic strawberries are in line with those on other organic fruits. Organic
yellow plums were found to be
richer in phenolic acids when grown in natural meadow or with a ground cover
of clover than conventionally grown plums [15]. Plum and clover extracts induced
apoptosis (cell death) and reduced
the viability of human liver cancer cells [16].
Absence of pesticides another tangible health benefit
Apart from providing secondary metabolites that fight diseases, the absence
of pesticide residues in food and feed is another tangible health benefit of
organic food. The “green revolution” has boosted food production in developing
countries through high inputs of pesticide and fertilizers. Investigators at
the Centre for Rural Development and Technology Dehli India studied residues
of organochlorine, organophosphorous, carbamate and pyrethroid pesticides in
conventionally grown wheat and rice and found that organic wheat and rice had
little or no detectable pesticide. Production of wheat and rice under conventional
system was higher than organic but this higher production is at the cost of
health risk and also poses other hazards to flora and fauna [17].
The National Research Council in the United States concluded in their 1993
report [18] that dietary intake is the major source of pesticide exposure for
infants and children in the United States, and this exposure may account for
increased pesticide related health risks in children compared to adults (see
Box 2).
Box 2
What
the US EPA says about pesticides in infants
The US Environmental
Protection Agency states [19]: “Laboratory studies show that pesticides
can cause health problems, such as birth defects, nerve damage, cancer,
and other effects that might occur over a long period of time. However these
effects depend on how toxic the pesticide is and how much of it is consumed.
Some pesticides also pose unique health risks to children.”
That is because [20], “their
internal organs are still developing and maturing”, and “in relation to
their body weight, infants and children eat and drink more than adults,
possibly increasing their exposure to pesticides in food and water.” Furthermore,
“certain behaviors – such as playing on floors or lawns or putting objects
in their mouths – increase a child’s exposure to pesticides used in homes
and yards.”
Pesticides may harm the
developing child by blocking the absorption of important food nutrients
necessary for healthy growth. Furthermore, if the child’s excretory system
is not fully developed, the body may not fully remove pesticides. There
may also be crucial periods in human development when exposure to toxin
can permanently change th way an individual’s system works. |
Researchers at the Rollins
School of Public Health, Emory University, Atlanta, and Department of Environmental
and Occupational Health Sciences, University of Washington, Seattle, Washington
in the United States measured dietary exposure in the urine of infants and
children before and after they switched from consuming conventional to organic
produce and then again back to conventional. They showed that the metabolites
of the organophosphates malathion and chlorpyrifos declined to undetectable
levels immediately after switching to organic diets, and remained undetectable
until they switched back to conventional diets [19]. This supported the earlier
conclusion that the children were mostly likely exposed to organophosphate
pesticides exclusively through their diets.
Children are not the only
ones affected by pesticides. In Denmark, a 1999 study on human sperm and semen
quality in relation to organic or conventional diet found that the group consuming
mainly organic food had a reduced pesticide intake based on the pesticide
levels measured in their food. The researchers concluded that pesticide exposure
in the diet did not entail a risk of impaired semen quality [20] even though
the group of men not consuming organic food had a significantly lower proportion
of morphologically normal sperm, which is generally considered predictive
of pregnancy outcome, as abnormal sperms are indicative of DNA damage [21,
22]. It is not clear why the investigators thought that increase in abnormal
sperms did not impair semen quality.
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