Organic Is Healthier: Kiwis
Prove That Green Is Good
In one of the most comprehensive and definitive studies of its
kind to date, a team of researchers at the University of California,
Davis have proven that organically grown kiwifruit contain more
health-promoting factors than those grown under conventional conditions.
The research is reported in the SCI's magazine Chemistry & Industry.
The debate over the relative health benefits of organic versus
conventional food has raged for years, with UK environment secretary
David Miliband declaring in January that buying organic is just
a lifestyle choice.
The Davis scientists, led by Drs. Maria Amodio and Adel Kader,
showed that organically grown kiwifruit had significantly increased
levels of polyphenols, the healthy compounds found in red wine
and coloured berries. They also had a higher overall antioxidant
activity, as well as higher levels of ascorbic acid (vitamin C)
and important minerals compared with their conventionally grown
counterparts (Journal of the Science of Food and Agriculture DOI
10.1002/jsfa.2820). Their work differed to previously inconclusive
studies, as they were able to compare like-for-like with kiwis
grown next to each other on the same farm at the same time, in
the same environmental conditions. Kader added: "[previous] studies
did not include phenolic compounds in the comparison."
The two categories of kiwifruit showed other differences which
Kadel believes are most likely due to the fruits having to be
able to survive against pests in the absence of pesticides. For
example, organic kiwis had thicker skins, which could help the
fruits resist insects, and higher antioxidant activity which is
thought to be a natural by-product of stress.
However, some people are still unsure about the potential benefits
of antioxidants and other compounds elevated in organic farm produce.
Carl Winter, director of the FoodSafe Program at UC Davies, asks
whether these increases in nutrients and antioxidants are of any
appreciable health perspective. He is also concerned about any
unknown negative effects on the health. "The authors also did
not look for any plant secondary metabolites of potential toxicological
According to the Soil Association, organic food sales in the
UK increased by 30% to £1.6bn in 2006. The world market for certified
organic foods was estimated to be worth US $23-25 billion in 2003
and is growing approximately 19% every year, making these products
the fastest-growing sector of the global food industry.
Also of interest in C&I issue 6 2007: Grapefruit diet has hearty
perks Compounds in grapefruit and oranges have been shown to lower
cholesterol levels in the blood. Two flavanones, hesperidin and
naringin, were extracted from citrus fruits and fed to rats split
into groups with some receiving high levels of cholesterol in
their diet. Shela Gorinstein of The Hebrew University in Jerusalem
found that after 30 days cholesterol levels in rats' blood reduced
by around 20-25% in those fed a cholesterol-rich diet (Journal
of the Science of Food and Agriculture DOI: 10.1002/jsfa.2834).
David Bender, Sub-dean at the Royal Free and University College
Medical School, London, believes that the results show a significant
reduction in the increase in plasma lipids caused by cholesterol
feeding. "This is potentially beneficial to health with regards
to heart disease", he added.
Casey Gauthier reports on this story in Chemistry & Industry.