Agriculture Reference
In-Depth Information
and pesticides means that the nutrient supply to the crops needs to be provided from sources
with a relatively slow release of plant nutrients. The lower levels of available N affects the plant
physiology so that there are relatively high concentrations of ascorbic acid (vitamin C) in the
plant tissues, including harvested vegetables (Mozafar 1993). But the effect is indirect, because
the regulation only specifies which inputs are banned, it does not specify the level of vitamin C
in the product, and the quality advantage can be lost without violating the regulation (e.g. if
the variety used by the organic farmer is one with a low capacity for forming vitamin C)
(Justesen et al . 1998). For processed foods, a few regulations directly inf luence specific aspects
of quality by banning of synthetic colourants, artificial f lavouring agents and antimicrobial
additives. Still, there are no requirements for positive taste or health effect qualities, only for
the absence of these additives, which are considered negative by many consumers even though
actual health risks for those additives that are allowed in conventional foods have not been
proven (Brandt and Mølgaard 2001). However, while the support from governments and
official agencies only refers to environmental benefits, many consumers are convinced that
organic foods taste better than conventional products and cite possible beneficial effects on
health as a major reason for buying organic foods (Schifferstein and Ophuis 1998, O'Doherty
Jensen et al . 2001). In response to the greatly increased market share of organic food, there is
an increasing interest in investigating whether there are any differences in the effects of organic
and conventional food on health.
Reiews of earlier studies of organic food and health
Numerous studies have compared food produced according to the organic standards with con-
ventionally produced food in attempts to elucidate whether different farming methods result in
different effects on human health. Several ministries and other organisations have organised
reviews of these studies; for example, those by Woese et al . (1997), O'Doherty Jensen et al . (2001),
Bourn and Prescott (2002), Food Standards Agency (2002), Soil Association (2002), Williams
(2002), AFSSA (2003), BMVEL (2003), Kouba (2003), Lotter (2003) and Magkos et al . (2003).
The reviews concluded that there is no evidence for any direct health benefits nor risks
definitively associated with the consumption of organic foods. Significant differences exist in
the average levels of several nutrients, contaminants or pathogens regarding food composition,
however. Most, but not all, of these differences appear to be beneficial on the part of the organic
food and organic foods tend to contain substantially lower levels of pesticide residues and
slightly higher vitamin C content, but there is no evidence that differences of the measured
magnitudes are so great as to have any effect on health. One of the reviews carried out by the
Soil Association (Soil Association 2002) chose to conclude therefore that while not definitive,
the evidence was in favour of a benefit of unknown magnitude from eating organic food. Other
reviews conducted by various agencies or expert groups financed by a government preferred
the more conservative interpretation of the same body of data in accordance with the conven-
tion normally used in science, that the available evidence does not allow rejection of the null
hypothesis of no effect. However, most of the reviews specifically pointed out that the absence
of evidence is due to absence of relevant data. There are no well-designed experimental studies
showing definitively that there is no difference. The studies included in the reviews were not
designed to be able to provide definitive evidence for differences between these two food pro-
duction systems in terms of effect on human health, and/or were not targeted to those aspects
where differences are most likely.
Due to this, the state of the art in terms of scientific consensus is that no well-defined
problem of direct toxicity, pathogenicity or nutrient deficiency, nor any benefit with a well-
defined impact on health, has been proven to be specifically associated with either organic or
conventional food. To place this in perspective, a similar statement can be made regarding the
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