by Paul Cribb, B.H.Sci HMS
AST Director of Research
Research questionnaires completed by consumers in the US, Australia and Great Britain suggest that individuals who purchase organically grown produce believe it is substantially more nutritious and less hazardous than the conventional alternative, and they are willing to pay significant premiums to obtain it. In many cases organic produce can cost 50-100% above the cost of conventional produce.
As I’ve explained in a number of previous articles and reports, a high intake of vegetables is a key “secret” weapon to achieving a lean, healthy physique. As a health-conscious person myself, I want to provide my family with the best nutritional choices, and I assume that many readers of our site want to do the same. That’s why I decided to investigate whether or not organic vegetables (and other organically-grown produce) really are a better choice than the conventional variety.
I like to make informed decisions. As a scientist, by nature I’m analytical (and probably a bit of the first half of that word too!). No matter what I’m researching, I like to know the facts and more importantly where and how the facts (data) were obtained. From there, I’ll make an educated decision – that’s all anyone can do. Therefore, in this article, I’ll present you with a concise overview of all the research I’ve examined. And, (in my usual straight-up, no BS Aussie style), I’ll also provide some insights I’ve obtained about this controversial topic. Above all, my aim is to provide you with an unbiased, informed opinion.
What is “organic”?
By definition, “organic” food is derived from crops or animals produced in a farming system that avoids the use of man-made fertilizers, pesticides, growth regulators and livestock feed additives. Organic farming systems rely on crop rotation, animal and plant manures, some hand weeding and biological pest control. Organic farming dates back to World War II but recent decades have seen a marked increase in the demand for organic foods, which reflects the consequential growth of this niche market.
This demand appears to reflect consumer concern regarding the safety of food produced under conventional (intensive) farming systems. One recent key report concluded that “a healthier choice” is a prime factor contributing to the willingness of the public to pay premium prices for organic food. In fact, 60% of the population (in Great Britain) would choose organic food if it was easily available and cost no more than conventional food. Despite the widespread conviction held by many people that organic food is ‘healthier’ than foods produced by conventional farming, science-based evidence to support this perception is difficult to identify. This difficulty arises because a very limited amount of research has been completed and much of the available data is either out-dated or obtained from poor study designs. I’ll provide you with some key examples.
Nutritional quality
One reason why some people chose organically-grown is the perception that the food is of higher nutritional quality. However, evidence that can clearly support or refute this perception remains equivocal. The number of systematically-controlled studies that have compared the nutritional quality of organic vs conventionally-grown crops is meager.
The extent of disagreement is well illustrated by two diametrically-opposed statements currently published on the web. An editorial on the website of the American Council on Science and Health 1 states, “not a single published study has shown any difference in the nutrient content of organic versus conventional farm produce”. The Mothernature site (
www.mothernature.com) supports the view that organic food is healthier than conventionally-grown food “… based on research in Denmark and Germany showing that organically grown foods contain higher levels of nutrients.”
However, if we look to the research, it is apparent that extensive scientific reviews in this area have failed to draw definitive conclusions.2,3,4,5 For this data, there appears to be trends for higher concentrations of some nutrients in organic produce compared with conventionally-grown produce. Interestingly, few studies show lower levels of nutrients in vegetables of organic origin. However, most (if not all) of these studies have serious limitations in terms of the quantity and quality of the data obtained. In most cases the accuracy of the data must be questioned.
The bottom line:
The quality and quantity of studies that have compared the nutritional quality of organic vs conventionally-grown produce is so poor that we really can’t draw any clear conclusions. The differences, if any appear to be minimal. Therefore, I’d be wary of people that claim big differences either way.
The concern of safety
Consumer concern over the safety of conventional food has intensified in recent years. Recent survey studies on populations such as children report concentrations of pesticide residues up to six times higher in kids eating conventionally farmed fruit and vegetables compared with those eating organic food.6
The routine use of synthetic pesticides is not allowed under organic standards. Currently, over 400 chemicals can be regularly used in conventional farming to kill weeds, insects and other pests that attack crops. For this reason, advocates of organic foods suggest that organically grown produce contains fewer pesticide residues, and that buying organic is one way to reduce the chances that your food containing pesticides.7 However, this may not necessarily be the case.
One (of few) well designed studies evaluated both conventionally and organically produced lettuce for organochlorine pesticide (OCP) residues.8 Using gas-chromatography, OCP residues in the tissues of two varieties of lettuce and the soil in which they were grown was analyzed.
Results showed that the soil from the conventional farm had higher OCP residues than organic, even though levels were well below minimal standards (5 ng/gram dry weight), which is indicative of a low polluted agricultural environment. However, despite no pesticides being used by the organic farm, the produce from both farms showed detectible amounts of OPC residues.8
Also, the different varieties of lettuce showed a high variability in pesticide uptake. This indicates that different vegetables, (and different types of a particular vegetable) may influence the amount of pesticide that accumulates within its tissues. Therefore, aside from this high variability among plant species, the researchers concluded that environmental conditions like presence or absence of trees, hedgerows or nearby to conventional farms can influence the occurrence and levels of pesticides in vegetables that are organically grown.8
Consumers of organic fruits and vegetables expect (and pay for) their produce to be “pesticide free” but as this research suggests, this may not be the case.
While organic fruits and vegetables can be expected to contain fewer chemical residues than conventionally grown alternatives; the significance of this difference is questionable. More recent studies show that actual levels of contamination in both types of food are generally well below acceptable limits.9 Some leafy, root, and tuber organic vegetables appear to have a lower nitrate content compared with conventional vegetables, but whether or not dietary nitrate indeed constitutes a threat to human health is not clear.
Additionally, these studies also report no differences between organic and conventional produce for environmental contaminants such as cadmium and other heavy metals. These are likely to be present in food from both origins.9
With respect to other food hazards such as endogenous plant toxins, biological pesticides and pathogenic micro-organisms, the evidence available is extremely limited. Results for mycotoxin contamination; a potentially lethal toxin produced by an organism of the fungus family, has been detected among a wide variety of both organic and non-organically-grown cereal crops.9 Hence, no clear picture emerges.
Although it is logical to assume that organic produce may contain lower levels of pesticides and synthetic fertilizers, the application of manure and reduced use of fungicides and antibiotics in organic farming could result in a greater contamination of organic foods by potentially lethal micro-organisms or microbial products. Therefore, it’s difficult to weigh the risks. However, what should be clear is that 'organic' does not automatically equal “safe.”9
Effects on human health
No studies in the last 65 years have compared effects of organic and conventional produce on human health. Such studies pose considerable problems of feasibility, cost and ethics. They would need to be carried out under very carefully controlled conditions over long periods of time, thereby limiting the number and type of subjects who would be eligible and available for study.
A few observational studies of sperm quality in organic and non-organic farmers have been published, with one study showing lower semen counts in conventional farmers than organic farmers and the other study showing no difference between the two groups.10,11 A few experiments conducted in Germany in the 1930s and 1940s compared effects on human health of foods produced using either organic or mixed (organic plus chemical) fertilizers. These studies report no effects in experiments involving 260 adolescents12 or 300 adults.13
Studies completed after World War II show that crops grown with mixed fertilisers had more b-carotene and minerals but lower levels of B vitamins than organically-grown crops. No effects of these products on blood variables were observed in adults, although in infants there was a higher daily growth rate and higher serum b-carotene in children fed on crops grown under mixed fertilizer conditions.14,15 Lack of relevant dietary data, heterogeneity in the study populations and limited information on growing conditions of the foods consumed means that much of this early data cannot be scrutinized according to current scientific criteria. Therefore, once again, it’s unwise to draw firm conclusions from these studies.
Some studies have found that people who eat conventionally grown fruits and vegetables have more pesticide by-products in their urine than those who favor organic produce. Yet, there is little evidence to suggest that pesticides in amounts normally consumed by humans can endanger health.
Obviously, it is prudent to minimize your intake of pesticides but this can be achieved quite simply by thoroughly washing fruits and vegetables before consumption. And if you’re really concerned, you might also consider peeling fruits and vegetables, where possible. However, these steps are recommended even if you purchase organic products; remember, organic farming involves the application of manure.
The botton line:
I understand that I’m starting to sound like a broken record here but I just call ‘em as I see ‘em. The quantity and quality of studies that have compared the safety of organic vs conventionally-grown produce is so scarce that we really can’t draw any clear conclusions. An organic choice may result in fewer pesticide residues but the amount (in most cases) is low and the significance of this difference is questionable. Additionally, simple steps (such as washing your food thoroughly) can serve to significantly reduce this risk. With regard to other environmental contaminants, it’s clear that an organic choice does not necessarily equate to a safer choice.
My take on the whole organic vs. non-organic thing….
I’m really surprised and disappointed at the lack of quality information on such an important topic. Regarding potential differences in nutritional quality; if there are any, they appear to be minimal. Therefore, I’d be wary of people that claim big differences either way.
Regarding safety concerns, I’ll stress the point I made previously; an organic choice may mean fewer pesticide residues but the amount (in most cases) is low and the significance of this difference is questionable. Simple steps (such as washing your food thoroughly) can serve to significantly reduce this risk. With regard to other environmental contaminants, it’s important to remember that an organic choice does not necessarily equate to a safer choice.
“Would I recommend choosing organic produce over the conventional kind?” From all I’ve read, it seems tough to justify the expense. The benefits of organic foods are minimal and at times questionable and often cost 50-100% more. Having said that, when it’s economical, I don’t have a problem with choosing the organic variety.
It is a lifestyle choice. However, above all, I think common sense must prevail. Parents that make a point of feeding their new-born babies only the finest organic produce often find themselves only a few years later, pulling into fast-food restaurants to quell their kids incessant pleas for the (fat, sugar and preservative-laden) treats.
References
1.
www.acsh.org/press/editorials/organicfood021700.html 2. Organic Farming, Ipswich, Suffolk: Farming Press, 557–611, 1990.
3. J Sci Food & Agri 74, 281–293, 1997.
4. Alternative Therapies 4,58–68, 1998.
5. Proc Nutr Soc 61(1), 2002.
6. Environ Health Perspec 111,377–382, 2003.
7. Sir John Krebs, Chair, Food Standards Agency, Cheltenham Science Festival debate, June 2003.
8. Food Chem Toxicol 43(2):261-9, 2005.
9. Crit Rev Food Sci Nutr. 46(1):23-56, 2006.
10. Lancet 347,1844, 1996.
11. Arch of Environ Contam & Toxicol 37,415–423, 1999.
12. Ernährung (Leipzig) 8, 281–295, 1943.
13. Emährung (Leipzig) 3, 53–69, 1938.
14. Ernährung (Leipzig) 9, 581–586, 1944.
15. Qualitas Planitarum 21, 381–398, 1972.
