Consumers feel in their gut that organically produced foods are safer to eat and healthier for the environment by dint of fewer chemical residues and inputs. Todd Runestad investigates whether the state of the science has matched consumer expectations
Do organic products really offer proven human health and environmental benefits over conventional food products? Do organic farming methods have beneficial effects on the nutritional quality of food? Are agricultural chemical residues in food and the environment bad for consumers? And if the answer is yes to any of the above issues that lie at the heart of organic advocacy, can the results be quantified?
When the organic standards were first proposed in the US more than a decade ago, there was little scientific evidence to support an affirmative answer to any of these questions. And while anything short of God handing down engraved tablets pronouncing organics to be better than chemical-intensive foods will not likely get the USDA to publicly proclaim so much, a body of evidence is accumulating. Although still preliminary, the research is looking like it is validating many of the claims asserted by organic advocates.
"We haven't been able to shake the label, yet, that we're 'alternative,'" says Mark Davis, chief executive officer of The Organic Center, the US research advocacy group. "In reality, organic farming has been the traditional, historic way to grow. It's using chemicals that is alternative. But we will shake that label."
Despite organic foods comprising almost three per cent of the entire retail food market in the US, federal funding aimed specifically at organic growers makes up $3 million annually — less than one tenth of one per cent of current farm-bill spending. The farm bill is up for its five-year renewal in 2007, and organics advocates are poised to get this spending increased dramatically — in Europe, a four-year government-sponsored organics research initiative is budgeted at 100 million Euros.
The challenge for researchers is to demonstrate an advantage that is more than merely being free of undesirable chemicals that may or may not amount to anything significant. The accumulated research can be broken down into a handful of areas. These range from differences on the farm — from usage of chemicals and energy to soil quality and yield — to chemical exposure in consumers, to nutrient density of crops and foods.
Down on the farm
The great benefit of chemical-intensive agricultural practices has been a significant increase in crop yield per acre. Indeed, post-World War II America was heralded as being able to feed the world with its vast acreage of crops throughout the heartland.
So it came as a great surprise to read the results of a 22-year farming trial led by Cornell University, New York, researchers, published in 2005, finding that organic farming produces the same yields of corn and soybeans as conventional agricultural practices - but does so using 30 per cent less energy and water, inducing less soil erosion, and maintaining soil quality - and all with no pesticides. For the first four years, organic-corn yields were about two thirds that of conventional, but over time wind and water erosion degraded the soil on the conventional farm whereas the organic farm soil steadily improved in organic matter, moisture, microbial activity and other quality indicators. During a ten-year drought, from 1988 to 1998, the organic-bean yield was 22 per cent higher compared to conventional.1
The risks of cumulative pesticide load on the human body is not a well-studied field. Like GMOs that have followed, the primary beneficiary has gone to the chemical supplier and the farmer, whose job presumably becomes easier with fewer diseased crops to be concerned about. Clearly fewer pesticide residues means less risk for the consumer, but the question remains whether the amount of exposure is significant.2
Studies of chemical residues in plants show lower concentrations in organic foods. In a three-year Greek study comparing organic olive oil to conventional, levels of the pesticide fenthion for conventional olive oils were 0.1222, 0.145 and 0.1702mg/kg compared to 0.0215, 0.0099 and 0.0035 for organic. For the pesticide dimethoate, conventional was 0.0226, 0.0264 and 0.0271, and organic was 0.0098, 0.0038 and 0.0010mg/kg.3 Both of these chemicals are deemed 'moderately hazardous' by the World Health Organization. The estimate of an acceptable daily intake (ADI) for humans for dimethoate is 0.01mg/kg, based on the no-observed-adverse-effect level in humans of 0.2mg/kg body weight per day. For fenthion, the ADI is 0.02mg/kg.4
That there were still detectable levels of chemicals in organic foods demonstrates that, although synthetic chemical pesticides and chemical fertilizers are not applied to organic crops, they still face exposure from being blown by the wind from nonorganic fields.
Studies show that eating organic foods results in 'dramatic and immediate' reduced exposure to pesticides used on crops. In one study funded by the US Environmental Protection Agency, children ages three to 11 who ate organic foods for 15 days experienced a decrease to nondetectable levels of two organophosphate pesticides — until they switched back to a conventional diet.5
Are exposure levels significant? According to one study: yes. Urine samples of children eating either an organic or conventional diet were compared. With dimethyl metabolites, conventional eaters were deemed to have an 'uncertain risk' vs organic eaters' 'negligible risk.' 6
Even pesticides that have been long banned in the US, such as DDT, are still used in countries that export their foods into the US, meaning that although DDT is not used in the US, American consumers may still face exposure to it.
"If you're looking for chemical WMDs, they're in our food and we put them there," observes Alan Greene, MD, a professor at the Stanford University School of Medicine and leading organic advocate.
A recent landmark study comparing the nutritional content of conventional fruits, vegetables and some crops grown in the US 50 years ago to those grown today found a drastically reduced nutrient content in today's food. One study comparing mineral depletion in foods between 1940 and 1991 found an average 47 per cent decline in iron content in 15 different kinds of meat and a 60 per cent decline in iron content of milk. Magnesium levels in meats fell 10 per cent and copper by 60 per cent.7
A more recent study comparing food composition data for 43 garden crops between 1950 and 1999 found a statistically significant decline in six nutrients — protein, calcium, iron, riboflavin, ascorbic acid and phosphorus. Specifically, the declines were: protein -6 per cent, calcium -16 per cent, phosphorus -9 per cent, iron -15 per cent, riboflavin -38 per cent, and vitamin C about -20 per cent. There were no statistically reliable median changes for ash, vitamin A, thiamin, niacin, carbohydrate or fat. The authors concluded that "there may be trade-offs between yield and nutrient content."8
At issue is whether the modern, chemically intensive agricultural practices are responsible, and whether organically produced foods can make up the difference.
The hypothesis is that high-yield crops grow bigger and faster, but do not take up nutrients from the soil at the same rates. The upshot is larger sizes of produce but with comparatively fewer nutrients per bite. This is commonly referred to as the 'dilution effect,' in which yield-enhancing methods like fertilisation and irrigation may decrease nutrient concentrations.9 This phenomenon may also be due to a higher water content in conventional crops, which causes nutrient dilution. Because organic foods tend to be smaller than their conventional counterparts, it is thought the attendant smaller cell size could translate to higher nutrient density.
In one assessment, USDA scientists assessed the lycopene content of 13 ketchup brands and found the average level in organic varieties to be about 55 per cent higher than the nonorganic varieties.10 A 2001 review of 41 studies comparing the nutritional value of organic and conventional produce found organic crops with an average 27 per cent higher levels of ascorbic acid, 21 per cent higher levels of iron, 29 per cent more magnesium, 14 per cent more phosphorus and lower levels of nitrate, and improved protein quality compared with conventionally grown crops.11
Organically raised plants that do not have chemical pesticides, herbicides and fungicides applied experience more stress because they must more or less fend for themselves. The result is they produce more endogenous antioxidants like phenolics to combat the stress factors. Hence, the self-made addition of more phytonutrients translates to a more nutritious food for the end user.12,13
This phenomenon also holds true for livestock fed organic diets — animal studies show better growth and reproduction in animals fed organically grown feed compared with those fed conventionally grown feed.14
In a three-year comparison of nutrient levels in organic vs conventional, researchers assessed total phenolics per cent soluble solids; ascorbic acid; and the flavonoid aglycones quercetin, kaempferol and luteolin in two varieties of tomato (Ropreco and Burbank) and two varieties of bell peppers (California Wonder and Excalibur). Significantly higher levels of per cent soluble solids (17 per cent), quercetin (30 per cent), kaempferol (17 per cent), and ascorbic acid (26 per cent) were found in Burbank tomatoes, whereas only levels of per cent soluble solids (10 per cent) and kaempferol (20 per cent) were significantly higher in organic Ropreco tomatoes. Burbank tomatoes generally had higher levels of quercetin, kaempferol, total phenolics and ascorbic acid as compared to Ropreco tomatoes. Bell peppers were influenced less by environment and did not display cropping system differences.15 This latter point suggests more research is needed to discern which specific food crops can benefit from organic growing conditions vis-á-vis nutrient content levels.
New research out of Belgium has centred upon the differences in bioactive concentrations within hops, which is a large focus of several companies pursuing these bioactives for anti-inflammatory, sedative/anxiolytic, and phyto-estrogenic applications. Three key points came out of this study. For one, like the tomato study mentioned above, this study also found that organically grown hops had higher concentrations of bioactives such as chalcones. Secondly, concentrations of the key compounds depended very much on climatological conditions showing, in general, the highest levels in poorest weather conditions. Thirdly, the first gold hop varietal showed the clearest results, with the admiral and wye challenger varietals having less clear distinctions between growing regimes. Again, this demonstrates that plants grown in stressful conditions tend to be more nutritious for human consumption.16
In contradistinction, recent German research found no difference in wheat grains.17 Similar results from Finnish researchers found no difference in blackcurrant bioactive profiles.18 A conservative assessment by Greek researchers in 2003 noted trends toward higher ascorbic-acid levels in leafy greens and potatoes, higher-quality protein levels in some vegetables and cereal crops, and better animal health — but findings have not yet been identified in humans.19 A recent British study found that organic milk contains 68 per cent more short-chain omega-3 fatty acids than conventional milk due to the higher proportion of clover forage in the diets of organic cows.20 However, the finding was disputed by the UK's Food Standards Agency because those levels were not significant enough to translate to clear human benefit. Again, the clear conclusion is the need for additional research in this area.
One provocative notion, with only a rat study to show thus far, is the idea that, with obesity, consumers eating organic foods will eat less foods, but those foods are more nutrient-dense, and not merely hollow calories.21
The organic future
Annual growth rates of 20 per cent testifies to consumers buying into the idea that they are doing something good - for the environment and for themselves — when they buy organic foods. The scientific record is far from complete, but at this point it would appear that research and marketing are headed in the same, positive direction. While comparisons of health outcomes in populations that habitually consume organic or conventional foods are inherently flawed by the large number of confounding factors that might contribute to differences reported, it is clear that organic agriculture is environmentally sound and more sustainable than mainstream agriculture, that fewer synthetic chemicals are used and consumed, and that organic foods tend to have higher nutrient levels, which may well be one of the answers to modern debilitating diseases that are found in modern societies eating modern diets. With organic foods, it seems, everything old is new again.
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