Is the organic produce more nutritious?
I don’t know about you, but when I go to my local supermarket I am always faced with an inscrutable dilemma: should I buy the conventional avocados or the organic ones? This is quite troublesome, especially when I am out there purchasing the ingredients for my weekly taco nights.
According to The New York Times, about 30 percent of Americans (i.e., over 90 million people) buy organic fruits and vegetables.1 In the United States and Europe, consumption of organic products has grown at an annual rate of 20–30% and 30–50%, respectively.2 In general, consumer demand stems from a growing concern about eating foods with the fewest possible additives that are produced in an environmentally friendly way with ethical and political considerations for the welfare of animals. In the United States, organic foods are perceived to be safer, healthier, and of greater nutritional and sensory qualities than conventional foods.2 The question that I ask myself is the following: is the nutritional quality of organic food higher than that of conventional foods? Should I just get the conventional avocados or pay a little bit more for the organically grown ones?
“Organic” is a labeling term that designates products produced under the authority of the Organic Foods Production Act (OFPA). The OFPA was established in 1990 by U.S. Congress to come up with uniform national standards for the production and handling of foods labeled as “organic.”3 According to the Environmental Protection Agency (EPA) website, organic food is that grown and processed using no synthetic fertilizers or pesticides.4 However, pesticides derived from natural sources (such as biological pesticides or biopesticides) are allowed4; in fact, over 195 biopesticides exist.5 Organic farming is thus considered “eco-friendly.” Certain methods that are practiced during organic farming and not during conventional farming include crop rotation, protection of crops to protect against soil erosion, the use of special crops known as “green manures” to enrich the soil, and the addition of aged animal manures and plant wastes, also known as compost, to the soil.4 On the other hand, during conventional farming chemical fertilizers, which contain nitrogen, potassium, and phosphorus, are used. These differences result in variations in soil fertility, affecting soil dynamics and plant metabolism, and possibly plant composition and nutritional quality.6
Comparisons in the nutritional quality of foods from organic and conventional systems are often complicated by differences in farming practices, soil quality, plant varieties, and the time of harvest.7 Reports supporting both sides can be found in the literature. A study conducted by Lester et al.8 found that Texas grown, conventional Rio Red grapefruit was higher in lycopene (a fat-soluble carotenoid) than the organic version. However, the juice from the organic fruit was higher in vitamin C and sugars, and lower in nitrate. In another study, organic strawberries had significantly higher total antioxidant activity (8.5% more), vitamin C (9.7% more), and total phenolics (10.5% more) than conventional berries, but significantly less phosphorus (13.6% less) and potassium (9.1% less).7 When comparing conventional to organically grown tomatoes, there were no significant differences in β-carotene, lycopene, vitamin C, total phenolics, and antioxidant activity.9 Corn grown organically had 52% more vitamin C and significantly more polyphenols than conventionally grown corn.10 Weibel et al.11 found no significant differences in total vitamin C content between the organic and non-organic apples. Magkos et al.12 also stated that no differences in vitamin and mineral content could be identified in the fruit, and comparable total polyphenol content was found in organically and conventionally grown apples.13
As a general rule, in studies that have paired common production variables and methodologies, organic crops tend to have more vitamin C, sugars, and phenolics (considered to be antioxidants) and fewer nitrates than conventionally grown produce. On the other hand, organic crops also tend to have less protein, β-carotene, and lycopene. With respect to minerals, trace elements, and vitamin B levels, there are no apparent differences between organic and conventional foods.2,14...