Antioxidants substantially higher in organic than conventional plant-based foods
Demand for organic foods is partially driven by consumers’ perceptions that they are more nutritious. However, scientific opinion is divided on whether there are significant nutritional differences between organic and non-organic foods, and two recent reviews have concluded that there are no differences.
Dr. Charles Benbrook, PhD, research professor at the Center for Sustaining Agriculture and Natural Resources at Washington State University and the lone American co-author of the paper published in the British Journal of Nutrition along with scientists at Newcastle University who led this study carried out meta-analyses based on 343 peer-reviewed publications that indicate statistically significant and meaningful differences in composition between organic and non-organic crops/crop-based foods.
The research team found the quality and reliability of comparison studies has greatly improved in recent years, leading to the discovery of significant nutritional and food safety differences not detected in earlier studies. For example, the new study incorporates the results of a research project led by Dr. John P. Reganold, PhD, Washington State University, regents’ professor of soil science and agroecology that compared the nutritional and sensory quality of organic and conventional strawberries grown in California.
In regards to the findings of this new paper Dr. Reganold commented “This is an impressive study, and its major nutritional findings are similar to those reported in our 2010 strawberry paper.”
In this study the researcher s found the concentrations of a range of antioxidants such as polyphenolics were found to be substantially higher in organic crops crop-based foods, with those of phenolic acids, flavanones, stilbenes, flavones, flavonols and anthocyanins being an estimated 19 (95 % CI5, 33) %, 69 (95 % CI 13, 125) %, 28 (95 % CI 12, 44) %, 26 (95 % CI 3, 48) %, 50 (95 % CI 28, 72) % and 51 (95 % CI 17, 86) % higher, respectively. With many of these compounds having been previously associated to a reduced risk of chronic diseases including cardiovascular disease and and neurodegenerative diseases and certain cancers, in dietary intervention and epidemiological studies.
The researchers found that organic crops have several nutritional benefits that derive from the way the crops are produced. A plant on a conventionally managed field will typically have access to high levels of synthetic nitrogen and will marshal the extra resources into producing sugars and starches. As a result, the harvested portion of the plant will often contain lower concentrations of other nutrients, including health-promoting antioxidants.
Without the synthetic chemical pesticides applied on conventional crops, organic plants tend to produce more phenols and polyphenols to defend against pest attacks and related injuries. In people, phenols and polyphenols can help prevent diseases triggered or promoted by oxidative damage, like coronary heart disease, stroke and certain cancers.
The results also showed the frequency of occurrence of pesticide residues was found to be four times higher in conventional crops, which also contained significantly higher concentrations of the toxic metal Cadmium.
While crops harvested from organically managed fields sometimes contain pesticide residues, the levels are usually 10-fold to 100-fold lower in organic food, compared to the corresponding, conventionally grown food.
In their conclusion the researchers write “In conclusion, organic crops, on average, have higher concentrations of antioxidants, lower concentrations of Cd and a lower incidence of pesticide residues than the non-organic comparators across regions and production seasons.”
Dr. Benbrook commented "This study is telling a powerful story of how organic plant-based foods are nutritionally superior and deliver bona fide health benefits.”
In closing Professor Carlo Leifert, Research Development Professor for Ecological Agriculture at Newcastle University commented "We benefited from a much larger and higher quality set of studies than our colleagues who carried out earlier reviews.”
This study is the largest of its kind.
This study is published in the British Journal of Nutrition.