A Systematic Review of Organic Versus Conventional Food Consumption: Is There a Measurable Benefit on Human Health?

Nutrients. 2019;12(1)
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The demand for organic products has risen rapidly over the last decades. The reasons why consumers may favour organic over conventional products are varied. They may be for personal health and wellbeing, environmental considerations, animal welfare or perceived higher nutritional profile - which is true for some, but not all components. While the long-term safety of pesticide consumption through conventional food production has been questioned, organic foods clearly show lower levels of toxic metabolites, like heavy metals and synthetic fertilizer and pesticide residues. This systematic review aimed to assess the current evidence of organic diet consumption and human health compared to conventionally produced foods. Included were 35 papers on clinical trials and observational studies. The clinical trials studied pesticide and phytochemical excretion, antioxidant capacity, body composition, lipids and inflammatory markers. The observational studies were focused on fertility, foetal and childhood development, pregnancy, lactation and levels of pesticides in children and adults, as well as nutritional biomarkers and cancer risk in adults. An increased intake of organic produce in long-term studies appeared to reduce the incidence of infertility, birth defects, allergies, middle ear infection, pre-eclampsia, metabolic syndrome, high BMI, and non-Hodgkin lymphoma. Organic intake was also linked to reduced urinary levels of organophosphorus pesticides and herbicides. Yet, the author highlighted that organic consumers are more likely to be health conscious, physically active, eat a more plant-based diet, have higher education levels and income, and therefore are not representative of the general population. They also argue that the possible benefits from an organic diet may be partially due to the quality and composition of the diet rather than a direct effect of organic food consumption. Whereby a growing number of findings demonstrate the health benefits of organic food consumption, according to the authors, the current evidence does not yield a solid and definitive answer.

Abstract

The current review aims to systematically assess the evidence related to human health outcomes when an organic diet is consumed in comparison to its conventional counterpart. Relevant databases were searched for articles published to January 2019. Clinical trials and observational research studies were included where they provided comparative results on direct or indirect health outcomes. Thirty-five papers met the criteria for inclusion in the review. Few clinical trials assessed direct improvements in health outcomes associated with organic food consumption; most assessed either differences in pesticide exposure or other indirect measures. Significant positive outcomes were seen in longitudinal studies where increased organic intake was associated with reduced incidence of infertility, birth defects, allergic sensitisation, otitis media, pre-eclampsia, metabolic syndrome, high BMI, and non-Hodgkin lymphoma. The current evidence base does not allow a definitive statement on the health benefits of organic dietary intake. However, a growing number of important findings are being reported from observational research linking demonstrable health benefits with organic food consumption. Future clinical research should focus on using long-term whole-diet substitution with certified organic interventions as this approach is more likely to determine whether or not true measurable health benefits exist.

Lifestyle medicine

Patient Centred Factors : Mediators/Organic food
Environmental Inputs : Diet ; Nutrients
Personal Lifestyle Factors : Nutrition ; Environment
Functional Laboratory Testing : Not applicable

Methodological quality

Jadad score : Not applicable
Allocation concealment : Not applicable
Publication Type : Journal Article ; Systematic Review

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