Researchers in Sweden reviewed the available evidence to examine the health benefits of organic food. Their study was published in Environmental Health.
Producing adequate quantities of sustainable healthy food is a high priority for many governments and international organizations. The choice of either conventional or organic farming methods can affect the sustainability of food production and both human and animal health. Researchers in Sweden performed a comprehensive review of the existing evidence on the health benefits of organic food.
What is organic food?
Food production methods are not always easy to classify, as practices used in organic and conventional farming often overlap. Conventional farming generally refers to intensive agriculture, typically with the high use of synthetic pesticides and mineral fertilizers on crops and close-housing and concentrate feed in animal production. Organic agriculture usually includes the use of organic fertilizers such as farmyard and green manure, ecological and non-chemical measures for pest control and livestock access to open air and roughage feed. In the European Union, the fraction of organically cultivated land has been steadily increasing over the last 30 years, reaching 6.2% in 2015.
What is the evidence of health benefits of organic food?
The researchers looked at the evidence from population studies and clinical trials comparing people with different dietary habits regarding eating mostly organic or mostly conventionally produced products. In addition, they looked at studies on the impact of organic versus conventional farming methods on human pesticide exposure, the nutritional composition of crops and animals, and the use of antibiotics in animal production.
Effects on human illness
The few human studies directly investigating the effects of organic food on health suggest that those who consume mostly organic food may have a lower risk of childhood allergies, weight gain, obesity, and some forms of cancer. However, it is not possible to conclude from these studies that organic food is the direct cause of these benefits, as people who chose to consume organic food were also noted to have healthier lifestyles overall.
Plant protection in conventional agriculture largely uses synthetic pesticides. Pesticide residues on conventionally produced fruit and vegetables are the main source of human pesticide exposure. Chemical pesticides undergo a thorough risk assessment and acceptable residue levels are calculated. However, there are concerns that this risk assessment may be inadequate in some areas, particularly the effects of long-term and cumulative exposure.
Studies in this area are problematic as it is difficult to assess pesticide exposure accurately and a long follow-up period is needed to look at effects on health. A few studies have looked at the brain development of young children in relation to their mother’s pesticide exposure levels during pregnancy. There has been some evidence of adverse effects on brain development at current levels of pesticide exposure, but this requires further investigation.
Organic farming generally relies on preventive and biological means for plant protection, such as crop rotation, intercropping (growing more than one crop together), using pest-resistant varieties of plants, introducing natural enemies of pests, hygiene practices and other measures. Some pesticides are approved for use in organic agriculture, but most of these are of low toxicity to consumers because they are human nutrients (e.g. spearmint oil, quartz sand), or are only approved for use in insect traps so are not in contact with the crops.
Organic agriculture methods mean that there are lower pesticide residues in food. Consumers of mostly organic food have comparatively low dietary exposure to pesticides. The plant protection practices used in organic agriculture may provide lessons which can be used in conventional agriculture.
Nutritional composition of organic vs conventional food
Studies show that organic dairy products and meat have about a 50% higher content of omega-3 fatty acids compared to conventional products. However, these products are only a minor source of omega-3 fatty acids in the average diet. The nutritional content of crops is largely unaffected by the method of production. There is a modestly higher content of phenolic compounds (which may have a role in disease prevention) in organic fruit and vegetables and possibly a lower content of cadmium (which can be toxic to kidneys) in organic cereal. However, these composition differences are modest and unlikely to be of any nutritional significance.
Use of antibiotics in organic vs conventional farming
Because of the intensive nature of housing and rearing conditions in conventional farming, antibiotics are widely used to prevent infections in livestock. This is of great concern as it may allow the development of antibiotic-resistant bacteria, which in turn could impact human health.
Antibiotic use is strongly restricted in organic animal farming. Organic methods aim to provide more space and healthier conditions for animals. Routine use of preventative antibiotics in organic animal production is not allowed. The prompt therapeutic use of antibiotics to treat infection is permitted, although organic farm animals are less likely to develop diseases related to intensive production. As a result, fewer antibiotics are required in farming organic animals. This decreases the risk of the development of antibiotic-resistant bacteria.
The use of antibiotics in animal production must decrease in order to prevent the further development of antibiotic resistance. The methods used in organic farming could provide a way to achieve this goal.
Several health benefits of organic food
From reviewing the available evidence, the researchers found that there are several health benefits of organic food. They concluded that the wider use of organic methods in conventional agriculture would most likely benefit human health. In particular, in reducing the levels of pesticide exposure and reducing the risk of the development of antibiotic-resistant bacteria.
- Mie A, Andersen HR, Gunnarsson S, et al. Human health implications of organic food and organic agriculture: A comprehensive review. Environmental Health (2017) 16:111. DOI: 10.1186/s12940-017-0315-4.