Is organic healthier? A summary of hundreds of scientific results speaks for itself

Today, strong interest is shown in this issue: are organic foods from organic farming healthier than their conventional, mass-produced counterparts? Are there measurable differences in the amount of nutritionally beneficial ingredients and contaminants? Over the past decades, a number of scientific studies have focused on how the nutritional content of plant and animal foods is affected by significantly different farming practices, nutrient supply and crop protection methods. Gyöngyi Györéné Dr. Kis, researcher at the Hungarian Research Institute of Organic Agriculture (ÖMKi), has published a review of the results of the international and national comparative studies.

Before summarising what and to what extent the researchers have found nutritionally significant differences between the products of the two farming methods, it is worth clarifying the main differences between organic and conventional, industrial food production systems.

Organic food – also known as bio- or eco food – is the product of a farming and food production system that prohibits or restricts the use of substances and technologies that are potentially harmful to health and the environment. These include synthetic chemical pesticides, fertilisers, genetically modified organisms and their derivatives in crop production; artificial veterinary drugs, hormones and yield enhancers in animal husbandry; and a range of synthetic additives and ionising radiation in food processing. An important added value is that organic production applies higher animal welfare standards than conventional production (e.g. free access, provision of adequate living space, prohibition of mutilation and curtailment). In this way, it contributes to the protection of the natural environment and sustainability. Organic operators work under strict legal conditions, with increased controls and certification from production through processing to trade.

Conventional – also known as common – agricultural production and its products, characterised by the use of chemical inputs and energy, are known to be the most widespread worldwide. The primary aim is to maximise yields and keep prices low, often focusing on quantity rather than quality.

“According to the literature, there are some scientifically plausible differences between the nutritional content of organic and conventional foods. This includes, for example, the higher phytonutrient content of organic vegetables, fruits and cereals, which are components with significant health-promoting properties due to their antioxidant characteristics. In addition, organic meat and dairy products have a higher concentration of omega-3 fatty acids and organic cereals have a lower cadmium content. It is also important to highlight the lower pesticide residue content of organic fruit and vegetables. The consumption of organic food has been shown to reduce exposure to pesticide residues. Practical experience and research show that this nutritional quality is the most important choice and value-adding factor for organic food consumers.” – Dr. Gyöngyi Györéné Kis, research project leader at the ÖMKi, summarised the most important differences in her doctoral dissertation on the subject reviewing the results of research over the last thirty years.

International scientific research has also compared nutritionally beneficial components of foods, such as macronutrients (e.g. proteins, carbohydrates and fats), minerals and secondary metabolites (e.g. antioxidants, polyphenols). The results show that there are generally no significant differences in the carbohydrate and protein content of organic and conventional vegetables, fruits and cereals. However, research on wheat reports higher protein and, within that, higher gluten content in conventional crops, while organic dairy products have higher protein than conventional. This may be explained by the effect of nitrogen fertiliser used in conventional cereal production on the carbohydrate and protein synthesis of the plant. Since organic farming does not allow the use of easily soluble nitrogen fertilisers and the maximum amount of nitrogen of animal origin that can be applied is limited by the relevant conditions (170 kg N/ha/year), organic crops tend to have a lower protein content but a more favourable amino acid composition.

There have also been several studies comparing the mineral content of organic and conventional foods. The review and summary studies are not consistent in terms of mineral content of vegetables, fruits, cereals and dairy products from the two production methods. Higher levels of vitamin C, vitamin E and beta-carotene (vitamin A pre-vitamin) have been reported in some studies in favour of organic vegetables and fruits, whereas in other studies the difference was not significant.

The main function of phytochemicals (e.g. polyphenols: flavonoids, anthocyanins, phenolic acids) in plant cells is to protect against negative external environmental (biological, chemical) effects, but they play an important health-protective role in the human body as well. International researches have shown that organic vegetables contain, on average about, 10-50% more phytochemicals than conventional vegetables. Studies have consistently confirmed that organic vegetables, fruits and cereals have higher antioxidant activity and polyphenol content than their conventionally grown counterparts.

There are several reasons for the higher phytochemical content of organic crops. On the one hand, in the absence of synthetic pesticides, plants produce more phytochemicals to protect their own cells. On the other hand, in organic farming, mainly disease-tolerant or disease-resistant varieties are grown, which tend to have a higher phytochemical content. Furthermore, nitrogen fertilisers used in conventional farming lead to increased green weight gain in plants. The concentration of phytochemicals is thus “diluted” in the plant tissues.

Differences in the fatty acid content and composition of animal products (meat and milk) can also be found depending on the production method. On average, 23% and 47% more polyunsaturated and omega-3 fatty acids were found in organic meat, respectively. In terms of the nutrient content of cow milk, the concentrations of total polyunsaturated and omega-3 fatty acids were also significantly higher in organic milk, by about 7% and 56% respectively compared to conventional milk. The concentrations of α-linolenic acid, long-chain omega-3 fatty acids and conjugated linoleic acid were also significantly higher in organic milk, by 69%, 57% and 41%, respectively. The researchers therefore concluded that organic bovine milk has a more favourable fatty acid composition than conventional milk, probably as a result of free range and more frequent grazing.

Food safety monitoring carried out by the European Food Safety Authority in 2022 showed that the number of exceedances of Maximum Residue Limits (MRLs) for pesticide residues in organic food was significantly lower than for conventional products in all food product categories, and negligible. Overall, the results of the studies suggest that organically produced fruits and vegetables and ready-to-eat foods have significantly lower pesticide residue levels than their conventional counterparts. Research over the last 50 years has consistently concluded that the consumption of organic food reduces consumer exposure to pesticide residues. The significantly lower pesticide residue content of organically grown crops is an obvious consequence of the ban on the use of synthetic pesticides, growth regulators, defoliants, herbicides and other chemicals used in storage.

Nitrates in drinking water and food are considered to be a health risk. The crops most vulnerable to nitrate accumulation are mainly leaf, root and tuber vegetables. While international research on organic fruits and cereals confirms the significantly lower nitrate content of organic products, a national study confirms the significantly lower nitrate content of carrots in organic farming.

The significant accumulation of nitrate is clearly due to a metabolic disturbance in the plants; the nitrogen taken up excessively cannot be fully converted into protein by the plants and therefore accumulates in the plant tissues in the form of nitrate. Organic nutrient supplementation prohibits the use of N fertiliser and limits the amount of nitrogen of animal origin that can be applied, so the likelihood of nitrate accumulation in organic crops with adverse health effects is much lower.

One of the cornerstones of food safety is the level of heavy metal contamination in food. The main environmental source of heavy metal contamination is primarily industrial emissions, but fertilisers and pesticides contaminated with heavy metals are also a significant source. Some research shows that organic crops contain smaller amounts of aluminium, mercury and lead. Cadmium is one of the most dangerous environmental contaminants, a highly toxic poison that accumulates in the body. Review studies have confirmed the significantly lower cadmium content of organic cereals. It is assumed that there is a link between the higher cadmium content of the crop and the use of phosphate fertilisers, often contaminated with heavy metals, in conventional crop production and the use of inadequately treated sewage sludge.