Jul 11, 2016

Organic food – Evidence for health.

vegetablesThere evidence that eating a regular diet of organic food reduces exposures to pesticides, herbicides, nitrates, antibiotic-resistant bacteria and food additives. Some studies have shown that organs food contain more polyphenols and essential nutrients. Growing food organically is certainly better for the environment and well being of the livestock but these farming practices make it more expensive.

The evidence that these nutritional attributes benefit health is weak – mainly due to the expense and difficultly in designing large scale studies. This article discussed the current research for organic foods and their potential health benefits.

The term “organic” mostly refers to the method of growing and processing foods. The term “organic” does not mean “natural”, it only refers to the method of food manufacture so the terms are not interchangeable. Organic agriculture involves avoiding use of synthetic fertilizers and pesticides. But instead use holistic methods weed control and deterring crop disease such as long crop rotations, using predator insects or insect traps all of which providing habitat variety which supports more biodiversity. This practice also does not contribute to fossil fuels in the making of pesticides and artificial fertilisers;  stores more carbon in permanent grassland and recycles nutrients.

Organic food cannot be completely free of synthetic chemical residues due to some allowed product and environmental pollution.[1] Likewise, some foods are naturally grown organically such as nuts and many olives but because the farmer has not applied for a certificate from the soil association or other regulatory body they cannot be labelled as such. This goes not mean they have high levels of pesticides or are unhealthy. Having a certificate is, nevertheless, reassuring for the consumer, as it is the only independently audited and legally recognised system to ensure across-the-board benefits to biodiversity, water, soils, climate change and animal welfare. In summary these include:

  • No genetically modified organisms (GMO)
  • No pesticides
  • No artificial fertiliser’s
  • No cloned or artificial genetic breeding
  • All livestock are free from malnutrition, physical and psychological discomfort, disease and unnecessary restriction in behavior.

In addition to these environmental and animal welfare benefits, the organic label also applies to how the food is processed and what is added before it reaches the shelf in supermarkets.  In summary these include restrictions or omission of:

  • Artificial preservatives,
  • Artificial sweeteners,
  • Colourings and flavourings,
  • No hydrogenated fats
  • Monosodium glutamate.

Is there evidence that organic foods have a better nutritional content?

There is considerable debate about the nutritional benefits of organic foods, especially as they are more expensive to produce so, with a growing world population, we need to be certain before putting undue pressure on farmers and consumers who will have to pay a higher price for food.

Although there still remains a lack of robust data there is still some interesting clues. The FDA website has league tables of the anti-oxidant capacities of foods called the Oxygen Radical absorbance Capacity. The relevance of these tables has dropped recently with the realisation that whole foods have so many more benefits than just their anti-oxidant properties but nevertheless these league tables can still be used as a good comparison between foods at least for this aspect of their phytochemical content. Goji berries, for example, in 2000 were almost top of the table – picked wild, at altitude and laid out in the Tibetan sun to dry before being touched with a human hand. Once the commercial potential of this superfood was realised, they became mass produced in fields next to power plants in China, sprayed with chemicals then ripped off the vine before they had ripened. It should not be a surprise then that by 2010, the ORAC rating had dropped lower than a standard apple. If you look at the wild variety of berries particularly blackberries, they are several levels above their farmed equivalent. Blackberry picking is therefore a very healthy activity and is strongly encouraged.

This finding is supported by a group at Newcastle University, who in 2014 analysed 343 studies to look at any differences between organic and conventional crops.  They found that a switch to eating organic fruit, vegetable and cereals would provide additional phytochemical levels equivalent to eating between 1-2 extra portions of fruit and vegetables a day[2]. In addition, significantly lower levels of toxic heavy metals were seen in consumers of organic crops versus conventionally grown ones.

The data is conflicting and not all studies support these benefits. The UK Food Standard agency funded a small review of the 45 scientific articles published over the past 50 years regarding the nutrient content of organic and conventional crops, meat and milk. They concluded that there are no difference in mineral and vitamins between organic versus conventional food1.

Likewise, scientists at Stanford University performed a large clinical review, including over 200 clinical trials, concluding that published scientific literature lacks strong evidence showing that organic foods are significantly more nutritious than conventional foods.[3]  Although they did report that eating an organic diet reduces exposures to pesticides, antibiotic-resistant bacteria and nitrates.[4],[5],[6]

Is there evidence that organic foods are healthier?

Organic food may have more nutrients and certainly have less artificial chemicals, but do these changes benefit our health.   It seems likely, but there is a major lack of robust research to prove it.  In fact, most trials have not shown any differences in health between people who eat organic foods compared to those eating food grown with pesticides and herbicides with the exception of five studies with had alarming findings:

Three of these compared the health of pregnant women who primarily eat organic with those who eat non-organic foods. These large studies found that eating organic vegetables or dairy products was associated with positive health impacts including a 58% reduced risk of genital deformation in boys[7],[8] and a 21% lower risk of pre-eclampsia (high blood pressure and a large amount of protein in the urine) during pregnancy.[9]. Although interesting the findings in these studies would still require confirmation in a larger randomised design.

The forth study, from the Netherlands, reported that in families that switched to organic milk from non-organic milk, there was a reduced risk of eczema in children younger than 2 years by 36%.[10]  The authors suggested that this may have been caused by the higher n-3 fatty acid concentrations in organic milk, since there is increasing evidence for anti-allergic effects of n-3 fatty acids14.

A largest study involved 623,080 middle-aged UK women, followed for over 9 years and reported a weak reduction in the risk of non-Hodgkin among those eating organic food11. There was no effect on other cancers but the authors noted that the organic groups still had moderate intake of non-organic foods, so pesticide intake between the “organic” and “non-organic” groups may not have be large as it could have been. Furthermore, there is usually a long lag time between exposure to environmental toxins and their effect on cancer development so even this 7-9 year study may not have been long enough to detect an association. Non-Hodgkin’s lymphoma has been previously been associated with glyphosate residue (a herbicide usually used as a weed-killer), as well as the insecticides malathion and diazinon.9,11,12,13. Although the Cancer Research UK states that the evidence is not strong enough to show a definite causation, these chemical have been re-classified as a probably carcinogenic by both the World Health Organisation and the UN’s International Agency for Research on Cancer (IARC).13


There is conflicting data about the benefits of eating organic foods, largely fuelled by the difficulties in conducting robust enough trials.  The evidence so far confirms eating an organic diet does reduce exposures to pesticides, herbicides, nitrates, antibiotic-resistant bacteria and food additives in its processing.  It is better for the environment and well being of the livestock but these farming practices make it more expensive. Some studies suggest they contain more phytochemicals and essential nutrients but this is not been substantiated in all evaluations.

So far there is little data to support that the differences in organic foods are enough to make any difference to our health. The trials to establish this would have to lasted 10-15 years and controlling the two growth would be difficult. One study, however, did show a weak association with non-Hodgkins’ lymphoma, another suggested a reduced risk of birth defects and another a reduction in the risk of eczema but they would all need substantiating before these are accepted by academics and national decision makers.

In the mean time, if you are concerned about the environment, animal welfare and wish to reduce your exposure to potential carcinogens if would be a good idea to introduce some organic food into your diet provided it is not prohibitively expensive.



1.     Institute of Food Science & Technology (IFST) website http://www.ifst.org/knowledge-centre/information-statements/organic-food 2014

2.     Dangour AD, et al. Nutritional quality of organic foods: a systematic review. Am J Clin Nutr. 2009, 90(3):680-5.

3.     Barański M, et al. Br J Nutr. 2014 Sep 14;112(5):794-811.

4.     Smith-Spangler C. et al. Are organic foods safer or healthier than conventional alternatives?: a systematic review. Ann Intern Med. 2012. 4;157(5):348-66.

5.     Bourn D (2002). A comparison of the , sensory qualities, and food safety of organically. Critical Reviews in Food Science and Nutrition 42:1-34.

6.     Woese K, (1997). A comparison of organically and conventionally grown foods. J of the Sc of Food & Agriculture 74:281-293.

7.     Brantsæter AL, et al. Organic Food Consumption during Pregnancy and Hypospadias and Cryptorchidism at Birth: The Norwegian Mother and Child Cohort Study (MoBa). Environ Health Perspect. 2016, 124(3):357-64.

8.     Christensen, J.S. et al. Association between organic dietary choice during pregnancy and Hypospadias in offspring: A study of 306 boys operated for hypospadias. The Journal of Urology (2013), 189, 1077-108.

9.     Torjusen H, et al. Reduced risk of pre-eclampsia with organic vegetable consumption: results from the prospective Norwegian Mother and Child Cohort Study. BMJ Open. (2014) 10;4(9):e006143.

10.  Woese K, Lange D, Boess C & Bogl KW (1995). Okologisch und konventionell erzeugte Lebensmittel im Vergleich. Eine Literaturstudie. [Comparison of organic and conventional food products. A literature review]. Bundesinstitut fur gesundheitlichen Verbraucherschutz und Veterinärmedizin Berlin.

11.  Bradbury KE, et al. Br J Cancer. 2014 Apr 29;110(9):2321-6

12.  Cancer Research UK website http://www.cancerresearchuk.org/about-cancer/causes-of-cancer/diet-and-cancer/food-controversies#food_controversies3

13.  Food Standards Agency website http://tna.europarchive.org/20120419000433/http://www.food.gov.uk/foodindustry/farmingfood/organicfood/

14.  Kummeling, I. Consumption of organic foods and risk of atopic disease during the first 2 years of life in the Netherlands. Br J Nutr (2008) 99, 598-605.


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