Eating organic food 'won’t make you healthier'

Behind the Headlines

Tuesday September 4 2012

Organic food is grown without artificial fertilisers or pesticides

“Organic food is not healthier,” The Daily Telegraph advises.

The news is based on a review of a large number of studies comparing the health effects of organic foods to conventional foods.

While there is no internationally agreed definition of “organic”, most people understand it to mean:

  • foods grown without the use of artificial fertilisers, pesticides or other chemicals
  • meat taken from animals that have not been given antibiotics or growth hormones

Many champions of organic food, such as Prince Charles, have claimed that food grown organically is healthier and more nutritious.

However, this review found no strong evidence to support the health benefits from eating organic instead of conventional foods. This may come as a relief to the more cash-stretched of us because, as the researchers point out, organic food can often be more expensive than conventionally sourced food.

The researchers did find that organic produce was less likely to be contaminated with pesticides. And any bacteria found in organically produced meat were less likely to be resistant to antibiotics.

Obviously there are other reasons, besides nutrition, that may make people choose organic food, such as concern for the environment.

Ultimately, the findings should be interpreted with some caution. There was a high level of variation between the studies in terms of the methods used, which makes the results of this review less reliable. It is also worth noting that few studies looked at relevant health effects and the studies ran for no longer than two years. This means no conclusions about long-term health benefits of organic foods can be drawn from this research.

 

Where did the story come from?

This review was carried out by researchers from the Stanford School of Medicine and the University of Stanford in California, and other US institutions. It did not receive external funding. The study was published in the peer-reviewed journal Annals of Internal Medicine.

The news stories accurately reflect the findings of this review. 

 

What kind of research was this?

This was a systematic review and meta-analysis that aimed to identify published studies on the health, nutritional and safety characteristics of organic and conventional foods.

A systematic review is considered to be the strongest level of evidence and it is the best way to summarise all of the existing research on the question of interest. During a systematic review researchers should rigorously search for and analyse the best available studies.

These sorts of reviews use set criteria which potential studies must meet to be included, covering appropriate study design, population, intervention or exposure, and outcomes assessed.

The strength of the conclusions drawn from a systematic review are dependent on the quality and homogeneity (sameness) of the studies that it pools together.

As the researchers concede, one of the inherent weaknesses of this study was that organic food production is a broad and complex topic that introduces a wide range of variables.

As a result, its findings may not be as reliable as those of a systematic review or meta-analysis focusing on a narrower issue, such as whether statins can prevent heart disease.

 

What did the research involve?

The authors searched seven relevant electronic databases to identify published studies that evaluated groups of people consuming diets of foods grown organically compared to conventional foods. There was no restriction on the type of study design and studies were included if they compared nutrient levels or bacterial, fungal or pesticide contamination in the following foods grown organically and conventionally:

  • fruits and vegetables
  • grains
  • meats and poultry
  • milk
  • eggs

Studies on processed foods were excluded from the review.

Two independent researchers then assessed the quality of the studies and gathered information including:

  • methods used in the studies
  • the amount of organic foods consumed in diets
  • reported outcomes in the individual studies which were then linked to health outcomes
  • nutrient levels of the foods
  • contaminant levels of the foods including pesticides, bacteria, fungal toxins and antibiotic resistance

Researchers then analysed their results using statistical methods and pooled results of eligible studies for the meta-analysis.

 

What were the basic results?

The researchers identified 237 relevant studies. These included 17 human studies that evaluated health outcomes among groups of people eating organic and conventional foods and 223 non-human studies that compared nutrient and contaminant levels in organic and conventional foods (three of which reported on both human and food outcomes). 

The main finding of this study was that organic produce was 30% less likely to be contaminated with pesticides compared with conventional produce (risk difference 30%, confidence interval [CI] -37% to -23%) but that differences in the risk of exceeding the allowed safety limits were small.

In addition there were only three studies out of the 237 (1.26%) where levels of pesticide contamination found in conventional products exceeded EU maximum safety limits.

Another finding was that the risk of bacteria being resistant to three or more antibiotics was higher in conventional pork and chicken compared with organic pork and chicken (risk difference 33%, 95% CI 21% to 45%).

Of the 17 human studies, only three looked at clinical outcomes in terms of the effects on symptoms such as eczema and wheezing. These studies found no significant differences between those eating organic foods compared with conventional foods.

Two studies reported significantly lower urinary pesticide levels among children consuming organic produce but this difference was not observed among adults. It is unclear what, if any, effects increased urinary pesticide levels have on children’s health.

The researchers report that studies were limited in number and varied in their quality. They also report high variation in the studies comparing nutrient and contaminant levels in foods. This was expected and the researchers did not allow results for contamination to be pooled in the meta-analysis.

 

How did the researchers interpret the results?

The authors conclude that, “the evidence does not suggest marked health benefits from consuming organic versus conventional foods, although organic produce may reduce exposure to pesticide residues and organic chicken and pork may reduce exposure to antibiotic-resistant bacteria”.

One of the researchers, Dr Dena Bravata, says, “there isn’t much difference between organic and conventional foods if you’re an adult and making a decision based solely on your health”.

 

Conclusion

Overall, this systematic review provides some limited evidence of the differences in the health effects of organic and conventional foods. The authors do note that results should be “interpreted with caution” due to the high variation between the included studies. They note these differences may be due to soil type, storage practices and variation within organic practices.

There are some additional limitations to this review. Some of the human studies had very small samples which ranged from six to 6,630 people. In addition, none of these studies ran for longer than two years, which means conclusions about the long-term health benefits of organic foods cannot be drawn. The authors also note that some of the included field studies may not reflect real-world organic practices. 

The researchers do suggest that a more effective method of assessing the relative benefits of “organic verses conventional food” would be to carry out a cohort or randomised controlled study. But these types of studies would be both very time consuming and expensive. 

Dr Bravata added when discussing the research that, “if you look beyond health effects, there are plenty of other reasons to buy organic instead of conventional”.

Analysis by Bazian. Edited by NHS Choices. Follow Behind the Headlines on twitter.

Links to the headlines

Organic food is 'not healthier'. The Daily Telegraph, September 4 2012

Organic food 'not any healthier'. BBC News, September 4 2012

Expensive organic food isn't healthier and no safer than produce grown with pesticides, finds biggest study of its kind. Daily Mail, September 3 2012

Links to the science

Smith-Spangler C, Brandeau ML, Hunter GE, et al. Are Organic Foods Safer or Healthier Than Conventional Alternatives?: A Systematic Review. Annals of Internal Medicine. Published online September 4 2012

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Comments

The 2 comments posted are personal views. Any information they give has not been checked and may not be accurate.

caveatman said on 12 December 2012

Fair points from previous commenter.
This trite 'tabloid headline' and poor/partial piece of codswallop journalism from the Telegraph seems to further confirm that the 'intelligent press' (?) is equally in cahoots with those who are pressing forward the agenda to undermine the benefits of organic, and further the aim to implement GM crops.
Sadly headlines are a powerful tool as many people don't 'really read' (i.e. inwardly digest and sagely critique a piece of journalism) full articles... They skim read and focus on 'bites' of information that may totally misinform and misdirect.
No doubt the research review was done well enough -- BUT the parts that are glossed-over/mentioned in passing/diminished by scant-attention in favour of the 'impact headline' are probably these: (quote)
"...The researchers did find that organic produce was less likely to be contaminated with pesticides. And any bacteria found in organically produced meat were less likely to be resistant to antibiotics.
Obviously there are other reasons, besides nutrition, that may make people choose organic food, such as concern for the environment..."
Noone should underestimate the negative impact on physical health of long-term regular consumption of higher levels of pesticides, herbicides, and other chemical/non-natural/manufactured adulterations found in foods of all kinds that are NOT organic. None of the research reviewed does or can deal explicitly with this, I am sure, and nor is it likely to thanks to the vested interests, and the sources of funding for research that seeks only to support the big-agro/big-pharma model!
No-one should underestimate the 'health benefit' in terms of psychological health of doing something that is acknowledged to have a beneficial impact on ecology/environment.... and making small contributions to a better world are the daily things that every individual should be doing.
Bravo to Dr. Bravata's final comment at least!

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Aaln1 said on 10 September 2012

Did Sir Robert McCarrison, Dr Weston A Price, Surgeon Commander T.L. Cleave, or Walter Yellowlees actually do any research at all one wonders? This group of renowned and rigorous scientists produced their research back in the 20th century. McCarrisons research helped the UK to victory in WW2. That, one presumes, does not make their research any less important or real today. But if their already well proven research is real, then this piece of desktop balderdash carried out in a few short months is in direct conflict with their many years of carefully founded research.
Why is this study receiving worldwide attention when its sole purpose seems specific in its contribution to confusion, and yet fails to throw any light upon the argument at all. Perhaps the NHS should revisit McCarrisons research? After all if there is the merest suspicion of competent research, perhaps it should be brought more into focus.
Perhaps you would like to interview persons on the Bristol diet, the Gerson diet, the Schwarzbein diet, the SC diet, The Budwig diet etc.
The answer would appear to be this: todays scientists think it sounds a bit much like hard work and who is going to employ them afterwards? Far better to stand over a sweaty computer and do "tons of analysis" to help you reach spurious "scientific" conclusions which the GMO and agribusiness lobby will ensure circles the media globe for some time to come. Your researcher has failed in his duty of care by stating that conclusions cannot be drawn concerning the long - term health benefits of organic food. To do this he has to have completely ignored the body of evidence built up on our behalf by a previous, honest generation of scientists.

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Analysis by Bazian

Edited by NHS Choices

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