Organic Myth Busting - Is it more Nutritious?

Dr Olliver Moore (Ollie) is an author, academic, journalist, blogger and all round organic expert. We asked him to tackle some of the more relevant myths or accepted wisdoms around organic foods. In this article, Ollie analyses the latest report released by the UK Food Standards Agency's comparing the benefits of organic and conventional foods.

When science speaks strongly and clearly, people listen. Thus the UK Food Standards Agency's review comparing organic and conventional foods in nutritional terms has attracted a lot of attention.

The study was carried out by the London School of Hygiene and Tropical Medicine (LSHTM) for the UK's Food Standards Agency.

The LSHTM’s team of researchers, led by Dr. Alan Dangour, claims to have reviewed all relevant papers published over the past 50 years that studied nutrient content and health differences between organic and conventional food.

Dangor concluded “our review indicates that there is currently no evidence to support the selection of organically over conventionally produced foods on the basis of nutritional superiority”.

Supposedly considering everything from 1958 to February 2008, this report has gravitas.

How could anyone claim anything about organic being superior in nutritional terms if this report claims that there is no evidence?

Whether the authors actually had the evidence to make such a claim  is very controversial.

There are at least two main areas where I have issues with this report:
 1: The publications it considers to be at its quality standard, and;
 2: The findings themselves.

1 (a) Despite claiming to be a systematic review of the relevant published literature, in actuality this report rejected 2/3 of all the relevant published literature. Thus, it is not in fact systematic.

Every publication from before 1990 was rejected. In a supposedly systematic study, encompassing 50 years of research, rejecting over 30 of those years is mind boggling. What's even more mind boggling is the fact that this rejection was obscured by the bizarre omission, revealed to me by a typo on the third last line on page 15 of the report itself.

When I spotted this, I contacted the lead author. Here's what he said to me:
“Thank you for spotting this. Not sure how it happened as it is not in my final version of the report. The second half of that paragraph should read:
Finally, more than half the studies in the review (54%) failed to provide a clear definition of the organic production methods used (we required a statement of certifying body, although if no certifying body was named it was inferred when possible from the text provided). No study published pre-1990 met this final quality criterion, largely due to the general lack of certifying bodies at that time, although even recent studies often failed to state the name of the organic production certifying body. In total, one third of studies included in the review (34%) met the pre-defined quality criteria (see Table 1).”

I have not come across this in other critiques of this report, though I'm sure over time others will spot it too.

1 (b) Certification.  Not only was every publication from before 1990 rejected, every publication where there was no private certification/inspection body listed or inferred was rejected too. In total only 55 of the 162 initially considered was accepted as being at the required standard.

Using this methodology of private certification is understandable to a point.  However, the underlying authority in the certification process is the state, not the private cert body. The state delegates authority to the cert body. Thus, in many cases the state's own research centres simply don't bother with private certification.  This is the case with all of the Irish Department of Agriculture, Fisheries and Food 's research: no private certification happens.

So irrespective of the quality of the research conducted, or the standard of the journal it was published in, relevant research without a private certification body listed or inferred was rejected.

2: In the 2/3 of peer reviewed research excluded from the findings and conclusions, most of the research suggesting organic is in fact nutritionally superior exists.
This fact is what might lead a conspiracy theorist to wonder about the methodology to reject the majority of the research. Remember this rejected research went through the peer review process and came out the other end, published in peer reviewed journals.

The report itself does actually list nutritional findings taken from an analysis of all 162 publications.

It is just that the official findings and conclusions, which suggest that there are no significant differences between organic and conventional in nutritional terms, come from their analysis of just 55 publications: i.e. the smaller 1/3 or 34%.

For example, they claim:
“Organically produced crops were found to have significantly higher levels of sugars, magnesium, zinc, dry matter, phenolic compounds and flavonoids than conventionally crops” (p 17).

These significant differences were found when taking all 162 peer reviewed published papers into account.

When taking the narrower quality criteria, and considering just a maximum of 55, or 1/3, only three differences were found: Conventional crops were found to have more nitrogen, and organic crops more phosphorus and titratable acidity.

Based on the latter three findings from the smaller set of publications, the authors claim that no significant differences were to be found between organic and conventional nutritionally.

The same holds for livestock products: 3 out of ten significant differences were found between organic and conventional. However with the narrower selection criteria, which leaves out 2/3 of all published research, just one was found. The other two were rejected due to insufficient data.

Out of a possible 162, just 25 in total dealt with all livestock products: i.e. all meat and dairy products.

Incredibly, within these 25, it seems that hardly any were considered to actually have met the quality criteria: according to appendix 13, p.3, no more than 6 publications were at the required level for the authors to draw findings and conclusions from.

So for example all of the recent research into organic milk as nutritionally superior, of which there is much, was blended into the overall livestock figures, or rejected for methodological reasons.

(Also, more research into milk, again suggesting that organic is superior nutritionally, was published in April 2008, just after the chosen cut off point of February 2008)

Overall, the mean differences revealed in the report point to the following higher levels in organic food: Protein 12.7%; Beta-carotene 53.6% Flavonoids 38.4%; Copper 8.3%; Magnesium 7.1%; Phosphorous 6%; Potassium 2.5%; Sodium 8.7%; Sulphur 10.5%; Zinc 11.3%; Phenolic compounds 13.2%.