Visit our Re-post guidelines
Recent research from Stanford University and the subsequent headlines from Reuters, NBC News, the New York Times and other mass media outlets have it all wrong: Choosing to grow and eat organic foods has little to do with nutritional content. Humanity must increasingly turn to organic foods. If we don't, we will damage our future food supply along with our health and the environment.
The mass media-focused meta-analysis of a numerous studies attempted to calculate consistencies among studies that compared nutrient content of organic versus conventional foods. The assumption of the researchers - and the mass media - is that nutrient content is the primary reason for consumers to purchase organic foods and a central reason to grow organic foods. They are mistaken.
Simply put, we can easily boost our vitamin A or C or protein levels with inexpensive supplements. Spending more for organic foods – as evidenced by a market that has exploded in the U.S. from $1 billion in sales to over $30 billion in just over two decades – relates to an entirely different set of principles. The research focus and the headlines missed those principles.
Before getting to those, let's examine how flawed the headlines are in of themselves in suggesting that organic foods are "no more nutritious" or "no better" than conventional foods.
The research being drawn from is not new research. It is simply a compilation – a meta-analysis – of other studies. This means the researchers created a process for analysis that tried to compile a large number of studies into a neat and tidy conclusion. The problem was, the broad swath of research all but allowed for a neat and tidy conclusion.
The meta-analysis was broad. It reviewed 17 human studies and 223 laboratory studies – a huge number that in itself increases the chance of error as an analysis method is configured and applied. A cohesive result from any meta-analysis requires that confounding factors be eliminated – which can skew the results and even eliminate solid research data.
While some meta-analyses can be quite easy to compile and very accurate, the Stanford four-year long review required limitations to data scope and the elimination of confounding variables in order to develop computable formulae.
Furthermore, the researchers' conclusion was not that there was not any difference between nutrient levels of conventional and organic foods. Their conclusion was that: "All estimates of differences in nutrient and contaminant levels in foods were highly heterogeneous."
"Heterogeneous" means the various study data were not uniform enough to make an accurate conclusion. Because a meta-analysis requires uniform results so that a composite may be calculated, heterogeneity means a true meta-analysis could not be made.
This is the traditional "apples to oranges" issue: It is hard to perform a calculation on sets of data that are dramatically different.
The researchers did not conclude that "organic foods do not contain more nutrients than conventional foods." Rather, they concluded: "The published literature lacks strong evidence that organic foods are significantly more nutritious than conventional foods." This is a guarded statement with several caveats rather than conclusive evidence one way or the other.
"Strong evidence" means there is little or no room for error in the data. And "significantly more nutritious" in this case is a judgment call relating to enough difference in nutrients considered by conventional medicine to produce diagnosable diseases if deficient in the diet.
There were many confounding variables in the research. For example, nutrient levels often have more to do with when a food is harvested, and where it is grown. A conventional fruit picked later will almost assuredly contain more nutrients than an organic fruit picked earlier in the harvest, and vice versa. This means unless this harvest variable is controlled, the data is useless.
Another problematic aspect of this meta-analysis is that a wide range of different foods and measurements used were lumped into the calculations. This can ignore the unique benefits of particular organic foods over their conventional counterparts.
For example, several studies have shown that organic strawberries maintain higher antioxidant content than their conventional counterparts, while wheat and oats maintain little difference. A combined meta-analysis of these data will produce equivocal results.
One study, done by Washington State University researchers two years ago, found that strawberries grown organically had significantly more vitamin C than conventionally grown strawberries. It turns out this important 2010 study was not included in the meta-analysis.
Another important study not included was a 2012 study by Spanish university researchers who determined that organic broccoli not only contains more vitamin C and other antioxidants and phytonutrients, but those phytonutrients remain intact longer in storage and heat conditions. The researchers tested organic and conventional broccoli side-by-side, and found that the organic broccoli's phenolic and antioxidant content was maintained longer than the conventional broccoli.
Another study, this from Italy's University of Bologna, found that organic red oranges contain significantly more anthocyanins, ascorbic acid and phenols than conventional red oranges.
The design of the meta-analysis that tries to capture the increased nutrient content of oranges, broccoli and strawberries together with other foods that show less or no difference between organic and conventional nutrients will hide the significance of the difference in these foods.
This was confirmed in another review of organic food research, this one from the Southwest College of Naturopathic Medicine in 2010. This review determined that while studies have varied in their type of data, outside of wheat, oats, and wine, "organic foods typically provide greater levels of a number of important antioxidant phytochemicals (anthocyanins, flavonoids, and carotenoids)." This review also concluded: "Clear health benefits from consuming organic dairy products have been demonstrated in regard to allergic dermatitis."
Stanford review still showed significant benefits for organic
Despite these compilation issues, the meta-analysis still proved significant nutritional and content differences exist between organic and conventional foods across the board:
- Organic foods contain more levels of phosphorus. Phosphorus is an important mineral for bone health, digestion, hormone regulation, protein production and cognitive function. While phosphorus is not difficult to find among western diets, organic foods provide more of this healthy mineral across the board.
- Organic foods contain significantly less bacteria resistant to three or more antibiotics. Our 'superbug' dilemma is partly due to the fact that conventional animals are dosed with antibiotics, which results in more outbreaks of antibiotic-resistant bacteria.
- The meta-analysis showed that organic foods contained significantly fewer pesticide residues. They found that while 38% of the conventional foods contained pesticide residues, only 7% of the organic foods contained pesticide residues – which can be caused by drift from neighboring fields. The critical piece here is that chemical residues can bioaccumulate in fat cells, producing more risk over time. They may also affect liver health, burden the kidneys and stimulate cancer growth. Children, the elderly and those who are immunosuppressed are significantly more sensitive to toxins such as pesticides and herbicides.
- The Stanford review also confirmed that organic produce contains more phytonutrients called phenols. Phenols have been shown in laboratory studies to inhibit the growth of tumors and cancer cells, and are vital nutrients to immunity, even though the USDA has not established a standard for their consumption.
- Organic milk was consistently found to contain higher levels of omega-3 fatty acids - important for cardiovascular and cognitive health.
- The research also suggested, as has previous reviews, that there is a potential relationship between increased phytonutrients derived from organic foods and increased cancer inhibition.
This was illustrated by a 2006 study from the Swedish University of Agricultural Sciences, which found that organic strawberries had higher levels of antioxidants and other phytonutrients that inhibited breast and colon cancer cells. They admitted that the cancer inhibition potential of organic strawberries "might lie in a synergistic action with other compounds."