Organic Crops Offer More Antioxidants
Largest study to date also finds lower levels of a toxic metal and rarer, smaller pesticide residues
Largest study to date also finds lower levels of a toxic metal and rarer, smaller pesticide residues
Why should people favor organic foods?
After all, the Green Revolution of the 1960's and 1970's – which relied on chemicals and hybrids – saved millions of lives.
That amazing feat won the late researcher and anti-hunger advocate Norman Borlaug the Nobel Peace Prize.
But Dr. Borlaug always stressed the limitations and pitfalls of his revolution … and the need for population control, lest its gains prove fleeting or even counterproductive.
And we're confident that he would endorse the goals of organic farming:
- Food safety
- Erosion control
- Optimal soil productivity
- Minimal carbon emissions
- Protection of water and wildlife
- Safety for farmers and farmworkers
- Reduced reliance on petroleum-based fertilizers and pesticides
Although Dr. Borlaug dismissed the capacity of organic farming to feed today's 8 billion people (see our sidebar, “The father of the Green Revolution on organic farming”), he may be proven wrong.
And research is revealing nutritional advantages to organic farming that Dr. Borlaug could not have anticipated.
It's tricky to compare the vitamin and mineral content of organic foods versus conventional crops, because it's hard to control for different soil, plant genetics, climates, and other conditions.
The truth about “antioxidants” in plant foods
The polyphenol and carotenoid compounds in whole plant foods are commonly called “antioxidants” because they behave that way in test tube experiments.
But in general, these health allies do not exert direct antioxidant effects in the body… at least not to a very substantial extent.
Instead, polyphenols appear to exert strong indirect effects on oxidation and inflammation via so-called “nutrigenomic” effects on gene switches (e.g., transcription factors) in our cells.
Polyphenols' nutrigenomic effects tend to moderate inflammation and stimulate the body's own antioxidant network … which includes enzymes, lipoic acid, CoQ10, melatonin, and vitamins C and E.
The richest known food source of polyphenols are raw (non-alkalized / non-“Dutched”) cocoa, berries, plums, prunes, tea, coffee, extra virgin olive oil, beans, and whole grains.
(Highly beneficial procyanidin-type polyphenols abound in cocoa, dark-hued berries – e.g., blackberries, blueberries açaí berries – grapes, red wine, and tea. Comparably beneficial anthocyanin-type polyphenols abound in cherries and most berries.)
Extra virgin olive oil is uniquely rich in hydroxytyrosol, oleuropein, oleocanthal, and other tyrosol esters … a particularly potent class of polyphenols with clinically documented vascular and brain benefits
But nutritional value can't be reduced to vitamin and mineral content, and evidence that organic methods yield healthier crops continues to grow.
For example, see “Organic Crops' Nutrition Advantage”, “Organic Crops Win for Antioxidants ... Again”, and “Organic Milk Found Richer in Omega-3s”, and “Strawberries Curb Cancer Cell Growth; Organic Berries Called Best”.
Note: It's misleading to call the beneficial compounds in plants antioxidants, and that term actually understates their importance to health … see our sidebar, “The truth about ‘antioxidants' in plant foods”.
(In brief, polyphenols exert “nutrigenomic” influences that should help reduce oxidative stress and inflammation ... two key drivers of heart disease, dementia, diabetes, and other common degenerative conditions.)
Now, the most comprehensive evidence review to date affirms the idea that organic agriculture has real advantages for human health, including, but ranging beyond pesticide reduction.
New evidence review affirms organic health advantages
The new US-UK review is the largest study of its kind to date, and it found that organic foods and crops contain more antioxidants, less cadmium (a toxic metal), and fewer, less frequent pesticide residues.
The massive evidence review comes from scientists at Washington State University (WSU) and Newcastle University in the UK (Barański M et al. 2014).
The authors analyzed 343 peer-reviewed papers in which researchers had compared the nutritional and safety profiles of organic and conventional fruits, vegetables, and grains.
According to co-author Charles Benbrook of WSU, “Our team learned valuable lessons from earlier reviews on this topic.” (WSU 2014)
They found that the quality and reliability of comparison studies has greatly improved in recent years, leading to the discovery of significant differences not detected in earlier studies.
(See “US-UK team surveyed more and better studies”, below.)
Most of the 343 papers compared organic and conventional crops grown in the same area on similar soils, to minimize the nutrient-content effects of those key variables.
The study was funded by the European Union and the Sheepdrove Trust, a private charity that supports research on sustainability, diversity and organic farming.
These were its key conclusions:
Finding #1 - Organic plants produce more antioxidants
Organic crops were found to contain 18 to 69 percent more antioxidants. And the team concluded that consumers who ate organic fruit, vegetables and cereals exclusively would consume 20 to 40 percent more antioxidants.
(Read our sidebar, “The truth about ‘antioxidants' in plant foods”, to get a more accurate picture of what these compounds really do for health.)
That's the equivalent of about two extra portions of fruit and vegetables a day, with no increase in calorie intake.
The US-UK team found that the nutritional benefits of organic crops stem from how they're produced.
A conventional crop will typically have access to high levels of synthetic nitrogen and will use it to produce more starches.
As a result, the harvested portion of the plant will often contain lower concentrations of other nutrients, including health-promoting antioxidants.
And without the synthetic pesticides applied to conventional crops, organic plants tend to produce more polyphenols to defend against pests.
The father of the Green Revolution on organic farming
Professor Borlaug dismissed the idea that organic methods could yield enough food to feed the world's eight billion people.
This is what he said in a 2009 interview, at the age of 95:
“Even if you could use all the organic material that you have – the animal manures, the human waste, the plant residues – and get them back on the soil, you couldn't feed more than 4 billion people. [And] you would have to increase cropland area dramatically, spreading out into marginal areas and cutting down millions of acres of forests.”
“If some consumers believe that it's better from the point of view of their health to have organic food, God bless them. Let them buy it. Let them pay a bit more. It's a free society. But don't tell the world that we can feed the present population without chemical fertilizer.”
We hope that Dr. Borlaug may yet be proven wrong ... but it'd be arrogant to dismiss the opinion of the most successful agronomist and life-saver in history.
It may take a combination of biotech and organic methods to feed the world with a minimum of chemical inputs.
That's the argument made in Tomorrow's Table: Organic Farming, Genetics, and the Future of Food, by husband-wife team Pamela C. Ronald (a plant geneticist at UC Davis) and R. W. Adamchak (director of organic farming at UC Davis).
Finding #2 - Organic crops had 10 to 100 times fewer pesticide residues
The researchers also found pesticide residues were three to four times more likely in conventional foods than organic ones, as organic farmers are not allowed to apply toxic, synthetic pesticides.
While crops harvested from organically managed fields sometimes contain pesticide residues, the levels are usually 10-fold to 100-fold lower in organic food, compared to the corresponding, conventionally grown food.
“This study is telling a powerful story of how organic plant-based foods are nutritionally superior and deliver bona fide health benefits,” said Benbrook (WSU 2014).
Finding #3 - Organic crops had only half as much toxic cadmium
Compared with organic crops, the analysis showed that conventional crops had roughly twice as much cadmium … a toxic heavy metal contaminant.
Why would that be true?
Synthetic fertilizers prohibited on organic farms somehow make cadmium more available to plant roots.
This difference matters, because a doubling of cadmium intake from food could push some people over safe daily intake levels.
US-UK team surveyed more and better studies
Many of the 343 studies in the new analysis were not available to the research teams that carried the most recent reviews prior to this one.
“We benefited from a much larger and higher quality set of studies than our colleagues who carried out earlier reviews,” said project leader Dr. Carlo Leifert of Newcastle University (WSU 2014).
A 2009 study commissioned by the UK Food Standards Agency found that organic crops had more magnesium, zinc, phosphorous, and polyphenols – the most common kinds of beneficial antioxidants – but did not find higher levels of other minerals, vitamins C, or beta-carotene (the plant form of vitamin A).
Likewise, a 2011 review from Stanford University found that organic crops typically contain more phosphorous and polyphenol-type antioxidants, but did not find substantial differences in other vitamins or minerals. See “Organic Food Gets a Mixed Review”.
- Barański M, Srednicka-Tober D, Volakakis N, Seal C, Sanderson R, Stewart GB, Benbrook C, Biavati B, Markellou E, Giotis C, Gromadzka-Ostrowska J, Rembiałkowska E, Skwarło-Sońta K, Tahvonen R, Janovská D, Niggli U, Nicot P, Leifert C. Higher antioxidant and lower cadmium concentrations and lower incidence of pesticide residues in organically grown crops: a systematic literature review and meta-analyses. Br J Nutr. 2014 Jun 26:1-18. [Epub ahead of print]
Györéné KG, Varga A, Lugasi A.
[A comparison of chemical composition and nutritional value of organically and conventionally grown plant derived foods]. Orv Hetil. 2006 Oct 29;147(43):2081-90. Review. Hungarian.
Smith-Spangler C, Brandeau ML, Hunter GE, Bavinger JC, Pearson M, Eschbach PJ, Sundaram V, Liu H, Schirmer P, Stave C, Olkin I, Bravata DM. Are organic foods safer or healthier than conventional alternatives?: a systematic review. Ann Intern Med. 2012 Sep 4;157(5):348-66. doi: 10.7326/0003-4819-157-5-201209040-00007. Review. Erratum in: Ann Intern Med. 2012 Nov 6;157(9):680. Ann Intern Med. 2012 Oct 2;157(7):532.
Washington State University (WSU). Major study documents benefits of organic farming. July 11, 2014. Accessed at https://news.wsu.edu/2014/07/11/major-study-documents-benefits-of-organic-farming/#.U8lxb_ldWSo