With the recent explosion of consumer interest in organic foods, it is—excuse the pun—only natural to raise the question, “Why buy organic?”

People who buy organic fruits, vegetables, grains and meats typically believe organic produce is more nutritious and better for the environment than its conventionally grown counterparts. Is this true? What is the evidence of the nutritional benefits? Do we clinicians have a scientific basis for recommending that our patients go organic?

I believe that the best available research signals a strong “Yes,” in response to these questions. But first, a quick study of the organic foods scene, circa 2006.

What was once a fringe movement has gradually become very mainstream. According to a recent market survey by industry consultants, The Hartman Group, roughly 23% of the US population buys organic products at least weekly, and 75% of the population shops organic occasionally, up from 55% in 2000.

It would seem that over the last 30 years, a relatively small community of individuals, bonded together by the book, Back to Nature, and Organic Gardening magazine (and lots of compost) have slowly taken over your local grocery store! What was once an impassioned movement of independent farmers, cattle ranchers, dairy families, health food store-owners, and environmentalists has evolved into a fully-fledged industry. Food business titans like Dean Foods have certainly taken notice. Heck, even Wal-Mart has caught on to organics; the mega-retailer recently introduced its own branded line of organic products.

Great Expectations

Production and marketing of organic foods has grown increasingly sophisticated, to keep pace with rising consumer demand for more organic offerings. The number of Americans buying and eating organic food has grown at an average of 20% since 1997. Consumer perceptions about organic food include: 1) increased food safety through reduced exposure to pesticides and herbicides, growth hormones, irradiation, antibiotics and genetically-modified organisms; 2) an Earth-friendly way of eating that decreases pollution; 3) a vision of “authenticity,” that organic means real food grown on rich soil by real farmers.

At its best, organic produce meets many of these expectations. The USDA National Organic Program (NOP) regulations prohibit the use of many unwanted agricultural chemicals on produce labeled organic. Additionally, the NOP rules also guide farmers on how to steward the health of their soil. So, in theory, the movement toward organic food should be able to deliver on the safety and ecological promises, so long as regulatory agencies do their jobs properly.

What about the nutritional value?

It’s hard to talk about nutrition without talking dirt. Soil is the basis for almost everything we eat—plants either feed us or feed the animals we consume. Without fertile soil, rich in healthful microorganisms and organic matter, the plants at the base of our food chain are not exposed to enough nutrients to deliver the nutrients we expect from them. So nutritional value of produce is directly connected to soil composition and quality.

Chemical fertilizers used in conventional farming foster increased crop yields in shorter periods of time. Unfortunately, this contributes to diminution of nutrient content of the fruits and vegetables because it limits the plants’ time to absorb nutrients, according to Donald Davis, a biochemist at the University of Texas, Austin. Dr. Davis found that of 13 major nutrients in common food crops, 6 have declined substantially (by as much as 38%) when compared with past decades. These nutrients include riboflavin, phosphorus, calcium, vitamin C and iron. His research is beginning to show a trend: higher yield with conventional agricultural methods means lower nutrient content.

Healthy Soil—Healthier Vegetables

At the University of California, Davis, researcher Alyson Mitchell studied antioxidant levels in organic corn, strawberries, and marionberries as compared with their conventional counterparts. Respectively, the organics had 58.5%, 50% and 19% higher antioxidant levels than their conventionally grown comparators.

Perhaps the most convincing evidence comes from a meta-analysis by Virginia Worthington, PhD, of the Johns Hopkins School of Public Health. Dr. Worthington reviewed 41 published studies comparing the nutritional value of organically grown and conventionally grown fruits, vegetables and grains. Her conclusion: organic crops contain significantly higher amounts of many key nutrients than their conventional counterparts. Included in this list are Vitamin C, iron, magnesium and phosphorus. Of note was her observation that five servings of organic vegetables (cabbage, potatoes, carrots, spinach and lettuce) met the RDI for Vitamin C for men and women, while an equivalent 5 servings of conventionally grown vegetables did not.

Finally, a team of curious Rutgers University researchers, intrigued by the claim that “Organic is Better,” decided to test it out. They shopped for both conventional and organic snap beans, cabbage, lettuce, tomatoes and spinach at local supermarket and natural foods store. They then analyzed the mineral content, theorizing that the organic samples would contain higher mineral levels.

The data overwhelmingly supported that theory. The organic snap beans contained three times the amount of calcium, four times the amount of magnesium and twenty times the amount of iron as their non-organic counterparts. The organic tomatoes had an astonishing 1,938 parts per million of iron as compared with 1 part per million in non-organic. The organic spinach had three times the amount of potassium, three hundred times the amount of iron, and twice the calcium of non-organic spinach.

Researchers throughout the US and Europe continue to look at the nutrition-organic connection. Studies are ongoing in Switzerland, Denmark, Washington state and California. The Organic Center, a non-profit dedicated to studying all sides of organic foods movement, steadily supports research along these lines.

Unanswered Questions

Though the available data does seem to support the notion that organic produce is more nutritious, there are still many reasonable and unanswered questions about both the methodology behind existing data, and the nutritional value of organic produce in general.

Were the organic foods tested in the available published studies fresher than their conventional counterparts? Did different soil amendments & farming practices (in either/or conventional and organic) yield significantly different crop nutrient contents? Are there nutritional benefits from hybrid or heirloom varieties that are unknown and not represented in these studies (consider high-lysine corn)? What are the standards we should apply to each crop’s nutrient content? How high is high enough to benefit humans? Putting it another way, is there really any additional health value to higher nutrient content beyond certain thresholds? Among organic growers, which farming practices produce the most nutritious crops?

In a way, it is ironic that organic food advocates feel pressure to scientifically substantiate the perceived benefits of organic produce. After all, there was a time not so long ago that everything was grown organically; modern agri-chemicals had not yet been invented. In some parts of the world, it is still that way, though admittedly areas untouched by pesticides, herbicides, synthetic fertilizers, and genetically modified plants are shrinking rapidly. One could argue that the burden of proof should be on the side of agri-businesses to prove that conventionally grown produce is safe and nutritionally equivalent to organically grown fruits, grains, and vegetables.

But with the rapid growth and the increasing commercialization of organic food, science to support the claims that “organic is better,” will be increasingly important. People want to know that they’re getting their money’s worth when they buy organic, and strong data is essential for winning the trust and advocacy of the larger medical community.

It appears from the current state of the evidence that organic is indeed more nutritious, and robust research based on stronger methodologies is slowly emerging. Pursuing these questions will yield definitive answers that consumers, physicians and organic industry folks will need. Just about anyone who has eaten organic foods on a regular basis comes away feeling that foods grown on healthier, nutrient rich soil provide better nutrition. Perhaps it is only a matter of time before science catches up with perception.

Resources

• The Organic Trade Association (www.ota.com)
• The Organic Center (www.organic-center.org)
• The Organic Pages (www.theorganicpages.com)
• Local Harvest (www.localharvest.org)
• The Eat-Well Guide (www.eatwellguide.com)

Laryn Callaway, ND, is a practicing naturopathic physician and chef in Scottsdale, AZ. She recently launched, Organic Bistro, a line of prepared flash-frozen meals featuring organic and sustainably harvested produce, seafood and poultry. Visit www.theorganicbistro.com or call for more information.