Last week the American Journal of Clinical Nutrition published a report stating that organic food is not nutritionally superior to conventional food, and now the "insert-the-crass-word-for-a-common-organic-fertilizer" has hit the fan.

The research, led by public health nutritionist Alan Dangour of London School of Hygiene and Tropical Medicine, analyzed 162 peer-reviewed studies from the past 50 years comparing organic and conventional foods. After winnowing this to 55 studies meeting a certain quality threshold, the researchers found no statistical difference in levels of most nutrients.

The reaction in the news media and on blogs was swift, reflecting a divide sowed long ago. The pro-organic movement, naturally, calls the analysis flawed if not rigged by agribusiness. Others see this as proof that paying premium prices for organic products is a waste of money.

But factors influencing nutritional composition of food in the journey from field to fork are so extensive — such as plant variety, seasonal differences due to weather, crop handling, processing, storage and cooking — that organic farming can only hope to make nominal contributions to nutrition.

One of the most potent factors affecting nutrition is freshness. Here, you are best served by foods grown locally, regardless of whether they are organic.

The study indeed has opened up a can of worms, but worms are good for the soil.

Data harvest

The strength of this study, undertaken at the request of the UK's Food Standards Agency (FSA), was that this is the first broad, systematic review investigating differences in nutrient content of organically and conventionally produced foodstuffs. Its weakness, stated clearly in the article's introduction, was that this work didn't look at pesticide residue or long-term effects of conventional farming.

So the FSA study is unlikely to change many eating habits. Many people who buy organic do so because of a perceived danger of synthetic pesticides and the effect of synthetic fertilizers on soil and water quality.

One criticism has been that the analysis excluded a four-year study funded by the European Union, led in part by Carlo Leifert, professor of ecological agriculture at Newcastle University in Newcastle, England. Leifert found that organic milk could contain 60 percent more antioxidants and healthy fatty acids compared to conventional milk. This study, however, was published last April and missed the FSA study's criterion of papers published between 1958 and February 2008.

A cutoff is a cutoff. Had Dangour included all of 2008 and 2009, he would have found four recently published papers in high-quality journals, such as the British Journal of Nutrition, showing no nutritional differences between organic and conventional potatoes, tomatoes, broccoli and carrots.

Nevertheless, the EU-funded study, which ended in April 2009, was conducted by the QualityLowInputFood project, whose participants are organic advocates. Perhaps great potential lies in the data this project has gathered, but so far studies have been sparse and sample sizes in those studies sparser.

Buy local, eat better

The FSA analysis doesn't champion conventional farming, which is infested with troubles. Pesticide and nutrient runoff pose perplexing questions about the sustainability of such farming practices. Sickness and death among field workers exposed to synthetic pesticides are well documented. Less is certain about food we consume with pesticide residue.

Organic farming, too, faces challenges. Low yields continue to dog the community. Lower yield means more land needed for farming. Many organic farmers are reluctant to accept genetically modified crops, which could otherwise boost yield and produce crops with built-in pest management.

Conventional farming doesn't always mean the wanton application of death chemicals. Most small, local farmers apply a practice called integrated pest management (IPM). The goal is to minimize and often eliminate pesticide use through intensive monitoring, biological controls, insect traps and other methods, relegating chemical pesticide application to a last resort. Emphasis is on control, not elimination, of pests and weeds.

Getting Americans to eat more fresh vegetables would reduce many of the cases of obesity, diabetes, heart disease and cancer plaguing this country. Most Americans consume more calories from soft drinks than from vegetables.

So from a public health stance, it doesn't matter much if those potato chips are organic. The goal is to make available more fresh and inexpensive vegetables. The local food movement, some of it organic and most of it IPM, is attempting to meet that goal.

Christopher Wanjek is the author of the books "Bad Medicine" and "Food At Work." His column, Bad Medicine, appears each Tuesday on LiveScience.