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Are organic foods more nutritious? Tomato study adds to the debate

USDA/Jess Sanson
Organically grown tomatoes were found to be, on average, about 40 percent smaller than those grown by conventional methods, but contained about 55 percent more vitamin C.

Organically grown tomatoes contain higher concentrations of natural sugars, vitamin C and other anti-oxidant compounds than conventionally grown tomatoes, according to a new Brazilian study.

The study’s findings, published Wednesday in the open-access journal PLOS One, add fuel to the ongoing scientific debate over whether organic foods are more nutritious than conventionally grown ones.

Just last September, for example, another team of researchers published a meta-analysis in which they found no difference in the vitamin content of organic and conventional foods. (That study did, however, find higher levels of pesticides and antibiotic-resistant bacteria in conventionally grown foods.)

But other studies have found that organic foods do have greater nutritional content. A 2007 study, for example, found that organic tomatoes contained almost twice as much of the anti-oxidants quercetin and kaempferol than conventionally grown ones.

Smaller size, but more nutrients

For the latest study, researchers compared tomatoes raised on organic and conventional farms located within less than a mile of each other (1.5 kilometers). This factor helped ensure that soil and weather conditions were similar.

The tomatoes grown organically were found to be, on average, about 40 percent smaller than those grown by conventional methods. Despite their smaller size, however, the organic tomatoes contained about 55 percent more vitamin C and about 140 percent more plant phenols, a class of anti-oxidant compounds that are believed to help protect against heart disease, diabetes, cancer and other chronic illnesses. (One of those compounds, lycopene, gives tomatoes their red color.)

The organic tomatoes also contained more natural sugars, which may explain why organic tomatoes tend to taste better than their conventionally grown counterparts.

A reaction to stress

The authors of the study believe that the higher levels of nutrients in the organic tomatoes may be because plants grown organically are exposed to greater biologic stress from insect predators and disease. The nutrients they produce may help minimize the cell damage caused by that stress.

Historically, conventional farming’s focus has been on yield and size. This study's findings suggest that such an approach may not be on the best interest of human health.

“[That focus] might be all right for staple food,” write the study’s authors, “but, as far as fruits and vegetables are concerned, it may be argued that gustative and micronutritional quality matter more than energy supply. Our observations suggest that, at least for fruit and vegetable production, growers should not systematically try to reduce stress to maximize yield and fruit size, but should accept a certain level of stress as that imposed by organic farming with the objective of improving certain aspects of product quality.”

You can read the study in full at the PLOS One website.

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Comments (6)

Not about nutrition

Most folks I know who prefer to eat organic food do so for the chemicals they don't contain. Nutrition is a secondary concern.

And for the lesser impact their cultivation has

On the natural systems with which they interact.

Yes, it is about nutrition.

Yes, it is about nutrition. If organic fruits and vegetables routinely provide more of the good stuff, as well as less or none of the bad stuff, what's not to like?

Only people who think in "either-or" terms would try to negate or minimize the value of this sort of research conclusion for organic farming and eating.


I don't like raw tomatoes at all, and will go to some trouble to avoid them, so the extra nutrition and flavor won't help me. What about other common vegetables (and fruit)?

Re-Are organic foods more nutritious?

As an agriculturalist, plant scientist, agricultural researcher, agricultural extension agent, organic farmer, and conventional farmer, I do not know of any farmer who wants to or intentionally grow a crop under any stressful condition of biotic - pest (insects, mites, mollusks, weeds, or pathogens), and/or abiotic - drought, water logging etc. The aim/objective of any farmer (as I do practice both!) is to grow a healthy crop and maximize its potential in quality and quantity. Therefore if a RESEARCH experiment is done to produce a crop by organic farming UNDER STRESSFUL CONDITION(S) that result in a particular QUALITY of that food, the same should be done for growing such food by conventional farming to compare the QUALITY results (or any results that the researcher is interested in). This is comparative research!

The above cited research has compared bad agricultural practice vs. good agricultural practice and therefore the results are expected to be different. If science tells us that only genetic determine the nutritional content/profile of a food, then manipulating the genetics under both farming systems should be consistent.

Read: http// ( for more on food nutritional profile.


Personally, if organic food has more nutritional value than conventional produce then that's simply a bonus. My main aim in buying organic food is to get a product that's low in chemicals and antibiotics and has a lesser impact on the environment. Everything beyond that is a secondary consideration, although the better flavor of organic foods also helps sway me in that direction.