A More Nutritious Organic Tomato?

A recent study comparing organic and conventional tomatoes found that the organic tomatoes have higher levels of flavonoids - an antioxident - but does this mean the tomatoes are "healthier"?

The researcher at the University of California Davis behind the study said the results were intriguing but not definitive. "There's a lot of confusion," said Alyson Mitchell, a professor of food chemistry and toxicology at the University of California, Davis, in this Sacramento Bee article. "For every study that shows there's a difference, there's another that shows there isn't."

Interestingly, this study took a long-term look at two particular flavonoids - quercetin and kaempferol - and found on average they were 79% and 97% higher, respectively, in organic tomatoes than conventional ones. 

Scientists theorize that "flavonoids are produced as a defense mechanism that can be triggered by nutrient deficiency, such as a lack of nitrogen in the soil," the BBC reports. Organic farms add compost to the soil to build fertility, rather than fast-acting synthetic nitrogen.

A previous study by Mitchell et al in 2003 found that organic berries contain higher levels of phenolics, which include vitamin C and antioxidents. They theorized then that plants developed these compounds in the absence of chemical fertilizers as a way to combat pests, diseases and natural stresses that may be present at higher levels on organic farms.

This new study may also support findings by the University of Texas, which found a long-term decline in certain nutritious elements in conventionally grown fruit and vegetables. The researchers theorized that this too reflected the increasing use of synthetic chemical fertilizers over a half-century - a theory that researchers around the world are pursuing, according to a San Francisco Chronicle report last year.

What's less clear is whether these nutritional differences are significant to human health. They should also not obscure a bigger point: that consuming a healthy amount of fruits and veggies each day is more important than eating too little or none at all.

- Samuel Fromartz

Comments

[Amanda Rose]

The research in this area is all over the place but the mechanism here with the flavonoids and phenolic compounds is very interesting.

One study on organic produce I thought was smart in its simplicity was this one:

Smith, B.L. 1993. Organic foods vs. supermarket foods: Element levels
Journal of Applied Nutrition 45:35-39.

Forget about experimental controls. This guy just went shopping and tested various organic and conventional food samples. In most cases nutrient values were much higher for the organic produce.

The University of Texas study suggested that the problem was most likely in new hybrid varieties, not in conventional fertilizer methods, adding another variable to the "decline in nutrient levels" argument. And it does make a good point: heirloom varieties not bred for their storage and transportation capabilities are simply likely to be higher in nutrients. Buying heirlooms (organic or not) may be a good strategy to increase the nutrients in our diets.

Is there a human health impact? Possibly yes for some nutrients. It is difficult to meet our DRI of magnesium without a supplement for instance. Vegetables are a key source. Magnesium levels in produce have declined over the last 50 years.

Of course, people have to be eating vegetables in the first place in order to be deprived of the magnesium that should have been in there. I agree with your conclusion -- just eat your vegetables.

Amanda