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20-02-2013 | Internal medicine | Article

Size isn’t everything when it comes to organic tomatoes


Free abstract

medwireNews: Research shows that while organic tomatoes are smaller than fruits grown using nonorganic methods, they are more healthy for consumers with significantly higher levels of vitamin C and plant phenols.

These findings support those of previous research showing that organic fruits such as tomatoes and strawberries have greater antioxidant content and activity than nonorganic fruits.

As reported in PLoS ONE, Raquel Miranda (Universidade Federal do Ceará, Brazil) and colleagues compared physical and chemical characteristics of immature, mature, and ripe tomatoes grown on organic and conventional nonorganic farms in Brazil.

At commercial maturity, organic tomatoes had a significantly greater mean vitamin C content (220.5 vs 175.3 mg/kg) and total phenolic content (508.3 vs 299.8 mg of galic acid equivalents per kg tomato) than those grown conventionally.

Organic tomatoes also had a higher level of yellow flavonoids when ripe than conventional tomatoes (43.7 vs 25.7 mg/kg) and a higher level of activity of the antioxidant superoxide dismutase both when mature and ripe (77.05 vs 47.38 units of activity [UA] per mg of protein [p] when mature, 121.76 vs 22.27 UA g/mg per p when ripe) than nonorganic fruit.

There has been some debate about the health benefits of plant phenols, but many studies have shown that they help stimulate antioxidant activity, for example, through activation of the human transcription factor NFE2L2 (nuclear factor [erythroid-derived 2]-like 2). This in turn can help suppress related disease processes such as carcinogenesis.

The researchers note that the organic tomatoes were considerably smaller than those grown nonorganically, which they believe may be due to increased oxidative stress on the plants due to the farming system.

Miranda and team concede that more research is needed to more accurately determine the effects of organic farming on the nutritional properties of fruit and vegetables.

However, "our work clearly demonstrates that tomato fruits from organic farming have indeed a smaller size and mass than fruits from conventional growing systems, but also a substantially better quality in terms of concentrations in soluble solids and phytochemicals such as vitamin C and total phenolic compounds," they write.

"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."

By Helen Albert, Senior medwireNews Reporter