Organic tomatoes contain higher levels of antioxidants than tomatoes grown with inorganic fertiliser

July 3rd, 2012 by Universitat de Barcelona

Guernsey Organics tomatoes at the Sausmarez Manor farmers' market (click image to expand - ©RLLord)

Organic tomatoes contain higher levels of phenolic compounds than conventional tomatoes according to the study “Evaluation of a Method To Characterize the Phenolic Profile of Organic and Conventional Tomatoes,” which was published by the University of Barcelona in the Journal of Agricultural and Food Chemistry,

Phenolic compounds are organic molecules found in many vegetables with proven human health benefits.

The University of Barcelona’s Natural Antioxidant Group, headed by lecturer Dr Rosa M. Lamuela, has previously proved that organic tomato juice and ketchup contain higher polyphenol content than juice and ketchup made from conventionally grown tomatoes.

Dr Lamuela pointed out that during the production process of ketchup and juice there are lower levels of polyphenols.

It was necessary to verify that the differences observed in previous studies had their origin in the tomatoes themselves and not in the technology used during the production process.

Polyphenols, natural antioxidants of plant origin, are considered to be of great nutritional interest because its consumption is associated with the prevention of cardiovascular and degenerative diseases, and some forms of cancer.

The team behind the study analysed a variety of tomato called Daniela and determined its phenolic profile by using liquid chromatography coupled to mass spectrometry.

The research group of the University of Barcelona identifed 34 different phenolic compounds in tomatoes.

“The benefit of taking polyphenols through foods is that they contain a wide variety of such molecules, which are increased. This would be more beneficial to health than the intake of supplements,” Dr Rosa M. Lamuela said.

Guernsey Organics produce at the Sausmarez Manor farmers' market (click image to expand - ©RLLord)

Tomatoes also contain lycopene and other carotenoids, and vitamin C.  According to Dr Lamuela “they contain many beneficial compounds.”

Differences between organic and conventional tomatoes can be explained by the manure used in both cases.

“Organic farming doesn’t use nitrogenous fertilizers. As a result, plants respond by activating their own defence mechanisms, increasing the levels of all antioxidants,” co-author  Anna Vallverdú Queralt said.

“The more stress plants suffer, the more polyphenols they produce,” Dr Rosa Lamuela said.

Numerous scientific investigations show that the consumption of these antioxidants has numerous health benefits.

Researchers claim that more studies of clinical evidence are still needed to be able to state that organic products are truly better for our health than conventional ones.

Dr Lamuela would like to carry out a study with humans comparing organic and conventional tomato consumers.

The UB research team (left to right) Alexander Medina Remón, Olga Jáuregui, Isidre Casals Ribes, Rosa M. Lamuela and Anna Vallverdú Queralt (click image to expand)

Also participating in this research, were researchers Olga Jáuregui, from the UB’s Scientific and Technological Centres (CCiTUB), and Alexander Medina Remón, who, together with Dr Rosa Lamuela and Anna Vallverdú Queralt, are from the UB’s Department of Nutrition and Bromatology, from the Reference Network on Food Technology of the Government of Catalonia (XaRTA) and from the Institute for Research on Nutrition and Food Safety (INSA-UB).

This research group is also affiliated to the Spanish Biomedical Research Centre in Physiopathology of Obesity and Nutrition (CIBERobn) and RETICS networks, from Carlos III Health Institute.

This research group, specialising in natural antioxidants, has also published a 2012 study, “Stability of the Phenolic and Carotenoid Profile of Gazpachos during Storage” to assess changes in individual phenolic and carotenoid compounds of commercial gazpachos kept in the fridge.

Their research showed that the storage of gazpachos for three months results in a slight decrease in their polyphenol and carotenoid content capacities. Commercial gazpachos are therefore a good source of nutrition.

“Gazpacho does not only contain polyphenols from tomato, but also polyphenols from onion and garlic which provides more complexity in terms of phenolic compounds,” Dr Rosa Lamuela said.

Also participating in the study was Sara Arranz, from the Hospital Clínic (UB-IDIBAPS), and Isidre Casals Ribes, from CCiTUB.


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