Researchers from the University of the Milan found that a daily intake of the commercial tomato drink, Lyc-o-Mato was linked to a drop in the inflammatory mediator TNF-alpha by 34 per cent after six weeks of supplementation of a normal diet.
Inflammation is linked to hardening of the walls of the arteries (atherosclerosis), and cardiovascular disease (CVD) - the cause of almost 50 per cent of deaths in Europe.
Tomato extract contains a mix of potent antioxidants including lycopene, beta-carotene, vitamin E and various other phytonutrients. The extract has been associated with lowering blood pressure and boosting immune function, although this last claim is hotly disputed by conflicting results.
"We report modest effects of the regular uptake of a tomato drink providing small amounts of carotenoids on the production of inflammatory mediators such as TNF-alpha in young healthy volunteers," said lead author Patrizio Riso in the Journal of Agricultural and Food Chemistry (Vol. 54, pp. 2563-2566).
The placebo-controlled, double-blind crossover trial divided 26 young healthy volunteers into two groups. Group one (N=13) was assigned to the sequence placebo/wash-out/Lyc-o-Mato, while the second group was assigned the inverse, Lyc-o-Mato/washout/placebo. People with kidney, heart, and liver diseases, and pregnant women taking supplements, were excluded from the study
The mediator for inflammation, TNF-alpha, and markers of immune response, the cytokine IFN-gamma, were measured by blood sample analysis. White blood cell DNA damage was also quantified.
After 26 days of either placebo or Lyc-o-Mato, the researchers found that TNF-alpha levels were significantly decreased by 34 per cent after consumption of the tomato drink. No changes were observed after placebo.
The authors suggest that the effects of the tomato juice are due to one of several mechanisms, including altering cytokine production, the boosting of T-lymphocyte function, or the inhibition of arachidonic acid metabolism that is catalysed by free radicals.
However, the appropriate compounds to support the latter mechanism were not found in an analysis of the volunteers urine.
Interestingly, levels of IFN-gamma increased after the placebo drink, a result that could not be explained by the researchers since the placebo drink was formulated to appear and taste like the tomato drink but did not contain any bioactive compounds. IFN-gamma levels after consuming the tomato drink were unchanged, indicating that the tomato drink had no effect on the immune system.
"These data add to the controversy of whether lycopene, and the other carotenoids, affect immune response," said Riso.
DNA damage was also insignificant in both groups, a result that could have been due to the young, healthy subjects having little DNA damage at baseline.
These results differ somewhat from other studies that have focused on predominantly elderly populations. Some have reported increases in immune function, and other have reported increases in inflammation mediators due to the tomato juice.
"Further intervention trials will follow in subjects with low carotenoid status and/or compromised immune system," said Riso.
Israeli-company LycoRed, producers of Lyc-o-Mato, supplied the tomato juice drink.