The study, performed with 21 healthy volunteers and published in the British Journal of Nutrition , supports the ever-growing body of research reporting the health benefits of tomato and tomato products.
"A high dietary intake of tomato products had atheroprotective effects, it significantly reduced LDL cholesterol levels, and increased LDL resistance to oxidation in healthy normocholesterolaemic adults," wrote the researchers, led by Marja-Leena Silaste from the University of Oulu.
"These atheroprotective features associated with changes in serum lycopene, beta-carotene and gamma-carotene levels."
Tomatoes are a valuable source of nutrients, including beta-carotene, vitamins C and E, and lycopene, a potent antioxidant that gives the fruit its characteristic red colour.
The link between the lycopene and prostate cancer risk has been reported in numerous studies, but doubts have been raised about the benefits of the carotenoid after the FDA reported finding no credible evidence supporting lycopene intake and a reduced risk of prostate, lung, colorectal, gastric, breast, ovarian, endometrial, or pancreatic cancer.
The FDA has approved a claim on the role of tomatoes in reducing the risk of prostate, gastric, ovarian and pancreatic cancers, indicating that the other compounds found in the whole fruit may be conferring benefits, possibly in synergy with lycopene.
The new study assigned the volunteers to an initial three-week low tomato diet before a three-week high tomato diet.
Subjects were asked to consume 30 mg of tomato ketchup and 400 ml of tomato juice daily.
At the end of the intervention period, the researchers report that total cholesterol levels were reduced by 5.9 per cent, while LDL levels were reduced by 12.9 per cent.
High cholesterol levels, hypercholesterolaemia, have a long association with many diseases, particularly cardiovascular disease (CVD), the cause of almost 50 per cent of deaths in Europe, and reported to cost the EU economy an estimated €169bn ($202bn) per year.
Blood samples also revealed that lycopene, beta-carotene, and gamma-carotene levels were increased.
Moreover, Silaste and co-workers also report that consumption of the high tomato diet was associated with a 13 per cent increase in the level of circulating LDL to resist the formation of oxidised phospholipids, a marker of oxidative stress.
The study supports the hypothesis that the antioxidant content of tomato offer synergistic benefits.
Last week, this website reported on findings from a University of Illinois at Urbana-Champaign study indicating that phytoene and phytofluene, lesser known compounds from tomatoes, can accumulate in significant quantities in key organs, such as the liver and prostate ( Nutrition Research , Vol. 27, pp 794-801).
Source: British Journal of Nutrition December 2007, Volume 98, Issue 6, Pages 1251-1258, doi: 10.1017/S0007114507787445 "Tomato juice decreases LDL cholesterol levels and increases LDL resistance to oxidation" Authors: M.-L. Silaste, G. Alfthan, A. Aro, Y.A. Kesaniemi and S. Horkko