Researchers from the University of the Negev found that a daily intake of the commercial encapsulated tomato extract Lyc-O-Mato, made by Israel-based LycoRed, was linked to a drop in systolic (SBP) and diastolic blood pressure (DBP) of ten and four points after eight weeks of supplementation of a normal diet.
"Reduction in BP from grade-1 hypertension to high-normal range, such as achieved in our pilot study, is clinically significant," wrote lead-author Dr Yechiel Engelhard in the January issue of the American Heart Journal (Vol. 151, No. 1, pp. 100.e6-100.e1).
Moderate, or Grade-1, hypertension is defined as a having SBP between 140 and 159 mmHg, a DBP between 90 and 99 mmHg, or both. The volunteers studied were not taking antihypertensive medication.
The tomato extract contains a mix of potent antioxidants including lycopene, beta-carotene, vitamin E and various other phytonutrients. Lycopene is said to be the most efficient antioxidant among the natural carotenoids.
The 16-week study followed 31 volunteers aged between 30 and 70. Smokers, people with diabetes or cardiovascular diseases, and people already taking vitamin supplements, were excluded from the study.
A four-week placebo period was followed by eight weeks taking the Lyc-O-Mato supplement as part of a normal diet, and a further four weeks of placebo. The placebo capsule was identical in appearance to Lyc-O-Mato.
Lipid peroxidation products, a marker for oxidative stress and cell membrane destruction, were also observed to decrease from 4.6 nmol/mg to 3.8 nmol/mg during the intervention period.
Reactive oxygen attack of the endothelium, the cells that line blood vessels, impairs vascular dilation and contributes to rise of hypertension. The researchers propose that the high antioxidant ability of lycopene, as well as beta-carotene and vitamin E, can explain the reduction in BP.
"Our assumption is that the reduction in BP observed in the study was due to antioxidant activity of the tomato extract," said Engelhard.
Since the intervention period was relatively short, it is unclear if supplementation would be equally beneficial in the long-term. Engelhard said: "Studies with larger and more diverse populations examining the antihypertensive effect for longer periods are required."
LycoRed, the company that supplied the Lyc-O-Mato and identical-looking placebo capsules, is the leader in natural lycopene market. Lyc-O-Mato capsules are available with lycopene concentrations between six and 15 per cent.
Commenting on the research, Belinda Linden, Head of Medical Information at UK charity the British Heart Foundation, told NutraIngredients.com: "This research into the blood pressure lowering effect of concentrated tomato extract is welcome because the more we understand about the benefits of specific fruit and vegetables, the better."
"However, this research paper doesn't comment on whether people involved in this study may have also eaten other fruit and vegetables, which may have influenced the results."
"There is still very good reason to make sure that we enjoy at least five fruit and vegetables a day," said Linden.