The heart benefits of a Mediterranean diet have been well documented. Last year, Medical News Today reported on a study suggesting that the diet reduces the risk of heart attack and stroke in patients at high risk of cardiovascular disease. Now, researchers claim that an extract found in tomatoes may play a part in such health benefits, by improving blood vessel function.
In the US, cardiovascular disease (CVD) is responsible for a death every 33 seconds. Although CVD incidence varies globally, the researchers of this latest study - from the University of Cambridge and the Cambridge University Hospitals National Health Service Foundation Trust in the UK - note that it is much lower in countries where a Mediterranean diet dominates.
This, alongside numerous studies, suggests that a Mediterranean diet benefits cardiovascular health. The diet mainly consists of plant-based foods, such as fruits and vegetables, whole grains, legumes and nuts. It also involves limiting consumption of red meat, eating fish and poultry at least twice a week and replacing butter with healthy fats, such as olive oils.
The researchers note that until now, it has been unclear as to why the Mediterranean diet poses benefits to cardiovascular health. However, past studies have suggested an association between lycopene - an antioxidant found in tomatoes - and reduced risk of cardiovascular disease.
According to the researchers, lycopene is a powerful antioxidant that is 10 times more potent than vitamin E. It is a naturally occurring compound that gives tomatoes and other fruits - such as watermelons and pink grapefruits - their color. Tomatoes and tomato products, including ketchup and tomato puree, have the highest concentrations of lycopene.
To investigate the effects of lycopene on cardiovascular health, the research team conducted a randomized, double-blind study on 36 patients with CVD and 36 healthy volunteers.
Participants were given either a supplement called Ateronon - containing 7 mg of lycopene - or a placebo once daily for 2 months. Subjects were asked to continue with their regular diets throughout the study period.
At the beginning and end of the study, subjects' forearm blood flow, arterial stiffness, blood pressure and blood lipid levels were measured.
Lycopene supplementation 'normalized endothelial function' in CVD patients
Although patients with CVD were taking statins to lower their cholesterol, they still demonstrated impaired endothelial function at study baseline, compared with healthy participants. The endothelium is the thin layer of cells on the interior surface of the blood vessels. Endothelial dysfunction has been associated with the development of atherosclerosis - the narrowing or hardening of the arteries - which can increase the risk of heart attack and stroke.
Lycopene - an antioxidant found in tomatoes - was found to improve blood vessel function for patients with CVD.
The researchers explain that endothelial function is determined by blood vessels' response to a naturally occurring molecule called acetylcholine.
Results of the study, recently published in the journal PLOS One, revealed that CVD patients who received lycopene supplementation showed improved blood vessel response to acetylcholine, compared with healthy volunteers, which indicated normalized endothelial function.
In detail, the team found that lycopene improved blood vessel response to acetylcholine by 53% in CVD patients. It worked by simulating the release of nitric oxide - a hormone that helps the blood vessels to dilate.
The team notes that lycopene had no effect on blood pressure, arterial stiffness or blood lipid levels among participants.
Overall, the researchers say their findings provide "mechanistic evidence" for the benefits of one component of the Mediterranean diet for patients with CVD.
Commenting on the team's findings, study co-author Dr. Joseph Cheriyan, of the University of Cambridge, says:
"We've shown quite clearly that lycopene improves the function of blood vessels in cardiovascular disease patients.
It reinforces the need for a healthy diet in people at risk from heart disease and stroke. A daily 'tomato pill' is not a substitute for other treatments, but may provide added benefits when taken alongside other medication.
However, Dr. Cheriyan adds that larger trials are needed to determine whether lycopene may reduce the risk of heart disease.
It is not only cardiovascular health that lycopene may benefit. Last year, Medical News Today reported on a study published in the Journal of Clinical Endocrinology and Metabolism, which suggested that 25 mg of lycopene may reduce the risk of breast cancer.