The researchers also found a strong link between dietary lycopene and higher plasma levels but said that the determinants of plasma lycopene concentrations need to be better understood.
Lycopene has been found to have significant antioxidant potential in laboratory studies but it has been more widely tested for its role in cancer prevention than prevention of cardiovascular disease. This is the second study to examine association of lycopene and cardiovascular disease exclusively in women. Heart disease is the leading cause of death in women worldwide, killing around 8 million each year - more than 18 times the rate caused by breast cancer.
The researchers, led by Howard Sesso of the Harvard School of Public Health in the US, used data from the ongoing, randomised, double-blind Women's Health Study. The 40,000 women included in the trial were free from cardiovascular disease at the start of the study.
After nearly five years of follow-up, the researchers recorded 483 cases of the disease. Subjects in the study were divided into four groups, in order of increasing plasma lycopene levels. Researchers then reviewed the data for associations with the presence of cardiovascular disease.
The 34 per cent reduction was found in the women in the top two quarters - those with plasma lycopene levels higher than the study population average. In addition, after excluding women with angina, those with plasma lycopene values in the top three quarters had a 50 per cent reduced risk of cardiovascular disease.
Women in the second quarter were still 22 per cent less likely to develop the disease than women in the first quarter, who had the lowest plasma lycopene values.
The study, published in this month's American Journal of Clinical Nutrition (vol 79, no1, 47-53), also showed that the women with highest levels of plasma lycopene were likely to have high values of other beneficial carotenoids such as lutein/zeaxanthin and alpha- and beta-carotene.
According to the data, consumption of more dietary lycopene is significantly related to higher plasma lycopene levels. Women with the highest plasma lycopene values (greater than or equal to 21.0 ug/dl) were consuming nearly 10 mg (plus/minus 6 mg) of lycopene per day.
The findings follow earlier research by Dr Sesso, reported in the Journal of Nutrition last year, which found that women with the highest intake of lycopene-rich tomato-based foods had a reduced risk for cardiovascular disease compared to women with low intake of those foods.
Researchers on the Kuopio Ischaemic Heart Disease Risk Factor study also reported last year that low serum lycopene levels were associated with increased risk of heart attack and stroke.
A US company, American Longevity, this week extended a list of health claims that it first filed with the US Food and Drug Administration last June, requesting approval for claims that lycopene, tomatoes and tomato-based products may reduce the risk of numerous cancers, including prostate, lung, gastric, colorectal and breast cancer.
Recent research has however suggested that the carotenoid alone may not be sufficient to fight the onset of prostate cancer and that other compounds found in the tomato work in synergy to produce the beneficial effects. And a UK firm, Provexis, says it has developed a drink made from tomatoes, but containing no lycopene, that protects people from developing heart disease.