Fruit and vegetable intake has long been associated with a lower risk of ischaemic stroke, said study author Jing Ma, assistant professor of medicine, at Brigham and Women's Hospital, Harvard Medical School, Boston. But the scientists set out to investigate which antioxidants in fruits and vegetables might have this positive effect.
A recent report on the $348.5 million (€291.4m) carotenoid market from market analysts Frost & Sullivan revealed that the European food and health industry has 'under-utilised' the nutraceutical properties of carotenoids, and consumers are still unaware of their health benefits.
Frost & Sullivan claims that carotenoids are still used primarily as a colouring agent for the food and feed industries. Consumers in most European regions are unaware of their use as a food fortifier and this poor level of public awareness about the health benefits of carotenoids is expected to stifle market growth in the short term.
Currently, the European carotenoid market is forecast to grow to €349.3 million in 2010.
The Physicians' Health Study involved 22,071 US male doctors, 68 per cent of whom provided blood samples at the start of the study in 1982. Among the 15,000 who did not have cardiovascular disease at the beginning of the study, 297 had an ischaemic stroke during the study's 13-year follow-up.
The team analysed blood samples from stroke patients and controls, to determine the concentration of antioxidants including carotenoids (alpha-carotene, beta-carotene, lycopene, lutein and beta-cryptoxanthin). They found that the men in the bottom 20 per cent of carotenoid levels based on alpha-carotene, beta-carotene and lycopene content had a 40 per cent higher risk of ischaemic stroke.
Once carotenoid concentrations rose above those in the bottom 20 per cent, progressively higher levels of carotenoids were not associated with increased protection. But the findings are not clear as to whether these carotenoids give fruit and vegetables their protective effects or if they are simply markers of the protective effects of fruit and vegetable intake.
"The carotenoid level could have been the result of these men eating fruits and vegetables or taking antioxidant supplements. The observational study shows an association between fruit and vegetable intake and stroke risk, but did not prove that eating fruits and vegetables caused the lower risk," the researchers note.
Despite this, Ma commented that the results of this study "support a diet high in fruits and vegetables to reduce ischaemic stroke risk".
According to the World Health Organisation (WHO), an estimated 17 million people worldwide die from cardiovascular diseases, particularly heart attacks and strokes, every year. Poor diet, smoking and physical inactivity are all possible risk factors in raising the risk of heart disease, a risk that increases with age and is greater for women than for men.
Full findings are published in the recent rapid access issue of Stroke, a publication of the American Heart Association.