Web edition: October 11, 2012
Print edition: November 17, 2012; Vol.182 #10 (p. 16)
Men with high blood levels of lycopene — the compound that makes tomatoes red — are about half as likely to have a stroke as those low on lycopene, researchers in Finland report October 9 in Neurology.
Some evidence suggests that lycopene quells inflammation, limits cholesterol production and inhibits blood clotting. But first and foremost, lycopene is a carotenoid, an antioxidant that sops up unstable molecules in the body called free radicals —agents that can induce DNA damage, kill cells, attack proteins and contribute to blood vessel disease.
Lycopene’s direct effect on stroke risk is less clear. Studies have found that a diet rich in fruits and vegetables, meaning plenty of carotenoids, seems to reduce the risk of heart disease and stroke. But few studies have analyzed lycopene’s effect specifically on stroke risk over time, the researchers note.
Jouni Karppi and colleagues at the University of Eastern Finland in Kuopio used blood tests to determine the lycopene levels of 1,031 men ages 46 to 65. Afterward, the men were monitored for a median of 12 years. The researchers tallied 67 strokes in the men over that span. Men with the lowest lycopene levels at the outset were more than twice as likely to have a stroke later as were those with the highest.
“This is a very good study, and I’m really surprised they were able to find this relationship with only 67 strokes,” says Lyn Steffen, a nutritional epidemiologist at the University of Minnesota.
The researchers also accounted for differences between the men such as smoking, body mass, blood pressure, LDL cholesterol, diabetes and any history of stroke.
It’s not certain that the effect apparent in this study arises solely from lycopene. Tomatoes are loaded with it, but they have many other useful ingredients as well, says John Erdman, a nutritionist at the University of Illinois at Urbana-Champaign. So high lycopene levels in the blood may suggest high tomato consumption, and therefore high levels of those other components, he says, such as polyphenols, folic acid, and vitamins C and E. Polyphenols are potent antioxidants that show up in red and purple fruits, chocolate, coffee, red wine and vegetables.
“There hasn’t been a heck of a lot of lycopene/tomato research in stroke,” Erdman says. “It’s encouraging that they’ve got these results.” Lycopene also appears in guava, papaya, pink grapefruit, red peppers, rose hips and watermelon.
Steffen says high lycopene levels might also flag people who have a healthy diet, ingesting lots of fruits, veggies and whole grains at the expense of red meats and processed grains. “In Finland they have this rye bread that’s really wonderful as a whole grain. So the risk of stroke is lower not just because of lycopene but also from the background diet.”
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