Friday, 29 May 2009
Tomatoes: Lycopene, Cancer & Heart Attacks
Tomatoes are rich in the antioxidant lycopene that's been linked to reduced rates of cancers, especially lung, stomach and prostate cancers.
A study by the Harvard School of Public Health showed that men that ate 10 or more servings of tomato-based foods a week had a 45% reduced prostate cancer rate.
Lycopene is bound inside cell walls, making it difficult for the body to extract it from raw tomatoes. This explains why cooked tomatoes (ie tomato sauce) seem to be more protective than raw tomatoes or tomato juice- the heat seems to release the lycopene.
Lycopene is also fat-soluble so cooking tomatoes in oil (ie. tomato sauce!) enhances the absorption of the antioxidant.
What's causing some confusion is a study conducted at the Ohio State University on about 200 rats (a good model for human prostate cancer, supposedly). Some rats were fed diets containing whole tomato powder and others were fed rat food fortified with pure lycopene (and, consequently, received more lycopene than the tomato powder group). Reserachers caused prostate cancer in these rats.The rats fed the pure lycopene actually had more tumors and a significantly greater risk of death!
What this study suggests is that there seems to be other components in tomatoes that have a protective effect- the whole food is beneficial whereas isolated lycopene may not be.
It seems that tomatoes may also protect the heart. An Itailan study looked at the diets of 507 heart attack victims and of 478 controls- one of the items on the food frequency questionnaire was pizza. Surprisingly, regular pizza eaters (eating about 500g or just over 1/2lbs pizza a week) were 40% less likely to suffer a heart attack than those who never ate pizza!
Maybe the pizza eaters were eating less high saturated fat hamburgers. Remember that real Italian pizzas are not like the North American meat-lovers-pepperoni-3 cheese- stuffed crust ones- they have a thin crust and are dressed with olive oil, a lot of tomato sauce and some cheese. Another possibility that Dr. Schwarcz proposes is that the tomatoes may be responsible: That yellow stuff around the seeds of tomatoes contain flavonoids that have anti-clotting properties... possibly reducing the risk of heart attacks!
Bottom line: Aim to treat yourself to tomatoes, processed tomatoes or tomato products cooked in oil every day. Stay away from lycopene supplements until more research is done.