WASHINGTON (AP) -- Eating lots of fresh and processed tomatoes can lower the risk of many kinds of cancer, according to a study published Wednesday.
A summary study in the Journal of the National Cancer Institute found there was enough data to show convincingly "that high consumers of tomatoes and tomato products are at substantially decreased risk of numerous cancers, although probably not all cancers."The study analyzed 72 past studies that had examined the link between various cancers and the consumption of tomatoes and tomato-based products. Some of the studies also analyzed the blood levels of lycopene, a compound principally found in tomatoes that protects cells from cancer-causing oxidants.
In all, 57 of the 72 studies linked tomato intake with a reduced risk of cancer, Dr. Edward Giovannucci of Harvard Medical School said in the report he authored. In 35 of these studies, he wrote, the connection was strong enough to be "statistically significant," while in another 15 the link was inconclusive or only "slight."
The data are most compelling for cancers of the prostate gland, lung and stomach, Giovannucci said. The findings also suggest links with lower levels of several other cancers, including pancreatic, colorectal, esophageal, oral, breast and cervical cancers.
Dr. Clare Hasler, executive director of the Functional Foods for Health Program at the University of Illinois, called Giovannucci's work the most comprehensive to date on the issue.
"It shows that people who eat a large amount of tomatoes have a reduced risk for a number of types of cancers," she said.
Overall, the study shows, "It is good to eat tomatoes as a part of a diet that is rich in other fruits and vegetables," said Dr. Moshe Shike, director of the Cancer Prevention and Wellness Program at Memorial Sloan-Kettering Cancer Center in New York.
The individual studies Giovannucci examined included tomatoes in many forms, including raw, ketchup, spaghetti sauce, tomato paste, soup and salsa. Benefits were found from all those forms, the study concluded, and cooking and processing tomatoes did not diminish the effect.
However, many processed foods containing tomatoes also contain fats and sugars that are not healthful when eaten in excess.