Agronomic practices can substantially increase the cancer-preventive phytochemicals in broccoli and tomatoes, as per a new study.
A University of Illinois study has suggested that improvements in agronomic methods can be instrumental in boosting benefits of tomatoes and broccoli.
"We enriched preharvest broccoli with different bioactive components, then assessed the levels of cancer-fighting enzymes in rats that ate powders made from these crops," said Elizabeth Jeffery, a U of I professor of food science and human nutrition.
A substance called selenium, when treated to broccoli, showed that the amount of one of the cancer-fighting compounds in broccoli was six times higher than in regular broccoli.
Selenium-treated broccoli was also most active in the liver, reaching a level of bioactivity that exceeded the other foods used in the experiment.
"We were intrigued to find that selenium initiated this amount of bioactivity," she said.
Along with garlic and other plants of the allium family, broccoli and other plants of the brassica family are unique in having a methylating enzyme that enables plants to store high concentrations of selenium, she said.
"Our bodies need a certain amount of selenium, but many areas of the world, including parts of the United States and vast areas of China, have very little selenium in the soil," she said.
"Not only could selenium in broccoli deliver this necessary mineral, it also appears to rev up the vegetable's cancer-fighting power," she added.
In a previous study, Jeffery and U of I colleague John W. Erdman Jr. showed that tomato and broccoli powders eaten together are more effective in slowing prostate cancer in laboratory rats than either tomato or broccoli alone.
In their current research, they are experimenting with ways to increase the bioactive components in these foods in order to test the efficacy of enriched broccoli and tomatoes in a new prostate cancer study.
An experiment on rats where they were fed tomatoes and broccoli rich in bioactive compounds, the scientists found increased levels of the compounds in body tissue and increased bioactivity in the animals.
"Carotenoids, which are phytochemical pigments found in fruits and vegetables, are thought to be excellent antioxidants and effective in cancer prevention," said Ann G. Liu, a U of I graduate student who worked on the study.
"A good rule is: the brighter the color, the higher the carotenoid content. If you're growing or buying tomatoes, select plants or produce that are a very bright red. High-lycopene tomatoes are now available through garden catalogs," she added.
"This research shows that you can greatly increase a food's bioactive benefits through normal farming practices, without resorting to genetic engineering. Farmers have traditionally been more concerned about yield than nutritional composition. Now we're asking, can we grow more nutritional broccoli and tomatoes?
And the answer is a definite yes," said Jeffery.