I eat lots of broccoli, mostly cooked. I need to eat more raw broccoli, and other cruciferous vegetables, such as cauliflower and cabbage, or cooked broccoli with tomato sauce, or both. Here’s why:
UCLA study finds that broccoli may help boost the aging immune system
UCLA researchers have found that a chemical in broccoli and other cruciferous vegetables may hold a key to restoring the body's immunity, which declines as we age.
Published in this week's online edition of the Journal of Allergy and Clinical Immunology, the study findings show that sulforaphane, a chemical in broccoli, switches on a set of antioxidant genes and enzymes in specific immune cells, which then combat the injurious effects of molecules known as free radicals that can damage cells and lead to disease.
Free radicals are byproducts of normal body processes, such as the metabolic conversion of food into energy, and can also enter the body through small particles present in polluted air. A supercharged form of oxygen, these molecules can cause oxidative tissue damage, leading to disease — for example, triggering the inflammation process that causes clogged arteries. Oxidative damage to body tissues and organs is thought to be one of the major causes of aging.
"The mysteries of aging have always intrigued man," said Dr. Andre Nel, the study's principal investigator and chief of nanomedicine at the David Geffen School of Medicine at UCLA. "While we have known for some time that free radicals are important in aging, most of the past attention has focused on the mechanisms that produce free radicals rather than addressing the pathways used by the body to suppress their production."
A dynamic equilibrium exists in the body between the mechanisms that lead to increased free radical production and those antioxidant pathways that help combat free radicals.
"Our study contributes to the growing understanding of the importance of these antioxidant defense pathways that the body uses to fight free radicals," said Nel, a practicing clinical allergist and immunologist at the Geffen School. "Insight into these processes points to ways in which we may be able to alleviate the effects of aging."
The delicate balance between pro-oxidant and antioxidant forces in the body could determine the outcome of many disease processes that are associated with aging, including cardiovascular disease, degenerative joint diseases and diabetes, as well as the decline in efficiency of the immune system's ability to protect against infectious agents.
"As we age, the ability of the immune system to fight disease and infections and protect against cancer wears down as a result of the impact of oxygen radicals on the immune system," Nel said.
According to the UCLA study, the ability of aged tissues to reinvigorate their antioxidant defense can play an important role in reversing much of the negative impact of free radicals on the immune system. However, until this current study, the extent to which antioxidant defense can impact the aging process in the immune system was not properly understood.
"Our defense against oxidative stress damage may determine at what rate we age, how it will manifest and how to interfere in those processes," Nel said. "In particular, our study shows that a chemical present in broccoli is capable of stimulating a wide range of antioxidant defense pathways and may be able to interfere with the age-related decline in immune function."
"Dietary antioxidants have been shown to have important effects on immune function, and with further study, we may be adding broccoli and other cruciferous vegetables to that list," Nel said.
For now, Nel suggests including these vegetables as part of a healthy diet.
Nel said that these findings offer a window into how the immune system ages.
"We may find that combating free radicals is only part of the answer. It may prove to be a more multifaceted process and interplay between pro- and antioxidant forces," he said.
More Broccoli
Women should go for the broccoli when the relish tray comes around during holiday celebrations this season.
While it has been known for some time that eating cruciferous vegetables, such as broccoli, cauliflower, and cabbage, can help prevent breast cancer, the mechanism by which the active substances in these vegetables inhibit cell proliferation was unknown - until now.
Scientists in the UC Santa Barbara laboratories of Leslie Wilson, professor of biochemistry and pharmacology, and Mary Ann Jordan, adjunct professor in the Department of Molecular, Cellular, and Developmental Biology, have shown how the healing power of these vegetables works at the cellular level. Their research is published in this month's journal Carcinogenesis.
"Breast cancer, the second leading cause of cancer deaths in women, can be protected against by eating cruciferous vegetables such as cabbage and near relatives of cabbage such as broccoli and cauliflower," said first author Olga Azarenko, who is a graduate student at UCSB. "These vegetables contain compounds called isothiocyanates which we believe to be responsible for the cancer-preventive and anti-carcinogenic activities in these vegetables. Broccoli and broccoli sprouts have the highest amount of the isothiocyanates.
"Our paper focuses on the anti-cancer activity of one of these compounds, called sulforaphane, or SFN," Azarenko added. "It has already been shown to reduce the incidence and rate of chemically induced mammary tumors in animals. It inhibits the growth of cultured human breast cancer cells, leading to cell death."
Azarenko made the surprising discovery that SFN inhibits the proliferation of human tumor cells by a mechanism similar to the way that the anticancer drugs taxol and vincristine inhibit cell division during mitosis. Mitosis is the process in which the duplicated DNA in the form of chromosomes is accurately distributed to the two daughter cells when a cell divides.
Hundreds of tiny tube-like structures, called microtubules, make up the machinery that cells use to separate the chromosomes. SFN, like the more powerful anticancer agents, interferes with microtubule functioning during mitosis in a similar manner to the more powerful anticancer drugs. However SFN is much weaker than these other plant-based drugs, and thus much less toxic.
"SFN may be an effective cancer preventive agent because it inhibits the proliferation and kills precancerous cells," said Wilson. It is also possible that it could be used as an addition to taxol and other similar drugs to increase effective killing of tumor cells without increased toxicity.
Consumption of raw, but not cooked, cruciferous vegetables and reduction of bladder cancer risk.
While researchers have long known that cruciferous vegetables are chock full of isothiocyanates (ITCs), which are a well-known class of cancer prevention agents especially promising in bladder cancer chemoprevention, they didn’t know how much one needed to eat to reap the protective benefits.
Researchers from Roswell Park Cancer Institute report that three or more servings a month of raw cruciferous vegetables like broccoli, cabbage and cauliflower, may reduce bladder cancer risk by approximately 40 percent, overall.
The Roswell Park team surveyed the dietary habits of 275 individuals with incident, primary bladder cancer and 825 individuals without cancer. The researchers surveyed patients about their pre-diagnostic intake of raw and cooked cruciferous vegetables, their smoking habits and other cancer risk factors. They observed a strong and statistically significant inverse association between bladder cancer risk and raw cruciferous vegetable consumption. When compared to smokers who ate less than three servings of raw vegetables, non-smokers who ate at least three servings a month were almost 73 percent less likely to develop bladder cancer, the researchers say.
A key factor in the research was that it’s a survey of raw cruciferous vegetables. Previous research had surveyed intake of any cruciferous vegetables – cooked or not – and results proved inconsistent. Cooking significantly reduces the availability of ITCs for absorption into the body, according to researchers.
“Cooking can reduce 60 to 90 percent of ITCs,” says Li Tang, M.D., Ph.D. of Roswell Park Cancer Institute and lead researcher on this study. “Heating destroys the enzyme that converts the precursor glucosinolates into ITCs, and also destroys ITCs already formed, which is why you need to eat raw cruciferous vegetables to receive the food’s maximum benefit.”
Broccoli, cabbage and cauliflower fight breast cancer
When your mother told you to eat your vegetables it appears that maternal wisdom had a scientific basis. Researchers have discovered a possible link between a diet rich in certain vegetables and a decreased risk for breast cancer. The study appears in the March issue of the American Journal of Clinical Nutrition.
Cruciferous vegetables contain some compounds that may have a cancer-inhibitory effect.
While there was only a small positive relationship between a diet high in these vegetables and a reduction in breast cancer risk for the overall study population, there was a striking risk reduction – 50 percent – among women with a certain genetic profile. Researchers identified three forms of the GSTP1 genotype among the cancer patients: Ille/Ile, Ile/Val and Val/Val.
“Women who consumed more of these cruciferous vegetables and who also had the Val/Val genetic polymorphism had a lower breast cancer risk. So we cautiously interpreted this as diet being a factor that may reduce the impact of genetic susceptibility in overall breast cancer risk,” said Fowke.
Studies by other researchers have suggested cruciferous vegetables may reduce the risk of lung, stomach, colorectal and bladder cancers.
Worried about prostate cancer? Tomato-broccoli combo shown to be effective
A new University of Illinois study shows that tomatoes and broccoli--two vegetables known for their cancer-fighting qualities--are better at shrinking prostate tumors when both are part of the daily diet than when they're eaten alone.__
"When tomatoes and broccoli are eaten together, we see an additive effect. We think it's because different bioactive compounds in each food work on different anti-cancer pathways," said University of Illinois food science and human nutrition professor John Erdman.__
In a study published in the January 15 issue of Cancer Research, Erdman and doctoral candidate Kirstie Canene-Adams fed a diet containing 10 percent tomato powder and 10 percent broccoli powder to laboratory rats that had been implanted with prostate cancer cells. The powders were made from whole foods so the effects of eating the entire vegetable could be compared with consuming individual parts of them as a nutritional supplement.__
Other rats in the study received either tomato or broccoli powder alone; or a supplemental dose of lycopene, the red pigment in tomatoes thought to be the effective cancer-preventive agent in tomatoes; or finasteride, a drug prescribed for men with enlarged prostates. Another group of rats was castrated.__
After 22 weeks, the tumors were weighed. The tomato/broccoli combo outperformed all other diets in shrinking prostate tumors. Biopsies of tumors were evaluated at The Ohio State University, confirming that tumor cells in the tomato/broccoli-fed rats were not proliferating as rapidly. The only treatment that approached the tomato/broccoli diet's level of effectiveness was castration, said Erdman.__
"As nutritionists, it was very exciting to compare this drastic surgery to diet and see that tumor reduction was similar. Older men with slow-growing prostate cancer who have chosen watchful waiting over chemotherapy and radiation should seriously consider altering their diets to include more tomatoes and broccoli," said Canene-Adams.
How much tomato and broccoli should a 55-year-old man concerned about prostate health eat in order to receive these benefits? The scientists did some conversions.
"To get these effects, men should consume daily 1.4 cups of raw broccoli and 2.5 cups of fresh tomato, or 1 cup of tomato sauce. I think it's very doable for a man to eat a cup and a half of broccoli per day or put broccoli on a pizza.
Erdman said the study showed that eating whole foods is better than consuming their components. "It's better to eat tomatoes than to take a lycopene supplement," he said. "And cooked tomatoes may be better than raw tomatoes. Chopping and heating make the cancer-fighting constituents of tomatoes and broccoli more bioavailable."
"When tomatoes are cooked, for example, the water is removed and the healthful parts become more concentrated. That doesn't mean you should stay away from fresh produce. The lesson here, I think, is to eat a variety of fruits and vegetables prepared in a variety of ways," Canene-Adams added.__
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