People who increase their fruit and vegetable intake but don't include cruciferous vegetables will not alter their risk for cancer, according to a study by J.W. Lampe and colleagues presented at the American Association for Cancer Research meeting in Washington D.C., April 20*24.
While cruciferous vegetables have been shown to increase serum GST-alpha concentrations in controlled studies, no increase was found when people simply added more fruits and vegetables to their diets, Lampe said.
"Serum Glutathione S-Transferase-Alpha Concentrations in a Vegetable and Fruit Intervention Trial" found that most participants in the intervention group preferred to augment their diets with raw carrots rather than broccoli, cabbage and cauliflower but indicated that only cruciferous vegetables have an effect on serum GST-alpha concentrates, the Phase II enzymes that help the body metabolize carcinogens and environmental pollutants, Lampe said.
"There was no real difference between the control and the intervention groups," she reported. Participants in the control group did not add more fruits and vegetables to their diets.
The researchers noted that the subjects were reluctant to eat more broccoli, cauliflower and cabbage even though these vegetables were suggested * although not specifically recommended * to them. Instead, they chose raw carrots, apparently for reasons of taste and convenience, Lampe said.
"Although the intervention increased overall vegetable and fruit intake, increased vegetable and fruit intake without emphasis on cruciferous vegetable intake did not influence serum GST-alpha concentrations," Lampe said. The study is a subset of a larger study on colonic polyp reduction.
She noted that allium vegetables and some berries were also found to have cancer-risk reduction properties, but not carrots.
Onions Cut Risk of Stomach Cancer
According to a Dutch study on the effect of eating allium vegetables on cancer risk, people who eat oniioons every day lower their risk of stomach cancer by one-half over those who don't eat onions at all. "Allium Vegetable Consumption and Risk for Cancer" is an ongoing study of 120,000 Dutch people by E. Dorant, P.A. Van den Brandt and R.A. Goldbohm of Maastricht, the Netherlands.
The researchers found a strong inverse association with onion consumption for some stomach cancers and an inverse association with onions for other stomach cancers between 1986 and 1989, the first three years of the study.
"The data show that you lower the risk of stomach cancer if you eat onions every day," Dorant said, noting that Dutch people eat an average of half an onion a day. "The more you eat, the lower the risk gets," Dorant said.
There was no similar correlation for leeks or other allium vegetables and stomach cancer, and eating onions or other allium vegetables did not affect the risk for lung, breast, colon or rectal cancers, she said.
High-Fat Diet Increases Breast Cancer Risk in Pregnant Rats Feeding high levels of dietary fat to pregnant rats increases their susceptibility to mammary tumors, researchers at the Lombardi Cancer Center, Georgetown University Medical Center, Washington, D.C., found in their study, "High-Fat Diet during Pregnancy Increases Breast Cancer Risk in Rats."
"If true for humans, these results may have an important implication for attempts to prevent breast cancer," said Leena Hilakivi-Clarke, an author of the study.
Diet may be one of the factors for the higher rates of breast cancer that we see today, Hilakivi-Clarke said, noting that breast cancer rates were lower prior to the 1950s. Before the 1950s, doctors recommended that women not gain a lot of weight during pregnancy, on the theory that smaller babies posed less of a risk to the mother during delivery, she explained.
However, in the 1950s doctors determined that maternal weight gain produced healthier babies and, with the advent of safer cesarean sections, encouraged exp
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he growth rate of prostate tumors in rats and that it possessed anti-proliferative effects in human breast cancer cells, the study said.
This was not a human study * GP-milk was applied to breast cancer cells only in the FDA-approved amount. The researchers stressed that further studies are needed.
Vitamin E Supplementation Not Recommended For Breast Cancer Patients "There is presently no basis for vitamin E supplementation for prevention of breast cancer," said P. Bougnoux, an author of "Alpha-Tocopherol and Hydroperoxide Content of Breast Adipose Tissue from Patients with Breast Tumors."
The French study found lower alpha-tocopherol values in the breast adipose tissue of breast cancer patients than in control patients. Breast cancer is associated with an altered lipid oxidation in breast adipose tissue, which might be related to a lower antioxidant content, according to the study.
Whether this low content of alpha-tocopherol is the result of a low dietary intake of vitamin E remains to be directly addressed, the researchers said.
"We don't know the significance of the finding, but if alpha-tocopherol levels are low in women with breast cancers, they didn't eat enough foods with vitamin E," Bougnoux said.
"But we don't recommend increasing alpha-tocopherol levels if tumors are present."
Not Smoking Prevents Lung Cancer Better than Antioxidants "Antioxidant Micronutrient Levels and the Risk of Lung Cancer in Men and Women" looked at whether prediagnostic ascorbic acid levels of carotenoids or alpha-tocopherol were associated with the development of lung cancer. The Johns Hopkins University study determined that while carotenoids other than beta carotene may be associated with a lower risk of lung cancer, the best way to prevent lung cancer is not to smoke. "Not smoking is a far more effective way to prevent lung cancer than taking antioxidants," said Kathy Helzlsouer, an author of the study.
- SOURCE : Food Chemical Newws1996.04.29
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