Source: Kardiologiia  |  Posted 7 years ago

By Charlene Laino

ORLANDO, FL -- March 29, 2004 -- In findings that the researchers say may help explain why studies exploring the association between red meat and colon cancer risk have had inconsistent results, a new study shows that heme iron appears to raise the risk of proximal colon cancer while dietary zinc appears to lower the risk of both proximal and distal colon cancer.

Duk-Hee Lee, MD, PhD, Assistant Professor, Department of Preventive Medicine, Kyungpook National University, Daegu, Republic of Korea, presented the findings here on March 28th at the American Association for Cancer Research 95th Annual Meeting.

"Heme iron and zinc, both contained in red meat, may counteract each other," Dr. Lee said. "This could explain why studies have had such inconsistent results."

Dr. Lee said most previous studies looking at red meat, iron and cancer risk have utilized total dietary iron, rather than analyzing heme and non-heme iron separately. "We thought it might be useful to look at heme iron -- a possible pro-oxidant - alone," she said.

Dr. Lee and colleagues analysed 15 years of follow-up data on 34,708 postmenopausal women aged 55 to 69 years at baseline, who completed a food-frequency questionnaire for the Iowa Women's Health Study.

After adjusting for each micronutrient, the relative risks for proximal colon cancer increased more than twofold across quintiles of heme iron intake (P for trend = .01) and the corresponding relative risks decreased more than 50% across quintiles for zinc intake (P for trend = .01).

The positive associations between colon cancer risk and heme iron and the inverse association with zinc intake were stronger among women who consumed alcohol -- a disruptor of iron homeostasis -- than among those who did not, Dr. Lee said.

Zinc intake was also associated with a decreased risk of distal colon cancer (P for trend =.03), regardless of alcohol or heme iron consumption.

"Some foods, like a kind of oyster, have a high zinc content," Dr. Lee said. "Our findings suggest that if you eat foods with relatively high zinc rather than high heme iron, it might be helpful."

[Study title: Heme Iron, Zinc, Alcohol Consumption, And Colon Cancer: Iowa Women's Health Study. Abstract 481]