December 12, 2005

Dietary iron linked to upper GI cancer risk

NEW YORK (Reuters Health) - Consumption of high levels of
dietary iron appear to be associated with an increased risk of
throat and stomach cancer, researchers report. However, the
risk is decreased with higher levels of zinc.

In a study published in the International Journal of
Cancer, Dr. David R. Jacobs, of the University of Minnesota,
Minneapolis, and colleagues examined data from the Iowa Women's
Health Study involving 34,708 postmenopausal women (ages 55 to
69 years at study enrollment) who completed food consumption

The women were followed for 16 years. During that period,
75 cases of upper digestive tract cancer (52 stomach cancers
and 23 throat cancers) were reported. The team found a positive
association between iron intake and the risk of upper digestive
tract cancer. However, an inverse association was observed
between zinc intake and cancer risk.

The subjects were divided into groups based on dietary iron
levels, and risk factors including age, total calorie
consumption, cigarette smoking and alcohol consumption, were

The increased risk of upper digestive tract cancers, from
the lowest to the highest dietary iron levels, were zero to
almost three-fold. The corresponding risks for dietary zinc
levels were zero to less than 13 percent.

The results were not altered after consideration of other
potential risk factors such as body mass index, physical
activity score, hormone replacement therapy, multivitamin
intake and intake of saturated fat, retinol, vitamin C, vitamin
E, and folate from food and supplements.

"Our current and previous results strongly suggest that
both iron and zinc play important roles in carcinogenesis of
digestive tract, probably through the mechanism of oxidative
stress," Jacobs and colleagues comment.

SOURCE: International Journal of Cancer, November 2005.