A
new study from the Indiana University School of Public Health-Bloomington has
bolstered the link between red meat consumption and heart disease by finding a
strong association between heme iron, found only in meat, and potentially
deadly coronary heart disease.
The
study found that heme iron consumption increased the risk for coronary heart
disease by 57 percent, while no association was found between nonheme iron,
which is in plant and other non-meat sources, and coronary heart disease.
The
study was published online ahead of print in the Journal of Nutrition. Along with first
author Jacob Hunnicutt, a graduate student in the school's Department of
Epidemiology and Biostatistics, the study's co-authors are Ka He and Pengcheng
Xun, faculty members in the department.
Hunnicutt
said the link between iron intake, body iron stores and coronary heart disease
has been debated for decades by researchers, with epidemiological studies
providing inconsistent findings. The new IU research, a meta-analysis, examined
21 previously published studies and data involving 292,454 participants during
an average 10.2 years of follow-up.
The
new study is unique because it looks at the associations of total iron
consumption as well as heme and nonheme iron intake in comparison to the risk
of coronary heart disease. The only positive association involved the intake of
heme iron.
The
body treats the two kinds of iron differently. It can better control absorption
of iron from vegetable sources, including iron supplements, but not so with
iron from meat sources.
"The
observed positive association between heme iron and risk of CHD may be
explained by the high bioavailability of heme iron and its role as the primary
source of iron in iron-replete participants," the researchers wrote in the
journal article. "Heme iron is absorbed at a much greater rate in
comparison to nonheme iron (37 percent vs. 5 percent). Once absorbed, it may
contribute as a catalyst in the oxidation of LDLs, causing tissue-damaging
inflammation, which is a potential risk factor for CHD."
Iron
stores in the body increase over time. The only way to reduce iron in the body
is by bleeding, donating blood or menstruation. Some dietary choices, such as
coffee and tea, also can inhibit iron absorption.
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