Processed and red meat consumption is associated with the risk of
colorectal cancer. Meta-analyses have suggested that the risk associated with processed meat is higher. Most processed meats are cured and cooked, which leads to formation of free nitrosyl
heme. We speculated that free nitrosyl
heme is more toxic than native
myoglobin. The promoting effect of a freeze-dried, cooked, cured ham diet was looked for in a 100-day study. Colon
carcinogenesis endpoints were
aberrant crypt foci and
mucin depleted foci (
MDF). A second study (14 days) was designed 1) to compare the effect of ham,
hemoglobin, and
hemin; and 2) to test the effect of
sodium chloride,
nitrite, and
phosphate in diet on early
biomarkers associated with
heme-induced promotion. In the 100-day study, control and ham-fed rats had 3.5 and 8.5
MDF/colon, respectively (P < 0.0001). Promotion was associated with cytotoxicity and lipid peroxidation. In the short-term study, cytotoxicity and lipid peroxidation of fecal water, and the urinary marker of lipid peroxidation, increased dramatically in ham- and
hemin-fed rat. In contrast, the
hemoglobin diet,
sodium chloride,
nitrite,
phosphate diet had no effect. Freeze-dried cooked ham can promote colon
carcinogenesis in a rodent model.
Hemin, but not
hemoglobin, mimicked ham effect on early
biochemical markers associated with
carcinogenesis.