Background/aim: Nut consumption is associated with lower risk of colorectal cancer (CRC). Previously, single nut varieties have been investigated but there is limited research on the consumption of a nut mixture and the underlying mechanisms. This study examined mixed nut consumption's effect on colonic cell proliferation, apoptosis, and gene expression involved in CRC.
Materials and methods: Thirty 21-day old Sprague Dawley rats were divided into three groups: control (no nuts), pistachio or mixed nut for 8 weeks. Ki-67 quantitative immunostaining was used to mark proliferative cells and terminal deoxynucleotidyl transferase dUTP nick-end labeling (TUNEL) assay for apoptotic cells. Real-time quantitative polymerase chain reaction analysis was used to determine colonic gene expression of prostaglandin endoperoxide synthase 2 (Ptgs2), nuclear factor kappa-B p65 subunit (Rela), cyclin D1 (Ccnd1), peroxisome proliferator-activated receptor gamma (Pparg), O6-methylguanine-DNA-methyltransferase (Mgmt), 8-oxoguanine glycosylase (Ogg1), superoxide dismutase (Sod), and catalase (Cat).
Results: DNA damage, determined using 8-oxo-deoxyguanosin, was found to be lower in the mixed nut group only (p<0.05). Differences in proliferation and apoptosis among all three groups were not significant. Lower levels of the inflammatory marker, Ptgs2, were observed between the pistachio group and the control (p=0.035). The pistachio and mixed nut groups had lower levels of Rela compared to the control (p=0.029). Differences among diets for Ccnd1, Pparg, Mgmt, Ogg1, Sod, and Cat were not significant.
Conclusion: Mixed nut consumption reduced DNA damage possibly via down-regulation of Rela inflammation gene expression without changes to colonic cell proliferation and apoptosis.
Keywords: 8-oxo-deoxyguanosine; Mixed nuts; colon cell proliferation; cyclooxygenase 2; pistachios.
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