Associations of Nut Intakes with Incident Sporadic Colorectal Adenoma Risk: A Pooled Case-Control Study Restricted; Files Only

Yin, Xin (Fall 2017)

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Nuts are rich in phytochemicals with antioxidant and anti-inflammatory properties, suggesting that consumption of them may reduce risk for colorectal carcinogenesis. However, there are few published reports on associations of nut intakes with colorectal adenoma, the immediate precursor to most colorectal cancers. To investigate an association of nut intakes with incident, sporadic colorectal adenoma, we pooled data from three case-control studies of incident, sporadic colorectal adenoma (n=785 cases, 2,107 controls), and analyzed them using multivariable unconditional logistic regression. The multivariable-adjusted odds ratios (OR) and 95% confidence intervals (CI) for the association of total nut product (all nuts and peanut butter combined) intakes, for those who consumed 0.5 – 1.5, 2.0 – 5.5, and ≥ 6 servings/week relative to no nut consumption were 0.81 (0.58, 1.12), 0.86 (0.61, 1.23), and 0.93 (0.65, 1.31), respectively (ptrend = 0.66).  The corresponding ORs and 95% CIs among women were 0.62 (0.40, 0.97), 0.57 (0.35, 0.94), and 0.78 (0.48, 1.25), respectively (ptrend = 0.86).  Findings similar to those for women were noted among those who were <56 years old, had a family history of colorectal cancer in a first degree relative, regularly took aspirin or other non-steroidal anti-inflammatory drugs, and those who had a lower balance of anti- to pro-oxidant exposures.  These results suggest a possible U-shaped association of total nut product intakes with risk for colorectal adenoma, possibly limited to women and other population subgroups.  The possible reasons for the estimated U-shaped association are unclear, and investigation in other populations/studies is needed.

Table of Contents

Chapter I: Background/Literature review-----------------------------------------------1

               Colorectal Cancer-------------------------------------------------------------1

               Nuts and Antioxidant/Anti-inflammatory Effects----------------------------2

               Nuts and Body Mass Index (BMI)--------------------------------------------4

               Nuts and Type 2 Diabetes----------------------------------------------------4

               Nuts and Colorectal Cancer--------------------------------------------------5


Chapter II: Manuscript-------------------------------------------------------------------13



                 Materials and Methods------------------------------------------------------16

                               Study Population-------------------------------------------------16

                               Dietary Assessment----------------------------------------------17

                               Statistical Analyses-----------------------------------------------18





Chapter III: Summary, Public Health Implications, Possible Future Directions----------37


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