Term of Award

Fall 2021

Degree Name

Doctor of Public Health in Epidemiology (Dr.P.H.)

Document Type and Release Option

Dissertation (restricted to Georgia Southern)

Copyright Statement / License for Reuse

Creative Commons License
This work is licensed under a Creative Commons Attribution 4.0 License.


Department of Biostatistics, Epidemiology, and Environmental Health Sciences

Committee Chair

Jian Zhang

Committee Member 1

Marian Tabi

Committee Member 2

JingJing Yin

Committee Member 3

Logan Cowan

Committee Member 3 Email


Non-Voting Committee Member

Logan Cowan


The mandatory food fortification with folic acid, a synthetic form of folate (vitamin B9), has led to a marked reduction in neural tube defects in the United States. However, this public health success may have unintended consequences for the general population due to folate overconsumption. Folate is central to carbon metabolism and is needed for DNA synthesis and DNA methylation, providing plausible biological mechanisms through which folate could modulate cancer risk. The optimized folate amount remains to be illustrated. To assess the relationship between folate and risk of colorectal cancer, the second cancer killer in the United States, we analyzed 14,528 adults aged 19 or older who participated in the 3rd National Health and Nutrition Examination Survey (1988-1994, before folic acid fortification) as the baseline examination. After 18 years of following up, we found that the risk of dying from colorectal cancer in adults with upper quarter folate intake was 1/10th (or 90% lower) of that in adults with lower quarter intake. More efforts are needed to delicately control other vitamins with cohorts exclusively recruited after the initiation of mandatory fortification.

Research Data and Supplementary Material


Available for download on Monday, January 04, 2027