Date of Publication


Degree Type

Honors Thesis



First Advisor

Dr. Bernardo Ortega, Assistant Professor, Biology


Crohn’s disease, a pathological condition characterized by gastrointestinal (GI) inflammation and mucosal changes is often associated with hypomagnesemia resulting from changes in the GI mucosa and an increased GI transit rate. Furthermore, certain types of bacteria are also implicated in the formation of GI neoplasia and carcinogenesis. A variety of physiologic changes such as an increase in the systemic stress response, severity of the inflammatory response, or an exaggerated immune response is known to occur in Magnesium (Mg2+) deficient mice and rats. To understand to what extent Mg2+ deficiency could contribute to the aggravation of such diseases by inducing specific changes in the GI microbiome, this study will focus on the effect of a Mg2+ deficient diet on the GI flora of Black-6 mice. Mice were fed diets containing known concentrations of Mg2+ for 1 week before being placed in a metabolic cage for 24 hours. After 24 hours the mice were sacrificed, blood, feces, and urine samples were collected, and total food consumption, urine excretion and feces excretion was determined. Bacterial analysis of feces, collected via dissection of the colon, revealed that a decrease in the amount of dietary Mg2+ consumed is associated with an increase in the number of Lactic Acid Bacteria (LAB) and Bifidobacterium Colony-Forming Units (CFU) found per gram of feces. Based on the average amount of Mg2+ excreted in the feces and urine of the mice on each diet (Regular, 2% Mg oxide, 2% Mg citrate, 1% Mg citrate, 0.5% Mg citrate, or Mg free) it was also determined that the Mg2+ in the 2% Mg citrate diet is absorbed into systemic circulation more efficiently than the Mg2+ in the other diets tested. Further research is still required to determine if the changes in GI flora associated with a lower dietary Mg2+ consumption are due to systemic hypomagnesemia or due to decreased luminal availability of Mg2+ in the GI tract, but based on the results of this study, it can be concluded that decreased dietary Magnesium consumption has a notable effect on the flora of the GI tract.