Constipation is a common condition that occurs in many people worldwide. While
magnesium oxide (MgO) is often used as the first-line drug for chronic
constipation in Japan,
dietary fiber intake is also recommended.
Dietary fiber is fermented by microbiota to produce
short-chain fatty acids (SCFAs). SCFAs are involved in regulating systemic physiological functions and circadian rhythm. We examined the effect of combining MgO and the water-soluble
dietary fiber,
inulin, on cecal SCFA concentration and microbiota in mice. We also examined the MgO administration timing effect on cecal SCFAs. The cecal SCFA concentrations were measured by gas chromatography, and the microbiota was determined using next-generation sequencing.
Inulin intake decreased cecal pH and increased cecal SCFA concentrations while combining MgO increased the cecal pH lowered by
inulin and decreased the cecal SCFA concentrations elevated by
inulin. When
inulin and MgO were combined, significant changes in the microbiota composition were observed compared with
inulin alone. The MgO effect on the cecal
acetic acid concentration was less when administered at ZT12 than at ZT0. In conclusion, this study suggests that MgO affects cecal SCFA and microbiota during
inulin feeding, and the effect on
acetic acid concentration is time-dependent.