In what the researchers call a first-of-its-kind study, supplementation with cycles of six daily probiotics, most of which were various strains of Lactobacillus, were associated with improvements in nausea and vomiting in a population of pregnant women.
 
In total, 32 pregnant women were enrolled in the study, and were assessed both while taking probiotic supplements and without the probiotics, in a cycle which lasted 16 days. Each capsule contained inulin and 10 probiotics including L. plantarum 299v, L. bulgaricus Lb-87, L. paracasei DSM 13434, L. plantarum DSM 15312, L. salivarius Ls-33, L. brevis Lbr-35, L. acidophilus La-14, B. lactis Bl-04, L. paracasei Lpc-37, and L. casei Lc-11. The participants would take a probiotic capsule twice daily for six days, and then took two days off before repeating the cycle once more.
 
Nausea and vomiting affect about 85% of pregnancies, and can significantly impact quality of life, with these symptoms mostly taking place during early pregnancy. “The cause of nausea and vomiting during pregnancy is unknown to this date. Various theories have been proposed, but none of them are conclusive,” Albert T. Liu, lead author of the study and professor of obstetrics and gynecology at UC Davis School of Medicine, said. “Nausea, vomiting, and constipation during pregnancy can significantly diminish the quality of patients’ lives. Once nausea and vomiting during pregnancy progress, they can become difficult to control, and sometimes the patient even needs to be hospitalized.”
 
The researchers theorized that probiotic supplementation may be beneficial to digestive system changes, as these may occur during pregnancy due to changes in hormones such as estrogen and progesterone.
 
The participants kept 17 daily observations of their symptoms during the duration of the study, for a total of 535 observations which were statistically assessed. The number of hours in which participants felt nauseous was reduced by 16% and the number of times they vomited was reduced by 33%. Probiotic intake also improved self-reported levels of fatigue, poor appetite, and difficulty maintaining social activities, the researchers noted.
 
During the study, participants also contributed fecal specimens, and researchers were able to study the type and number of microbes and the different byproducts of digestion. They were able to correlate certain biomarkers with more severe nausea – namely, lower amounts of bacteria that carry bile salt hydrolase were associated with more vomiting, while probiotics are known to increase bile salt hydrolase-producing bacteria.
 
The gut microbes Akkermansia and A. muciniphila were also associated with more vomiting, and probiotic supplementation reduced these species while reducing vomiting in tandem, leading researchers to believe there could be a link between these species and vomiting in pregnancy.
 
Lastly, vitamin E levels increased after taking probiotics in the study population, and higher levels of this vitamin were associated with low vomiting scores throughout. While the findings are intriguing, the authors of the study cautioned that due to the small sample size more trials are necessary to further substantiate the results seen here.
 
“This research provides key insights about the impact of gut microbes on gastrointestinal function during pregnancy. Our gut microbiota explains why we are what we eat, and why bacteria-generated metabolites and products have a huge impact on our health,” Yu Jui Yvonne Wan, co-author of the study, noted. “The current study might be one of the first to show the benefits of probiotics in pregnancy. It would be interesting and important to further test whether probiotics can reduce nausea and vomiting caused by chemotherapy in cancer patients.”