Probiotic Food Supplement Effects on Cortisol and C-Reactive Protein in First Graders in Ivory Coast

• In Event: Poster Session 11
  In Poster Session: PS 11 Topic - Biological Processes: Psychophysiology

Abstract

Chronic stress and inflammation are widely recognized as risk factors for poor health. Higher levels of cortisol, the main effector hormone of the hypothalamic-pituitary-adrenal axis and a biological marker of stress, have been associated with cardiovascular risk, depression, and changes in hippocampal structure (Abell et al., 2016; Kuehl et al., 2015; Lupien et al., 1998). C-reactive protein (CRP), an acute-phase protein produced in the liver that supports the immune system, is a marker of systemic inflammation. Chronic inflammation is linked with slower wound healing, a lessened ability to fight infection, and a number of serious illnesses (e.g., Cunningham et al., 2009; Kaspersen et al., 2015; Kiecolt-Glaser et al., 2005).
Probiotics, or bacteria with known health benefits, may reduce stress responses and inflammation, though the literature is mixed. Some studies find probiotic ingestion linked with lower cortisol (e.g., Takada et al., 2016; Yoshihisa et al., 2015); others do not (e.g., Soldi et al., 2019). Studies using serum CRP find probiotic use associated with lower CRP in at risk populations (e.g., Lowe et al. 2020). However, one study using salivary CRP found no probiotic effects (Pay & Shaw, 2019). The current investigation is a semi-randomized controlled trial examining whether prolonged probiotic consumption is associated with salivary cortisol or CRP in first grade children in Ivory Coast.
Method: Participants were 270 3- to 8-year-old children recruited from two schools in a low-income area of Abidjan, Ivory Coast. After baseline data collection (not a part of this study), children from one school were randomly assigned to receive probiotic (n = 86) or placebo dêguê (n = 83) each day they were in school for 18 weeks (excepting 18 days due to holidays, etc.). The probiotic dêguê was fermented using Lactobacillus Rhamnosus GG and Streptococcus Thermophilus bacterium; placebo dêguê with Streptococcus Thermophilus only. Children at the other school (N = 101) followed their diets as usual.

Salivary cortisol and CRP were secondary outcomes and were collected at the end of the trial, along with each child’s height and weight. Children provided two saliva samples on consecutive days; values were averaged. Demographics were collected through a caregiver interview. Children’s height, weight, age, and gender were used to calculate zBMI scores. Probiotic effects on cortisol and log transformed CRP values were examined using complete case analysis with and without covariates (socioeconomic status and zBMI). In the probiotic and placebo groups, exploratory analyses examined potential effects of probiotic dose and regularity of consumption.

Results: Children in the probiotic group had lower cortisol at the end of the study than children in the other two groups, but CRP concentrations were comparable (Figure 1). Exploratory analyses revealed group but not dose effects on cortisol; placebo group membership predicted higher cortisol. A significant interaction between dose and group predicted CRP; placebo group children who consumed more dêguê had lower CRP (Figure 2). In analyses examining regularity of consumption, regular consumption and placebo group membership independently predicted higher cortisol.

Results are discussed in light of current literature on milk supplements and probiotics.

Authors

• Bonnie Erin Brett, Radboud Universiteit Nijmegen
  Presenting Author

• Carolina de Weerth, Radboud University Medical Center
  Non-Presenting Author