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Probiotic Supplementation Improves Cognitive Function and Mood with Changes in Gut Microbiota in Community-Dwelling Older Adults: A Randomized, Double-Blind, Placebo-Controlled, Multicenter Trial.
Kim, CS, Cha, L, Sim, M, Jung, S, Chun, WY, Baik, HW, Shin, DM
The journals of gerontology. Series A, Biological sciences and medical sciences. 2021;76(1):32-40
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Plain language summary
Aging is characterized by progressive decline in biological functions of the organism. Diet is one of the critical lifestyle factors for physical and mental well-being throughout the life span, including later life. The aim of this study was to investigate the effects of probiotics consumption on intestinal and brain health in elders over the age of 65. This study is a randomised, double-blind, placebo-controlled, multicentre trial. All participants, study coordinators, and researchers were blinded throughout the entire study. Sixty-three participants were randomized, with 31 and 32 subjects in the placebo and probiotics group, respectively. Results demonstrate that probiotics have system-wide effects on the gut–brain axis in healthy community-dwelling older adults by promoting cognitive and mental health and changing the gut microbial composition. Authors conclude that their findings provide evidence that probiotics have health-promoting properties as part of a healthy diet in the general population of independently living older adults.
Abstract
Probiotics have been proposed to ameliorate cognitive impairment and depressive disorder via the gut-brain axis in patients and experimental animal models. However, the beneficial role of probiotics in brain functions of healthy older adults remains unclear. Therefore, a randomized, double-blind, and placebo-controlled multicenter trial was conducted to determine the effects of probiotics on cognition and mood in community-dwelling older adults. Sixty-three healthy elders (≥65 years) consumed either placebo or probiotics containing Bifidobacterium bifidum BGN4 and Bifidobacterium longum BORI for 12 weeks. The gut microbiota was analyzed using 16S rRNA sequencing and bioinformatics. Brain functions were measured using the Consortium to Establish a Registry for Alzheimer's disease, Satisfaction with life scale, stress questionnaire, Geriatric depression scale, and Positive affect and negative affect schedule. Blood brain-derived neurotrophic factor (BDNF) was determined using enzyme-linked immunosorbent assay. Relative abundance of inflammation-causing gut bacteria was significantly reduced at Week 12 in the probiotics group (p < .05). The probiotics group showed greater improvement in mental flexibility test and stress score than the placebo group (p < .05). Contrary to placebo, probiotics significantly increased serum BDNF level (p < .05). Notably, the gut microbes significantly shifted by probiotics (Eubacterium and Clostridiales) showed significant negative correlation with serum BDNF level only in the probiotics group (RS = -0.37, RS = -0.39, p < .05). In conclusion, probiotics promote mental flexibility and alleviate stress in healthy older adults, along with causing changes in gut microbiota. These results provide evidence supporting health-promoting properties of probiotics as a part of healthy diet in the older adults.
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Effects of oral ingestion of sucralose on gut hormone response and appetite in healthy normal-weight subjects.
Ford, HE, Peters, V, Martin, NM, Sleeth, ML, Ghatei, MA, Frost, GS, Bloom, SR
European journal of clinical nutrition. 2011;65(4):508-13
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Plain language summary
There have been significant advances in the understanding of how hormonal signals released from the gastrointestinal (GI) tract interact with circuits within the central nervous system to control appetite and energy intake. The aim of this study is to investigate whether oral ingestion of sucralose, at a dose that would be consumed in a normal diet, increases circulating gut hormones (glucagon-like peptide [GLP-1] or peptide YY [PYY] concentrations in man. This study is a randomised, single-blinded, crossover design study. Subjects were randomly assigned to receive one of four solutions on four separate study sessions. Eight normal-weight, healthy volunteers were recruited, all of which were non-smokers, aged 22–27 years (seven females and one male) with a stable body weight. Results indicate that oral ingestion of the artificial sweetener sucralose does not increase plasma GLP-1 or PYY concentrations nor does it affect subjective feelings of appetite or energy intake at the next meal in healthy volunteers. Based on their findings, authors conclude that a dietary dose of sucralose does not stimulate the sweet-taste receptor in the GI tract to release GLP-1 and PYY.
Abstract
BACKGROUND/OBJECTIVE The sweet-taste receptor (T1r2+T1r3) is expressed by enteroendocrine L-cells throughout the gastrointestinal tract. Application of sucralose (a non-calorific, non-metabolisable sweetener) to L-cells in vitro stimulates glucagon-like peptide (GLP)-1 secretion, an effect that is inhibited with co-administration of a T1r2+T1r3 inhibitor. We conducted a randomised, single-blinded, crossover study in eight healthy subjects to investigate whether oral ingestion of sucralose could stimulate L-cell-derived GLP-1 and peptide YY (PYY) release in vivo. METHODS Fasted subjects were studied on 4 study days in random order. Subjects consumed 50 ml of either water, sucralose (0.083% w/v), a non-sweet, glucose-polymer matched for sweetness with sucralose addition (50% w/v maltodextrin+0.083% sucralose) or a modified sham-feeding protocol (MSF=oral stimulation) of sucralose (0.083% w/v). Appetite ratings and plasma GLP-1, PYY, insulin and glucose were measured at regular time points for 120 min. At 120 min, energy intake at a buffet meal was measured. RESULTS Sucralose ingestion did not increase plasma GLP-1 or PYY. MSF of sucralose did not elicit a cephalic phase response for insulin or GLP-1. Maltodextrin ingestion significantly increased insulin and glucose compared with water (P<0.001). Appetite ratings and energy intake were similar for all groups. CONCLUSIONS At this dose, oral ingestion of sucralose does not increase plasma GLP-1 or PYY concentrations and hence, does not reduce appetite in healthy subjects. Oral stimulation with sucralose had no effect on GLP-1, insulin or appetite.