The Effect of Probiotics on Health Outcomes in the Elderly: A Systematic Review of Randomized, Placebo-Controlled Studies

Abstract

Increasing evidence suggests that probiotic supplementation may be efficacious in counteracting age-related shifts in gut microbiota composition and diversity, thereby impacting health outcomes and promoting healthy aging. However, randomized controlled trials (RCTs) with probiotics in healthy older adults have utilized a wide variety of strains and focused on several different outcomes with conflicting results. Therefore, a systematic review was conducted to determine which outcomes have been investigated in randomized controlled trials with probiotic supplementation in healthy older adults and what has been the effect of these interventions. For inclusion, studies reporting on randomized controlled trials with probiotic and synbiotic supplements in healthy older adults (defined as minimum age of 60 years) were considered. Studies reporting clinical trials in specific patient groups or unhealthy participants were excluded. In addition to assessment of eligibility and data extraction, each study was examined for risk of bias and quality assessment was performed by two independent reviewers. Due to the heterogeneity of outcomes, strains, study design, duration, and methodology, we did not perform any meta-analyses and instead provided a narrative overview of the outcomes examined. Of 1997 potentially eligible publications, 17 studies were included in this review. The risk of bias was low, although several studies failed to adequately describe random sequence generation, allocation concealment, and blinding. The overall study quality was high; however, many studies did not include sample calculations, and the majority of studies had a small sample size. The main outcomes examined in the trials included microbiota composition, immune-related measurements, digestive health, general well-being, cognitive function, and lipid and other biomarkers. The most commonly assessed outcome with the most consistent effect was microbiota composition; all but one study with this outcome showed significant effects on gut microbiota composition in healthy older adults. Overall, probiotic supplementation had modest effects on markers of humoral immunity, immune cell population levels and activity, as well as the incidence and duration of the common cold and other infections with some conflicting results. Digestive health, general-well-being, cognitive function, and lipid and other biomarkers were investigated in a very small number of studies; therefore, the impact on these outcomes remains inconclusive. Probiotics appear to be efficacious in modifying gut microbiota composition in healthy older adults and have moderate effects on immune function. However, the effect of probiotic supplementation on other health outcomes remains inconclusive, highlighting the need for more well-designed, sufficiently-powered studies to investigate if and the mechanisms by which probiotics impact healthy aging.

Potential Modulation of Inflammation by Probiotic and Omega-3 Supplementation in Elderly with Chronic Low-Grade Inflammation—A Randomized, Placebo-Controlled Trial

“…Here, we present the first study to investigate the dual effects of a multi-strain probiotic and omega-3 PUFA supplements on low-grade inflammation in elderly participants. As the Lactobacilli and Bifidobacteria strains in the multi-strain probiotic [ 12 , 13 , 14 , 15 ] and n -3 PUFA supplements [ 16 , 24 ] have been shown to reduce inflammation, we hypothesized that the synergy of these supplements may provide additive health benefits. The study did not find any significant treatment effects, although a trend of lower values of hs-CRP, a well-characterized marker of inflammation, was seen in the active treatment group compared to placebo at 8 w. These findings are consistent with another study that could not observe a positive effect of a multi-strain probiotic (containing B. longum Bar33 and L. helveticus Bar 13) on hs-CRP levels in elderly participants [ 42 ].…”

“…Furthermore, the efficacy of probiotics to reduce inflammation may have potential use in treating Alzheimer’s disease (AD) and cognitive impairment [ 14 ]. Although the majority of these studies included small numbers of participants, the findings suggest that probiotic supplementation may be efficacious in reducing inflammation and improving immune function in elderly [ 15 ].…”

Effects of physical distancing by COVID-19 pandemic on diet quality, neurological and immunological markers, and fecal microbiota of Brazilian older women

“…Some studies associated decrease in Lactobacillus spp. with frailty in older people and its role as probiotic enhancing anti-inflammatory functions ( 114 , 115 ). In fact, these correlations between serum markers and the Lactobacillaceae family observed after 6 months of physical distancing could evidence the microbiota role on damage-control mechanisms.…”

The Potential Roles of Probiotics, Resistant Starch, and Resistant Proteins in Ameliorating Inflammation during Aging (Inflammaging)

“…In addition to bacteria that may attenuate inflammation, bacteria that produce SFCAs also contribute to healthy aging. Several recent reports revealed that the supplementation of some strains in the diet ameliorated age-related loss of mucin and demonstrated health and immune benefits in elderly and aged animals [28,79,80]. In addition to probiotic supplementation, fecal microbiota transplantation also effectively extends the lifespan of progeroid mice [81].…”