The effects of dairy and dairy-derived products on the human gut microbiota remains understudied. A systematic literature search was conducted using Medline, CINAHL, Embase, Scopus, and PubMed databases with the aim of collating evidence on the intakes of all types of dairy and their effects on the gut microbiota in adults. Risk of bias was assessed using the Cochrane risk-of-bias tool. The search resulted in 6,592 studies, of which eight randomized controlled trials (RCTs) met predetermined eligibility criteria for inclusion, consisting of a total of 468 participants. Seven studies assessed the effect of type of dairy (milk, yogurt, and kefir) and dairy derivatives (whey and casein) on the gut microbiota, and one study assessed the effect of the quantity of dairy (high dairy vs low dairy). Three studies showed that dairy types consumed (milk, yogurt, and kefir) increased the abundance of beneficial genera Lactobacillus and Bifidobacterium. One study showed that yogurt reduced the abundance of Bacteroides fragilis, a pathogenic strain. Whey and casein isolates and the quantity of dairy consumed did not prompt changes to the gut microbiota composition. All but one study reported no changes to bacterial diversity in response to dairy interventions and one study reported reduction in bacterial diversity in response to milk intake.In conclusion, the results of this review suggest that dairy products such as milk, yogurt, and kefir may modulate the gut microbiota composition in favor to the host. However, the broader health implications of these findings remain unclear and warrant further studies.

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Selective serotonin reuptake inhibitors (SSRIs) have been shown to have a clinically significant impact on bone metabolism. To explore this further, we aimed to determine whether these agents are associated with serum markers of bone turnover utilising a population-based sample of men (n = 1138; 20-96 year) participating in the Geelong Osteoporosis Study. Blood samples were obtained and the bone resorption marker, C-telopeptide (CTx) and formation marker, type 1 procollagen amino-terminal-propeptide (PINP) were measured. Anthropometry and socio-economic status (SES) were determined and information on medication use and lifestyle was obtained via questionnaire. Lifetime mood disorders were assessed using semi-structured clinical interviews. Thirty-seven (3.3%) men reported using SSRIs. Age was an effect modifier in the association between SSRIs and markers of bone turnover. Among younger men (20-60 year; n = 557), adjusted mean CTx and PINP values were 12.4% [16.7 (95% CI 14.6-18.8) vs 19.1 (95% CI 18.7-19.4) pg/ml, p = 0.03] and 13.6% [5.6 (95% CI 4.9-6.3) vs 6.4 (95% CI 6.3-6.6) pg/ml, p = 0.02] lower among SSRI users compared to non-users, respectively. No differences in SSRI use and markers of bone turnover were detected among older men (61-94 year; all p > 0.05). These patterns persisted after further adjustment for activity, alcohol, smoking, SES, depression, bone active medications and other antidepressants. Our data suggest that SSRI use is associated with alterations in bone turnover markers among younger men. The observed decreases in both CTx and PINP are likely to contribute to a low bone turnover state and increased skeletal fragility with this potential imbalance between formation and resorption resulting in subsequent bone loss.

IntroductionBipolar spectrum disorder is a chronic, episodic illness, associated with significant personal, social and economic burden. It is estimated to affect ∼2.4% of the population worldwide and is commonly associated with psychological and/or physiological comorbidities. Osteoporosis is one such comorbidity, a disease of bone that is asymptomatic until a fracture occurs. This systematic review attempts to capture, collate, assess and discuss the literature investigating the association between bipolar spectrum disorder and bone health.Methods and analysisWe aim to identify articles that investigate the association between bipolar spectrum disorder and bone health in adults by systematically searching the MEDLINE, PubMed, OVID and CINAHL databases. Two independent reviewers will determine eligibility of studies according to predetermined criteria, and methodological quality will be assessed using a previously published scoring system. A meta-analysis will be conducted, and statistical methods will be used to identify and control for heterogeneity, if possible. If numerical syntheses are prevented due to statistical heterogeneity, a best evidence synthesis will be conducted to assess the level of evidence for associations between bipolar spectrum disorder and bone health.Ethics and disseminationEthical permission will not be required for this systematic review since only published data will be used. This protocol will be registered with PROSPERO. Findings of the review will be published in a peer-reviewed scientific journal, and will be presented to clinical and population health audiences at national and international conferences.