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A Narrative Review of The Role of Foods as Dietary Sources of Vitamin D of Ethnic Minority Populations with Darker Skin: The Underestimated Challenge.
Guo, J, Lovegrove, JA, Givens, DI
Nutrients. 2019;11(1)
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Vitamin D is essential for healthy bones, and low vitamin D status is associated with an increased risk of chronic diseases such as cardiovascular disease and type 2 diabetes. Ethnic minority populations with darker skin are considered as a high-risk group for vitamin D deficiency, owing mainly to having less ability to synthesise vitamin D from sunlight due to the skin pigment melanin and/or reduced skin exposure due to clothing required by religious or cultural traditions. The aim of this literature review was to evaluate vitamin D intake and status of ethnic minority populations with darker skin. The authors examined previous observational studies and randomised controlled trials. Ethnic minority populations generally have a lower vitamin D status than white populations. Compared with Caucasians, there is evidence that Asians require approximately three times longer periods of sunlight exposure, and Africans six times the same exposure, to achieve the same blood levels of vitamin D. The main food sources for dietary vitamin D intake were different for ethnic minority populations and white populations. There is limited evidence on the impact of vitamin D supplementation on different ethnic groups. The authors concluded that food fortification could be explored to increase dietary vitamin D intake in ethnic minority populations who generally have lower levels of vitamin D.
Abstract
In recent years, vitamin D deficiency has attracted attention worldwide. Especially many ethnic minority populations are considered at high-risk of vitamin D deficiency, owing to a lesser ability to synthesis vitamin D from sunlight (ultraviolet B), due to the skin pigment melanin and/or reduced skin exposure due to coverage required by religious and cultural restrictions. Therefore, vitamin D intake from dietary sources has become increasingly important for many ethnic minority populations to achieve adequate vitamin D status compared with the majority of the population. The aim of the study was critically evaluate the vitamin D intake and vitamin D status of the ethnic minority populations with darker skin, and also vitamin D absorption from supplements and ultraviolet B. Pubmed, Embaase and Scopus were searched for articles published up to October 2018. The available evidence showed ethnic minority populations generally have a lower vitamin D status than the majority populations. The main contributory food sources for dietary vitamin D intake were different for ethnic minority populations and majority populations, due to vary dietary patterns. Future strategies to increase dietary vitamin D intake by food fortification or biofortification needs to be explored, not only for the majority population but more specifically for ethnic minority populations who are generally of lower vitamin D status.
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Alpha-Linolenic and Linoleic Fatty Acids in the Vegan Diet: Do They Require Dietary Reference Intake/Adequate Intake Special Consideration?
Burns-Whitmore, B, Froyen, E, Heskey, C, Parker, T, San Pablo, G
Nutrients. 2019;11(10)
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Fish and seafood are good sources of long-chain omega-3 fatty acids, like eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). A vegan diet does not include animal-sourced foods and is therefore void of EPA and DHA, unless algae-derived omega-3 supplements are consumed. Thus, vegans rely on the body's own production of long-chain fatty acids from plant-derived alpha-linolenic acid (ALA). However, adequate conversion can have several limitations. Vegan diets are generally rich in linoleic acid (LA), an omega-6 fatty acid, which in high levels can impede the conversion of ALA to EPA and DHA. Furthermore, the efficiency of conversion is influenced by gender, age or health conditions like obesity. This review sought to discuss whether vegans require special dietary recommendations for fatty acids and what these suggestions could be. Most studies assessing biological indicators of fatty acid status showed that vegans had lower levels of EPA and DHA compared to omnivores. Thus, the authors concluded that special consideration should be given to ALA and LA intake in vegan diets. In the absence of a set recommendation for a fatty acid ratio, a ratio of 4:1 (omega-6:omega-3) was proposed for vegans and omnivores. A reduction in LA and an increased intake of ALA of 2.2–4.4 g/day (or 1.1 g/day/1000 Kcals) was suggested to achieve such. This article is a useful guide when considering adequate fatty acid balance and omega-3 conversion for individuals following a vegan diet.
Abstract
Good sources of the long-chain n-3 fatty acids, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) include cold-water fish and seafood; however, vegan diets (VGNs) do not include animal-origin foods. Typically, US omnivores obtain enough dietary EPA and DHA, but unless VGNs consume algal n-3 supplements, they rely on endogenous production of long-chain fatty acids. VGN diets have several possible concerns: (1) VGNs have high intakes of linoleic acid (LA) as compared to omnivore/non-vegetarian diets. (2) High intakes of LA competitively interfere with the endogenous conversion of alpha-linolenic acid (ALA) to EPA and DHA. (3) High somatic levels of LA/low ALA indicate a decreased ALA conversion to EPA and DHA. (4) Some, not all VGNs meet the Dietary Reference Intake Adequate Intake (DRI-AI) for dietary ALA and (5) VGN diets are high in fiber, which possibly interferes with fat absorption. Consequently, health professionals and Registered Dietitians/Registered Dietitian Nutritionists working with VGNs need specific essential fatty acid diet guidelines. The purpose of this review was: (1) to suggest that VGNs have a DRI-AI Special Consideration requirement for ALA and LA based on VGN dietary and biochemical indicators of status and (2) to provide suggestions to ensure that VGNs receive adequate intakes of LA and ALA.
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Nutrition Interventions in Rheumatoid Arthritis: The Potential Use of Plant-Based Diets. A Review.
Alwarith, J, Kahleova, H, Rembert, E, Yonas, W, Dort, S, Calcagno, M, Burgess, N, Crosby, L, Barnard, ND
Frontiers in nutrition. 2019;6:141
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Rheumatoid arthritis (RA) is a chronic autoimmune disease characterised by joint pain and inflammation with both genetic and modifiable risk factors. Research suggests a plant-based diet may play a role in management and remission. The aim of this review was to summarize the associations between plant-based diet patterns and RA symptoms. Current studies indicate an association between improvements in RA symptoms with weight loss and with plant-based diets. Based on these findings, the authors conclude excess weight and diets that include animal products may exacerbate symptoms associated with RA, whereas plant-based diets may help reduce pain and inflammation in these patients. The authors suggest further research is needed to test the effectiveness of plant-based diets on patients with RA.
Abstract
Rheumatoid arthritis (RA), a chronic inflammatory autoimmune disease, affects roughly 1% of the world's population. RA pathogenesis remains unclear, but genetic factors account for 50-60% of the risk while the remainder might be linked to modifiable factors, such as infectious diseases, tobacco smoking, gut bacteria, and nutrition. Dietary triggers may play an inciting role in the autoimmune process, and a compromised intestinal barrier may allow food components or microorganisms to enter the blood stream, triggering inflammation. In addition, excessive body weight may affect pharmacotherapy response and the likelihood of disease remission, as well as the risk of disease mortality. Evidence suggests that changes in diet might play an important role in RA management and remission. Several studies have shown improvements in RA symptoms with diets excluding animal products. Studies have also shown that dietary fiber found in these plant-based foods can improve gut bacteria composition and increase bacterial diversity in RA patients, thus reducing their inflammation and joint pain. Although some of the trigger foods in RA patients are individualized, a vegan diet helps improve symptoms by eliminating many of these foods. This review examines the potential role of a plant-based diet in mediating RA symptoms. Further research is needed to test the effectiveness of plant-based diets on joint pain, inflammation, and quality of life in patients with RA.
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The Effects of Vegetarian and Vegan Diets on Gut Microbiota.
Tomova, A, Bukovsky, I, Rembert, E, Yonas, W, Alwarith, J, Barnard, ND, Kahleova, H
Frontiers in nutrition. 2019;6:47
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The difference in gut microbiota composition between individuals following vegan or vegetarian diets and those following omnivorous diets is well documented. A plant-based diet appears to be beneficial for human health by promoting the development of more diverse and stable microbial systems. This diversity appears to have an important association with BMI, obesity, and arterial compliance. This review highlights the effects of different diets, particularly plant-based diets, on the gut microbiota composition and production of microbial metabolites affecting the host health. The ratio between Bacteroidetes and Firmicutes is discussed and how different diets can change it. It explains how diet can affect the three main enterotypes: Prevotella, Bacteroides, and Ruminococcus. The food components proteins, carbohydrates, fats and polyphenols are discussed and how they influence gut microbiota. Up to date knowledge suggests that a plant-based diet may be an effective way to promote a diverse ecosystem of beneficial microbes that support overall health. However, due to the complexity and inter-individual differences, further research is required to fully characterize the interactions between diet, the microbiome, and health outcomes.
Abstract
The difference in gut microbiota composition between individuals following vegan or vegetarian diets and those following omnivorous diets is well documented. A plant-based diet appears to be beneficial for human health by promoting the development of more diverse and stable microbial systems. Additionally, vegans and vegetarians have significantly higher counts of certain Bacteroidetes-related operational taxonomic units compared to omnivores. Fibers (that is, non-digestible carbohydrates, found exclusively in plants) most consistently increase lactic acid bacteria, such as Ruminococcus, E. rectale, and Roseburia, and reduce Clostridium and Enterococcus species. Polyphenols, also abundant in plant foods, increase Bifidobacterium and Lactobacillus, which provide anti-pathogenic and anti-inflammatory effects and cardiovascular protection. High fiber intake also encourages the growth of species that ferment fiber into metabolites as short-chain fatty acids (SCFAs), including acetate, propionate, and butyrate. The positive health effects of SCFAs are myriad, including improved immunity against pathogens, blood-brain barrier integrity, provision of energy substrates, and regulation of critical functions of the intestine. In conclusion, the available literature suggests that a vegetarian/vegan diet is effective in promoting a diverse ecosystem of beneficial bacteria to support both human gut microbiome and overall health. This review will focus on effects of different diets and nutrient contents, particularly plant-based diets, on the gut microbiota composition and production of microbial metabolites affecting the host health.
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Gut feeling: randomized controlled trials of probiotics for the treatment of clinical depression: Systematic review and meta-analysis.
Nikolova, V, Zaidi, SY, Young, AH, Cleare, AJ, Stone, JM
Therapeutic advances in psychopharmacology. 2019;9:2045125319859963
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Major depression is a common and complex illness that significantly diminishes quality of life. Currently, most pharmacological treatments target neurotransmitter activity in the brain and are known to have a delayed onset of effect as well as a range of side-effects. The aim of this study was to identify and synthesize all published data from randomized controlled trials (RCTs) on the efficacy of probiotics as treatment for depression in clinically depressed patients. This study is a systematic review of three studies. Within the three included RCTs, a total of 229 clinically depressed patients were randomized, with an average age of 36 years and a gender distribution of 76% female. Results indicate a non-significant difference in depressive symptoms between the probiotic and placebo groups post-intervention. Authors conclude that further larger studies in well-defined clinical populations are needed, both to determine the clinical utility of this novel treatment approach, and to investigate potential underlying mechanisms.
Abstract
BACKGROUND Recently the gut microbiota has attracted significant interest in psychiatric research due to the observed bidirectional gut-brain communication. A growing body of evidence from preclinical work has suggested that probiotics may be effective in reducing stress and anxiety and alleviating low mood. It is unclear to what extent these effects are seen in clinical populations. We aimed to identify all published evidence on the efficacy of probiotics as treatment for depression in clinically depressed populations. METHODS Randomized controlled trials of patients with depression where probiotics were used as supplementary or standalone treatment were considered eligible. A literature search with the terms (probiotic* OR bacteria OR Lactobacillus OR Bifidobacterium) AND depress* was performed in PubMed and Web of Science. Data on study population characteristics, treatment effectiveness, tolerability and risk of bias were extracted from eligible studies. A random effects model was used for meta-analyses. RESULTS Only three studies met inclusion criteria (229 individuals randomized), two of which administered probiotics as a supplementary treatment to antidepressants and one as a standalone treatment. Upon removal of the latter study from the meta-analysis due to clinical heterogeneity, there was an overall positive effect of probiotics on depressive symptoms (standardized mean difference = 1.371, 95% confidence interval 0.130-2.613). CONCLUSIONS There is limited evidence for the efficacy of probiotics in depression at present, although there may be a beneficial effect of probiotics on depressive symptoms when administered in addition to antidepressants. Further studies are required to investigate this and explore potential mechanisms.
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Inflammaging and Oxidative Stress in Human Diseases: From Molecular Mechanisms to Novel Treatments.
Zuo, L, Prather, ER, Stetskiv, M, Garrison, DE, Meade, JR, Peace, TI, Zhou, T
International journal of molecular sciences. 2019;20(18)
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Reactive oxygen species (ROS) are produced during normal metabolic processes or can be induced by environmental factors. High levels of ROS in the cell can lead to oxidation causing cellular damage and a subsequent increase in inflammation, which is a significant contributor to disease. Age-associated increases in such chronic, low-grade inflammation is also referred to as inflammaging. This review summarizes how inflammaging plays a role in various age-related health conditions. Described are the mechanisms of how ROS and the age-related decline in cellular turn-over and immune activation contribute to the pathology of cardiovascular disease, cancer, neurodegeneration concerning Alzheimer’s and Parkinson’s disease, diabetes and rheumatoid arthritis. Furthermore, the authors discuss potential treatments that could assist in the management of such inflammaging-related diseases. These include vaccines to stimulate immune activity, stem cell intervention, drugs like metformin, nutritional and nutraceutical supplements like zinc, vitamin E, vitamins C, D, carotenoids, polyphenols and flavonoids like resveratrol, red algae extract and melatonin. Addressed are also general dietary concepts like calorie restriction, the benefits of the Mediterranean diet or a whole foods diet, and the potential of specific plant derived compounds like baicalin and sulforaphanes. The authors also briefly highlight the importance of the gut microbiome, as a poor gut microbiota has been associated with unfavourable age-related immune alterations and overall inflammaging. This review provides a comprehensive resource, detailing the effects and mechanisms of oxidative damage and its contribution to age-related diseases, including a list of interventions to consider when navigating the impact and risks associated with inflammaging.
Abstract
It has been proposed that a chronic state of inflammation correlated with aging known as inflammaging, is implicated in multiple disease states commonly observed in the elderly population. Inflammaging is associated with over-abundance of reactive oxygen species in the cell, which can lead to oxidation and damage of cellular components, increased inflammation, and activation of cell death pathways. This review focuses on inflammaging and its contribution to various age-related diseases such as cardiovascular disease, cancer, neurodegenerative diseases, chronic obstructive pulmonary disease, diabetes, and rheumatoid arthritis. Recently published mechanistic details of the roles of reactive oxygen species in inflammaging and various diseases will also be discussed. Advancements in potential treatments to ameliorate inflammaging, oxidative stress, and consequently, reduce the morbidity of multiple disease states will be explored.
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Tryptophan Metabolism in Inflammaging: From Biomarker to Therapeutic Target.
Sorgdrager, FJH, Naudé, PJW, Kema, IP, Nollen, EA, Deyn, PP
Frontiers in immunology. 2019;10:2565
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Inflammation is a normal physiological process activated by the immune system in response to injury or infection. As we age, the immune system changes and the balance between pro- and anti-inflammatory agents can shift. This causes a chronic inflammatory state referred to as inflammaging. The rate of inflammaging is strongly associated with age-related disability, disease and mortality. The way in which the essential amino acid tryptophan (Trp) is broken down affects inflammation. If it is converted to kynurenine (Kyn) and its metabolites, inflammation is modulated. Studies have shown that the Kyn/Trp ratio, measured in blood, is strongly associated with ageing in humans. It could therefore be a useful marker to predict the onset of age-related diseases. This review discusses the metabolism of Trp and the links to inflammation. The authors hypothesize how intervening in these pathways could impact health- and lifespan. Future studies are needed to confirm the value of Trp metabolism as a biomarker for (un)healthy ageing and as drug target for inflammaging-related disease.
Abstract
Inflammation aims to restore tissue homeostasis after injury or infection. Age-related decline of tissue homeostasis causes a physiological low-grade chronic inflammatory phenotype known as inflammaging that is involved in many age-related diseases. Activation of tryptophan (Trp) metabolism along the kynurenine (Kyn) pathway prevents hyperinflammation and induces long-term immune tolerance. Systemic Trp and Kyn levels change upon aging and in age-related diseases. Moreover, modulation of Trp metabolism can either aggravate or prevent inflammaging-related diseases. In this review, we discuss how age-related Kyn/Trp activation is necessary to control inflammaging and alters the functioning of other metabolic faiths of Trp including Kyn metabolites, microbiota-derived indoles and nicotinamide adenine dinucleotide (NAD+). We explore the potential of the Kyn/Trp ratio as a biomarker of inflammaging and discuss how intervening in Trp metabolism might extend health- and lifespan.
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Meta-inflammaging at the crossroad of geroscience.
Chen, G, Yung, R
Aging medicine (Milton (N.S.W)). 2019;2(3):157-161
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The concept of “geroscience” represents a perspective in the understanding of the molecular underpinning of aging. Currently, seven biological processes are regarded as the underpinning of the aging process. This study is a review which focused on the link between chronic low‐grade sterile inflammation prevalent in old age and obesity‐associated metabolic inflammation. Old age, particularly in elderly adults with poor physical function or frailty, is linked to a state of chronic low‐grade sterile inflammation (inflammaging) with elevated pro‐inflammatory cytokines [a general term for the immunoregulatory cytokines that favour inflammation]. Another potential source of pro‐inflammatory cytokines in aging is adipose, or fat tissue, which can be the largest organ in obese individuals. Obesity has been linked to a low‐grade sterile chronic inflammatory state, with similarities to inflammaging, and is termed “metainflammation”. Adiposity has emerged as a major source of inflammation in both diet‐ and aging‐associated obesity, which in turn is linked to most common diseases in old age.
Abstract
Geroscience posits that selected fundamental biological processes are the foundation of age-related chronic diseases and are responsible for the decline in physical and mental function in old age. Late-life chronic low-grade inflammation ("inflammaging") and altered signal transduction pathways in metabolism have been identified as two of the key themes in the aging process. Age-related changes in the immune and metabolic responses are also recognized as playing a critical pathogenic role in most common chronic medical conditions that plague the elderly. Emerging investigations emphasize the interconnectedness of the immune and metabolic responses in aging, an area of gerontological research that can be termed "meta-inflammaging."
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A Scientific Perspective of Personalised Gene-Based Dietary Recommendations for Weight Management.
Drabsch, T, Holzapfel, C
Nutrients. 2019;11(3)
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Basic recommendations of eat less, move more can have varying levels of success in weight loss depending on the individual. As a result, the focus has begun to shift to personalised nutrition based on genetics, however evidence is lacking. This review paper aimed to evaluate what evidence was available. The authors stated that the literature has no set definition for personalised nutrition but did state that it should consider social, lifestyle, genetic and metabolic factors and the microbiome. 500 genes have been recognised as associated with body morphology and although the function of most of them is still unclear, the fat mass and obesity associated (FTO) gene has the strongest effect on body weight. Individuals can carry different versions of the FTO gene, and the research has been conflicting on whether weight loss is greater depending on which version an individual carries. The regulation of food intake and the amount of fat and protein consumed may also be affected by the FTO version. The use of dietary recommendations based on genetic tests that can be bought by the general public was also reviewed and it was concluded that this science is still in its infancy. The authors concluded that personalised nutrition based on genetics is complex and further studies are warranted.
Abstract
Various studies showed that a "one size fits all" dietary recommendation for weight management is questionable. For this reason, the focus increasingly falls on personalised nutrition. Although there is no precise and uniform definition of personalised nutrition, the inclusion of genetic variants for personalised dietary recommendations is more and more favoured, whereas scientific evidence for gene-based dietary recommendations is rather limited. The purpose of this article is to provide a science-based viewpoint on gene-based personalised nutrition and weight management. Most of the studies showed no clinical evidence for gene-based personalised nutrition. The Food4Me study, e.g., investigated four different groups of personalised dietary recommendations based on dietary guidelines, and physiological, clinical, or genetic parameters, and resulted in no difference in weight loss between the levels of personalisation. Furthermore, genetic direct-to-consumer (DTC) tests are widely spread by companies. Scientific organisations clearly point out that, to date, genetic DTC tests are without scientific evidence. To date, gene-based personalised nutrition is not yet applicable for the treatment of obesity. Nevertheless, personalised dietary recommendations on the genetic landscape of a person are an innovative and promising approach for the prevention and treatment of obesity. In the future, human intervention studies are necessary to prove the clinical evidence of gene-based dietary recommendations.
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Fermented Foods: Definitions and Characteristics, Impact on the Gut Microbiota and Effects on Gastrointestinal Health and Disease.
Dimidi, E, Cox, SR, Rossi, M, Whelan, K
Nutrients. 2019;11(8)
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Fermented foods have grown in popularity due to their proposed health benefits but there is limited clinical evidence for the effectiveness of most fermented foods in gastrointestinal health. This review paper looks at non-dairy fermented foods which have been studied in at least one RCT: kefir, sauerkraut, natto, and sourdough bread. The health benefits are attributed to the high ratio of probiotic microorganisms, metabolites, or ability to convert compounds into active metabolites, as well as prebiotics and vitamins contained in these foods. Kimchi has the greatest evidence from epidemiological and case control studies investigating risk of gastric cancers. Different food composition of kimchi is shown to both increase and decrease risks, whilst it had no impact on H. pylori levels. There were no studies on kefir in functional bowel disorders however, it was shown to help lactose malabsorption and reduce H. pylori levels. A small RCT on Sauerkraut showed it reduced IBS severity in patients and increased in vitro activity of key liver and kidney detoxifying enzymes. There are small pockets of data that show that tempeh may influence gut microbiota in humans, and that natto may increase bifidobacterial and short-chain fatty acids in healthy volunteers. There are numerous limited cohort studies on miso and cancer risk but no studies on gastrointestinal conditions. Finally, sourdough was shown to reduce FODMAPS and be better tolerated in IBS patients, reducing bloating, nausea and discomfort. Overall, all the studies provide insufficient evidence on fermented foods and gastrointestinal health.
Abstract
Fermented foods are defined as foods or beverages produced through controlled microbial growth, and the conversion of food components through enzymatic action. In recent years, fermented foods have undergone a surge in popularity, mainly due to their proposed health benefits. The aim of this review is to define and characterise common fermented foods (kefir, kombucha, sauerkraut, tempeh, natto, miso, kimchi, sourdough bread), their mechanisms of action (including impact on the microbiota), and the evidence for effects on gastrointestinal health and disease in humans. Putative mechanisms for the impact of fermented foods on health include the potential probiotic effect of their constituent microorganisms, the fermentation-derived production of bioactive peptides, biogenic amines, and conversion of phenolic compounds to biologically active compounds, as well as the reduction of anti-nutrients. Fermented foods that have been tested in at least one randomised controlled trial (RCT) for their gastrointestinal effects were kefir, sauerkraut, natto, and sourdough bread. Despite extensive in vitro studies, there are no RCTs investigating the impact of kombucha, miso, kimchi or tempeh in gastrointestinal health. The most widely investigated fermented food is kefir, with evidence from at least one RCT suggesting beneficial effects in both lactose malabsorption and Helicobacter pylori eradication. In summary, there is very limited clinical evidence for the effectiveness of most fermented foods in gastrointestinal health and disease. Given the convincing in vitro findings, clinical high-quality trials investigating the health benefits of fermented foods are warranted.