1.
Yogurt, cultured fermented milk, and health: a systematic review.
Savaiano, DA, Hutkins, RW
Nutrition reviews. 2021;79(5):599-614
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Many fermented foods are associated with health benefits, including fermented dairy products. Whereby diary itself is part of many nutritional guidelines, the guidances rarely distinguish between dairy and fermented dairy. This qualitative, systematic review sought to capture how consumption of fermented milk products influences health. The review included 108 studies, with over 70% reporting beneficial health outcomes. A small number of studies reported insignificant or neutral results and four unfavourable ones. The aspects of health that were considered included lactose digestion and tolerance, gut health and disease, diarrhoea and constipation, irritable bowel syndrome, cardiovascular health and disease, hypertension, blood lipids, cancer risk, colorectal/breast/prostate cancer, weight and body composition, diabetes risk and metabolic syndrome and bone health. The authors concluded that eating fermented dairy products aided lactose digestion and showed a consistent link with reduced risk of breast and colorectal cancer, type 2 diabetes, and improved weight maintenance, cardiovascular, bone, and gastrointestinal health. As dairy appears to increase the risk for prostate cancer, fermented dairy seems to be no different here to unfermented dairy at increasing the risk. Some potential mechanisms are proposed in the discussion section, how fermented dairy may elicit its health benefits. Given the predominant health benefits of fermented dairy, the authors encouraged to include fermented dairy into national nutrition guidelines and stress distinction between dairy and fermented dairy products. This review captures current evidence of the widespread health benefits of fermented dairy consumption worthwhile considering in clinical practice. In the absence of more clear findings in relation to prostate cancer and prevention, a cautious approach to dairy and fermented dairy consumption may be warranted.
Abstract
Consumption of yogurt and other fermented products is associated with improved health outcomes. Although dairy consumption is included in most dietary guidelines, there have been few specific recommendations for yogurt and cultured dairy products. A qualitative systematic review was conducted to determine the effect of consumption of fermented milk products on gastrointestinal and cardiovascular health, cancer risk, weight management, diabetes and metabolic health, and bone density using PRISMA guidelines. English language papers in PubMed were searched, with no date restrictions. In total, 1057 abstracts were screened, of which 602 were excluded owing to lack of appropriate controls, potential biases, and experimental design issues. The remaining 455 papers were independently reviewed by both authors and 108 studies were included in the final review. The authors met regularly to concur, through consensus, on relevance, methods, findings, quality, and conclusions. The included studies were published between 1979 and 2017. From the 108 included studies, 76 reported a favorable outcome of fermented milks on health and 67 of these were considered to be positive or neutral quality according to the Academy of Nutrition and Dietetics' Quality Criteria Checklist. Of the 32 remaining studies, the study outcomes were either not significant (28) or unfavorable (4), and most studies (18) were of neutral quality. A causal relationship exists between lactose digestion and tolerance and yogurt consumption, and consistent associations exist between fermented milk consumption and reduced risk of breast and colorectal cancer and type 2 diabetes, improved weight maintenance, and improved cardiovascular, bone, and gastrointestinal health. Further, an association exists between prostate cancer occurrence and dairy product consumption in general, with no difference between fermented and unfermented products. This article argues that yogurt and other fermented milk products provide favorable health outcomes beyond the milk from which these products are made and that consumption of these products should be encouraged as part of national dietary guidelines. Systematic review registration: PROSPERO registration no. CRD42017068953.
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The Effect of Kefir Supplementation on Improving Human Endurance Exercise Performance and Antifatigue.
Lee, MC, Jhang, WL, Lee, CC, Kan, NW, Hsu, YJ, Ho, CS, Chang, CH, Cheng, YC, Lin, JS, Huang, CC
Metabolites. 2021;11(3)
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Compared to sedentary people, athletes exhibit a much more abundant and diverse composition of gut bacteria. Hence the relationship between gut microbes and energy usage and exercise performance has attracted much attention in recent years. Probiotics and prebiotic-related products have demonstrated the potential to enhance metabolic pathways and influence energy levels, energy consumption and exercise performance. And previous studies demonstrated positive effects on exercise endurance associated with the consumption of kefir, a fermented dairy product containing Lactobacilli species as part of the microbial symbiosis. This study investigated whether kefir can promote changes in the gut microbiota, improve exercise endurance performance, and influences fatigue during and after exercise. The study enrolled sixteen, untrained 20–30-year-old for a double-blind crossover design study, supplementing with SYNKEFIR™ for 28 days whilst observing changes in metabolic markers, body composition, exercise endurance and faecal gut bacteria. In summary, supplementation with SYNKEFIR™ significantly improved exercise performance and reduced the production of lactic acid after exercise. In addition, kefir supplementation seemed to reduce fatigue and accelerated the recovery from fatigue after exercise, with a marked reduction in lactic acid production after exercise. Though kefir supplementation had no significant effect on other post-exercise fatigue biochemical indicators nor did it induce notable changes in gut bacteria composition. As SYNKEFIR™ is a starter culture isolated from traditional kefir it could be expected that other traditional kefir products would have similar effects. Kefir as a food product is suited to a wide range of people, and it could be considered part of a healthy diet plan for untrained individuals wishing to support their exercise performance.
Abstract
Kefir is an acidic, carbonated, and fermented dairy product produced by fermenting milk with kefir grains. The Lactobacillus species constitutes an important part of kefir grains. In a previous animal study, kefir effectively improved exercise performance and had anti-fatigue effects. The purpose of this research was to explore the benefits of applying kefir to improve exercise performance, reduce fatigue, and improve physiological adaptability in humans. The test used a double-blind crossover design and supplementation for 28 days. Sixteen 20-30 year-old subjects were divided into two groups in a balanced order according to each individual's initial maximal oxygen uptake and were assigned to receive a placebo (equal flavor, equal calories, 20 g/day) or SYNKEFIR™ (20 g/day) every morning. After the intervention, there were 28 days of wash-out, during which time the subjects did not receive further interventions. After supplementation with SYNKEFIR™, the exercise time to exhaustion was significantly greater than that before ingestion (p = 0.0001) and higher than that in the Placebo group by 1.29-fold (p = 0.0004). In addition, compared with the Placebo group, the SYNKEFIR™ administration group had significantly lower lactate levels in the exercise and recovery (p < 0.05). However, no significant difference was observed in the changes in the gut microbiota. Although no significant changes in body composition were found, SYNKEFIR™ did not cause adverse reactions or harm to the participants' bodies. In summary, 28 days of supplementation with SYNKEFIR™ significantly improved exercise performance, reduced the production of lactic acid after exercise, and accelerated recovery while also not causing any adverse reactions.
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Dairy intake revisited - associations between dairy intake and lifestyle related cardio-metabolic risk factors in a high milk consuming population.
Johansson, I, Nilsson, LM, Esberg, A, Jansson, JH, Winkvist, A
Nutrition journal. 2018;17(1):110
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Dairy intake and mortality has been evaluated in many studies but the results have been inconclusive. The aim of this cross-sectional and longitudinal study was to evaluate the association between different types of dairy products and metabolic risk markers for cardiovascular disease. Utilising data from the Swedish Vasterbotten Intervention Programme, 90,512 participants completed a food frequency questionnaire and had metabolic risk markers measured for the cross-sectional component of this study. From this cohort, 27,682 subjects returned within 8-11 years to complete the longitudinal component. Dairy intake was further classified as non-fermented milk, fermented milk, cheese and butter. Based on this cross-sectional and longitudinal data, the likelihood of having an undesirable body mass index (BMI) decreased with increasing amount of total dairy, cheese and butter intake, but increased with increasing non-fermented milk intake. According to these results, the authors conclude confounding variables are likely influencing the association between dairy intake and metabolic disease and suggest future studies be stratified by dairy type.
Abstract
BACKGROUND The association between milk and dairy intake and the incidence of cardiometabolic diseases, cancer and mortality has been evaluated in many studies, but these studies have had conflicting results with no clear conclusion on causal or confounding associations. The present study aims to further address this association by cross-sectional and longitudinal evaluation of the associations between exposure to various types of dairy products and metabolic risk markers among inhabitants in northern Sweden while taking other lifestyle factors into account. METHODS Respondents in the Västerbotten Intervention Programme with complete and plausible diet data between 1991 and 2016 were included, yielding 124,934 observations from 90,512 unique subjects. For longitudinal analysis, 27,682 participants with a visit 8-12 years after the first visit were identified. All participants completed a validated Food Frequency Questionnaire. Metabolic risk markers, including body mass index (BMI), blood pressure, serum (S) cholesterol and triglycerides, and blood glucose, were measured. Participants were categorized into quintiles by intake of dairy products, and risk (odds ratios, OR) of undesirable levels of metabolic risk markers was assessed in multivariable logistic regression analyses. In longitudinal analyses, intake quintiles were related to desirable levels of metabolic risk markers at both visits or deterioration at follow-up using Cox regression analyses. RESULTS The OR of being classified with an undesirable BMI decreased with increasing quintiles of total dairy, cheese and butter intake but increased with increasing non-fermented milk intake. The OR of being classified with an undesirable S-cholesterol level increased with increasing intake of total dairy, butter and high fat (3%) non-fermented milk, whereas an undesirable S-triglyceride level was inversely associated with cheese and butter intake in women. In longitudinal analyses, increasing butter intake was associated with deterioration of S-cholesterol and blood glucose levels, whereas increasing cheese intake was associated with a lower risk of deterioration of S-triglycerides. CONCLUSIONS Confounding factors likely contribute to the demonstrated association between dairy intake and mortality, and other medical conditions and analyses should be stratified by dairy type.
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Dietary and Policy Priorities for Cardiovascular Disease, Diabetes, and Obesity: A Comprehensive Review.
Mozaffarian, D
Circulation. 2016;133(2):187-225
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Diet-related cardiometabolic conditions, such as heart disease and diabetes, pose a significant health and economic burden across the world. In recent years, scientific advances and research have generated enormous insights, yet there remain many controversies and unanswered questions. This extensive review summarizes recent evidence of key-dietary components and their impact on cardiometabolic health. Amongst the topics covered are dietary patterns, food quality and processing, genetics, personalized nutrition, supplements, functional foods and the existing knowledge on selected food groups such as carbohydrates, meat and fats alongside relevant vitamins, minerals and plant compounds. The author highlights how an oversimplified concept of nutrition from previous decades, has led to an array of conflicting advice and undermined the nuanced and complex impact that diet and nutrition can have on the body. Thus in light of the evidence, food-based interventions and dietary patterns are suggested as favourable, with less focus on dietary components in isolation. Throughout the paper, the need for adjunct support to facilitate sustainable health-promoting behaviour changes is recognized. Calling for additional measures to address behaviour change, health systems reforms, targeting socioeconomic inequalities, employing novel technologies, and adequate policymaking. This overview of recent evidence yields a comprehensive source of information, worthwhile reviewing when designing personalised diet plans in support of cardiometabolic health.
Abstract
Suboptimal nutrition is a leading cause of poor health. Nutrition and policy science have advanced rapidly, creating confusion yet also providing powerful opportunities to reduce the adverse health and economic impacts of poor diets. This review considers the history, new evidence, controversies, and corresponding lessons for modern dietary and policy priorities for cardiovascular diseases, obesity, and diabetes mellitus. Major identified themes include the importance of evaluating the full diversity of diet-related risk pathways, not only blood lipids or obesity; focusing on foods and overall diet patterns, rather than single isolated nutrients; recognizing the complex influences of different foods on long-term weight regulation, rather than simply counting calories; and characterizing and implementing evidence-based strategies, including policy approaches, for lifestyle change. Evidence-informed dietary priorities include increased fruits, nonstarchy vegetables, nuts, legumes, fish, vegetable oils, yogurt, and minimally processed whole grains; and fewer red meats, processed (eg, sodium-preserved) meats, and foods rich in refined grains, starch, added sugars, salt, and trans fat. More investigation is needed on the cardiometabolic effects of phenolics, dairy fat, probiotics, fermentation, coffee, tea, cocoa, eggs, specific vegetable and tropical oils, vitamin D, individual fatty acids, and diet-microbiome interactions. Little evidence to date supports the cardiometabolic relevance of other popular priorities: eg, local, organic, grass-fed, farmed/wild, or non-genetically modified. Evidence-based personalized nutrition appears to depend more on nongenetic characteristics (eg, physical activity, abdominal adiposity, gender, socioeconomic status, culture) than genetic factors. Food choices must be strongly supported by clinical behavior change efforts, health systems reforms, novel technologies, and robust policy strategies targeting economic incentives, schools and workplaces, neighborhood environments, and the food system. Scientific advances provide crucial new insights on optimal targets and best practices to reduce the burdens of diet-related cardiometabolic diseases.