Vegane Ernährung und Darmgesundheit – Zusammenhänge mit Mikrobiota und Gallensäurekonzentrationen im Stuhl

A vegan diet is often supposed to be rich in dietary fiber and low in fat intake compared to an omnivorous diet. Following a vegan diet is discussed with health benefits, such as a low risk of the onset of obesity or for total cancer. A diet also plays a major role in microbiota composition, which may impact the health status. Bile acids are strongly re-lated to diet, in particular to fat and meat intake as they mediate fat digestion. Some bacteria of the microbiota convert primary bile acids into secondary bile acids, which are discussed to increase the risk of colorectal carcinoma. So far, only few studies have investigated the differences in microbiota and fecal bile acids in a meatless diet com-pared to an omnivorous diet. First, this cumulative thesis compared the microbiota composition of vegans and vege-tarians with omnivores in a systematic review. In the second publication, fecal and se-rum bile acids of vegans were compared with omnivores. A dietary pattern should iden-tify food groups contributing most to fecal bile acid concentrations. Both publications were conducted with data from the cross-sectional study “Risks and benefits of a vegan diet” (RBVD) with 36 vegans and 36 omnivores. In RBVD, the diet was assessed with 3-day weighing protocols. Each participant provided a complete stool sample for bile acids and microbiota analyses. The dietary pattern was derived by reduced rank regression with food groups as predictor and fecal bile acid concentra-tions as response variables. In the systematic review, a literature research was con-ducted in PubMed and Embase. Studies that compare the microbiota composition of healthy vegans or vegetarians with omnivores were selected. Furthermore, the RBVD results were considered in this review. In the systematic review, 16 studies were included. The number of significant differ-ences in bacterial abundances in vegans or vegetarians compared to omnivores was small. In RBVD, fecal secondary and conjugated bile acids were significantly lower in vegans than in omnivores (p<0.01). The derived dietary pattern can be described as a fatty omnivorous pattern, and it was associated with increasing bile acids across the score. Processed meat, fried potatoes, fish, margarine and coffee correlated positively with higher bile acid concentration, whereas muesli was inversely associated. The systematic review could not reveal a “vegan” or “vegetarian” microbiota composi-tion, which may be attributed to the high individuality of microbiota and different analyz-ing methods. Lower concentrations of fecal secondary bile acids in vegans compared to omnivores could refer to a more favorable risk profile towards the development of a colorectal carcinoma. Yet, the cross-link of diet, microbiota and bile acid metabolism is not fully understood, so further research is needed.Eine vegane Diät ist häufig reicher an Ballaststoffen und ärmer an Fett als eine Misch-kost und wird mit gesundheitlichen Vorteilen, wie z.B. einem geringeren Risiko für Adi-positas oder Krebs diskutiert. Ernährung beeinflusst auch die Zusammensetzung der Mikrobiota, welche auf den Gesundheitsstatus wirken kann. Der Gallensäuren Stoff-wechsel steht eng im Zusammenhang mit der Ernährung, insbesondere mit Fett- und Fleischverzehr. Einige Bakterien der Mikrobiota wandeln primäre Gallensäuren in se-kundäre Gallensäuren um, die ein Risiko für die Entstehung eines Kolonkarzinoms dar-stellen können. Unterschiede in der Mikrobiota und fäkalen Gallensäuren bei einer fleischfreien Ernährung im Vergleich zu Mischkost sind bisher nur wenig untersucht. Für diese kumulative Promotion wurde zunächst in einem systematischen Review die Mikrobiota von Veganern und Vegetariern mit der von Mischköstlern verglichen. In der zweiten Publikation wurden Assoziationen zwischen veganer Ernährung und Gallensäu-ren in Stuhl und Serum im Vergleich zu Mischkost untersucht. Über die Herleitung von Ernährungsmustern wurden Lebensmittel identifiziert, die den größten Einfluss auf fäka-le Gallensäuren haben könnten. Für beide Publikationen wurden Daten der Querschnittstudie “Risiken und Benefits einer veganen Diät” (RBVD) mit je 36 Veganern und Mischköstlern genutzt. Die Ernährung wurde mit 3-Tage-Wiegeprotokollen erhoben. Jeder Teilnehmer gab eine Stuhlprobe für die Analyse der Mikrobiota und der Gallensäuren ab. Ernährungsmuster wurden mittels Reduced Rank Regression hergeleitet mit Lebensmitteln als Prädiktoren und Gallensäu-ren als Responder. Für den systematischen Review wurde eine Literaturrecherche in PubMed und Embase durchgeführt. Es wurden Studien ausgewählt, welche die Zu-sammensetzung der Mikrobiota von Veganern bzw. Vegetariern mit der von Mischköst-lern verglichen. Im Review wurden Ergebnisse aus der RBVD Studie berücksichtigt. In dem systematischen Review wurden 16 Studien aufgenommen. Die Zahl der signifi-kanten Unterschiede an Bakterien zwischen Veganern bzw. Vegetariern im Vergleich zu Mischköstlern war gering. Fäkale sekundäre Gallensäuren waren bei Veganern niedriger als bei Mischköstlern (p<0.01). Das hergeleitete Ernährungsmuster ging mit steigenden Konzentrationen aller fäkalen Gallensäuren einher und kann als fettreiches Mischkost-Muster beschrieben werden. Verarbeitetes Fleisch, frittierte Kartoffeln, Fisch, Margarine und Kaffee waren positiv, Müsli war dagegen invers assoziiert. In dem systematischen Review konnte keine „vegane“ oder „vegetarische“ Mikrobiota identifiziert werden. Eine hohe Interindividualität der Mikrobiota und verschiedene Aus-wertungsmethoden könnten dazu beigetragen haben. Niedrige sekundäre Gallensäuren bei Veganern im Stuhl könnten im Vergleich mit Mischköstlern auf ein günstigeres Risi-koprofil hinsichtlich der Entstehung eines Kolonkarzinoms hinweisen. Das Zusammen-spiel von Diät, Mikrobiota und Gallensäure-Stoffwechsel bedarf weiterer Forschung

Nutritional Intake and Biomarker Status in Strict Raw Food Eaters

Following a strict raw food diet (primarily based on fresh fruit and raw vegetables, waiving any consumption of heated or processed food) has the risk of undersupply of energy and certain macro- and micronutrients. In this cross-sectional study, we compared 16 non-smoking strict raw food eaters (5 women and 11 men, age 44.6 ± 12.3 years, duration of following the diet 11.6 ± 10.8 years) with the non-smoking participants (32 vegans, 27 omnivores) of the “Risk and Benefits of a Vegan Diet” (RBVD) study. We investigated body composition, dietary intake from 3-day weighed food records, and relevant fasting blood and serum parameters. Food choice and dietary behavior were very heterogenic in raw food eaters. They had lower mean values of BMI and percentage of body fat than the respective RBVD participants. The same holds true for energy supply and intakes of protein, carbohydrate, calcium and iodine. Serum levels revealed lower levels of HDL cholesterol, triglycerides, zinc, and vitamin D3. The raw food eaters with (n = 9) and without (n = 7) supplementation of vitamin B12 had median vitamin B12 levels of 399 and 152 ng/L, respectively. Accordingly, eight raw food eaters (50%) had homocysteine levels above 12 µmol/L. The study allows a close look at strict raw food eaters with respect to possible dietary deficiencies, but also provides insights into motivations and daily life

Short- and Branched-Chain Fatty Acids as Fecal Markers for Microbiota Activity in Vegans and Omnivores

A vegan diet could impact microbiota composition and bacterial metabolites like short-chain (SCFA) and branched-chain fatty acids (BCFA). The aim of this study was to compare the concentrations of SCFA, BCFA, ammonia, and fecal pH between vegans and omnivores. In this cross-sectional study (vegans n = 36; omnivores n = 36), microbiota composition, fecal SCFA, BCFA, and ammonia concentrations and pH were analyzed in complete stool samples. A random forest regression (RFR) was used to identify bacteria predicting SCFA/BCFA concentrations in vegans and omnivores. No significant differences in SCFA and BCFA concentrations were observed between vegans and omnivores. Fecal pH (p = 0.005) and ammonia concentration (p = 0.01) were significantly lower in vegans than in omnivores, while fiber intake was higher (p &lt; 0.0001). Shannon diversity was higher in omnivores compared to vegans on species level (p = 0.04) only. In vegans, a cluster of Faecalibacterium prausnitzii, Prevotella copri, Dialister spp., and Eubacterium spp. was predictive for SCFA and BCFA concentrations. In omnivores, Bacteroides spp., Clostridium spp., Ruminococcus spp., and Prevotella copri were predictive. Though SCFA and BCFA did not differ between vegans and omnivores, the results of the RFR suggest that bacterial functionality may be adapted to varying nutrient availability in these diets

Associations between Dietary Patterns and Bile Acids—Results from a Cross-Sectional Study in Vegans and Omnivores

Bile acids play an active role in fat metabolism and, in high-fat diets, elevated concentrations of fecal bile acids may be related to an increased risk of colorectal cancer. This study investigated concentrations of fecal and serum bile acids in 36 vegans and 36 omnivores. The reduced rank regression was used to identify dietary patterns associated with fecal bile acids. Dietary patterns were derived with secondary and conjugated fecal bile acids as response variables and 53 food groups as predictors. Vegans had higher fiber (p &lt; 0.01) and lower fat (p = 0.0024) intake than omnivores. In serum, primary and glycine-conjugated bile acids were higher in vegans than in omnivores (p &le; 0.01). All fecal bile acids were significantly lower in vegans compared to omnivores (p &lt; 0.01). Processed meat, fried potatoes, fish, margarine, and coffee contributed most positively, whereas muesli most negatively to a dietary pattern that was directly associated with all fecal bile acids. According to the pattern, fat intake was positively and fiber intake was inversely correlated with bile acids. The findings contribute to the evidence that, in particular, animal products and fat may play a part in higher levels of fecal bile acids

Creatine and creatine forms intended for sports nutrition

Creatine is a popular ergogenic supplement in sports nutrition. Yet, supplementation of creatine occasionally caused adverse effects such as gastrointestinal complaints, muscle cramps and an increase in body weight. Creatine monohydrate has already been evaluated by different competent authorities and several have come to the conclusion that a daily intake of 3 g creatine per person is unlikely to pose safety concerns, focusing on healthy adults with exclusion of pregnant and breastfeeding women. Possible vulnerable subgroups were also discussed in relation to the safety of creatine. The present review provides an up-to-date overview of the relevant information with special focus on human studies regarding the safety of creatine monohydrate and other marketed creatine forms, in particular creatine pyruvate, creatine citrate, creatine malate, creatine taurinate, creatine phosphate, creatine orotate, creatine ethyl ester, creatine pyroglutamate, creatine gluconate, and magnesium creatine chelate. Limited data are available with regard to the safety of the latter creatine forms. Considering an acceptable creatine intake of 3 g per day, most of the evaluated creatine forms are unlikely to pose safety concerns, however some safety concerns regarding a supplementary intake of creatine orotate, creatine phosphate, and magnesium creatine chelate are discussed here