People who identify themselves as severely lactose-intolerant may mistakenly attribute a variety of abdominal symptoms to lactose intolerance. When lactose intake is limited to the equivalent of 240 ml of milk or less a day, symptoms are likely to be negligible and the use of lactose-digestive aids unnecessary.

Large quantities of yogurt are consumed by some lactase-deficient population groups. We used breath hydrogen measurements to determine whether lactase-deficient subjects absorbed lactose in yogurt better than lactose in milk. Ingestion of 18 g of lactose in yogurt resulted in only about one third as much hydrogen excretion as a similar load of lactose in milk or water, indicating a much better absorption of lactose in yogurt. Ingestion of yogurt also resulted in fewer reports of diarrhea or flatulence than did a similar quantity of lactose ingested in milk or a water solution. The enhanced absorption of lactose in yogurt appeared to result from the intraintestinal digestion of lactose by lactase released from the yogurt organisms. This autodigesting feature makes yogurt a well-tolerated source of milk for lactase-deficient persons and may explain the widespread consumption of yogurt by lactase-deficient population groups.

BackgroundThe influence of diet on intestinal microflora has been investigated mainly using conventional microbiological approaches. Although these studies have advanced knowledge on human intestinal microflora, it is imperative that new methods are applied to facilitate scientific progress. Culture-independent molecular fingerprinting method of Polymerase Chain Reaction and Denaturing Gradient Gel Electrophoresis (PCR-DGGE) has been used to study microbial communities in a variety of environmental samples. However, these protocols must be optimized prior to their application in order to enhance the quality and accuracy of downstream analyses. In this study, the relative efficacy of four commercial DNA extraction kits (Mobio Ultra Clean® Fecal DNA Isolation Kit, M; QIAamp® DNA Stool Mini Kit, Q; FastDNA® SPIN Kit, FSp; FastDNA® SPIN Kit for Soil, FSo) were evaluated. Further, PCR-DGGE technique was also assessed for its feasibility in detecting differences in human intestinal bacterial fingerprint profiles.MethodTotal DNA was extracted from varying weights of human fecal specimens using four different kits, followed by PCR amplification of bacterial 16S rRNA genes, and DGGE separation of the amplicons.ResultsRegardless of kit, maximum DNA yield was obtained using 10 to 50 mg (wet wt) of fecal specimens and similar DGGE profiles were obtained. However, kits FSp and FSo extracted significantly larger amounts of DNA per g dry fecal specimens and produced more bands on their DGGE profiles than kits M and Q due to their use of bead-containing lysing matrix and vigorous shaking step. DGGE of 16S rRNA gene PCR products was suitable for capturing the profiles of human intestinal microbial community and enabled rapid comparative assessment of inter- and intra-subject differences.ConclusionWe conclude that extraction kits that incorporated bead-containing lysing matrix and vigorous shaking produced high quality DNA from human fecal specimens (10 to 50 mg, wet wt) that can be resolved as bacterial community fingerprints using PCR-DGGE technique. Subsequently, PCR-DGGE technique can be applied for studying variations in human intestinal microbial communities.

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.

Texting repeated messages appears to be an acceptable and effective way to increase nutrition knowledge and promote positive diet-related behaviors in college students.