In vitro experiments with cell cultures, studies with the TNO gastrointestinal model, animal experiments, and studies with human volunteers are used in nutrition research on the assessment of efficacy and safety of ingredients that can be used as bio actives in functional foods, functional drinks and dietary supplements. Human volunteer studies are considered to be the final and decisive step in these different types of studies. In fact health claims should not be used without demonstration of efficacy in human volunteer studies. For such studies many issues are important to arrive at valid conclusions: selection of eligible volunteers (inclusion- and exclusion criteria, medical examination), measurement of validated bio markers, check of compliance, measurement of safety parameters, application of documented standard operation procedures etc. Attention should also be given to selection of the most appropriate study design. Ideally, a randomized double blind parallel- or cross over design placebo-controlled is preferred. Special attention should be given to the number of volunteers participating in the study to have adequate statistical power and thus reduce the risk of type II statistical errors. No study should be started without prior power calculation. In nutrition studies with humans also the dose-effect relationship should be addressed. Selection of suitable (realistic) doses of the bio active substance is critical. Moreover attention should be given to potential matrix effects in the food, drink or supplement, that could influence bio availability and/or bio efficacy. A detailed protocol for the study should be developed. The protocol should be approved by a Medical Ethics Committee. Candidate volunteers should receive both written and oral information on the study and to be eligible they should sign consent forms.
The specific health benefits of individual food components have been recognised for centuries, but only relatively recently has there been a determined effort by pioneering individuals in Countries such as Japan, to take advantage of the huge public health benefits that are on offer. It is a sad fact that in almost all Countries that have adopted Legislation or Codes of Practice, it is the pressure derived from exaggerated health claims on food products that lead to controls. Absurd product health claims created with little or no regard for the scientific evidence results in the Authorities fi ghting a rearguard action to limit claims, rather than adopting an initial neutral attitude and approach that would lead to fresh thinking. In the European Economic Community, current National practices and legislation in the 15 Member States effectively create different approaches towards food fortification, food supplements, herbal products and the availability of non-prescription products. In the absence of a specific Directive from Brussels, it is not surprising that the majority of EU Member States have in place, or are currently working on National Codes of Practice in an attempt to control foods that carry health messages. In an attempt to harmonise the basic requirements for controls on functional foods, the CIAA has produced a pan-European document that sets out the principle requirements. We also need to consider the effect that officially recognising health claims for food will have on specialised product sectors where a surprising degree of freedom already exists for health claims. In my paper I will compare individual Codes of Practice and Legislation and discuss representative examples of food and supplement products. I will point out the current advantages for some market sectors, together with the failings in well-established legislation that can prevent the marketing of bona fide foods with health claims.
Bile acids are transformed by intestinal microflora. Secondary bile acids including deoxycholic acid and lithocholic acid appear to show a strong correlation with colorectal cancer. However, the role of intestinal bacteria in the transformation of bile acids in vivo is still not clear. We attempted to evaluate which bacterial groups are responsible for bile acid transformation in vivo. First, we orally inoculated germfree (GF) mice with human intestinal bacteria that have the ability to transform bile acids in vitro, and showed that it is not necessarily true that bacterial transforming ability of bile acids in vitro is reflected in vivo. Then GF mice were orally inoculated with human fecal dilution or various components of human feces. In the cecal contents of ex-GF mice associated with human fecal dilutions of 10-2 or 10-6, or the anaerobic growth from a dilution of 10-6, free-form bile acids accounted for more than 80% and DCA for about 20% of total bile acid. When GF mice were associated only with clostridia, free-form bile acids made up less than 40% of total bile acids, but the percentage of secondary bile acids was the same as in the other groups. These results indicate that predominant bacteria -mainly bacteroides in human feces, which are the main bacterial group for deconjugation of bile acids-and clostridia may play an important role in 7α-dehydroxylation of free-form primary bile acids in the intestine. The combination of five strains of bile acid-deconjugating bacteroides and five strains of bile acid 7α-dehydroxylating clostridia isolated from ex-GF mice converted tauro-conjugated cholic acid into DCA both in vitro and in the intestine. This GB mouse model should be useful in studies of bile acid metabolism by human intestinal bacteria in vivo.
The purpose of the present study was to classify seventeen isolates of Bifidobacterium from infant faeces using PCR-based and 16S rDNA partial sequences analysis methods. For the rapid classification of Bifidobacterium isolates, genus and species specific PCR primers were used. The sensitivity of the genus-specific primers were assessed by testing different genus of bacteria and all of the bifidobacteria tested produced one band with the size of approximately 1.35 kbp. Species-specific primers for Bifidobacterium pseudocatenulatum produced approximately 289 bp DNA band. Specificity of these primers was determined by testing with other species of bacteria, which did not result in any DNA band. Comparison between fermentative characteristic and analysis of homology of the 16S rDNA sequences of Bifidobacterium isolates from infant faeces with that of other bifidobacteria deposited in databases do not allow similar classification.
We investigated the influence of the extract of soy protein fermented with lactic acid bacteria and yeast (ESFL) on 1, 2-dimethylhydrazine (DMH)-induced colon cancer and aberrant crypt foci (ACF) in ICR female mice. In all the experiments, 8-week old mice were given subcutaneous DMH injections at 35 mg/kg once a week. In the experiment for colon cancer, mice were divided into groups A, B and C, with 20 mice each, and groups A and B were given DMHinjections for 10 weeks. Group C were injected with only PBS. Group A were fed a 5%-ESFL diet and groups B and C were fed normal mouse diets throughout the experiment for 35 weeks. Group A showed a 28.5% inhibition in incidence and a 59.1% inhibition in average number of tumors compared to group B, but the results were not statistically significant. In ACF experiments, mice were divided into 4 groups, 10%-ESFL group, 1%-ESFL group, 0.1%-ESFL group, and a control with 10 mice each. All the mice were given DMH injections for 4 weeks. ESFL-supplemented diets were given throughout the experiment for 8 weeks. ACF formation decreased in all the ESFL-fed groups in a dose-dependent manner and the results were statistically significant in the 10%-ESFL group (69% inhibition, p<0.001) and 1%-ESFL group (40% inhibition, p<0.05) compared to the control. The present study suggests that ESFL could contain an effective anticarcinogenic substance (s).
The microflora of twenty samples of the Masai fermented milk, 8 of Maziwa lala, 8 of Mursik and 4 of Klenaoto were investigated. The total microbial counts in the twenty Masai fermented milk samples ranged from 1.9×108 to 8.8×109 c.f.u./ml. The predominating microorganisms in most of the Masai fermented milk were lactic acid bacteria composed of lactococci, lactobacilli and leuconostocs. Two hundred ten strains were isolated and identified as Lactococcus lactis ss. lactis, Leuconostoc mesenteroides ss. mesenteroides, Lactobacillus plantarum, Lactococcus sp. group 1, Lactobacillus maltaromaticus, Lactobacillus casei/paracasei, Lactobacillus curvatus, Lactobacillus fermentum, Lactobacillus confusus, Lactococcus garviae, Lactobacillus tolerans, Lactobacillus sake, Lactobacillus coryniformis ss. coryniformis, Lactobacillus sp. groups 1, 2, and 3, in descending order of the number of the isolates. Within the lactococci, lactobacilli, and leuconostocs, Lactococcus lactis ss. lactis, Lactobacillus plantarum, and Leuconostoc mesenteroides ss. mesenteroides were generally predominating species, respectively. The distribution of the species of lactic acid bacteria in the Masai fermented milk samples differed according to the samples.
The effects of a Lactobacillus gasseri SBT2055 (LG2055) on ulcerative colitis (UC) were studied in a rat model of UC induced by dextran sulfate sodium (DSS). Daily oral administration of LG2055 improved the characteristics of feces, body weight gain and food consumption. LG2055 treatment was also associated with a change of the spleen weight, and an improvement of the hematological parameters and histological findings of the large intestine. These findings indicate that LG2055 may be useful for the treatment and/or prevention of UC.
In the past ten years, some probiotics were authorized to use for the clinical treatment of diseases caused by imbalance of intestinal flora, in China. These probiotics preparation shall meet the quality standards issued by State Drug Administration.