Histamine dilutions modulate basophil activation.

BACKGROUND: In order to demonstrate that high dilutions of histamine are able to inhibit basophil activation in a reproducible fashion, several techniques were used in different research laboratories. OBJECTIVE: The aim of the study was to investigate the action of histamine dilutions on basophil activation. METHODS: Basophil activation was assessed by alcian blue staining, measurement of histamine release and CD63 expression. Study 1 used a blinded multi-centre approach in 4 centres. Study 2, related to the confirmation of the multi-centre study by flow cytometry, was performed independently in 3 laboratories. Study 3 examined the histamine release (one laboratory) and the activity of H(2) receptor antagonists and structural analogues (two laboratories). RESULTS: High dilutions of histamine (10(-30)-10(-38) M) influence the activation of human basophils measured by alcian blue staining. The degree of inhibition depends on the initial level of anti-IgE induced stimulation, with the greatest inhibitory effects seen at lower levels of stimulation. This multicentre study was confirmed in the three laboratories by using flow cytometry and in one laboratory by histamine release. Inhibition of CD63 expression by histamine high dilutions was reversed by cimetidine (effect observed in two laboratories) and not by ranitidine (one laboratory). Histidine tested in parallel with histamine showed no activity on this model. CONCLUSIONS: In 3 different types of experiment, it has been shown that high dilutions of histamine may indeed exert an effect on basophil activity. This activity observed by staining basophils with alcian blue was confirmed by flow cytometry. Inhibition by histamine was reversed by anti-H2 and was not observed with histidine these results being in favour of the specificity of this effect We are however unable to explain our findings and are reporting them to encourage others to investigate this phenomenon.

Peroxisomal enzymes and 8-hydroxydeoxyguanosine in rat liver treated with perfluorooctanoic acid.

Although peroxisome proliferators are considered non-genotoxic agents, most of them, nevertheless, were found to promote and/or induce, hepatocellular carcinoma (HCC) in rodents. The aim of the present study is, first, to investigate whether the peroxisome proliferator perfluorooctanoic acid (PFOA) possesses inherent liver cancer promoting activity, and second, to study the possible mechanisms involved. To acheive these aims two protocols have been applied, a biphasic protocol (initiation by diethyl-nitrozamine (DEN) 200 mg/kg i.p. followed by treatment with 0.005% or 0.02% perflourooctanoic acid (PFOA) for 14 and 25 weeks) and a triphasic initiation, selection-promotion (IS) protocol (initiation by giving 200 mg/kg DEN i.p. followed by a selection procedure for 2 weeks consisting of giving 0.03% 2-acetylaminofluorene (2-AAF) in diet). In the middle of this treatment a single oral dose of carbon tetrachloride (2.0 ml/kg) was given, followed by giving diet containg 0.015% of PFOA for 25 weeks. After applying both protocols, our results showed slight increase in the catalase activity while acyl CoA oxidase activity was markedly increased. Both experiments indicated that PFOA has a liver cancer promoting activity. Other groups of rats were given either basal diet or diet containing 0.02% PFOA. Five or nine weeks later they were sacrificed and the levels of 8-hydroxydeoxyguanosine in the isolated DNA were estimated. The data showed a slight nonetheless insignificant increase in 8-hydroxydeoxyguanosine. From the present data, it is concluded that PFOA is a true liver cancer promoter that may not require extensive initial DNA damage for its promoting activity.

Global view on functional foods: European perspectives.

In the context of this presentation, European means the European scientific community, which, over the last decade, has been working on the concepts for functional foods, producing a number of documents including a consensus paper, guidelines and scientific publications. The Functional Food Science in Europe (FUFOSE) project has been quite a unique attempt to establish a strong scientific framework to justify the functional food concept, to discover and develop new functional foods that are primarily function-driven, and to substantiate claims scientifically. Being clearly positioned as part of nutrition, the functional food concept is, however, quite distinct from other approaches like food supplementation or food fortification, and functional foods are different from nutraceuticals, pharmafoods, vitafoods and 'alicaments', all terms that are not defined conceptually. Functional foods are food products to be taken as part of the usual diet in order to have beneficial effects that go beyond what are known as traditional nutritional effects. Moreover, these beneficial effects have to be demonstrated scientifically to justify two specific types of claim: the enhanced function claim or the reduction of disease risk claim. Functional food is a key concept for the future of nutrition as a science because it results from the implementation in nutrition of all the basic scientific knowledge that has accumulated over the past two or three decades. To the benefit of public health this progress cannot be ignored, it needs to be recognized fully and used. But, today, functional food is still mainly a scientific concept that serves to stimulate research and the development of new products.

Functional food concept and its application to prebiotics.

A food can be regarded as functional if it is satisfactorily demonstrated to affect beneficially one or more target functions in the body, beyond adequate nutritional effects, in a way which is relevant to either the state of wellbeing and health or the reduction of the risk of a disease. A food can be made functional by increasing the concentration, adding or improving the bioavailability of a particular component. Functional food science will serve to establish claims based either on enhanced function or disease risk reduction. Inulin and oligofructose are functional food ingredients present in miscellaneous edible plants. They are non-digestible oligosaccharides classified as dietary fibres. The target for their functional effects is the colonic microflora that ferment them and for which they serve as selective "fertilizers"; the gastrointestinal physiology; the immune functions; the bioavailability of minerals; the metabolism of lipids; and colonic carcinogenesis. The scientific data available on the nutritional effects of inulin and oligofructose provide strong evidence for a prebiotic effect (i.e., selective stimulation of growth of bifidobacteria in colonic microbiota), improvement of bowel habit (both stool frequency and stool weight) and improved calcium bioavailability.

Experimental evidences on the potential of prebiotic fructans to reduce the risk of colon cancer.

Inulin is extracted from the chicory root. It is a set of fructans with its monomers linked by means of beta(2-1) bonds. This linkage cannot be hydrolysed by either pancreatic or by brush border digestive enzymes in the upper intestinal tract of humans. As such the carbohydrates arrive in the colon, where they are fermented by bifidobacteria and other lactic acid producing bacteria, thus enhancing their relative populations in the gut. Recent research in experimental animal models revealed that inulin has significant anticarcinogenic properties. It acts chemopreventively by reducing the incidence of azoxymethane (AOM) - induced aberrant crypt foci and tumours in the colon. These effects may be due to the stimulation of bifidobacteria, which themselves have been shown to act as antigenotoxic in the colon and to reduce AOM-induced tumours. Also fermentation products, including the short-chain fatty acid butyrate, could contribute to the protective effects. In this case a mechanism may be the induction of apoptosis of already transformed cells. The experimental evidence from animal studies and from studies elucidating potential mechanisms strongly supports the possibility that inulin will contribute to reducing risks for colon cancer in humans. In order to obtain more insight into this possibility, human dietary intervention studies relating biomarkers of reduced risk to inulin consumption are needed.

Inulin/oligofructose and anticancer therapy.

The results of our investigations indicate that dietary treatment with inulin or oligofructose incorporated in the basal diet for experimental animals: (i) reduced the incidence of mammary tumors induced in Sprague-Dawley rats by methylnitrosourea; (ii) inhibited the growth of transplantable malignant tumors in mice; and (iii) decreased the incidence of lung metastases of a malignant tumor implanted intramuscularily in mice. Moreover, besides such cancer risk reduction effects, the dietary treatment with inulin or oligofructose significantly potentiated the effects of subtherapeutic doses of six different cytotoxic drugs commonly utilized in human cancer treatment. If confirmed, such dietary treatment with inulin or oligofructose potentiating cancer therapy might become an interesting approach to complement classical protocols of human cancer treatment without any additional risk for the patients.

Inulin and oligofructose as dietary fiber: a review of the evidence.

This critical review article examines the composition and source of inulin and oligofructose, the physiological effects of their consumption, and how these materials relate to the concept of dietary fiber. Inulin and oligofructose are fructans extracted on a commercial basis from the chicory root. Inulin has been defined as a polydisperse carbohydrate material consisting mainly, if not exclusively, of beta (2-1) fructosyl-fructose links ranging from 2 to 60 units long. Native chicory inulin has an average degree of polymerization (DP) of 10 to 20, whereas oligofructose contains chains of DP 2 to 10, with an average DP of 4. While a universally accepted definition for dietary fiber does not exist, it is generally agreed that this term includes saccharides (+ lignin) that are not hydrolyzed or absorbed in the upper part of the gastrointestinal tract. These materials reach the colon, where they may be totally fermented, partially fermented, or remain unfermented. In addition, fibers contribute to fecal bulking. Inulin and oligofructose are not digested in the upper part of the gastrointestinal tract or are they absorbed and metabolized in the glycolytic pathway, or directly stored as glycogen like 'sugars' or starches. None of the molecules of fructose and glucose that form inulin and oligofructose appear in the portal blood. These materials are quantitatively fermented by the microflora of the colon; further, it has been demonstrated that this fermentation leads to the selective stimulation of the growth of the bifidobacteria population. After reviewing their chemistry, origin, and physiological effects, it is the opinion of the authors that inulin and oligofructose are dietary fiber. They share the basic common characteristics of dietary fibers, that is, saccharides of plant origin, resistance to digestion and absorption in the small intestine, and fermentation in the colon to produce short-chain fatty acids that are absorbed and metabolized in various parts of the body. Moreover, this fermentation induces a bulking effect.

Prebiotics: preferential substrates for specific germs?

A prebiotic is "a non-digestible food ingredient that beneficially affects the host by selectively stimulating the growth and/or the activity of one or a limited number of bacteria in the colon." The premise is based on the hypothesis that the large gut in humans contains bacteria that are beneficial or detrimental to health. Although this generalization probably gives too simplistic a view of gut microbiology, it is a feasible working concept. Currently, food components that seem to exert the best prebiotic effects are inulin-type fructans. In pure culture, most species of bifidobacteria are adapted to the utilization of these nondigestible oligosaccharides but many other bacteria are also capable of metabolizing them. Clearly, these studies of pure bacteria are of limited use unless their results are supported by the results of studies using mixed cultures. Indeed, as many components of the gut microbiota as possible should be measured to indicate a true prebiotic effect. Simple stimulation of bifidobacteria is insufficient to demonstrate an effect; the effects on other gut microorganisms in vivo with human volunteers is necessary. Adjustment of the composition and activities of the colonic microflora so that health-promoting activities are optimized remains key in functional food development. New methods are being applied extensively to human gut microbiology and promise the degree of reliability required to detect subtle changes in colonic microflora composition and to correlate such changes with health benefits. This is a review of the present state of knowledge concerning prebiotics, with emphasis on the criteria used for classification, mechanisms of selective growth stimulation, and physiologic effects.

Concepts and strategy of functional food science: the European perspective.

Recent knowledge supports the hypothesis that, beyond meeting nutrition needs, diet may modulate various functions in the body and play detrimental or beneficial roles in some diseases. Concepts in nutrition are expanding from emphasis on survival, hunger satisfaction, and preventing adverse effects to emphasizing the use of foods to promote a state of well-being and better health and to help reduce the risk of disease. In many countries, especially Japan and the United States, research on functional foods is addressing the physiologic effects and health benefits of foods and food components, with the aim of authorizing specific health claims. The positive effects of a functional food can be either maintaining a state of well-being and health or reducing the risk of pathologic consequences. Among the most promising targets for functional food science are gastrointestinal functions, redox and antioxidant systems, and metabolism of macronutrients. Ongoing research into functional foods will allow the establishment of health claims that can be translated into messages for consumers that will refer to either enhanced function or reduction of disease risk. Only a rigorous scientific approach that produces highly significant results will guarantee the success of this new discipline of nutrition. This presents a challenge for the scientific community, health authorities, and the food industry.

Prebiotics and probiotics: are they functional foods?

A probiotic is a viable microbial dietary supplement that beneficially affects the host through its effects in the intestinal tract. Probiotics are widely used to prepare fermented dairy products such as yogurt or freeze-dried cultures. In the future, they may also be found in fermented vegetables and meats. Several health-related effects associated with the intake of probiotics, including alleviation of lactose intolerance and immune enhancement, have been reported in human studies. Some evidence suggests a role for probiotics in reducing the risk of rotavirus-induced diarrhea and colon cancer. Prebiotics are nondigestible food ingredients that benefit the host by selectively stimulating the growth or activity of one or a limited number of bacteria in the colon. Work with prebiotics has been limited, and only studies involving the inulin-type fructans have generated sufficient data for thorough evaluation regarding their possible use as functional food ingredients. At present, claims about reduction of disease risk are only tentative and further research is needed. Among the claims are constipation relief, suppression of diarrhea, and reduction of the risks of osteoporosis, atherosclerotic cardiovascular disease associated with dyslipidemia and insulin resistance, obesity, and possibly type 2 diabetes. The combination of probiotics and prebiotics in a synbiotic has not been studied. This combination might improve the survival of the bacteria crossing the upper part of the gastrointestinal tract, thereby enhancing their effects in the large bowel. In addition, their effects might be additive or even synergistic.

Fn-type chicory inulin hydrolysate has a prebiotic effect in humans.

The partial enzymatic hydrolysis of chicory inulin (GFn; 2 < or =n < or =60) yields an oligofructose preparation that is composed of both GFn-type and Fn-type oligosaccharides (2 < or =n < or =7; 2 < or =m < or =7), where G is glucose, F is fructose, and n is the number of beta(2-->1) bound fructose moieties. Human studies have shown that feeding GFn-type oligomers significantly modifies the composition of the fecal microflora especially by increasing the number of bifidobacteria. The experiments reported here were used to test the hypothesis that the Fn-type molecules have the same property. During a controlled feeding study, 8 volunteers (5 females and 3 males) consumed 8 g/d of an Fn-rich product for up to 5 wk. Fecal samples were collected and analyzed for total anaerobes, bifidobacteria, lactobacilli, bacteroides, coliforms and Clostridium perfringens. Both 2 and 5 wk of oligofructose feeding resulted in a selective increase in bifidobacteria (P<0.01). In addition, a daily intake of 8 g of the Fn-type oligofructose preparation reduced fecal pH and caused little intestinal discomfort.

Comparison of viable cell counts and fluorescence in situ hybridization using specific rRNA-based probes for the quantification of human fecal bacteria.

Conventional cultivation and fluorescence in situ hybridization (FISH) using 16S rRNA-based probes were compared for the enumeration of human colonic bacteria. Groups of common intestinal anaerobic bacteria were enumerated in slurries prepared from fecal samples of three healthy volunteers. To introduce variation between the samples, they were incubated for 48 h in batch culture (anaerobic) fermenters at 37 degrees C, and pure cultures of Bifidobacterium infantis, Clostridium perfringens, or Lactobacillus acidophilus were added. Samples were taken from the fermenters at different times. Total anaerobes, bifidobacteria, bacteroides, clostridia, and lactobacilli were enumerated by both plating and FISH. The results showed that plate counts of total anaerobes, bifidobacteria, lactobacilli and bacteroides were approximately ten-fold lower than the corresponding FISH counts. Numbers of clostridia were higher using the plating method, probably because the clostridia probe used in FISH analyses was designed to only detect part of the genus Clostridium. The introduced variation in the methods could be detected by both methods and was comparable.

Nondigestible oligosaccharides.

Dietary carbohydrates range in molecular size from simple sugars to complex polymers with a degree of polymerization (DP) of up to 100,000 or more. Oligosaccharides are generally defined as carbohydrates from 2 to 20 monomeric units long. Oligosaccharides have been dietary staples since antiquity but have received much less attention than other carbohydrates such as simple sugars or dietary fiber. Recently, interest in oligosaccharides has increased not only because of properties that include sweetening ability and fat replacement, but also because of resistance to digestion in the upper gastrointestinal tract and fermentation in the large bowel. Thus, some oligosaccharides have functional effects similar to soluble dietary fiber such as enhancement of a healthy gastrointestinal tract, improvement of glucose control, and modulation of the metabolism of triglycerides. These oligosaccharides are the nondigestible oligosaccharides. These compounds are easily incorporated into processed foods and hold much promise as functional ingredients in nutraceutical products.

Inhibitory effect of dietary inulin or oligofructose on the development of cancer metastases.

The possible influence of continuous dietary treatment with 15% inulin or oligofructose on the development of lung metastases of a transplantable liver tumor in young male C3H mice was investigated. Microscopical examination demonstrated a distinct inhibitory effect of this dietary treatment on the development of lung metastases of this tumor. There were 59% of mice bearing lung metastases in the control group, 36% in the inulin fed group and 35% in the oligofructose fed group. The total number of lung metastases was 37 in the control group, 18 in inulin fed and 6 in oligofructose fed mice. Several possible, mechanisms hypothetically involved in this astonishing inhibition of the development of lung metastases by dietary treatment with inulin or oligofructose are discussed.

Nontoxic potentiation of cancer chemotherapy by dietary oligofructose or inulin.

Our previously published results indicated that dietary treatment with oligofructose or inulin inhibited malignant tumor growth in experimental animals. Thus it appeared to be interesting to investigate whether the same treatment could have a positive influence on tumor chemotherapy. The chemotherapy-potentiating effect of 15% oligofructose or inulin incorporated into the basal diet for experimental animals was investigated on a transplantable mouse liver tumor. This dietary adjuvant therapy was started seven days before intraperitoneal transplantation of transplantable liver tumor and was continued until the end of experiments. A single, subtherapeutic dose of six different cytotoxic drugs commonly utilized in treatment of human cancer was intraperitoneally injected 48 hours after tumor transplantation. In all experiments, dietary oligofructose or inulin significantly potentiated the therapeutic effects of six different cytotoxic drugs. Such dietary treatment potentiating cancer chemotherapy could be introduced into classical protocols of human cancer treatment as a new, nontoxic, and easily applicable adjuvant cancer therapy without any supplementary risk for patients.

Fructo-oligosaccharide malabsorption: benefit for gastrointestinal functions.

Fructo-oligosaccharides or inulin-type fructans are mixtures of oligomers that are composed primarily of beta-D-fructose monomers linked by beta2-1 osidic bonds. They are natural constituents of many edible plants. They resist digestion and are not absorbed in the upper part of the gastrointestinal tract, but they are fermented in the colon. That fermentation produces short-chain fatty acids, which acidify the colonic content; increase bacterial biomass and, consequently, fecal mass; and modify the composition of the microflora, especially by stimulating the growth of bifidobacteria. Fructo-oligosaccharides are thus prebiotics and a method of the Association of Official Analytical Chemists exists to measure them in food products. Because of this behavior in the gastrointestinal tract, inulin-type fructans have a low caloric value compared with carbohydrate absorbed in the small intestine, they improve Ca absorption and Ca balance, and, at least in experimental models, they inhibit the development of chemically induced aberrant crypt foci. Moreover, at a systemic level, they may contribute to modulating lipogenesis and reducing triglyceridemia. The data reviewed in this article support the classification of inulin-type fructans as functional food ingredients for which claims will or should become authorized when data for humans become available.

What is beneficial for health? The concept of functional food.

'Functional Food' is now a very popular term. The conceptual approach developed in the EU-founded FUFOSE (Functional Food Science in Europe) project is rather restrictive, making functional food a food product to be part of the usual dietary pattern. Functional food science that supports the development of functional foods is and must remain part of the science of nutrition. Finally, all that exercise, that extended over the last 3 years, was function-driven because the functions and their modulation are universal, as opposed to a food or food component-driven approach,which is likely to be very much influenced by local, traditional or cultural characteristics.