Relationship of prebiotics and food to intestinal microflora

Dietary carbohydrates that escape digestion in the small intestine, undergo bacterial fermentation in the colon. This process affects the microbial ecology of the gastrointestinal tract and influences gut metabolism and function. Prebiotics are non-digestible but fermentable oligosaccharides that are specifically designed to change the composition and activity of the intestinal microbiota with the prospect to promote the health of the host. Dietary fiber and non-digestible oligosaccharides are the main growth substrates of gut microorganisms. Their fermentation results in the acidification of the colonic contents and the formation of short chain fatty acids which serve as fuels in different tissues and may play a role in the regulation of cellular processes. Prebiotics specifically stimulate the growth of endogenous microbial population groups such as bifidobacteria and lactobacilli which are perceived as being beneficial to human health. In spite of the interesting nutritional properties of prebiotics it is questionable whether a wholesome diet rich in fruit and vegetables needs to be supplemented with prebiotics for optimal health effects.     

Antioxidant capacity of vegetables, spices and dressings relevant to nutrition

Vegetables are the most important sources of phenolics in the Mediterranean diet. Phenolics, especially flavonoids, are suggested as being essential bioactive compounds providing health benefits. In this study, twenty-seven vegetables, fifteen aromatic herbs and some spices consumed in Central Italy (the Marches region) were studied to reveal total phenolic, flavonoid and flavanol content as well as their antioxidant capacity measured by the oxygen radical absorbance capacity (ORAC) method. A comparison in terms of antioxidant capacity was made between different salads, as well as between salads to which aromatic herbs had been added. Lemon balm and marjoram at a concentration of 1.5 % w/w increased by 150 % and 200 % respectively the antioxidant capacity of a salad portion. A 200 g portion of a salad enriched with marjoram corresponded to an intake of 200 (SD 10) mg phenolics and 4000 (SD 300) ORAC units (micromol Trolox equivalents). Olive oils and wine or apple vinegars were the salad dressings that provided the highest increase in antioxidant capacity. Among the spices tested, cumin and fresh ginger made the most significant contribution to the antioxidant capacity. The results are useful in surveying the antioxidant parameters of vegetables, herbs and spices produced and consumed in our geographical area as well as in quantifying the daily intake of phenolics and ORAC units. The results can be used in public health campaigns to stimulate the consumption of vegetables able to provide significant health protection in order to prevent chronic diseases.     

The role of fruit juice in the diet: an overview

Over recent years, consumers have shown an increasing interest in health and wellbeing, with many wanting food and drink products that are healthy and nutritious, yet fit in with busy lifestyles. Fruit juice is one beverage that has seen a dramatic increase in consumer purchasing since the 1970s, and is now consumed by nearly half the UK population. While the beneficial effects of consuming diets rich in fruit and vegetables are well documented, the specific health effects of consuming fruit juice are less so. Further, the role of fruit juice in conditions such as obesity has also recently come under scrutiny, due to questions over how liquid calories affect subsequent energy intake. Limitations in the literature in this area include a lack of studies looking at different types of fruit juices and their effects on health, as well as studies that differentiate fruit juice from fruit and vegetable intake. Consuming a diet rich in fruit and vegetables (to which fruit juice can count once towards the 5 A DAY target) can help to reduce an individual's risk of suffering from a variety of chronic diseases, and should therefore be encouraged.     

Plant secondary metabolites and gut health: the case for phenolic acids

Plant-based diets contain a plethora of secondary metabolites that may impact on health and disease prevention. Much attention has been focused on the potential bioactivity and nutritional relevance of several classes of phytochemicals such as flavonoids, carotenoids, phyto-oestrogens and glucosinolates. Less attention has been paid to simple phenolic acids that are widely found in fruit, vegetables, herbs, spices and beverages. Daily intakes may exceed 100 mg. In addition, bacteria in the gut can perform reactions that transform more complex plant phenolics such as anthocyanins, procyanidins, flavanones, flavonols, tannins and isoflavones into simple phenolic metabolites. The colon is thus a rich source of potentially active phenolic acids that may impact both locally and systemically on gut health. Both the small and large intestine (colon) contain absorption sites for phenolic acids but low post-prandial concentrations in plasma indicate minimal absorption early in the gastrointestinal tract and/or rapid hepatic metabolism and excretion. Therefore, any bioactivity that contributes to gut health may predominantly occur in the colon. Several phenolic acids affect the expression and activity of enzymes involved in the production of inflammatory mediators of pathways thought to be important in the development of gut disorders including colon cancer. However, at present, we remain largely ignorant as to which of these compounds are beneficial to gut health. Until we can elucidate which pro-inflammatory and potentially carcinogenetic changes in gene expression can be moderated by simple phenolic acids, it is not possible to recommend specific plant-based foods rich in particular phenolics to optimise gut health.     

Phytonutrient deficiency: the place of palm fruit

The oil palm (Elaeis guineensis) is native to many West African countries, where local populations have used its oil for culinary and other purposes. Large-scale plantations, established principally in tropical regions (Asia, Africa and Latin America), are mostly aimed at the production of oil, which is extracted from the fleshy mesocarp of the palm fruit, and endosperm or kernel oil. Palm oil is different from other plant and animal oils in that it contains 50% saturated fatty acids, 40% unsaturated fatty acids, and 10% polyunsaturated fatty acids. The fruit also contains components that can endow the oil with nutritional and health beneficial properties. These phytonutrients include carotenoids (alpha-,beta-,and gamma-carotenes), vitamin E (tocopherols and tocotrienols), sterols (sitosterol, stigmasterol and campesterol), phospholipids, glycolipids and squalene. In addition, it is recently reported that certain water-soluble powerful antioxidants, phenolic acids and flavonoids, can be recovered from palm oil mill effluent. Owing to its high content of phytonutrients with antioxidant properties, the possibility exists that palm fruit offers some health advantages by reducing lipid oxidation, oxidative stress and free radical damage. Accordingly, use of palm fruit or its phytonutrient-rich fractions, particularly water-soluble antioxidants, may confer some protection against a number of disorders or diseases including cardiovascular disease, cancers, cataracts and macular degeneration, cognitive impairment and Alzheimer's disease. However, whilst prevention of disease through use of these phytonutrients as in either food ingredients or nutraceuticals may be a worthwhile objective, dose response data are required to evaluate their pharmacologic and toxicologic effects. In addition, one area of concern about use of antioxidant phytonutrients is how much suppression of oxidation may be compatible with good health, as toxic free radicals are required for defence mechanisms. These food-health concepts would probably spur the large-scale oil palm (and monoculture) plantations, which are already seen to be a major cause of deforestation and replacement of diverse ecosystems in many countries. However, the environmental advantages of palm phytonutrients are that they are prepared from the readily available raw material from palm oil milling processes. Palm fruit, one of only a few fatty fruits, is likely to have an increasingly substantiated place in human health, not only through the provision of acceptable dietary fats, but also its characteristic protective phytonutrients.     

Enhancing health benefits of berries through phenolic antioxidant enrichment: focus on cranberry

Emerging epidemiological evidence is increasingly pointing to the beneficial effects of fruits and vegetables in managing chronic and infectious diseases. These beneficial effects are now suggested to be due to the constituent phenolic phytochemicals having antioxidant activity. Cranberry like other fruits is also rich in phenolic phytochemicals such as phenolic acids, flavonoids and ellagic acid. Consumption of cranberry has been historically been linked to lower incidences of urinary tract infections and has now been shown to have a capacity to inhibit peptic ulcer-associated bacterium, Helicobacter pylori. Isolated compounds from cranberry have also been shown to reduce the risk of cardiovascular diseases. Recent evidence suggests the ability of phytochemical components in whole foods in being more effective in protectively supporting human health than compared to isolated individual phenolic phytochemicals. This implies that the profile of phenolic phytochemicals determines the functionality of the whole food as a result of synergistic interaction of constituent phenolic phytochemicals. Solid state bioprocessing using food grade fungi common in Asian food cultures as well as cranberry phenolic synergies through the addition of functional biphenyls such as ellagic acid and rosmarinic acid along with processed fruit extracts have helped to advance these concepts. These strategies could be further explored to enrich cranberry and cranberry products with functional phytochemicals and further improve their functionality for enhancing health benefits.     

Age and gender dependent profile of food choice

Several studies have described remarkable differences in food choice between men and women. Consistently, women are reported to have higher intakes of fruit and vegetables, higher intakes of dietary fiber and lower intakes of fat. In accordance with such more healthy food choice, women usually attach greater importance to healthy eating. In addition, the motivation of weight control is more prominent in women and they are more likely to diet or restrain their eating behavior. Recently, studies found that health beliefs and weight control motivation may explain up to 50 percent of gender differences in food choice. In addition, less healthy food choice profiles of men may be related to their poorer nutritional knowledge. However, health beliefs, eating attitudes and dieting appear to be phenomena which vary throughout the life span. In growing older, changes in the chemosensory perceptual systems play an important role in food choice. The decline of gustatory and--perhaps even more pronounced--in olfactory function may lead to a decrease of the pleasantness of food, thus limiting the reinforcing properties of food intake which eventually results in a decrease of appetite, often reported in elderly people. In addition, there are some indications that sensory-specific satiety diminishes with age. Sensory-specific satiety is the reduction in the pleasantness of food as it is consumed. This decrease of pleasantness usually motivates the choice of other foods and therefore, a varied diet. Therefore, the decrease of sensory-specific satiety may in part explain the limited variety of the diet sometimes seen in elderly people. However, lifestyle, socio-economic situation and other variables may limit the influence of such physiological changes and help to maintain an adequate food intake despite these age-related processes.     

Whole grains and CVD risk

There is an increasing body of evidence, including that from prospective population studies and epidemiological observational studies, suggesting a strong inverse relationship between increased consumption of wholegrain foods and reduced risk of CVD. This evidence has translated into specific dietary recommendations in the USA to consume at least three servings of whole grain per d, and has informed the development of specific health claims for wholegrain foods both in the USA and in Europe. Wholegrain foods are rich sources of many nutrients and phytochemicals, including complex carbohydrates, dietary fibre, minerals, vitamins, antioxidants and phyto-oestrogens such as lignans. Many of these components are lost from the grain during processing and although some may be replaced (such as in the mandatory fortification of white flour), this practice ignores the possible synergistic effects of the 'natural' constituents. The notion that wholegrain foods are simply a source of dietary fibre has been dispelled, although the additional components that contribute to the health benefits have not been clearly identified. In addition, the mechanisms by which wholegrain foods may have their effect are poorly understood. At present there are few strictly-controlled intervention studies that have confirmed a beneficial effect of increased consumption of wholegrain foods, demonstrated the level of consumption required to elicit a beneficial effect or provided evidence of modes of action. Although wholegrain foods are considered amongst the healthiest food choices available, their consumption falls well below current recommendations, which have been based mainly on epidemiological evidence. Well-controlled intervention studies are needed to provide more detailed mechanistic evidence to support the health claims and findings which can be used to develop effective public health strategies to promote whole-grain consumption.     

Fermented foods: patented approaches and formulations for nutritional supplementation and health promotion

Fermentation has had a long history in human food production and consumption. Fermented foods and beverages can comprise anywhere between 5-40% of the human diet in some populations. Not only is this process beneficial for extending shelf-life for foods and beverages, but also fermentation can enhance nutritional properties in a safe and effective manner. In many developed countries, traditional methods are now replaced with specific technologies for production of fermented foods, and an emerging industrial practice allows for higher quality standardization of food products in the market place. Due to changes in fermentation processes and the increased consumption of these products, a detailed review of recent patents involving fermented foods and beverages and their impact on health is warranted. Fermented food products that can enhance nutrition, improve health, and prevent disease on a global level will require consistent fermentation methods, evaluation of nutritional compositions, and food safety testing. This review is intended to guide the development of fermented foods for enhanced human health benefits and suggests the need for multidisciplinary collaborations and structural analysis across the fields of food science, microbiology, human nutrition, and biomedical sciences.     

The strawberry: composition, nutritional quality, and impact on human health

Strawberries are a common and important fruit in the Mediterranean diet because of their high content of essential nutrients and beneficial phytochemicals, which seem to have relevant biological activity in human health. Among these phytochemicals, anthocyanin and ellagitannins are the major antioxidant compounds. Although individual phytochemical constituents of strawberries have been studied for their biological activities, human intervention studies using whole fruits are still lacking. Here, the nutritional contribution and phytochemical composition of the strawberry are reviewed, as is the role played by the maturity, genotype, and storage effects on this fruit. Specific attention is focused on fruit absorption, metabolism, and the possible beneficial biological activity on human health.     

Non-polyol low-digestible carbohydrates: food applications and functional benefits

Many LDCs currently on the market are not digested in the upper gastrointestinal tract and become fermented in the large intestine. They possess physiological benefits similar to those of dietary fibre. For some of these materials the fermentation process is highly specialised and leads to the selective stimulation and growth of beneficial gut bacteria, e.g. bifidobacteria. These materials are described as prebiotics, which are defined as nutrients fermented in the large bowel that favour the growth of desirable large bowel microflora. This activity has been demonstrated for inulin and oligofructose. Two other carbohydrates with low digestibility that offer desirable physiological properties are resistant starch (RS) and polydextrose (PD). These 'functional benefits have led to considerable interest from the food industry leading to the use of these ingredients in the development of new 'healthy' products. This paper describes the use of these materials in the development of 'healthy' products, some of their functional properties, and the benefits they confer on different food systems.     

In vitro fermentation of gum acacia – impact on the faecal microbiota

Interest in the consumption of gum acacia (GA) has been associated with beneficial health effects, which may be mediated in part by prebiotic activity. Two doses of GA and fructooligosaccharide (FOS) (1 and 2%) were tested for their efficacy over 48?h in pH- and temperature-controlled anaerobic batch cultures inoculated with human faeces. Samples were taken after 0, 5, 10, 24 and 48?h of fermentation. The selective effects of GA (increases in Bifidobacterium spp. and Lactobacillus spp.) were similar to those of the known prebiotic FOS. The 1% dose of substrates showed more enhanced selectivity compared to the 2% dose. The fermentation of GA also led to SCFA production, specifically increased acetate after 10, 24 and 48?h of fermentation, propionate after 48?h and butyrate after 24 and 48?h. In addition, FOS led to significant increase in the main SCFAs. These results suggest that GA displays potential prebiotic properties.     

Cold-storage affects antioxidant properties of apples in Caco-2 cells

Data on the composition of phenolic antioxidant compounds present in food plants and assessment of their activity are essential for epidemiological explanation of the health benefits of fruit and vegetables. Various factors such as cultivation methods, industrial processing, and storage may affect the final concentrations of phytochemicals in food plants and their eventual bioactivity. This study investigated the influence of commercial cold-storage periods on the antioxidant properties of apples grown either by organic or integrated systems. In both cases, total phenolics and total antioxidant activity decreased only in the first 3 mo and only in apples with skin (P < 0.05), suggesting that cold storage rapidly impoverishes these properties in skin but not in pulp. Assessment of antioxidant bioactivity in vitro, measured in terms of intracellular antioxidant, cytoprotective, and antiproliferative activity in human colon carcinoma (Caco-2) cells (differentiated to normal intestinal epithelia for intracellular antioxidant and cytoprotective effects), showed strong, time-related decreases over 6 mo of cold storage for all 3 parameters (P < 0.01), irrespective of the cultivation system. These findings with integrated and organic apples further support the concept that organic systems of cultivation do not generally provide real health benefits. Moreover, the data from the present study clearly show that factors such as cold storage may affect the antioxidant properties of apples. Epidemiological studies on the cancer-preventive benefits of fruits and vegetables should take into account the cold-storage bias for apples, and possibly for other products.     

Health and social factors affecting the food choice and nutritional intake of elderly people with restricted mobility

Background: Little is known about the magnitude of social and health factors which affect the food choices and nutritional intake of elderly people with restricted mobility. Design: Semistructured taped interviews were used to capture expressions used in the identification of health and social factors which affect food choices and nutritional intake of 13 female subjects and three male subjects living in the community with restricted mobility. Twenty-four-hour recall assessment was used to establish their dietary intake and meal patterns. Results: There was an inadequate intake of fluid, fruit and vegetables and nonstarch polysaccharide by the subjects. In addition, there was an infrequent consumption of cooked meals. Health and social factors which affect the food choices and nutritional intake of older people were identified as being inadequate money, inadequate food storage facilities, physical disabilities affecting food preparation, poor access to shops, difficulties in undertaking the shopping, type of cooking facilities, loneliness and bereavement. Conclusion: Elderly people living in the community with restricted mobility may be unable to consume an optimum nutritional intake due to the health and social factors identified which affect their food choices and nutritional intake.     

The physiology of colonic metabolism. Possibilities for interventions with pre- and probiotics

The awareness is increasing that in the colon many metabolic processes take place in relation to the fermentation of our food, which might be relevant for health and disease. However, the relation between food, colon metabolism and health or disease is far from clear. In this overview, the physiology of colonic metabolism and possibilities for its modification by the use of pre- and probiotics are discussed. Results of in vitro and animal studies indicate a beneficial impact of probiotics on adverse metabolic processes in the colon, but confirmation in human studies has to be extended. The administration of prebiotics seems to be promising with regard to their capacity to modulate the bacterial composition in the colon and there are indications that prebiotics can beneficially influence colonic metabolism. Whether these modulations brought about by pre- or probiotics have an effect on the health of the host, however, needs to be established in most cases.     

Prebiotic inulin-type fructans: nutritional benefits beyond dietary fibre source

Summary   For several years, there has been an increasing awareness of the fundamental role that the complex bacterial ecosystem plays in our health. Inulin and oligofructose are prebiotic dietary fibres naturally present in the chicory root. They escape metabolism in the small intestine, and their selective fermentation by the human colonic microflora leads to a shift in the composition of the indigenous bacterial ecosystem, in favour of health-promoting bifidobacteria. In addition to their dietary fibre effects on improved bowel regularity, several physiological advantages are linked to their specific pattern of fermentation in the colon, including improved mineral absorption, enhanced natural host defences and colonic protection, improved gut health, and beneficial influence on appetite regulation. The aim of the present review was to highlight the nutritional benefits of inulin-type fructans, focusing on key physiological functions.     

Satiety-enhancing products for appetite control: science and regulation of functional foods for weight management

The current review considers satiety-based approaches to weight management in the context of health claims. Health benefits, defined as beneficial physiological effects, are what the European Food Safety Authority bases their recommendations on for claim approval. The literature demonstrates that foods that target within-meal satiation and post-meal satiety provide a plausible approach to weight management. However, few ingredient types tested produce the sustainable and enduring effects on appetite accompanied by the necessary reductions in energy intake required to claim satiety/reduction in hunger as a health benefit. Proteins, fibre types, novel oils and carbohydrates resistant to digestion all have the potential to produce beneficial short-term changes in appetite (proof-of-concept). The challenge remains to demonstrate their enduring effects on appetite and energy intake, as well as the health and consumer benefits such effects provide in terms of optimising successful weight management. Currently, the benefits of satiety-enhancing ingredients to both consumers and their health are under researched. It is possible that such ingredients help consumers gain control over their eating behaviour and may also help reduce the negative psychological impact of dieting and the physiological consequences of energy restriction that ultimately undermine weight management. In conclusion, industry needs to demonstrate that a satiety-based approach to weight management, based on single-manipulated food items, is sufficient to help consumers resist the situational and personal factors that drive overconsumption. Nonetheless, we possess the methodological tools, which when employed in appropriate designs, are sufficient to support health claims.     

The Health Impact of Nighttime Eating: Old and New Perspectives

Nighttime eating, particularly before bed, has received considerable attention. Limiting and/or avoiding food before nighttime sleep has been proposed as both a weight loss strategy and approach to improve health and body composition. Indeed, negative outcomes have been demonstrated in response to large mixed meals in populations that consume a majority of their daily food intake during the night. However, data is beginning to mount to suggest that negative outcomes may not be consistent when the food choice is small, nutrient-dense, low energy foods and/or single macronutrients rather than large mixed-meals. From this perspective, it appears that a bedtime supply of nutrients can promote positive physiological changes in healthy populations. In addition, when nighttime feeding is combined with exercise training, any adverse effects appear to be eliminated in obese populations. Lastly, in Type I diabetics and those with glycogen storage disease, eating before bed is essential for survival. Nevertheless, nighttime consumption of small (~150 kcals) single nutrients or mixed-meals does not appear to be harmful and may be beneficial for muscle protein synthesis and cardiometabolic health. Future research is warranted to elucidate potential applications of nighttime feeding alone and in combination with exercise in various populations of health and disease.     

A standardised approach towards PROving the efficacy of foods and food constituents for health CLAIMs (PROCLAIM): providing guidance

Diet is well known to have beneficial health properties that extend beyond traditionally accepted nutritional effects. The approach involved in elucidating these beneficial physiological effects is becoming more important, as reflected by increasing research being undertaken. With growing consumer awareness of foods and food constituents and their relationship to health, the key questions for regulators, scientists and the food industry continue to relate to: (1) how consumers could be protected and have confidence that the health claims on foods are well supported by the evidence; (2) how research on physiological effects of food (constituents) and their health benefits could be stimulated and supported; (3) how research findings could be used in the development of innovative new food products. The objectives of this paper are to provide a set of recommendations on the substantiation of health claims for foods, to develop further guidance on the choice of validated markers (or marker patterns) and what effects are considered to be beneficial to the health of the general public (or specific target groups). Finally, the case for developing a standardised approach for assessing the totality of the available scientific data and weighing the evidence is proposed.