The immune system acts to protect the host from infectious agents that exist in the environment (bacteria, viruses, fungi, parasites) and from other noxious insults. The immune system is constantly active, acting to discriminate ‘non-self’ from ‘self’. The immune system has two functional divisions: the innate and the acquired. Both components involve various blood-borne factors (complement, antibodies, cytokines) and cells. A number of methodologies exist to assess aspects of immune function; many of these rely upon studying cells in culture ex vivo. There are large inter-individual variations in many immune functions even among the healthy. Genetics, age, gender, smoking habits, habitual levels of exercise, alcohol consumption, diet, stage in the female menstrual cycle, stress, history of infections and vaccinations, and early life experiences are likely to be important contributors to the observed variation. While it is clear that individuals with immune responses significantly below ‘normal’ are more susceptible to infectious agents and exhibit increased infectious morbidity and mortality, it is not clear how the variation in immune function among healthy individuals relates to variation in susceptibility to infection. Nutrient status is an important factor contributing to immune competence: undernutrition impairs the immune system, suppressing immune functions that are fundamental to host protection. Undernutrition leading to impairment of immune function can be due to insufficient intake of energy and macronutrients and/or due to deficiencies in specific micronutrients. Often these occur in combination. Nutrients that have been demonstrated (in either animal or human studies) to be required for the immune system to function efficiently include essential amino acids, the essential fatty acid linoleic acid, vitamin A, folic acid, vitamin B6, vitamin B12, vitamin C, vitamin E, Zn, Cu, Fe and Se. Practically all forms of immunity may be affected by deficiencies in one or more of these nutrients. Animal and human studies have demonstrated that adding the deficient nutrient back to the diet can restore immune function and resistance to infection. Among the nutrients studied most in this regard are vitamin E and Zn. Increasing intakes of some nutrients above habitual and recommended levels can enhance some aspects of immune function. However, excess amounts of some nutrients also impair immune function. There is increasing evidence that probiotic bacteria improve host immune function. The effect of enhancing immune function on host resistance to infection in healthy individuals is not clear.

The source and pattern of N supply was varied in the rumen simulation technique (RUSITEC) in order to determine if continuous, rather than transient, availability of peptides was required for optimum ruminal fermentation. The energy source was fibre prepared from sugar-beet pulp. N was added as NH3 continuously infused (AC) or peptides (Bacto® Casitone, a pancreatic hydrolysate of casein; Difco Laboratories, Detroit, MI, USA) continuously infused (PC) or added as a single dose at the time of feeding (PS). Free peptides were detected in the fermenter liquid for 4 h after feeding in the AC treatment, for 10 h in the PS treatment, and at all times with the PC treatment. Treatments had no effect on DM degradation. Approximately 40 % of the degradation occurred during the time no peptides were detected in the PS treatment. Microbial N flow tended to be higher with the peptide additions (P<0·061), with no significant difference between the two peptides treatments. The production of liquid-associated micro-organisms (LAM) was higher in the PC treatment (P<0·05) and the proportion of LAM derived from NH3 lower (P<0·05). However, LAM only accounted for 20–30 % total microbial population. Our main conclusion was that peptides had a small stimulatory effect on the fermentation, but there was no indication that synchrony of supply of energy and amino acid-N in the fermenter promoted a more efficient fermentation than non-synchronous supply. This conclusion must be qualified, however, because some N remained in the fibre and may have become available progressively as the fibre was digested by the micro-organisms.

The present study was designed to evaluate the effect of increased viscosity of the intestinal digesta on proliferation of enterotoxigenic Escherichia coli and the intestinal spirochaete Brachyspira pilosicoli in weaned pigs. Pigs were fed an experimental diet based on cooked white rice (R), which was supplemented with carboxymethylcellulose (CMC; 40 g/kg diet) to increase digesta viscosity. Thirty-six piglets weaned at 21 d of age were divided into six groups, three of which were fed R and three R+CMC. Addition of CMC increased digesta viscosity in the ileum (P=0·01), caecum (P=0·0007) and colon (P=0·0035), without increasing indices of large intestinal fermentation. Pigs fed R+CMC developed a natural infection with enterotoxigenic E. coli after weaning and had more (P<0·0001) diarrhoea than pigs fed R. Subsequent experimental infection of two groups of pigs with B. pilosicoli resulted in more (P<0·0001) colonisation in pigs fed R+CMC than R. At this time, all pigs fed R+CMC had wetter (P<0·0001) faeces than those fed R, irrespective of whether they were infected with B. pilosicoli, but infected pigs also had an increased (P=0·025) number of days with diarrhoea post-infection irrespective of diet. In pigs fed R+CMC, it was not clear to what extent the increased viscosity associated with CMC, or the concurrent infection with enterotoxigenic E. coli, was responsible for the increased proliferation of B. pilosicoli. In a second experiment, five pigs that were weaned onto an R diet were transferred onto R+CMC 3 weeks later. These pigs did not develop a natural infection with enterotoxigenic E. coli after the diet change, confirming the particular susceptibility of pigs to enterotoxigenic E. coli proliferation immediately post-weaning.

Colorectal cancer is one of the most important causes of cancer morbidity and mortality in Western countries. While a myriad of healthful effects have been attributed to the probiotic lactic acid bacteria (LAB), perhaps the most controversial remains that of anticancer activity. It should be pointed out that there is no direct experimental evidence for cancer suppression in man as a result of consumption of lactic cultures in fermented or unfermented dairy products. However, there is a wealth of indirect evidence, based largely on laboratory studies, in the literature. The precise mechanisms by which LAB may inhibit colon cancer are presently unknown. However, such mechanisms might include: alteration of the metabolic activities of intestinal microflora; alteration of physico-chemical conditions in the colon; binding and degrading potential carcinogens; quantitative and/or qualitative alterations in the intestinal microflora incriminated in producing putative carcinogen(s) and promoters (e.g. bile acid-metabolising bacteria); production of antitumourigenic or antimutagenic compounds; enhancing the host's immune response; and effects on physiology of the host. These potential mechanisms are addressed in the present paper.

The effects of the dietary oligosaccharide raffinose on immune responses, with special reference to its anti-allergic functions, were examined in vivo. First, feeding a diet supplemented with 50 g raffinose/kg to BALB/c mice significantly (P<0·05) increased interleukin (IL) 12 secretion from isolated Peyer's patch (PP) cells in vitro compared with feeding control diet. When isolated PP cells were used as antigen-presenting cells (APC) for CD4+ T-splenocytes isolated from ovalbumin (OVA)-specific T-cell receptor transgenic (Tg) mice in the presence of OVA as antigen, significantly (P<0·05) higher levels of interferon-γ were observed in the cultures using APC from raffinose-fed mice than those cultures using APC from control mice. Second, the diet containing 50 g raffinose/kg or control diet was fed to OVA Tg mice, and subsequently, OVA was added to each diet to prime T cells in vivo. CD4+ T-cells from the mesenteric lymph nodes of the raffinose-fed mice secreted significantly (P<0·05) higher levels of IL-2 and significantly (P<0·05) lower levels of IL-4 following in vitro antigenic stimulation compared with those of the control mice. These present results suggest that feeding raffinose may suppress differentiation of naïve T-helper (Th) cells into Th2 cells in the mesenteric lymphoid nodes. Last, feeding raffinose suppressed rises of serum immunoglobulin E levels in the Tg mice treated with long-term ingestion of OVA. In conclusion, it is suggested that dietary raffinose suppresses serum immunoglobulin E response through suppression of Th2-type immune response against oral antigen in the lymphoid organs located in or near the intestine.

Starch and fibre can be extracted, using wet or dry processes, from a variety of grain legumes and used as ingredients for food. a-Galactosides can be isolated during wet processes from the soluble extract. Starch isolates or concentrates are mostly produced from peas, whereas dietary fibre fractions from peas and soyabean are commercially available. The physico-chemical characteristics of fibre fractions very much depend on their origin, outer fibres being very cellulosic whereas inner fibres contain a majority of pectic substances. Inner fibres are often used as texturing agents whereas outer fibres find their main uses in bakery and extruded products, where they can be introduced to increase the fibre content of the food. Most investigations on impacts on health have been performed on soyabean fibres. When positive observations were made on lipaemia, glucose tolerance or faecal excretion, they were unfortunately often obtained after non-realistic daily doses of fibres. Legume starches contain a higher amount of amylose than most cereal or tuber starches. This confers these starches a lower bioavailability than that of most starches, when raw or retrograded. Their low glycaemic index can be considered as beneficial for health and especially for the prevention of diseases related to insulin resistance. When partly retrograded, these starches can provide significant amount of butyrate to the colonic epithelium and may help in colon cancer prevention. a-Galactosides are usually considered as responsible for flatus but their apparent prebiotic effects may be an opportunity to valorize these oligosaccharides.

The development of the sports food market and industrial involvement have led to numerous nutritional studies to define the type of nutrients that are most suited to support energy metabolism, fluid balance and muscle function. The key question in many of these studies was: ‘Does the product lead to a significant product/consumer benefit that can be used as a claim on the package?’ New methods and techniques have been developed, partly with sponsorship of the food industry, with the goal of measuring the effects of specific nutrients and supplements on athletic performance and metabolism. In line with this development, a wide variety of supplements and sports foods/drinks labelled with various performance or health benefit statements have been launched on the sports nutrition market. Although a variety of products have been tested clinically, there are also many products on the market with benefit claims that cannot be supported by sound nutritional and sports physiological science. The current short review highlights some of the methods and biomarkers that are used to substantiate product/consumer benefit claims for foods and drinks that are marketed as functional foods for athletes.

We have tested the effect of dietary fatty acids on aspects of innate and specific adaptive T helper (Th) 1- and Th2-driven immune responses in a murine sensitisation model using dinitrochlorobenzene as sensitiser. Six groups of fifteen BALB/c mice were fed diets containing 30 % fat (by energy) for 8 weeks. Diets were rich in saturated fatty acids, n-6 polyunsaturated fatty acid (PUFA), or n-3 PUFA, each at a sufficient (11, 35 and 68 mg/kg) and a supplemented vitamin E level (1028, 1031 and 1030 mg/kg respectively). Feeding n-6 PUFA marginally decreased % phagocytosing cells at the low vitamin E level, but had no other effects on immune function. The n-3 PUFA diets decreased production of prostaglandin E2 while increasing oxidative burst and tumour necrosis factor α production. In addition adaptive Th1-driven responses (immunoglobulin, Ig)G2a, IgG2b, interferon-γ:interleukin 4) were decreased, whereas Th2-driven and mucosal immune responses were increased (IgE) or unaffected (IgG1, IgA). Combination with high levels of α-tocopherol did not affect the reduced prostaglandin E2 production, augmented the increase of tumour necrosis factor α production and tended to ameliorate the selective suppressive effects of n-3 PUFA on certain Th1-driven effects (interferon-γ:interleukin 4 ratio and IgG2a levels). We conclude that the sensitisation model appears useful for application in nutrition research. It allows a broad assessment of the effects of dietary intervention on various aspects of immune responsiveness, and as such provides a valuable model to assess, characterise and rank effects of foods and/or nutrients on a range of immune functions, including Th1–Th2 polarisation.

Folate intake is strongly influenced by various methods of cooking that can degrade the natural forms of the vitamin in foods. The aim of the present study was to determine the effect of different cooking methods on folate retention in various foods that contribute to folate intake in the UK diet. Typical purchasing and cooking practices of representative food folate sources were determined from a questionnaire survey of local shoppers (n 100). Total folate was determined by microbiological assay (Lactobacillus casei NCIMB 10463) following thermal extraction and tri-enzyme (α-amylase, protease and conjugase) treatment in raw foods and after typical methods of cooking. Boiling for typical time periods resulted in only 49 % retention of folate in spinach (191·8 and 94·4 μg/100 g for raw and boiled spinach respectively; P<0·005), and only 44 % in broccoli (177·1 and 77·0 μg/100 g for raw and boiled broccoli respectively, P<0·0001). Steaming of spinach or broccoli, in contrast, resulted in no significant decrease in folate content, even for the maximum steaming periods of 4·5 min (spinach) and 15·0 min (broccoli). Prolonged grilling of beef for the maximum period of 16·0 min did not result in a significant decrease in folate content (54·3 and 51·5 μg/100 g for raw and grilled beef respectively). Compared with raw values, boiling of whole potatoes (skin and flesh) for 60·0 min did not result in a significant change in folate content (125·1 and 102·8 μg/100 g for raw and boiled potato respectively), nor was there any effect on folate retention whether or not skin was retained during boiling. These current results show that the retention of folate in various foods is highly dependent both on the food in question and the method of cooking. Thus, public health efforts to increase folate intake in order to improve folate status should incorporate practical advice on cooking.

The objective of this investigation was to compare, at several levels of intake, the capacity of diverse cold-pressed plant oils to support development of acquired immune competence assessed in vivo in the weanling mouse. Safflower, maize, soyabean, rapeseed, flaxseed and olive oils were selected to represent widely differing 18: 1n-9, 18: 2n-6 and 18: 3n-3 contents, and each oil was fed at three dietary levels (40, 80 and 160 g/kg) as the exclusive source of fat. C57BL/6J mice, ten males and ten females, had free access to each diet for 28 d beginning at 19 d of age. The primary serum haemagglutinin response to sheep red blood cells and the primary cutaneous delayed hypersensitivity response to dinitrochlorobenzene were used to assess humoral and cell-mediated competence respectively, on day 28. A zero-time control group, assessed immunologically at 19 d of age, was also included (n 32). Independently of dietary oil level, flaxseed, rapeseed, olive and soyabean oils supported development of a more vigorous antibody response than safflower (a useful point of reference, being rich in 18: 2n-6 but low in 18: 1n-9 and 18: 3n-3), whereas only flaxseed oil supported development of cell-mediated responsiveness exceeding that of safflower-fed mice. Independently of oil type, development of both immunological indices correlated negatively with intake of 18: 2n-6, and development of humoral competence varied inversely with dietary oil level. A low content of 18: 2n-6, perhaps less than 20 g/100 g fatty acids, appears important to the capacity of a plant oil to support development of acquired immune competence in the young.

The short-term consumption of foods that differed in energy density (ED) and/or NaHCO3 supplementation, on subsequent food intake and diet selection in sheep were measured. Thirty sheep weighing 35·9 (SD 2·89) KG WERE USED. TWO FOODS WERE FORMULATED: H HAD 11 AND L HAD 8 MJ METABOLIZABLE ENERGY/KG FRESH MATTER. FOUR FURTHER FOODS WERE FORMULATED BY ADDING EITHER 40 G NAHCO3/KG OR 16·5 G NACL/KG TO FOODS H AND L. NACL WAS ADDED TO GIVE THE SAME NA CONCENTRATION AS WITH 40 G NAHCO3/KG TO CONTROL FOR ANY EFFECTS OF NA PER SE. IN A PRELIMINARY TEST, IT WAS FOUND THAT A 2 H CONSUMPTION OF FOOD H SUPPLEMENTED WITH NAHCO3 COULD BUFFER POTENTIAL IMPACT ON THE RUMEN ENVIRONMENT OF SUBSEQUENT CONSUMPTION OF FOOD H ALONE (AS JUDGED BY RUMEN PH AND ACID-BUFFERING CAPACITY); HOWEVER, IT WAS NOT AS EFFECTIVE AS THE CONSUMPTION OF FOOD L ALONE IN DOING SO. EACH FOOD TREATMENT WAS OFFERED TO ONE OF SIX GROUPS (N 5) FOR 2 H FOLLOWING 16 H OF FOOD DEPRIVATION. SHEEP WERE THEN OFFERED A CHOICE BETWEEN H AND L FOR A FURTHER 6 H. SUPPLEMENTING H OR L WITH EITHER NAHCO3 OR NACL HAD NO SIGNIFICANT EFFECT ON EITHER INTAKE OR DIET SELECTION. ED SIGNIFICANTLY (P<0·01) AFFECTED INTAKE DURING THE 2 H SINGLE FEEDING PERIOD, WITH SHEEP OFFERED H OR L CONSUMING 540 AND 663 (sed 37) g respectively, but had no effect on subsequent intake during the choice period. During the choice period all sheep showed a preference for food H, but sheep previously offered L selected significantly more H (0·873 g/g) than sheep previously offered H (0·544 (sed 0·028) g/g; P<0·001). It is concluded that short-term consumption of foods that differ in ED, and hence in their potential impact on the rumen environment, significantly affects subsequent diet selection. This is in agreement with the hypothesis that ruminant animals select a diet to help maintain the rumen environment within a certain physiological range. Food H with 40 g NaHCO3 added/kg may not have been sufficient to affect subsequent diet selection. It is suggested that larger, rather than smaller, changes in the rumen environment achieved through previous feeding should be expected to alter subsequent diet selection.

Although protein–energy malnutrition is a common cause of immunodeficiency, the immune function in underweight anorexia nervosa (AN) patients usually seems to be better preserved than would be expected. However, a deranged cytokine production and its consequences are currently being investigated in these patients. This study was aimed at measuring, over time, the capacity of peripheral blood mononuclear cells (PBMC) from AN in-patients to produce several cytokines involved in the regulation of immune responses. The in vitro production of interferon (IFN)-γ, interleukin (IL)-2, tumour necrosis factor (TNF)-α, IL-6 and IL-1β by phytohaemagglutinin-stimulated PBMC were assessed on forty female adolescents with AN. These measures were carried out twice, upon hospital admission and at discharge, which occurred on average after 1 month. Thirty-five control subjects were also studied. Cytokines were measured by ELISA kits. The production of TNF-α and IL-6 was lower and production of IL-1β higher in AN patients than in the control group at both time points of assessment. Refeeding for 1 month was not enough time to reverse these differences and patients still had a low body weight at discharge. IFN-γ production was lower in the patients than in control subjects only at discharge and no differences were found in IL-2 production between both groups. The results suggest that a mechanism involving modifications in the secretion pattern of proinflammatory cytokines could explain some immune function findings in underweight AN patients.

Early postnatal overnutrition (PNO) induced by restricting litter size in rats leads to increased body-weight (BW) and body-fat gain in later life. PNO rats are used as an animal model of moderate obesity and early hyperinsulinism. We investigated whether the increased adiposity could be due to a decreased energy expenditure. Male newborn Wistar rats were raised in litters of either two (SL) or twelve pups (NL), weaned at 4 weeks of age and subsequently fed ad libitum. BW was recorded continuously until 12 weeks of age. Daily energy intake, total daily energy expenditure (EE, measured by indirect calorimetry) and body composition were measured in weaned pups at 5, 8 and 12 weeks of age. SL rats displayed increased BW compared with NL rats from week 2 to 5 and again from week 10 to 12. Lean body mass, body fat and protein content and total EE were increased in SL rats at week 5. The same linear correlation described the relationship between BW and total EE in NL and SL rats. At week 8 to 12 no differences in energy metabolism could be found, but the total fat content was increased in SL rats at week 12. Energy balance, i.e. assimilated energy minus EE, was no different between SL and NL at any time that it was measured. We conclude that although PNO rats display increased adiposity in early life, there seem to be no long-lasting effects on energy metabolism in later life, even if a tendency to increased adiposity can still be detected.

Probiotics could represent an effective alternative to the use of synthetic substances in nutrition and medicine. The data concerning the efficacy of probiotics are often contradictory. This paper focuses on the enhancement of the efficacy of probiotics by their combination with synergistically acting components of natural origin. Maltodextrins can be obtained by enzymatic hydrolysis of starch and are suitable for consumption. Administration of Lactobacillus paracasei together with maltodextrin decreased the number of Escherichia coli colonising the jejunal mucosa of gnotobiotic piglets by 1 logarithm compared to the control group. Fructo-oligosaccharides (FOS) are naturally occurring oligosaccharides, mainly of plant origin. L. paracasei administered in combination with FOS significantly increased counts of Lactobacillus spp., Bifidobacterium spp., total anaerobes and total aerobes compared to the control group as well as the L. paracasei group. It also significantly decreased Clostridium and Enterobacterium counts in the faeces of the weanling piglets compared with the control group. Dietary lipids influence the gastrointestinal microbiota and specifically the population of lactic acid bacteria. In gnotobiotic piglets the oral administration of an oil containing polyunsaturated fatty acids (PUFA) significantly increased the number of L. paracasei adhering to jejunal mucosa compared to the control group. Our results showed that maltodextrin KMS X-70 and PUFA can be used to enhance the effect of probiotic micro-organisms in the small intestine, and similarly FOS enhance the effect of probiotic micro-organisms in the large intestine.

Total energy expenditure (EE) can be assessed in children by the heart-rate (HR) monitoring technique calibrated against open-circuit indirect calorimetry (IC). In this technique, sleeping EE is usually estimated as the lowest value of a 30 min resting EE measurement×0·90 to give an average for the total sleeping period. However, sleeping is a dynamic process in which sleeping EE is modulated by the effect of factors such as body movement and different sleep stages. The aim of the present study was to determine a new method to improve the sleeping EE measurement by taking into account body movements during sleep. Twenty-four non-obese children participated in the present study. All subjects passed through a calibration period. HR and EE measured by IC were simultaneously collected during resting, the postprandial period, and during different levels of activity. Different methods for computing sleeping EE (resting EE×0·90 with different breakpoints (‘flex point’ HR with linear regression or ‘inflection point’ (IP) HR with the third order polynomial regression equation (P3)) were compared with EE measured for least 2·0 h in eight sleeping children. The best method of calculation was then tested in sixteen children undergoing HR monitoring and with a body movement detector. In a subset of eight children undergoing simultaneous sleeping EE measurement by IC and HR, the use of the equation resting EE×0·8 when HR<IP and P3 when HR>IP during the sleeping period gave the lowest difference (1 (SD 5·4) %) compared with other methods (linear or polynomial regressions). The new formula was tested in an independent subset of sixteen other children. The difference between sleeping ee computed with the formula resting EE×0·90 and sleeping EE computed with resting EE×0·8 when HR<IP and the P3 equation when HR>IP during sleeping periods was significant (13 (sd 5·9)%) only for active sleeping subjects (n 6 of 16 subjects). The correlation between the difference in the results from the two methods of calculation and body movements was close (r 0·63, P<0·005, Spearman test) as well as computed sleeping EE (Spearman test, r 0·679, P<0·001), indicating that this new method is reliable for computing sleeping EE with HR monitoring if children are moving during sleep and improves the total EE assessment.

Glutamine (GLN) and arginine (ARG) are recognized for their ability to modulate immune cell function. However, the metabolic pathways involved in their action remain unclear. It was recently shown that GLN- or ARG-enriched diets increased radical oxygen species (ROS) production by neutrophils from stressed rats. Since these two amino acids have a tied metabolism, we hypothesized that conversion between GLN and ARG (and its active metabolites NO• and polyamines) might be involved. To test this hypothesis male Sprague–Dawley rats (n 117) were randomized into thirteen groups: rats in eleven groups were rendered catabolic by dexamethasone injection (1·5 mg/kg per d for 5 d) and 6·8 mmol either GLN, ARG or non-essential amino acids (NEAA; glycine, alanine and histidine)/kg per d were given by the enteral route; one group was pair-fed to the treated groups. The regimens of all the groups were rendered isonitrogenous by the addition of NEAA. The last group was not treated and was fed ad libitum. For each supplementation three subgroups were formed, each of which received a specific inhibitor: methionine sulfoximine (inhibitor of GLN synthase; 100 mg/kg per d), S-methylthiourea (inhibitor of inducible NO• synthase (iNOS); 50 mg/kg per d) and difluoromethylornithine (inhibitor of ornithine decarboxylase (ODC); 50 mg/kg per d). Oxidative metabolism, intracellular H2O2, and extracellular O2•- production were measured in unstimulated and phorbol myristate acetate-stimulated polymorphonuclear neutrophils. GLN- and ARG-enriched diets increased respiratory burst by neutrophils (oxidative metabolism of 152 (SEM 24) AND 138 (sem 45) v. 57 (sem 18) mV for GLN-, ARG- and NEAA-enriched diets respectively, P<0·05). In vivo inhibition of iNOS or ODC decreased ROS production induced by GLN and ARG. In vivo inhibition of GLN synthase did not modify the effect of ARG on ROS production. In conclusion, GLN and ARG modulate ROS production in neutrophils from stressed rats by the same pathway involving polyamine and NO• synthesis.

Self-reports of alcohol consumption account for approximately 50 % of the reported sales of alcohol. In the absence of a gold standard, it is not known how accurately different methods of measurement reflect actual consumption and whether under-reporting varies among different populations. The objective of the present study was to compare the consumption reported by the widely used quantity-frequency questionnaire (QFQ) with that reported in a cross-check dietary history interview (DHI), which has higher face validity. In 171 male and 197 female subjects of the Amsterdam Growth and Health Longitudinal Study (mean age 36 years), alcohol consumption was assessed by both the QFQ and the DHI. Most subjects reported a moderate consumption of alcohol by both measures. Spearman correlation coefficients were high (0·77 and 0·87 in men and women respectively). Overall, greater alcohol consumption was reported using the DHI. The difference between the DHI and QFQ reports was usually greater for wine than for beer. Backward stepwise regression analysis showed that the difference in reporting was positively related to a more irregular drinking pattern, and in wine drinkers to the square of the QFQ report. Sex, drinking alone or with others and the CAGE (acronym for four questions on drinking behaviour) score were not related to the difference in reporting. The precision of DHI estimation from QFQ reports and other factors was low. Serious questions arise as to the validity and precision of alcohol consumption measurements based on the QFQ alone. QFQ information may be improved by incorporating questions on the type of beverage and drinking patterns.

It is easier to demonstrate the consistent effects of foods on satiety than on cognitive performance. This is understandable since the satiety system incorporates physiological signalling systems that mediate the effects of foods on function. Specific manipulations of proteins, carbohydrates and fats have the potential to act as functional foods for appetite control. Because of the importance of the optimal functioning of cognitions for survival, these functions are quite strongly protected against short-term dietary and physiological perturbances. Therefore, food manipulations may be better detected through the degree of effort exerted to maintain performance rather than via changes in the actual performance itself. This procedure has not been widely used hitherto. The concept of biomarkers may have to be interpreted differently from research on physiological systems or clinical endpoints. For satiety, adjustments in the profile of hunger could serve as a biomarker or surrogate endpoint. For cognitions, correlated physiological variables may be more difficult to measure than the functional endpoint itself. Changes related to unitary functions (such as tracking) could serve as biomarkers for more complex, integrated skills (such as car driving). Since food manipulations may affect multiple functions, the challenge is to design foods with good satiety control that do not impair mental performance; or alternatively to engineer foods that optimise cognitive performance without compromising satiety. This rapidly developing field has great potential for close collaboration between academia and industry in the production of commercially successful products that show clear improvements in human functioning with the capacity to protect against disease or impairment.

Pulses supply many bioactive substances found in minor amounts in food, but which may have significant metabolic and/or physiological effects. These compounds have long been classified as antinutritional factors, but many studies have reconsidered their impact on health. Some could play a role in the prevention of the major diseases of affluent societies. As these compounds can be beneficial or adverse, depending on conditions, an assessment of their various physiological effects is necessary to determine whether they should be preserved or eliminated in each main nutritional situation.

Seventy-two 8-week-old ram lambs from three breeds, Suffolk, Soay and Friesland, were offered one of four diets based on dried grass and formulated to have a similar fatty acid content (60 g/kg DM) and containing: Megalac (high in 16 : 0, control; Volac Ltd, Royston, Herts., UK), whole linseed (18 : 3n-3), fish oil (20 : 5n-3 and 22 : 6n-3) or whole linseed plus fish oil. The lambs were slaughtered at approximately half of their mature live weight (43, 21 and 43 kg for Suffolk, Soay and Friesland lambs, respectively). Fish oil reduced DM intake and lamb live-weight gain (P<0·001), while DM intake, live-weight gain and subcutaneous fat content were highest in Suffolk and lowest in Soay lambs. Linseed feeding doubled the proportion (×100) of 18 : 3n-3 in the longissimus dorsi from 1·4 to 3·1 and in the subcutaneous adipose tissue from 1·2 to 2·6 (P<0·001). Suffolk and particularly Soay lambs contained higher proportions of 18 : 3n-3 than Friesland lambs in the longissimus dorsi, while in the adipose tissue, Suffolk lambs had the highest level. Feeding fish oil increased the muscle proportion (×100) of 20 : 5n-3 from 0·7 to 2·3 and 22 : 6n-3 from 0·3 to 0·8 (P<0·001). By contrast, the proportions of the longer-chain n-3 polyunsaturated fatty acids were similar across all three breeds. All three lipid supplements containing n-3 polyunsaturated fatty acids increased the content of muscle trans-18 : 1 relative to the control values, but conjugated linoleic acid (cis-9,trans-11–18 : 2) only increased in the muscle of lambs fed linseed. Feeding linseed or fish oil lowered the n-6 : n-3 ratio in sheep meat, but neither diet nor breed had much effect on the polyunsaturated fatty acid: saturated fatty acid ratio.