Lutein is one of the most widely found carotenoids distributed in fruits and vegetables frequently consumed. Its presence in human tissues is entirely of dietary origin. Distribution of lutein among tissues is similar to other carotenoids but, along with zeaxanthin, they are found selectively at the centre of the retina, being usually referred to as macular pigments. Lutein has no provitamin A activity in man but it displays biological activities that have attracted great attention in relation to human health. Epidemiological studies have shown inconsistent associations between high intake or serum levels of lutein and lower risk for developing cardiovascular disease, several types of cancer, cataracts and age-related maculopathy. Also, lutein supplementation has provided both null and positive results on different biomarkers of oxidative stress although it is effective in increasing macular pigment concentration and in improving visual function in some, but not all, subjects with different eye pathologies. Overall, data suggest that whereas serum levels of lutein have, at present, no predictive, diagnostic or prognostic value in clinical practice, its determination may be very helpful in assessing compliance and efficacy of intervention as well as potential toxicity. In addition, available evidence suggests that a serum lutein concentration between 0·6 and 1·05 μmol/l seems to be a safe, dietary achievable and desirable target potentially associated with beneficial impact on visual function and, possibly, on the development of other chronic diseases. The use of lutein as a biomarker of exposure in clinical practice may provide some rationale for assessing its relationship with human health as well as its potential use within the context of evidence-based medicine.

A method for measuring unlabelled Fe absorption has been investigated in a pilot study using a simple mathematical model. The metabolism of newly absorbed Fe can be approximated as a single-compartment model with the sampled compartment being the plasma pool. Five female volunteers (aged 30–55 years) were recruited to participate in the pilot study. After a 10 mg oral dose of unlabelled ferrous sulfate, the change in plasma Fe concentration over the following 6 h was used to estimate the quantity of absorbed Fe from the mathematical model. To assess the accuracy of the new technique, a 1 mg oral dose of 57Fe-labelled iron sulfate was given simultaneously with a 225 μg intravenous dose of 58Fe as iron citrate. The plasma appearance of the labelled Fe was used to estimate the absorption of the oral label from the traditional area under the curve method. There was no significant difference (P=0·61) between the geometric mean absorption of the unlabelled (19 (- 1 sd 12, +1 sd 28) %) and the labelled Fe (17 (- 1 sd 10, +1 sd 29) %). These initial results are encouraging, but further work needs to be undertaken with smaller doses, as typically found in meals. The effect of diurnal variation in serum Fe concentration on the estimation of unlabelled Fe absorption needs further assessment.

Polyunsaturated fatty acids (FA) regulate genes involved in lipid metabolism. The effects of polyunsaturated FA on the transcription factor adipocyte determination and differentiation-dependent factor (ADD) 1 and fatty acid synthase (FAS) mRNA in differentiating porcine adipocytes were measured using a stromal vascular cell culture system. Porcine stromal vascular cells were isolated from subcutaneous adi-pose tissues and plated in Dulbecco's modified Eagle's medium (DMEM)–nutrient mixture F-12 Ham (F-12) plus fetal bovine serum (100 ml/l) for 24 h. Then cells were differentiated in DMEM–F12 plus insulin, hydrocortisone and transferrin without or with polyunsaturated FA at 6·25, 25·00 or 100·00 μm. The ADD1 mRNA was decreased by 100·00 μm-arachidonic acid, 6·25 to 100·00 μm-docosahexaenoic acid or cis-9,trans-11-conjugated linoleic acid. The polyunsaturated FA reduced the transcription rate of FAS, but not of ADD1. All three polyunsaturated FA accelerated degradation of ADD1 and FAS mRNA to reduce the abundance of ADD1 and FAS mRNA. Results also showed that polyunsaturated FA inhibit the ADD1 expression, not only of mRNA concentration, but also of mature ADD1 protein concentration, suggesting an overall reduction of ADD1 function by polyunsaturated FA. Our present experiments demonstrate that polyunsaturated FA regulate the gene expression of ADD1 and enzymes involved in lipid metabolism in porcine adipocytes.

The present study was designed to determine the effects of various levels of capsaicin (CAP) on endurance capacity in forty-nine male Sprague–Dawley rats, aged 4 weeks, which were assigned to four groups. Rats were given orally either control (0) or 6, 10 or 15 mg CAP/kg body weight 2 h before exercise by stomach intubations using a round-ended needle. The rats in each group were divided into two subgroups for resting or swimming exercise. Swimming exercise was performed with a weight corresponding to 3 % body weight attached to the tail, and endurance capacity was evaluated by swimming time to exhaustion. The highest dose (15 mg/kg) of CAP significantly (P < 0·05) increased endurance performance time and caused plasma non-esterified fatty acid to rise significantly by about 1·4-fold compared with that of non-CAP treated rats at exhaustion (P < 0·05). The highest dose of CAP had no effect on liver and gastrocnemius muscle glycogen (white and red) in resting rats, but significantly increased glycogen contents of both muscles at exhaustion (P < 0·05). At rest, plasma noradrenalin levels of the rats receiving the highest dose were greater than that of non-CAP-treated rats and remained greater until exhaustion. The effects of CAP on endurance capacity have received little attention and have conveyed conflicting impressions. Kim et al. (1997) failed to show the maximal effect of 10 mg/kg doses of CAP on swimming endurance time in mice. The influences of various doses of CAP on endurance capacity were still unclear. Matsuo et al. (1996) reported that the intake of CAP have little sparing effect on glycogen in the liver and soleus muscles at rest and during exercise in rats previously fed a CAP-containing diet ad libitum for 1 week. Our present results suggest more than the highest dose of CAP (15 mg/kg) can cause the increase of endurance capacity, which might be induced through the sparing of muscle glycogen and the rise of non-esterfied fatty acids following the increase of circulating catecholamine.

Improvement in the nutritional quality of Bangladeshi rice-based diets is sought through increasing the amounts of vegetables, fish and legumes consumed. The aim of the present study was to compare the effects of rice-based diets on selected parameters of Ca and P availability and retention in young, growing rats. The study was designed as a randomised balance trial with five diets, eight animals per diet, and two balance periods of 1 week each. Apart from diet 1, which was a pure rice diet, the other four diets were composite diets and included the leafy vegetable, amaranth leaves (Amaranthus gangeticus), the small fish, mola (Amblypharyngodon mola), and lentils (Lens culinaris) in different amounts to simulate the average rural rice-based diet, the recommended diet, the recommended diet diluted with starch, and the recommended diet excluding amaranth leaves. The inclusion of amaranth leaves, mola and lentils significantly improved N and growth retention in the rats compared with the pure rice diet. However, a minor addition of amaranth (0·66 g/100 g DM) significantly reduced the fractional Ca absorption and retention. Femur bone mass and Ca and P densities were significantly lower in the rats fed the diets that included amaranth leaves. The observed inhibitory effect of the amaranth leaves on Ca absorption and utilisation was probably due to the oxalate content. It is concluded that the formulation of a recommended diet cannot be based only on nutrient content values of individual food components due to interactions between nutrients and anti-nutrients in the diet.

The efficiency of myristic acid (14:0) as a feed additive to suppress CH4 emissions of ruminants was evaluated under different dietary conditions. Six sheep were subjected to a 6 × 6 Latin square arrangement. A supplement of non-esterified 14: 0 (50 g/kg DM) was added to two basal diets differing in their forage:concentrate values (1:1/5 and 1: 0/5), which were adjusted to dietary Ca contents of 4/2 and 9/0 g/ kg DM, respectively. Comparisons were made with the unsupplemented basal diets (4/2 g Ca/kg DM). The 14:0 supplementation decreased (P < 0/001) total tract CH4 release depending on basal diet type (interaction, P < 0/001) and dietary Ca level (P < 0/05, post hoc test). In the concentrate-based diet, 14:0 suppressed CH4 emission by 58 and 47% with 4/2 and 9/0 g Ca/kg DM, respectively. The 14:0 effect was lower (22%) in the forage-based diet and became insignificant with additional Ca. Myristic acid inhibited (P < 0/05) rumen archaea without significantly altering proportions of individual methanogen orders. Ciliate protozoa concentration was decreased (P < 0/05, post hoc test) by 14:0 only in combination with 9/0 g Ca/kg DM. Rumen fluid NH3 concentration and acetate:pro-pionate were decreased (P < 0/05) and water consumption was lower (P < 0/01) with 14:0. The use of 14:0 had no clear effects on total tract organic matter and fibre digestion; this further illustrates that the suppressed methanogenesis resulted from direct effects against methanogens. The present study demonstrated that 14:0 is a potent CH4 inhibitor but, to be effective in CH4 mitigation feeding strategies, interactions with other diet ingredients have to be considered.

Anaemia is a common complication of pulmonary tuberculosis. The precise mechanism of anaemia in pulmonary tuberculosis is not clearly known, but anaemia of inflammation as well as of Fe deficiency has been implicated. Both are common in developing countries. It is extremely difficult to distinguish anaemia of Fe deficiency from anaemia of inflammation with the haematological indices used routinely. Therefore, Fe preparations are usually prescribed for all anaemic patients irrespective of the aetiology. This approach has been questioned. The present study aimed to assess the effect of Fe supplementation on anaemic patients with pulmonary tuberculosis. Adult male patients 15–60 years of age with pulmonary tuberculosis and a blood haemoglobin concentration 80–110 g/l were included in the study; healthy adult males matched for age and socio-economic status were taken as controls. Blood haemoglobin concentration, total erythrocyte count (TEC), packed cell volume (PCV), mean corpuscular volume (MCV), mean corpuscular haemoglobin and serum Fe, total Fe-binding capacity and ferritin were estimated before treatment and 1, 2 and 6 months after treatment. The patients were divided randomly into three groups and during the initial 2 months of treatment were provided with one of three supplementary regimens consisting of placebo, Fe alone or Fe with other haematinics. Significant improvements in haematological indices and Fe status were noticed in all three groups. Blood haemoglobin concentration, MCV and PCV were significantly higher at 1 month in both Fe-supplemented groups than the placebo group. This difference, however, disappeared at 2 and 6 months with similar values in all three groups. The increase of other haematological indices was similar in all groups. Serum Fe and Fe saturation of transferrin were significantly higher in both Fe-supplemented groups than the placebo group up to 2 months; this effect, however, disappeared at 6 months. There was a consistent increase in TEC and decrease in ferritin values up to 6 months in all groups. Radiological and clinical improvement was similar in all three groups. These observations suggest that Fe supplementation in mild to moderate anaemia associated with pulmonary tuberculosis accelerated the normal resumption of haematopoiesis in the initial phases by increasing Fe saturation of transferrin. However, consistent improvement of haematological status was dependent only on the improvement of the disease process.

The glycaemic index (GI) of commonly consumed bakery products supplemented with increasing levels of coconut (Cocos nucifera) flour was determined in ten normal and ten diabetic subjects. Using a randomized crossover design, the control and test foods were fed in random order on separate occasions after an overnight fast. Blood samples were collected through finger prick before and after feeding and were analysed for glucose levels using a clinical chemistry analyser. The significantly low-GI (< 60) foods investigated were: macaroons (GI 45·7 (sem 3·0)) and carrot cake (GI 51·8 (sem 3·3)), with 200–250 g coconut flour/kg (P<0·05). The test foods with 150 g coconut flour/kg had GI ranging from 61·3 to 71·4. Among the test foods, pan de sal (GI 87·2 (sem 5·5)) and multigrain loaf (GI 85·2 (sem 6·8)) gave significantly higher GI with 50 and 100 g coconut flour/kg respectively (P<0·05). On the other hand, granola bar and cinnamon bread with 50 and 100 g coconut flour/kg respectively gave a GI ranging from 62·7 to 71·6 and did not differ significantly from the test foods with 150 g coconut flour/kg (P < 0·05). A very strong negative correlation (r– 0·85, n 11, P < 0·005) was observed between the GI and dietary fibre content of the test foods supplemented with coconut flour. In conclusion, the GI of coconut flour-supplemented foods decreased with increasing levels of coconut flour and this may be due to its high dietary fibre content. The results of the present study may form a scientific basis for the development of coconut flour as a functional food. However, the fat content of coconut flour-supplemented food should always be considered to optimize the functionality of coconut fibre in the proper control and management of diabetes mellitus.

The beneficial effect of bovine whey protein (WP) on bone metabolism has been shown in adult human subjects and ovariectomised rats. However, its effect on bone formation in earlier life, particularly during periods of bone mineral accrual, has not been investigated. Twenty-one male rats (4 weeks old, Wistar strain) were randomised by weight into three groups of seven rats each and fed ad libitum on a semi-purified low-Ca diet (3·0 g Ca/kg diet) containing 0 (control), 10 (diet WP1) or 20 (diet WP2) g bovine WP/kg for 47 d. On day 34 of the dietary intervention, all rats had two gelatine capsules containing demineralised bone powder implanted subcutaneously in the thorax region (a well-established in vivo model of ectopic bone formation). At 14 d after implantation, alkaline phosphatase activity (reflective of bone formation) in the bone implants from animals fed WP1 and -2 diets was almost 2-fold (P<0·01) that of control animals. Insulin-like growth factor (IGF)-I mRNA levels were about 3-fold (P<0·05) higher in implants from animals fed the WP diets compared with those from control animals. Serum- and urine-based biomarkers of bone metabolism and bone mineral composition in intact femora were unaffected by WP supplementation. In conclusion, the present findings suggest that bovine WP can enhance the rate of ectopic bone formation in young growing rats fed a Ca-restricted diet. This effect may be mediated by an increased synthesis of IGF-I in growing bone. The effect of WP on bone formation warrants further investigation.

As the physiological roles of dietary lecithin have not yet been clearly defined, we examined the effects of lecithin on lipid absorption in male Wistar rats with a mesenteric lymph cannula. Lymphatic absorption was observed after the infusion of 1 ml emulsion containing 100 mg test oil emulsified with sodium taurocholate (10 g/l) in three separate experiments. Test oils (100 mg) were: soyabean oil (triacylglycerol (TG) source, SO) and soyabean oil + lecithin (75 mg soyabean oil+25 mg lecithin, LE) in Expt 1; SO, LE or soyabean oil + lysolecithin (75 mg soyabean oil plus 25 mg lysolecithin, LY) in Expt 2; hydrolysed soyabean oil (HSO) or HSO+lysolecithin (75 mg HSO+25 mg lysolecithin, HLY) in Expt 3. After LE and LY infusions, lymph flow and the lymphatic output of TG was higher than after SO infusion at 0-30 min and 0-90 min respectively (Expts 1 and 2). Lecithin-induced increases in lymph TG output remained constant when HSO was infused (Expt 3). There were no differences in the TG:phospholipid ratio in the lymph after infusion among the groups; nevertheless, the lymphatic output of TG was much higher after infusion with LE than with SO. Fatty acid was released more efficiently from SO than from LE and LY by in vitro digestion with rat bile–pancreatic juice. These present results demonstrate that a TG emulsion containing soyabean lecithin or its hydrolysates promote lymphatic TG output and suggest that the increases in TG absorption do not depend on TG digestion.

Long-Evans Cinnamon (LEC) rats spontaneously develop fulminant hepatitis, associated with excess Cu accumulation in the liver: thus, they are considered an animal model of Wilson's disease. In the present study, we investigated the ability of excess dietary histidine to reduce the excess accumulation of liver Cu in LEC rats by comparing them with Fischer rats. The results clearly showed that the excess-histidine diet markedly stimulated the Cu excretion in urine, and significantly decreased the liver Cu content in LEC rats by 47·5%. The serum Cu content in LEC rats was not influenced by excess dietary histidine. We also compared the effects of excess dietary histidine on some liver antioxidant enzyme activities, liver and serum lipid levels and serum alanine aminotransferase activity of LEC and Fischer rats. Dietary histidine decreased the activities of total and Cu, Zn-superoxide dismutase in the liver of both strains. In LEC rats, the liver cholesterol content decreased, and serum cholesterol and phospholipids levels increased on feeding the excess-histidine diet. When fed on the basal diet, the serum alanine aminotransferase activity was higher in LEC rats than in Fischer rats, but a significant decrease in serum alanine aminotransferase activity of LEC rats was observed on feeding the excess-histidine diet. These results suggest that excess dietary histidine is effective in removing Cu ions from the liver of LEC rats. Thus, it may be of benefit in the prevention or treatment of liver injury in LEC rats and in patients with Wilson's disease.

Fructo-oligosaccharides (FOS) may have potential benefits, since they exhibit many soluble dietary fibre-like properties. Foods currently available for weaning infants are generally low in fibre content and lack these potential benefits. Data documenting tolerance of FOS in weaning foods are greatly lacking. Our present objective was to evaluate the tolerance and gastrointestinal effects of FOS-supplemented infant cereal used as a daily addition to the diet of healthy infants. Healthy infants were randomly assigned to receive either 0·75 g FOS per serving of cereal or placebo for 28 d. The primary outcome of interest was gastrointestinal tolerance, which was assessed by daily parental reporting of functional variables for 28 d, including stool patterns and signs and symptoms of gastrointestinal tolerance. Secondary outcomes were also measured including: cereal intake (g cereal and g FOS/d), stool pH, changes in anthropometric measurements and adverse events. The study population included a total of fifty-six infants, age range 16·2–46·2 weeks with a mean age of 32·5 (sd 8·9) weeks; twenty-nine infants were randomized to the control group (age 31·8 (sd 9·0) weeks) and twenty-seven to the FOS-supplemented group (34·7 (sd 8·9) weeks). Average daily total intake per infant and average intake per serving were similar in both groups. Average FOS consumption was 0·74 (sd 0·39) g/d and as high as 3·00 g/d. Stool consistency was less likely to be described as ‘hard’, and more likely to be described as ‘soft’ or ‘loose’, in the FOS v. control group. The mean number of stools per infant was 1·99 (sd 0·62) per d in the FOS-supplemented group compared with 1·58 (sd 0·66) in the control group (P=0·02). There were no differences between the groups in reporting for crying, spitting-up or colic. No differences were found for stool pH. FOS-supplements added to cereal were well tolerated in doses of up to 3·00 g/d. FOS consumption led to more regular and softer stools, without diarrhoea, as well as less-reported frequency of symptoms associated with constipation such as hard stools or skipped days without stool. The present study is one of few studies documenting tolerance to increased fibre intake in the form of FOS as part of a weaning food.

Evidence from epidemiological and animal-feeding trials suggests that a western-style diet that is high in fat, and low in Ca, vitamin D and folic acid may result in low bone mass and poor bone quality: this leads to an increased risk of fragility fracture. The overall objective of the present study was to determine the effect of feeding a western-style diet (low in Ca (0·4 g/kg diet, Ca:P ratio 1:10), cholecalciferol (3 μg/kg diet), folic acid (0·23 mg/kg diet) and fibre (20 g/kg diet), and high in fat (200 g/kg diet)) for 17 weeks on bone mineral content (BMC) and the biomechanical bone strength of rat femurs. A secondary objective was to determine whether femurs from male and female rats (seven to eight rats per group) respond differently to the western-style diet. Male and female rats weighing 150–180 g were fed a western-style diet or a control diet for 17 weeks. At the end of the feeding trial, femur BMC was measured by ashing, and biomechanical properties were determined by three-point bending. Femur BMC and the majority of biomechanical properties measured were lower (P<0·05) among male and female rats fed a western-style diet compared with a control diet, despite similar weight gain and final body weight within genders. However, the western-style diet had a greater negative effect on femur BMC and biomechanical strength properties among male rats compared with females. This may be because male rats experienced greater overall body growth, as assessed by weight gain, than female rats, and suggests that the nutrient composition of the western-style diet did not support the development of strong femurs.

The aim of the present study was to compare the response of a range of atherogenic and thrombogenic risk markers to two dietary levels of saturated fatty acid (SFA) substitution with monounsaturated fatty acids (MUFA) in students living in a university hall of residence. Although the benefits of such diets have been reported for plasma lipoproteins in high-risk groups, more needs to be known about effects of more modest SFA-MUFA substitutions over the long term and in young healthy adults. In a parallel design over 16 weeks, fifty-one healthy young subjects were randomised to one of two diets: (1) a moderate-MUFA diet in which 16 g dietary SFA/100 g total fatty acids were substituted with MUFA (n 25); (2) a high-MUFA diet in which 33 g dietary SFA/100 g total fatty acids were substituted with MUFA (n 26). All subjects followed an 8-week run-in diet (reference diet), with a fatty acid composition close to the UK average values. There were no differences in plasma lipid responses between the two diets over 16 weeks of the study with similar reductions in total cholesterol (P <0·001) and LDL-cholesterol (P<0·01) in both groups; a small but significant reduction in HDL-cholesterol was also observed in both groups (P<0·01). Platelet responses to ADP (P<0·01) and arachidonic acid (P<0·05) differed with time on the two diets; at 16 weeks, platelet aggregatory response to ADP was significantly lower on the high-MUFA than the moderate-MUFA (P<0·01) diet; ADP responses were also significantly lower within this group at 8 (P<0·05) and 16 (P<0·01) weeks compared with baseline. There were no differences in fasting factor VII activity (factors VIIc and VIIag), fibrinogen concentration or tissue-type plasminogen activator activity between the diets. There were no differences in postprandial factor VIIc responses to a standard meal (area under the curve) between the diets after 16 weeks, but postprandial factor VIIc response was lower than on the high-MUFA diet compared with baseline (P<0·01). In conclusion, a high-MUFA diet sustains potentially beneficial effects on platelet aggregation and postprandial activation of factor VII. Moderate or high substitution of MUFA for SFA achieves similar reductions in fasting blood lipids in young healthy subjects.

Effects of colloids isolated from apple pomace extraction juices (so-called B-juices) produced by enzymic liquefaction on food intake, body and faecal weights, short-chain fatty acid (SCFA) profile and selected intestinal microbiota were investigated in rats. Ten male Wistar rats per group were fed diets without any apple dietary fibre (DF) (control) or supplement with 5 % B-juice colloids or an alcohol-insoluble substance (AIS) from apples for 6 weeks. Rats fed with apple DF (5 % B-juice colloids or AIS) gained less weight than control rats (P<0·05). B-juice colloids did not affect food intake, whereas feeding AIS resulted in a 10% higher food consumption than in control rats. Both juice colloids and AIS increased the weight of caecal contents in rats and lowered luminal pH values (P<0·05). In addition, SCFA concentrations and total yields were also raised (P<0·05) in caecum of these rats indicating good fermentability of apple substrates by gut microflora. Distinctly higher concentrations of acetate and propionate were found in intestinal contents of juice colloid-fed rats (P < 0·05), whereas AIS also increased butyrate yield. Changes in microbiota due to apple DF in diets were restricted in the caecum to the Eubacterium rectale cluster (AIS; P<0·05) and in faeces to the Bacteroidaceae (juice colloids and AIS; P<0·05). The present study shows the physiological effects of apple DF isolated from pomace extraction juices produced by enzymic liquefaction on intestinal fermentation. Results may be helpful for the development of such innovative juice products that are rich in DF of fruit origin.

Batch cultures of mixed rumen micro-organisms were used to study the effects of different concentrations of disodium fumarate on the fermentation of five concentrate feeds (maize, barley, wheat, sorghum and cassava meal). Rumen contents were collected from four Merino sheep fed lucerne hay ad libitum and supplemented with 300 g concentrate/d. Disodium fumarate was added to the incubation bottles to achieve final concentrations of 0, 4, 7 and 10 mm-fumarate. In 17 h incubations, the final pH and total volatile fatty acid production increased (P<0·001) linearly for all substrates as fumarate concentration increased from 0 to 10 mm. Propionate and acetate production increased (P<0·05), while the value of the acetate:propionate ratio decreased (P<0·05) linearly with increasing doses of fumarate. In contrast, l-lactate and NH3-N concentrations in the cultures were not affected (P>0·05) by the addition of fumarate. For all substrates, fumarate treatment decreased (P<0·05) CH4 production, the mean values of the decrease being 2·3, 3·8 and 4·8 % for concentrations of 4, 7 and 10 mm-fumarate respectively. Addition of fumarate did not affect (P>0·05) the total gas production. If the results of the present experiment are confirmed in vivo, fumarate could be used as a feed additive for ruminant animals fed high proportions of cereal grains, because it increased pH, acetate and propionate production and it decreased CH4 production.

The efficiency of rumen microbial production (EMP) in vitro and in vivo was examined for three roughages (lucerne (Medicago sativa L.) hay, oat (Avenia sativa L.)–berseem clover (Trifolium alexandrinum cultivar BigBee) hay and maize (Zea mays L.) crop residue (MCR)) and for five isonitrogenous (106 g crude protein (N × 6·25)/kg) diets formulated from lucerne hay, oat–berseem clover hay, MCR, soya-bean meal and maize grain to provide degradable intake protein for the production of 130 g microbial protein/kg total digestible nutrients. EMP in vivo was determined by intestinal purine recovery in sheep and ranged from 240 to 360 g microbial biomass/kg organic matter truly degraded in MCR and in one of the diets respectively (P<0·05). EMP in vitro was estimated by the substrate degraded: gas volume produced thereby (termed partitioning factor, PF (mg/ml)) at times of estimated peak microbial production and after 16·0 and 24·0h of incubation. For the diets, PF values were significantly related to EMP in vivo at peak microbial production (P = 0·04), but not after 16·0 (P = 0·08) and 24·0h (P = 0·66). For roughages, PF values were significantly related to EMP in vivo only when measured after 16·0 h (P = 0·04). For MCR and diets, a close non-linear relationship was found between PF values at peak microbial production and EMP in vivo (R2 0·99, P<0·0001) suggesting a maximum EMP in vivo of 0·39. Low gas production per unit substrate degraded (high PF) was associated with high EMP in vivo. The in vitro study of the products of fermentation, short-chain fatty acids, gases and microbial biomass (by purine analysis) after 16·0h of incubation showed very strong relationships (R2 ≥ 0·89, P<0·0001) between short-chain fatty acids, gases and gravimetrically measured apparent degradability. Except for maize grain, the true degradability of organic matter estimated by neutral-detergent solution treatment agreed with the sum of the products of fermentation (R2 0·81, P=0·0004). After 16·0h of incubation, the synergistic effects of diet ingredient on diets were greater for microbial biomass (18%) than for short-chain fatty acids and gas production (7 %). It is concluded that measurement of gas production only gives incomplete information about fodder quality; complementation of gas measurements by true degradability measurements is recommended.

The isoflavone genistein is found predominantly in soyabeans and is thought to possess various potent biological properties, including anti-carcinogenic effects. Studies have shown that genistein is extensively degraded by the human gut microflora, presumably with a loss of its anti-carcinogenic action. The aim of the present study was to investigate the potential of a prebiotic to divert bacterial metabolism away from genistein breakdown: this may be of benefit to the host. Faecal samples were obtained from healthy volunteers and fermented in the presence of a source of soyabean isoflavones (Novasoy™ (10g/l); ADM Neutraceuticals, Erith, Kent, UK). Bacterial genera of the human gut were enumerated using selective agars and genistein was quantified by HPLC. The experiment was repeated with the addition of glucose (10g/l) or fructo-oligosaccharide (10g/l; FOS) to the fermentation medium. The results showed most notably that counts of Bifidobacterium spp. and Lactobacillus spp. were significantly increased (P<0·05 and P<0·01 respectively) under steady-state conditions in the presence of FOS. Counts of Bacteroides spp. and Clostridium spp. were, however, both significantly reduced (P<0·05) during the fermentation. A decline in genistein concentration by about 52 and 56% over the 120h culture period was observed with the addition of glucose or FOS to the basal medium (P<0·01), compared with about 91% loss of genistein in the vessels containing Novasoy™ (ADM Neutraceuticals) only. Similar trends were obtained using a three-stage chemostat (gut model), in which once again the degradation of genistein was about 22% in vessel one, about 24% in vessel two and about 26% in vessel three in the presence of FOS, compared with a degradation of genistein of about 67% in vessel one, about 95% in vessel two and about 93% in vessel three in the gut model containing Novasoy™ (ADM Neutraceuticals) only. The present study has shown that the addition of excess substrate appeared to preserve genistein in vitro. In particular, the use of FOS not only augmented this effect, but also conferred an additional benefit in selectively increasing numbers of purportedly beneficial bacteria such as bifidobacteria and lactobacilli.

Habitual meal frequency was assessed as a possible function of components of energy expenditure (EE) in human subjects. Fifty-six subjects participated (four categories differing in body composition): ten older women (fat-free mass (FFM) 42·0 (sd 6·3) kg, aged 59 (sd 2) years, BMI 27·5 (sd 6·9) kg/m2), fifteen younger women (FFM 45·5 (sd 5·2) kg, aged 34 (sd 10) years, BMI 21·9 (sd 2·3) kg/m2), twelve older men (FFM 56·8 (sd 5·9) kg, aged 62 (sd 4) years, BMI 25·7 (sd 3·3) kg/m2) and nineteen younger men (FFM 63·9 (sd 7·5) kg, aged 23·1 (sd 3·9) years, BMI 22·9 (sd 1·8) kg/m2). Measurements consisted of habitual meal frequency by validated food-intake diaries, physical activity by tri-axial accelerometers and resting EE by a ventilated hood system. Habitual meal frequency was expressed as a function of resting EE (including resting EE as a function of FFM), and of activity-induced EE, using regression analysis. FFM differed according to gender and age categories (P < 0·01). Physical activity level was higher in the younger men than in the other categories (P < 0·05). No relationship of meal frequency with the variables assessed was observed in subjects with a low FFM (the women). In the subjects with a medium FFM (the older men), meal frequency was positively related to resting EE (r2 0·4, P < 0·05), but not to the residuals of resting EE as a function of FFM, and inversely related to activity-induced EE (r2 0·3, P < 0·05). Resting EE explained 40% of the variation in meal frequency; adding activity-induced EE increased this to 60%. In the subjects with a high FFM (the younger men), meal frequency was inversely related to resting EE (r2 0·8, P < 0·0001) and to the residuals of resting EE as a function of FFM (P = 0·03), and positively related to activity-induced EE (r2 0·6, P < 0·0001). Resting EE explained 85% of the variation in meal frequency; adding activity-induced EE increased this to 89%. Habitual meal frequency was a function of components of EE, namely resting EE and activity-induced EE, only in subjects with a medium to high FFM (men). FFM-related differences in these relationships suggest a role of physical activity.