The influence of the source of dietary fat on postprandial thermogenesis and substrate oxidation rates, was examined in twelve postmenopausal women aged 57–73 years, with BMI 21·9–38·3 kg/m2. A single blind, randomised, paired comparison of two high-fat, isoenergetic, mixed test meals was conducted. The major source of fat was either cream (CREAM) or extra virgin olive oil (EVOO). RMR, diet-induced thermogenesis (DIT) and substrate oxidation rates over 5 h were measured by indirect calorimetry. There were no differences in body weight, RMR, fasting carbohydrate or fat oxidation rates between the two occasions. DIT (EVOO 97 (sd 46) v. CREAM 76 (sd 69) kJ/5 h and EVOO 5·2 (sd 2·5) v. CREAM 4·1 (sd 3·7)% energy) did not differ between the two test meals. The postprandial increase in carbohydrate oxidation rates, relative to their respective fasting values (ΔCOX), was significantly lower following the EVOO meal (EVOO 10·6 (sd 8·3) v. CREAM 17·5 (sd 10) g/5 h; paired t test, P=0·023), while postprandial fat oxidation rates (ΔFOX) were significantly higher (EVOO 0·0 (sd 4·4) v. CREAM -3·6 (sd 4·0) g/5 h; P=0·028). In the eight obese subjects, however, DIT was significantly higher following the EVOO meal (EVOO 5·1 (sd 2·0) v. CREAM 2·5 (sd 2·9) %; P=0·01). This was accompanied by a significantly lower ΔCOX (EVOO 10·9 (sd 9·9) v. CREAM 17·3 (sd 10·5) g/5 h; P=0·03) and significantly higher ΔFOX (EVOO 0·11 (sd 4·4) v. CREAM −4·1 (sd 4·5) g/5 h, P=0·034). The present study showed that olive oil significantly promoted postprandial fat oxidation and stimulated DIT in abdominally obese postmenopausal women.

The aim of the present study was to evaluate Mg absorption from a test meal served with an oxalate-rich vegetable, spinach, as compared with a test meal served with a vegetable with a low oxalate content, kale. Mg absorption was measured by a stable-isotope technique based on extrinsic labelling of the test meals and faecal monitoring of the excreted isotope labels. Nine healthy adults participated in the study. The test meals were based on 100g phytate-free white bread, served with 300g spinach (6·6mmol oxalate; 0·7mmol 25Mg label added, 5·0mmol total Mg) or 300g kale (0·1mmol oxalate; 1·2mmol 26Mg label added, 4·8mmol total Mg). The test meals were served on days 1 and 3, at breakfast and lunch, using a cross-over design. The results from the present study demonstrated that apparent Mg absorption was significantly lower from the meal served with spinach (26·7 (sd 10·4) %) than the meal served with kale (36·5 (sd 11·8) %) (P=0·01). However, the lower fractional apparent Mg absorption from the test meal served with spinach can be assumed to be, at least partly, counterbalanced by the higher native Mg content of spinach as compared with kale. Although based on indirect evidence, i.e. not based on an evaluation of added (or removed) oxalic acid, the difference in Mg absorption observed in the present study is attributed to the difference in oxalic acid content between the two vegetables.

The objective of the present study was to investigate the time course for recovery of lymphoid tissue and T cell subset numbers when Zn-deficient (ZD) or energy-restricted (ER) rats were repleted with control diet; in a second experiment, the link between the stress axis and lymphoid organs was explored. During the deficiency phase, rats were fed a ZD (<1 mg Zn/kg) or control diet (30 mg Zn/kg, nutritionally complete) either as pair-fed controls (ER) or ad libitum-fed controls (CTL) for 3 weeks. During the repletion phase, all rats were fed control diet ad libitum for 3, 7 or 23 d. After the deficiency phase, ZD and ER had lower T cell subset numbers in the thymus compared with CTL, and ZD had reduced T cell subset numbers in the spleen compared with both ER and CTL. T cell subset numbers and lymphoid organ weights recovered from dietary Zn deficiency and energy restriction by 7 d of repletion (except 23 d for thymus weight in ZD), while body weight required more than 23 d for recovery. At the end of the deficiency phase, ZD and ER had higher circulating corticosterone concentrations compared with CTL; plasma TNFα was not detectable and there were no differences in plasma haptoglobin, an acute-phase protein. In conclusion, Zn deficiency and energy restriction elevated circulating corticosterone and reduced T cell subset numbers in the thymus and spleen of growing rats. Repletion with a nutritionally complete diet allowed recovery of T cell subset numbers and lymphoid organ weight.

The present controlled-training double-blind study (supplemented (S) group, n 7; placebo (P) group, n 10) was designed to investigate whether an antioxidant mixture (Se 150 μg, retinyl acetate mg, ascorbic acid 120 mg, α-tocopheryl succinate) would allow overloaded triathletes to avoid adaptation failure in the antioxidant system. Dietary intakes were recorded. The supplement of Se, and vitamins A and E provided 100 % of the French RDA. Four weeks of overloaded training (OT) followed 4 weeks of normal training (NT). After NT and OT, biological studies were conducted at rest and after a duathlon test (run 5 km, cycle 20 km, run 5 km). During the 4-week period of NT, blood levels of GSH levels increased in response to supplementation (P<0·05) and remained elevated during OT. Plasma glutathione peroxidase activity was significantly higher in the S group in all situations after NT and OT (P<0·01). The S group had increased erythrocyte Cu,Zn-superoxide dismutase activity in response to OT (P<0·05). Supplementation significantly reduced (P<0·05) the magnitude in duathlon-induced creatine kinase isoenzyme MB mass increase, which tended to be higher with OT (P=0·09). We conclude that the antioxidant mixture helped to preserve the antioxidant system during an OT-induced stress in subjects with initially low antioxidant intakes. Effects of supplementation during NT and/or OT are shown mostly by the alleviated muscle damage. The effects of the antioxidant mixture were observed for doses that can be provided by a diversified and well-balanced diet. The maintenance of normal nutritional status with regard to the antioxidant intake (Se, vitamins C and E) plays a key role in antioxidant adaptive effects during NT and OT.

The effects of dietary lipids on the abundance of dendritic cells in adipose tissue in anatomically defined relationships to chronically inflamed lymph nodes were investigated in mature male rats fed plain chow or chow plus 20 % sunflower-seed or fish oil. The popliteal lymph nodes were stimulated by local subcutaneous injection of 20 μg lipopolysaccharide to both hindlegs three times/week for 2 weeks. The masses of the major adipose depots and the numbers of dendritic cells emerging from perinodal adipose tissue and samples 5 and 10 mm from the popliteal lymph nodes were measured, and those from omental and mesenteric adipose tissue around and remote from lymphoid tissue, and mesenteric and popliteal lymph nodes. Dendritic cells were most numerous in the perinodal adipose tissue, with the corresponding ‘remote’ samples containing 25–50 % fewer such cells under all conditions studied. Dietary sunflower-seed oil increased the numbers of dendritic cells by about 17 % in all adipose samples and fish oil reduced the numbers in perinodal tissue by about 5 %. The fish-oil diet diminished responses of the intra-abdominal adipose depots to local stimulation of the popliteal node. Correlations in dendritic cell numbers were stronger between perinodal samples from different depots than between remote and perinodal samples from the same depot and after the sunflower-seed-oil diet compared with fish oil. These data show that dietary lipids modulate the number of dendritic cells in lymphoid tissue-containing adipose depots and support the hypothesis that perinodal adipose tissue interacts locally with lymphoid cells.

Dietary Si, as soluble orthosilicic acid (OSA), may be important for the growth and development of bone and connective tissue. Beer appears to be a major contributor to Si intake, although the Si content of beer and its bioavailability in human subjects have not been well established. Here we investigated the Si content of different beers and then estimated Si absorption from beer in healthy volunteers. The Si content of seventy-six different beers was estimated using inductively coupled plasma optical emission spectrometry and one of the beers, used in the ingestion study, was ultrafiltered to determine OSA content. Next, following the ingestion of 0·6 litres beer (22·5mg Si; 4·6% (v/v) ethanol), serum and urinary Si levels were measured in nine healthy volunteers over a 6h period. A solution of OSA was similarly investigated as a positive control and water and 4·6% ethanol as negative controls. The mean Si level of beer was 19·2 (SD 6·6) mg/l; the median Si level was 18·0mg/l. There was no significant difference in the Si levels of the different beers by geographical origin or type of beer. Serum and urinary Si levels increased considerably following the ingestion of beer or a solution of OSA but not with the ingestion of either 4·6% ethanol or water. The ultrafilterability of Si from beer (about 80%) and its absorption in volunteers (about 55%) was comparable with that of a solution of OSA suggesting that Si in beer is present chiefly in a monomeric form and is readily bioavailable.

The role for leptin in food intake regulation in the mink, a polytocous seasonal breeder with altricial young, was investigated in pregnant and lactating dams and data were related to quantitative energy metabolism measurements and plasma concentrations of other important metabolic hormones. A total of nine mink dams were measured in consecutive 1-week balance periods, each including a 22h measurement of heat production by means of indirect calorimetry, and blood was sampled at weekly intervals throughout gestation and during lactation weeks 1–4. Intake of metabolisable energy (ME) was high and energy balance was positive until the first third of true gestation. During mid- and late gestation ME intake decreased (P<0·001) while heat production remained almost constant, resulting in negative energy balance and the loss of body weight. From late gestation until lactation week 4, ME intake increased by 3·5 times, but weight loss continued. Plasma concentrations of leptin were approximately doubled during the last two-thirds of true gestation (P<0·01), demonstrating a clear gestational hyperleptinaemia. Concentrations declined rapidly after parturition and then remained stable. Insulin was independent of leptin, with low concentrations coincident with hyperleptinaemia. Also, concentrations of thyroid hormones declined during gestation, probably reflecting the low food intake. Hyperleptinaemia concomitant with low ME intake, negative energy balance and mobilisation of body reserves suggested an anorexigenic effect of leptin in pregnant mink. This suppression of food intake in late gestation might be permissive for the rapid increase in food intake occurring after parturition.

The oxidised derivatives of phytosterols (oxyphytosterols) were identified in plasma samples from thirteen healthy human volunteers, using MS. All the samples contained noticeable quantities of (24R)-5β,6β-epoxy-24-ethylcholestan-3β-ol (β-epoxysitostanol) and (24R)-ethylcholestan-3β,5α,6β-triol (sitostanetriol) and also trace levels of (24R)-5α,6α-epoxy-24-ethylcholestan-3β-ol (α-epoxysitostanol), (24R)-methylcholestan-3β,5α,6β-triol (campestanetriol) and (24R)-ethylch olest-5-en-3β-ol-7-one(7-ketositosterol). The amounts of these oxyphytosterols in plasma varied from 4·8 to 57·2 ng/ml. There are two possibilities concerning the origin of these compounds. First, they could come from the small amounts of oxyphytosterols in food. Second, they could originate from the in vivo oxidation of phytosterols in plasma. Very few data actually exist concerning these compounds. Their identification in human samples suggests that further research is necessary in this field.

The human pathogen Escherichia coli O157:H7 is thought to be spread by direct or indirect contact with infected animal or human faeces. The present study investigated the effects of the plant coumarin esculin and its aglycone esculetin on the survival of a strain of E. coli O157 under gut conditions. The addition of these compounds to human faecal slurries and in vitro continuous-flow fermenter models simulating conditions in the human colon and rumen caused marked decreases in the survival of an introduced strain of E. coli O157. When four calves were experimentally infected with E. coli O157 and fed esculin, the pathogen was detected in five of twenty-eight (18 %) of faecal samples examined post-inoculation, compared with thirteen of thirty-five (37 %) of faecal samples examined from five control calves not fed esculin. Coumarin compounds that occur naturally in dietary plants or when supplemented in the diet probably inhibit the survival of E. coli O157 in the gut.

To determine the effects of EPA, stearidonic acid (STA) or γ-linolenic acid (GLA) on immune outcomes, healthy male subjects consumed one of seven oil blends for 12 weeks. EPA consumption increased the EPA content of peripheral blood mononuclear cells (PBMC). Consumption of GLA (2·0 g/d) in the absence of STA or EPA increased di-homo-GLA content in PBMC. Neither STA nor its derivative 20:4n-3 appeared in PBMC when STA (<1·0 g/d) was consumed. However, STA (1·0 g/d), in combination with GLA (0·9 g/d), increased the proportion of EPA in PBMC. None of the treatments altered neutrophil or monocyte phagocytosis or respiratory burst, production of inflammatory cytokines by monocytes, T lymphocyte proliferation or the delayed-type hypersensitivity response. Production of cytokines by T lymphocytes increased in all groups, with no differences among them. The proportion of lymphocytes that were natural killer cells decreased significantly in subjects receiving 2·0 g EPA or GLA/d. There were no other effects on lymphocyte sub-populations. Plasma IgE concentration decreased in most groups, but not in the control group. Plasma IgG2 concentration increased in the EPA group. Thus, EPA or GLA at a dose of 2·0 g/d have little effect on key functions of neutrophils, monocytes and T lymphocytes, although at this dose these fatty acids decrease the number of natural killer cells. At this dose EPA increases IgG2 concentrations. STA can increase immune cell EPA status, but at 1·0 g/d does not affect human immune function.

Protein synthesis and turnover in ruminal micro-organisms were assessed by stable-isotope methods in order to follow independently the fate of amino acid (AA)-C and -N in different AA. Rumen fluid taken from sheep receiving a grass hay–concentrate diet were strained and incubated in vitro with starch–cellobiose–xylose in the presence of NH3 and 5 g algal protein hydrolysate (APH)/l, in incubations where the labels were 15NH3, [15N]APH or [13C]APH. Total 15N incorporation was calculated from separate incubations with 15NH3 and [15N]APH, and net N synthesis from the increase in AA in protein-bound material. The large difference between total and net AA synthesis indicated that substantial turnover of microbial protein occurred, averaging 3·5 %/h. Soluble AA-N was incorporated on average more extensively than soluble AA-C (70 v. 50 % respectively, P=0·001); however, incorporation of individual AA varied. Ninety percent of phenylalanine-C was derived from the C-skeleton of soluble AA, whereas the incorporation of phenylalanine-N was 72 %. In contrast, only 15 % aspartate-C + asparagine-C was incorporated, while 45 % aspartate-N+asparagine-N was incorporated. Deconvolution analysis of mass spectra indicated substantial exchange of carboxyl groups in several AA before incorporation and a condensation of unidentified C2 and C4 intermediates during isoleucine metabolism. The present results demonstrate that differential labelling with stable isotopes is a way in which fluxes of AA synthesis and degradation, their biosynthetic routes, and separate fates of AA-C and -N can be determined in a mixed microbial population.

The urinary excretion of soya isoflavones and gut microflora metabolites was investigated in infants and children who had been fed soya-based infant formulas in early infancy. These infants and children were compared with cows'-milk formula-fed controls, to determine at what age gut microflora metabolism of daidzein to equol and/or O-desmethylangolensin (O-DMA) was established, and whether exposure to isoflavones in early infancy influences their metabolism at a later stage of development. Sixty infants and children (aged 4 months–7 years) participated in the study; thirty in each of the soya and control groups. There were four age groups. These were: 4–6 months (seven in the soya group and seven in the control group); 7–12 months (seven in the soya group and nine in the control group); 1–3 years (six in the soya group and eight in the control group); 3–7 years (ten in the soya group and six in the control group). Urine samples were collected to measure isoflavonoids by MS, and faecal samples were collected to measure gut-health-related bacterial composition, by fluorescent in situ hybridisation with oligonucleotide probes, and metabolic activity. A soya challenge (typically a soya yoghurt alternative product containing 4·8g soya protein and on average 22mg total isoflavones) was given to control-group infants (>6 months) and children, and also to soya-group children that were no longer consuming soya, to determine their ability to produce equol and/or O-DMA. Urinary genistein, daidzein and glycitein were detected in all infants (4–6 months) fed soya-based infant formula; O-DMA was detected in 75% of infants but equol was detected in only 25%. In the controls (4–6 months), urinary isoflavonoids were very low or not detected. In the older age groups (7 months–7 years), O-DMA was found in the urine samples of 75% of the soya group and 50% of the controls, after the soya challenge. Equol excretion was detected in 19% of the soya-group infants and children, and in only 5% of the controls. However, in the oldest (3–7 years) children, the proportion excreting O-DMA and equol was similar in both groups. Faecal bacterial numbers for bifidobacteria (P<0·001), bacteroides and clostridia (P<0·05) were significantly lower for the soya group compared with the control group. There appears to be no lasting effect of early-life isoflavone exposure on isoflavone metabolism.

Epidemiological evidence suggests that dietary intake of carotenoids and tocopherols may influence the risk of certain chronic diseases, such as cancer and CVD. In vitro studies investigating the synergistic effects of mixtures of carotenoids and tocopherols have been hindered due to the difficulty of solubilising these lipophilic compounds. The objective of the present study was to develop a system for delivering tocopherols and carotenoids simultaneously to cells in culture. Differentiated human colonic adenocarcinoma cells (CaCo-2) were incubated with a mixture of these phytochemicals for 24 h. The phytochemical mixture included carotenoids (astaxanthin, canthaxanthin, lutein, lycopene, α-carotene, β-carotene) and tocopherols (α-tocopherol and γ-tocopherol). The emulsifiers polyoxyethylene sorbitan monopalmitate (Tween 40) and polyoxyethylene sorbitan monooleate (Tween 80) were employed as the delivery vehicles, and were compared with tetrahydrofuran (THF). Each vehicle was added at a maximum concentration of 1 ml/l. No toxic effects to the CaCo-2 cells were noted when Tween 40 or Tween 80 were used. Both Tween 40 and Tween 80 resulted in greater solubility of the mixture and delivered substantially more carotenoids and tocopherols to the cells than THF. In particular, lycopene was detected within the cells when Tween 40 and Tween 80 were employed, whereas it was below the limits of detection by HPLC when THF was used as the delivery vehicle. The phytochemicals were retained within the cells for 24 h after supplementation. Tween 40 and Tween 80 have potential as simple, rapid and non-toxic methods for delivering mixtures of carotenoids and tocopherols to cells in culture.

The effects of various dietary fibres on gut health have been studied extensively but their combined effects are scarcely documented. In the present study the effects of 2 % (w/w) polydextrose (PDX), 2 % (w/w) disaccharide lactitol, or 2 % (w/w) PDX+2 % (w/w) lactitol on gut microflora, microbial metabolism and gut immune responses were investigated in rats. Both PDX and lactitol alone had an effect on many of the studied parameters, but their combination had stronger than additive effects in some parameters. The PDX+lactitol combination altered the microbial community structure as seen by a culture-independent method, percentage guanine+cytosine (%G+C) profiling, increasing the areas of %G+C 35–39 (P<0·0001) and %G+C 45–49 (P=0·0002), and decreasing %G+C 65–74 (P<0·0003). These changes were also reflected in the microbial metabolism so that the production of biogenic amines and branched volatile fatty acids was significantly reduced, by 12 (P=0·03) and 50 % (P=0·002), respectively, indicating a shift from putrefactive towards saccharolytic metabolism. PDX increased the secretion of IgA in the caecum (P=0·007). Secretion of IgA increased even more, almost ten-fold, with the combination of PDX+lactitol (P<0·0001) when compared with the control group. Lactitol increased the production of butyrate by caecal microbes by two- to three-fold when compared with the PDX or control group (P<0·0001). Butyrate is a preferred energy source for mucosal cells; thus a boost in the availability of energy for immune cells may have still added to the synergistic effects of PDX and lactitol on immune cells. It is noteworthy that improvement in the IgA secretion occurred without signs of mucosal inflammation.

Lingzhi (Ganoderma lucidum) is a woody mushroom highly regarded in traditional medicine and is widely consumed in the belief that it promotes health and longevity, lowers the risk of cancer and heart disease and boosts the immune system. However, objective scientific validation of the putative health benefits of Lingzhi in human subjects is lacking, and issues of possible toxicity must be addressed. The present double-blinded, placebo-controlled, cross-over intervention study investigated the effects of 4 weeks Lingzhi supplementation on a range of biomarkers for antioxidant status, CHD risk, DNA damage, immune status, and inflammation, as well as markers of liver and renal toxicity. It was performed as a follow-up to a study that showed that antioxidant power in plasma increased after Lingzhi ingestion, and that 10 d supplementation was associated with a trend towards an improved CHD biomarker profile. In the present study, fasting blood and urine from healthy, consenting adults (n 18; aged 22–52 years) was collected before and after 4 weeks supplementation with a commercially available encapsulated Lingzhi preparation (1·44 g Lingzhi/d; equivalent to 13·2 g fresh mushroom/d) or placebo. No significant change in any of the variables was found, although a slight trend toward lower lipids was again seen, and antioxidant capacity in urine increased. The results showed no evidence of liver, renal or DNA toxicity with Lingzhi intake, and this is reassuring. The present study of the effects in healthy, well-nourished subjects provides useful, new scientific data that will support controlled intervention trials using at-risk subjects in order to assess the therapeutic effect of Lingzhi in the promotion of healthy ageing.

Ferric pyrophosphate is a water-insoluble Fe compound used to fortify infant cereals and chocolate-drink powders as it causes no organoleptic changes to the food vehicle. However, it is only of low absorption in man. Recently, an innovative ferric pyrophosphate has been developed (Sunactive Fe™) based on small-particle-size ferric pyrophosphate (average size 0·3 μm) mixed with emulsifiers, so that it remains in suspension in liquid products. The aim of the present studies was to compare Fe absorption of micronised, dispersible ferric pyrophosphate (Sunactive Fe™) with that of ferrous sulfate in an infant cereal and a yoghurt drink. Two separate Fe absorption studies were made in adult women (ten women/study). Fe absorption was based on the erythrocyte incorporation of stable isotopes (57Fe and 58Fe) 14 d after the intake of labelled test meals of infant cereal (study 1) or yoghurt drink (study 2). Each test meal was fortified with 5 mg Fe as ferrous sulfate or micronised, dispersible ferric pyrophosphate. Results are presented as geometric means. There was no statistically significant difference between Fe absorption from micronised, dispersible ferric pyrophosphate- and ferrous sulfate-fortified infant cereal (3·4 and 4·1 % respectively; P=0·24) and yoghurt drink (3·9 and 4·2 % respectively; P=0·72). The results of the present studies show that micronised, dispersible ferric pyrophosphate is as well absorbed as ferrous sulfate in adults. The high relative Fe bioavailability of micronised, dispersible ferric pyrophosphate indicates the potential usefulness of this compound for food fortification.

The present study examined the effect of glutamine (Gln)-enriched diets before sepsis or Gln-containing total parenteral nutrition (TPN) after sepsis, or both, on the phagocytic activity and blood lymphocyte subpopulation in rats with gut-derived sepsis. Rats were assigned to a control group or one of four experimental groups. The control group and groups 1 and 2 were fed a semipurified diet; groups 3 and 4 had part of casein replaced by Gln. After feeding the diets for 10d, sepsis was induced by caecal ligation and puncture (CLP); TPN was maintained for 3d after CLP. The control group and groups 1 and 3 were infused with conventional TPN and groups 2 and 4 were supplemented with Gln in the TPN solution. All rats were killed 3d after CLP or sham operation to examine their immune responses. The results showed that compared with the control group, the phagocytic activities of peritoneal macrophages were enhanced in groups 3 and 4, but not in groups 1 and 2. The proportion of CD3+ cells in group 1 was significantly lower (P<0·05) than that of the control group, whereas no differences were observed among the control and Gln-supplemented groups. The CD4+ cell proportion was significantly lower (P<0·05) in group 1 compared with the control group and groups 3 and 4. These findings suggest that Gln-enriched diets before CLP significantly enhanced peritoneal macrophage phagocytic activity, preserved CD4+ cells and maintained blood total T lymphocytes in gut-derived sepsis. However, parenteral Gln administration after caecal ligation and puncture had no favourable effects on modulating immune response in septic rats.

Many people take dietary supplements, but information on characteristics associated with their use is lacking. The relationship between lifestyle behaviours, morbidity and use of dietary supplements has not been examined and earlier studies have limited applicability to a general population. These issues were addressed in the current study. Information was obtained by postal questionnaire sent to a sample of the general population. The questionnaire was completed by 70·5% of the sample (15465 from a total sample of 21923), with at least one-third (35·5%) taking dietary supplements. In adjusted analyses, supplement users were more likely to be women, white, home-owners, non-smokers and physically active. Use of vitamin, mineral and/or antioxidant supplements was associated with eating more fruits and vegetables, and taking fish-oil supplements was associated with eating oil-rich fish. A history of CVD or risk factors for CVD reduced the risk of taking vitamins, minerals and/or antioxidants or fish-oil supplements. Those reporting musculoskeletal disorders such as arthritis were more likely to take fish-oil supplements For the first time, we have shown that dietary supplement use is related to different types of morbidity. In particular, people at risk of primary or secondary CVD seem less likely to use dietary supplements, despite possible benefits shown in clinical trials. Public health organisations need to develop guidelines for the public and health professionals regarding the uncontrolled use of dietary supplements in the community.

Acetate is normally regarded as an endproduct of anaerobic fermentation, but butyrate-producing bacteria found in the human colon can be net utilisers of acetate. The butyrate formed provides a fuel for epithelial cells of the large intestine and influences colonic health. [1-13C]Acetate was used to investigate the contribution of exogenous acetate to butyrate formation. Faecalibacterium prausnitzii and Roseburia spp. grown in the presence of 60 mm-acetate and 10 mm-glucose derived 85–90 % butyrate-C from external acetate. This was due to rapid interchange between extracellular acetate and intracellular acetyl-CoA, plus net acetate uptake. In contrast, a Coprococcus-related strain that is a net acetate producer derived only 28 % butyrate-C from external acetate. Different carbohydrate-derived energy sources affected butyrate formation by mixed human faecal bacteria growing in continuous or batch cultures. The ranking order of butyrate production rates was amylopectin > oat xylan > shredded wheat > inulin > pectin (continuous cultures), and inulin > amylopectin > oat xylan > shredded wheat > pectin (batch cultures). The contribution of external acetate to butyrate formation in these experiments ranged from 56 (pectin) to 90 % (xylan) in continuous cultures, and from 72 to 91 % in the batch cultures. This is consistent with a major role for bacteria related to F. prausnitzii and Roseburia spp. in butyrate formation from a range of substrates that are fermented in the large intestine. Variations in the dominant metabolic type of butyrate producer between individuals or with variations in diet are not ruled out, however, and could influence butyrate supply in the large intestine.

The present study was conducted to investigate whether green tea may improve weight maintenance by preventing or limiting weight regain after weight loss of 5 to 10% in overweight and moderately obese subjects. The study had a randomised, parallel, placebo-controlled design. A total of 104 overweight and moderately obese male and female subjects (age 18–60 years; BMI 25–35kg/m2) participated. The study consisted of a very-low-energy diet intervention (VLED; 2·1MJ/d) of 4 weeks followed by a weight-maintenance period of 13 weeks in which the subjects received green tea or placebo. The green tea contained caffeine (104mg/d) and catechins (573mg/d, of which 323mg was epigallocatechin gallate). Subjects lost 6·4 (sd 1·9) kg or 7·5 (sd 2·2) % of their original body weight during the VLED (P<0·001). Body-weight regain was not significantly different between the green tea and the placebo group (30·5 (sd 61·8) % and 19·7 (sd 56·9)%, respectively). In the green tea treatment, habitual high caffeine consumption was associated with a higher weight regain compared with habitual low caffeine consumption (39 (sd 17) and 16 (sd 11)%, respectively; P<0·05). We conclude that weight maintenance after 7·5% body-weight loss was not affected by green tea treatment and that habitual caffeine consumption affected weight maintenance in the green tea treatment.