A review covering different methods for the analysis of phyto-oestrogens in biological matrices is presented. Sample pretreatment and analysis of isofiavonoids and lignans by HPLC and GC with various detection methods are discussed. The immunoassay method is also briefly presented.

The effect of 4-coumaric and 3,4-dihydroxybenzoic (protocatechuic) acid on the basal oxidative DNA damage of rat colonic mucosa in vivo was studied, relative to vitamin E. F344 rats were treated with 4-coumaric or protocatechuic acid mixed in the diet (25 or 50 mg/kg for 2 weeks). It was observed that 4-coumaric acid (50 mg/kg) significantly decreased the basal level of the oxidative damage assessed as 8-OH-2′-deoxyguanosine levels in DNA and by the comet assay. Moreover, it was found that vitamin E (10 mg/kg) had no effect on colonic mucosa oxidation damage, whereas at a higher dose (55 mg/kg) it actually enhanced oxidative stress. The effect of 4-coumaric acid (50 mg/kg) on the expression of some glutathione-related enzymes (glutathione-S-transferase (GST)-P, GST-M2, GST-M1, γ-glutamylcysteine synthetase, glutathione peroxidase (GSPX)1 and GSPX4) was also investigated at the level of the colonic mucosa. Only the expression of GST-M2 was significantly induced by 4-coumaric acid, while protocatechuic acid was inactive. The data suggest that 4-coumaric acid acts as an antioxidant in the colonic mucosa in vivo.

Dietary trans fatty acids are associated with increased risk of CHD. We hypothesized that the changes in plasma lipids associated with a high intake of trans fatty acids would cause adverse effects on procoagulant and fibrinolytic activities. A randomized crossover controlled feeding study was conducted in twenty-nine men. A trans-rich diet supplying 10 % energy as trans- 18:1 was compared with diets in which the trans fatty acids were replaced either with carbohydrate or oleate; each diet was taken for 2 weeks in random order. Fasting fibrinogen and D-dimer concentrations and factor VII coagulant, plasminogen activator inhibitor type 1 and tissue plasminogen activator did not differ between diets. Postprandially, tissue plasminogen activator activity increased and plasminogen activator inhibitor type 1 activity decreased on all diets. Factor VIIc increased postprandially by 15 and 17 % on the trans and oleate diets respectively, compared with an 11 % increase on the carbohydrate diet; the mean difference between oleate and carbohydrate diets was 6 (95 % CI 0·2, 11·9) %. The LDL-cholesterol:HDL-cholesterol and apolipoprotein B: apolipoprotein A-I ratios increased by 13 (95 % CI 5·7, 21·8) and 10 (95 % CI 3·1, 17·2) % respectively on the trans diet compared with the oleate diet and by 6 (95 % CI 0·1,12·7) and 7 (95 % CI 0, 13·5) % respectively compared with the carbohydrate diet. Plasma HDL2-cholesterol concentration was 18 (95 % CI 0·7, 35·9) % lower on the trans diet compared with the oleate diet. The results confirm adverse effects of trans fatty acids on HDL-cholesterol concentrations, but suggest that trans fatty acids do not have any specific effects on known haemostatic risk markers for cardiovascular disease in healthy young men in the short-term.

This present study was designed to investigate the combined modulatory effect of garlic oil (GO) and fish oil (FO) on the antioxidant and drug metabolism systems. Rats were fed either a low-maize oil (MO) diet (50 g MO/kg), high-MO diet (235 g MO/kg) or high-FO diet (205 g FO+30 g MO/kg) and received different doses of GO (0–200 mg/kg body weight) three times per week for 6 weeks. Fatty acid analysis showed that 20: 5n−3 and 22: 6n−3 were incorporated into serum lipid at the expense of 18: 2n−6 and 20: 4n−6 in rats fed the high-FO diet. GO dose-dependently increased hepatic glutathione S-transferase (GST), glutathione reductase, superoxide dismutase (SOD) and ethoxyresorufin O-deethylase (EROD) activities, but decreased glutathione peroxidase and N-nitrosodimethylamine demethylase (NDMAD) activities (P<0·05). With the exception of glutathione peroxidase, the activities of glutathione reductase, SOD, GST, EROD and NDMAD were modulated by the dietary fat. The high-FO group had greater SOD and EROD activity than either MO-fed group; it also had greater NDMAD activity than the low-MO group (P<0·05). GST activity was higher in rats fed high-FO or high-MO diets than rats fed the low-MO diet. Change in erythromycin demethylase activity, however, was not caused by either dietary fat or GO. Immunoblot assay showed that GO dose-dependently enhanced the protein level of the Ya, Yb1, Yc isoenzymes of GST and cytochrome P450 (CYP) 1A1 and 3A1, but GO suppressed CYP2E1 expression. Regardless of the dosage of GO, the high-FO diet increased CYP1A1, CYP3A1 and CYP2E1 levels compared with the high- and low-MO diets. Accompanying the changes observed in immunoblots, CYP1A1 and CYP3A1 mRNA levels were increased by GO in a dose-dependent manner and also increased additively in combination with FO feeding. These present results indicate that co-administration of GO and FO modulates the antioxidant and drug-metabolizing capacity of animals and that the effect of GO and FO on drug-metabolizing enzymes is additive.

The accepted biological potencies of vitamin E (United States Phamacopeia, 1985) for 1 mg all-rac-α-tocopheryl acetate (synthetic form) is 1·00 IU and that of 1 mg (RRR)-α-tocopheryl acetate (natural form) is 1·36 IU. In the present study, a stable isotopic (2H) technique was employed to evaluate the bioavailability of natural v. synthetic forms of vitamin E and to determine whether the potency of the forms is the stated relationship of 1·36:1·00 (RRR)-α-tocopheryl acetate:all-rac-α-tocopheryl acetate. Sixty female in-bred guinea pigs received either 40 or 80 mg vitamin E/kg diet with equal levels of (RRR)-α-tocopheryl acetate and all-rac-α-tocopheryl acetate throughout gestation and lactation. At late-term pregnancy (day 50 or 60) and during early lactation, dams and their corresponding fetuses or neonates were killed and various tissues collected for subsequent α-tocopherol analysis. Vitamin E analysis of fetal and neonatal tissues indicated a substantial transfer of 2H-labelled α-tocopherol across the placenta and through the mammary gland. Total α-tocopherol concentrations were significantly influenced by tissue type and dose level, but not by stage of gestation or lactation. The relative bioavailability (d3:d6) across fetal and neonatal tissues was on average 1·81:1·00, with a range from 1·62:1·00 to 2·01:1·00. Maternal tissues had a mean ratio of 1·77:1·00. A higher relative bioavailability (P≤0·05) was observed with natural compared with synthetic α-tocopherol as shown by a higher d3:d6 ratio in all tissues examined. Vitamin E was highest in colostrum on day 2 then declined through to day 5. Results from this present experiment further question the accepted biological potencies of natural:synthetic α-tocopheryl acetate of 1·36:1·00.

In a previous study, we found that the extent of dietary n-3 docosahexaenoic acid (DHA)-stimulated tissue lipid peroxidation was less than expected from the relative peroxidizability index of the total tissue lipids in rats with adequate vitamin E nutritional status. This suppression of lipid peroxidation was especially prominent in the liver. To elucidate whether this phenomenon was unique to DHA, we compared the peroxidation effects of n-3 α-linolenic acid (α-LN) and n-3 eicosapentaeonic acid (EPA) with those of DHA in rats. Either α-LN (8·6 % of total energy), EPA (8·2 %), or DHA (8·0 %) and one of two levels of dietary vitamin E (7·5 and 54 mg/kg diet) were fed to rats for 22 d. Levels of conjugated diene, chemiluminescence emission and thiobarbituric acid (TBA)-reactive substance in the liver, kidney, and testis were determined as indicators of lipid peroxidation. In rats fed the DHA diet deficient in vitamin E (7·5 m/g diet), TBA values in the liver, kidney, and testis correlated well with the tissues' relative peroxidizability indices. In rats fed the α-LN diet with an adequate level of vitamin E (54 m/g diet), a close association between relative peroxidizability indices and lipid peroxide levels was observed in all the tissues analysed. However, in rats fed either the EPA diet or the DHA diet with an adequate level of vitamin E, the extent of lipid peroxidation in each tissue was less than expected from the relative peroxidizability index. This suppression was particularly marked in the liver. We concluded that suppression of lipid peroxidation below the relative peroxidizability index was not unique to DHA, but was also seen with EPA, which has five double bonds, in rats with adequate vitamin E nutritional status, but not with α-LN, which has three double bonds.

The objective of the Vegetal Estrogens in Nutrition and the Skeleton (VENUS) project was to evaluate existing data on dietary exposure to compounds with oestrogenic and anti-oestrogenic effects present in plant foods as constituents or contaminants, and to identify and disseminate in vitro and in vivo methodologies to analyse the effects of such compounds on bone. To permit the assessment of exposure to isoflavones in European populations (Italy, the UK, Ireland, The Netherlands), the VENUS database of phyto-oestrogen levels in foods was established. Data on the isoflavone (genistein and daidzein) content of 791 foods, including almost 300 foods commonly consumed in Europe, were collected. Levels of coumestrol, formononetin and biochanin A in a limited number of foods were also included. Lignan levels (secoisolariciresinol and matairesinol) in 158 foods were incorporated into the database, which also contains information on the references sourced for the compositional data, on the analytical methods used by each author and on the number of foods analysed in each reference. The VENUS database was constructed in Microsoft® Access 2000, which is widely available as part of Microsoft® Office Professional. This paper outlines the procedures used for the selection and evaluation of existing literature data for incorporation into the database. In addition, the design of the database is described, along with the data entry and quality control procedures used in its construction. Limitations of the data are discussed and guidelines for its use are provided.

The composition of the raw legume Phaseolus vulgaris L. var. athropurpurea (PhVa) and its effects on the metabolism of young growing rats have been evaluated. The levels of protein, unsaturated fatty acids, carbohydrate, fibre and bioactive factors present in PhVa were comparable with those in other Phaseolus vulgaris varieties. However, the lectins of PhVa were predominantly of the leucoagglutinating type, and concentrated in the albumin protein fraction. Rats fed a diet (110 g total protein, 16·0 M/g) in which PhVa meal provided about half of the protein excreted high levels of N in faeces and urine, and grew more slowly, than rats fed a high-quality control diet (ad libitum or pair-fed). Small intestine, large intestine and pancreas weights were increased (by almost 100 %, P<0·05), whilst skeletal muscle, thymus and spleen weights were reduced. Blood insulin 16·20 v. 0·50 m/, P<0·05, thyroxine, glucose, protein (60·5 v. 48·3 /, P<0·05) and LDL-cholesterol were lowered, whilst glucagon (155·3 v. 185·4 n/, P<0·05), triiodothyronine and urea were elevated, as were urinary urea, creatinine and glucose. These changes in the local (gut) and systemic metabolism of rats were probably mediated primarily by lectins in PhVa, which were concentrated in the albumin protein fraction, whereas in many other Phaseolus vulgaris lines they are distributed across the globulin and albumin fractions.

The effect of adaptation time on the concentration and pattern of short-chain fatty acids (SCFA) formed in the hindgut of rats given resistant starch (RS) in the form of raw potato starch (RPS) or high-amylose maize starch (HAS) was evaluated. Each starchy material was tested in diets containing 100 g indigestible carbohydrate/g DM, and fed for 13, 28 and 42 d. At the end of each period, the content of SCFA was determined in caecum, distal colon and faeces. The caecal concentration of total and individual SCFA increased for both diets with increasing adaptation time. The concentration of butyric acid was higher in the group fed RPS than in that fed HAS at all adaptation times. The caecal proportion of butyric acid was low both in rats fed RPS and HAS (6 and 4 %, respectively) following 13 d of adaptation. However, after 28 d of adaptation, the proportion of butyric acid had increased to 19 % in rats given RPS. A longer adaptation period (42 d) did not increase the proportion of butyric acid further. With HAS, there was also a significant (P<0·01) increase in the proportion of butyric acid with longer adaptation time. However, the increase was much slower and the proportion of butyric acid reached 6 and 8 % after 28 and 42 d respectively. It is concluded that the pattern of SCFA formed from RS in rats is dependent on adaptation time. It cannot be excluded that the different patterns of SCFA reported in the literature for RS may be due to the time of adaptation.

The aim of this study was to identify the level of isoflavone intake (total isoflavones, daidzein and genistein) in four European countries: Ireland, Italy, The Netherlands and the UK. For this purpose national food composition databases of isoflavone content were created in a comparable way, using the Vegetal Estrogens in Nutrition and the Skeleton (VENUS) analytical data base as a common basis, and appropriate food consumption data were selected. The isoflavone intake in Ireland, Italy, The Netherlands and the UK is on average less than 1 mg/d. Small groups of consumers of soya foods could be identified in Ireland, The Netherlands and the UK. The estimated intake levels are low compared with those found in typical Asian diets (∼20–100 mg/d) and also low compared with levels where physiological effects are expected (60–100 mg/d). The results (including a subgroup analysis of soya product consumers) showed that such levels are difficult to achieve with the European diets studied here.

Nitrates have long been considered as harmful dietary components and judged responsible for deleterious effects on human health, leading to stringent regulations concerning their levels in food and water. However, recent studies demonstrate that dietary nitrate may have a major role in human health as a non-immune mechanism for host defence, through its metabolism to NO in the stomach. NO is a versatile molecule and although evidence exists showing that administration of low doses of exogenous NO protects against gastrointestinal inflammation, higher NO doses have been shown to exacerbate injury. So, the effect of an ingestion of nitrates in doses corresponding to a normal diet in human consumers on an experimental gastritis induced by iodoacetamide in rats was investigated. During gastritis one of the following compounds was given orally: water; KNO3; the NO donor sodium nitroprusside; the NO scavenger haemoglobin given with either water or KNO3. N(G)-nitro-L-arginine methyl ester (L-NAME), a non-specific NO synthase inhibitor, was administered with either water, iodoacetamide alone, or combined with KNO3. After killing, the stomach was resected and microscopic damage scores, myeloperoxidase and NO synthase activities were determined. Iodoacetamide-induced gastritis was significantly reduced by KNO3 administration, an effect which was reproduced by sodium nitroprusside and reversed by haemoglobin. L-NAME induced gastric mucosal damage in itself, and KNO3 did not prevent the gastritis induced by iodoacetamide associated with L-NAME. In conclusion, dietary nitrate exerts a protective effect against an experimental gastritis in rats by releasing NO in the stomach but such an effect requires the production of endogenous NO.

Consumption of isoflavone-rich soyabean protein is reported to reduce total and LDL-cholesterol, but the specific components responsible are undetermined. In a previous crossover trial we showed that purified isoflavones, derived from red clover (Trifolium pratense), raised HDL3-cholesterol in premenopausal women; however, these findings were inconclusive due to period and carryover effects. In an attempt to overcome this problem, we utilised a parallel study designed to re-examine the effects of purified isoflavones on plasma lipoproteins and markers of insulin resistance in premenopausal women. Twenty-five healthy premenopausal women participated in a double-blind, randomised, parallel study. The treatment group (n 12) consumed a placebo for the first menstrual cycle and an isoflavone supplement (86 mg/d, derived from red clover) for three cycles, while the placebo group (n 13) consumed a placebo supplement for four menstrual cycles. Blood samples were collected weekly during cycles 1, 3 and 4. Supplementation with isoflavones resulted in a 15-fold increase in urinary isoflavone excretion (P<0·0001). There were no significant effects on total cholesterol, LDL- and HDL-cholesterol, HDL subfractions, triacylglycerol, lipoprotein(a), glucose or insulin concentrations. Our present results indicate that purified isoflavones derived from red clover have no effect on cholesterol homeostasis or insulin resistance in premenopausal women, a group which is at low risk of CHD.

We have conducted studies with juvenile yellow perch (Perca flavescens) over a period of 20 weeks to address the question of the interaction between water- and lipid-soluble antioxidant vitamins. Fish (2·25±0·14 g) were divided into twelve groups, and triplicate groups were fed one of four casein-based, semi-purified diets formulated to contain low or high vitamin E levels of either 5 or 160 mg/kg without or with vitamin C supplementation (250 mg/kg). Diets were designated as −C−E, −C+E, +C−E, or +C+E, respectively. The fish fed the +C+E diet showed significantly higher weight gain, feed intake, and feed efficiency than the groups fed vitamin C-deficient diets. Total ascorbate concentrations of liver were significantly higher in fish fed vitamin C-supplemented diets than in fish fed the vitamin C-deficient diet after 16 and 20 weeks. The liver α-tocopherol concentrations were increased by supplemental vitamin C in vitamin E-deficient dietary groups which indicates a sparing or regenerating effect of vitamin C on vitamin E. Fish fed vitamin C-deficient diets (−C−E and −C+E) exhibited severe deficiency symptoms, such as scoliosis, lens cataracts, anorexia, and haemorrhages. The cumulative mortality was significantly higher in the −C−E groups. The thiobarbituric acid-reactive substances value was significantly higher in blood plasma of fish fed a diet unsupplemented with both vitamins. The findings in the present study with yellow perch support the hypothesis that vitamin C regenerates and/or spares vitamin E in vivo.

The cat (Felis silvestris catus) has a higher dietary protein requirement than omnivores and herbivores, thought to be due to metabolic inflexibility. An aspect of metabolic flexibility was examined with studies of whole-body protein turnover at two levels of dietary protein energy, moderate protein (MP; 20 %) and high protein (HP; 70 %), in five adult cats in a crossover design. Following a 14 d pre-feed period, a single intravenous dose of [15N]glycine was administered and cumulative excretion of the isotope in urine and faeces determined over 48 h. N flux increased (P<0·005) with dietary protein, being 56 (SE 5) MMOL /G BODY WEIGHT (BW) PER D FOR CATS FED THE MP DIET AND 146 (se 8) mmol /g BW per d for cats fed the HP diet. Protein synthesis was higher (P<0·05) on the HP diet (75 (se 10) mmol /g BW per d; 6·6 (se 1) g protei/g BW per d) than the MP diet (38 (se 5) mmol /g BW per d; 3·4 (se 0·4) g protei/g BW per d). Protein breakdown was higher (P<0·05) on the HP diet (72 (se 8) mmol /g BW per d; 6·3 (se 0·7) g protei/g BW per d) than the MP diet (44 (se 3) mmol /g BW per d; 3·9 (se 0·3) g protei/g BW per d). Compared with other species the rate of whole-body protein synthesis in the well-nourished cat (9·7 (se 1·3) g protei/g BW0·75 per d) is at the lower end of the range. These results show that feline protein turnover adapts to dietary protein as has been shown in other species and demonstrates metabolic flexibility. Further work is required to determine exactly why cats have such a high protein requirement.

Rhubarb (Rheum rhapontiam) stalk fibre was previously shown to be hypolipidaemic under clinical and experimental conditions. The present study was undertaken to investigate whether rhubarb stalk fibre has a hypolipidaemic effect under diabetic conditions. Two models of diabetic rats were used: streptozotocin-induced diabetic rats, and diabetes-prone BB (BBdp) rats. The plasma cholesterol and triacylglycerol concentrations were elevated after the onset of diabetes in BBdp rats, but not in sterptozotocin-induced diabetic rats. The rhubarb-fibre diet had no effect on the plasma cholesterol or triacylglycerol concentrations of diabetic rats. The hypolipidaemic effect of rhubarb stalk fibre has been suggested to be due to the bile-acid-binding capacity of rhubarb fibre, which in turn up regulates cholesterol 7α-hydroxylase (cyp7a) activity. cyp7a is the first and the rate-limiting enzyme in the breakdown of cholesterol to bile acids. We measured the cyp7a activity and mRNA levels in control and diabetic rats fed rhubarb- and cellulose-fibre diets. The cyp7a activity and mRNA abundance were increased in both diabetic rat models, indicating that bile acid synthesis is enhanced in diabetes. Feeding a diet enriched with rhubarb fibre caused a slight but significant increase (P<0·05) in cyp7a enzyme activity in BBdp rats, but no change in cyp7a mRNA abundance was detected. These results suggest that although a rhubarb-fibre-enriched diet increased cyp7a activity in BBdp rats, there was no apparent therapeutic benefit in terms of lowering plasma cholesterol concentrations.

Information on phyto-oestrogen intake in various populations has been scanty until now, primarily because data on the content of these compounds in foods were lacking. We report here on expansion of the Finnish National Food Composition Database (Fineli®) with values for the plant lignans matairesinol and secoisolariciresinol and the isoflavones daidzein and genistein. The values, expressed as aglycones, were based on food analyses (mainly GC–MS) or imputed from analytical data for 180 foods for lignans and 160 foods for isoflavones; additionally, over 1000 values were derived from the recipe database of Fineli. Average intake of these phyto-oestrogens was calculated using food consumption data of the National Dietary Survey FINDIET 1997, which was carried out in a random sample of the adult population in five areas in Finland. The dietary data were collected by 24 h recall (n=2862). The mean lignan intake was 434 (standard deviation (SD) 1575) μg/d and the mean isoflavone intake was 788 (SD 673) μg/d. Women had a higher lignan density (μg lignans/MJ) in their diet than men (P<0·05). Men had a higher mean daily isoflavone intake, 902 (SD 368) μg, than women, 668 (SD 963) μg (P<0·05). The sources of lignans were many: seeds, cereals, fruit, berries and vegetables. The main sources of isoflavones appeared to be processed meat products/sausages containing soya as an ingredient, and legumes as such. The average intake of lignans and isoflavones in Finland seems to be low, but intake varies throughout the population.

The intake of a carotenoid-rich diet is epidemiologically related to a lower risk for different chronic disorders like cardiovascular disease, some types of cancer or age-related macular degeneration. Red pepper (Capsicum annuum L.) and its dietary products contain a variety of carotenoids, which may contribute to the carotenoid pattern of human blood and tissues. The objective of the present study was to assess the availability of carotenoids from paprika oleoresin, including zeaxanthin, β-cryptoxanthin, β-carotene and the paprika-specific oxocarotenoids capsanthin and capsorubin. After overnight fasting, the volunteers (n 9) ingested a single dose of the paprika oleoresin containing 6·4 mg zeaxanthin, 4·2 mg β-cryptoxanthin, 6·2 mg β-carotene, 35·0 mg capsanthin and 2·0 mg capsorubin. At different time points the carotenoid pattern in the chylomicron fraction was analysed to evaluate carotenoid absorption. From the major carotenoids present in the paprika oleoresin only zeaxanthin, β-cryptoxanthin and β-carotene were detectable in considerable amounts. Although the xanthophylls in paprika oleoresin were mainly present as mono- or di-esters, only free zeaxanthin and β-cryptoxanthin were found in human samples. The bioavailability of the pepper-specific carotenoids capsanthin and capsorubin from paprika oleoresin is very low. However, oleoresin is a suitable source for the provitamin A carotenoids β-carotene and β-cryptoxanthin and the macular pigment zeaxanthin.

The effects of fructans in the diet on the mucosal morphometry (height of villi, depth of the crypts, number of goblet cells), the thickness of the epithelial mucus layer and the histochemical composition of intestinal mucosubstances in the distal jejunum and the distal colon were investigated by comparing germ-free (GF) rats, rats harbouring Bacteroides vulgatus and Bifidobacterium longum (diassociated (DA) rats), and rats with a human faecal flora (HFA). The rats were fed either a commercial standard diet (ST) or ST + (50 g oligofructose (OF)–long-chain inulin (lcIN))/kg. Changes in total bacteria, bifidobacteria and Bacteroides–Prevotella in response to feeding these diets were investigated by fluorescent in situ hybridization with 16S rRNA-targeted probes both in intestinal contents (lumen bacteria) and tissue sections (mucosa-associated bacteria). The OF–lcIN-containing diet resulted in higher villi and deeper crypts in bacteria-associated, but not in GF rats. In DA and HFA rats, the colonic epithelial mucus layer was thicker and the numbers of the goblet cells were greater than in GF rats. These effects were enhanced by the OF–lcIN-containing diet. In both dietary groups, bacterial colonization of GF rats caused an increase in neutral mucins in the distal jejunum and colon. Bacteria-associated rats had more acidic mucins in the colon than GF rats, and the OF–lcIN-containing diet stimulated sulfomucins as the predominant type of acidic mucins, while sialomucins dominated in the ST-fed groups. The number of mucosa-associated bifidobacteria detected in the colon of DA and HFA rats was greater with OF–lcIN than ST (4·9 and 5·4 v. 3·5 and 4·0 log10/mm2 mucosal surface respectively), whereas the number of luminal bifidobacteria was only affected by fructans in DA rats. Bacteroides did not differ between the groups. The stabilisation of the gut mucosal barrier, either by changes in the mucosal architecture itself, in released mucins or by stimulation of mucosal bifidobacteria with fructans, could become an important topic in the treatment and prophylaxis of gastrointestinal disorders and health maintenance.

A cross-sectional study of 132 adults attending an HIV clinic in Cape Town, South Africa, was conducted to determine predictors of low plasma vitamin A and Zn levels. No patients were on antiretroviral therapy. The possible confounding effect of the acute-phase response was controlled by including C-reactive protein levels in multivariate analysis and by excluding active opportunistic infections. Retinol levels were low (<1·05 μmol/l) in 39 % of patients with early disease (WHO clinical stages I and II) compared with 48 and 79 % of patients with WHO stage III and IV respectively (P<0·01). Plasma Zn levels were low (<10·7 μmol/l) in 20 % of patients with early disease v. 36 and 45 % with stage III and IV disease respectively (P<0·05). C-reactive protein levels were normal in 63 % of subjects. Weak, positive associations were found between CD4+ lymphocyte count and plasma levels of retinol (r 0·27; 95 % CI 0·1, 0·43) and Zn (r 0·31; 95 % CI 0·25, 0·46). Multivariate analysis showed the following independent predictors of low retinol levels: WHO stage IV (odds ratio 3·4; 95 % CI 2·1, 5·7) and body weight (odds ratio per 5 kg decrease 1·15; 95 % CI, 1·08, 1·25), while only body weight was significantly associated with low Zn levels (OR per 5 kg decrease 1·19; 95 % CI 1·09, 1·30). CD4+ lymphocyte count <200/μl was not significantly associated with either low retinol or Zn levels. In resource-poor settings, simple clinical features (advanced disease and/or weight loss) are associated with lowered blood concentrations of vitamin A and/or Zn. The clinical significance of low plasma retinol and/or Zn levels is unclear and more research is required to establish the role of multiple micronutrient intervention strategies in HIV disease.

Postprandial concentrations of glucose, insulin and triacylglycerols (TG) correlate to risk for CHD. Carbohydrates affect many metabolites that could have a potential effect on cardiovascular risk factors. The objective of the present study was to examine, using a randomised prospective study, the acute (day 1) and ad libitum medium-term (day 24) effects of four diets: a high-fat diet (HIGH-FAT; 50 % fat, >34 % monounsaturated fatty acids); a low-glycaemic index (GI) diet (LOW-GI; high-carbohydrate, low-GI); a high-sucrose diet (SUCROSE; high carbohydrate increase of 90 g sucrose/d); a high-GI diet (HIGH-GI; high-carbohydrate, high-GI). Daytime profiles (8 h) (breakfast, lunch and tea) of lipid and carbohydrate metabolism were completed during day 1 and day 24. Seventeen middle-aged men with one or more cardiac risk factors completed the study. There was no change from day 1 or between diets in fasting glucose, lipids or homeostatic assessment model (HOMA) on day 24. The HIGH-FAT compared with the three high-carbohydrate diets was associated with lower postprandial insulin and glucose but higher postprandial TG and non-esterified fatty acids (NEFA). There was a significant increase in the 6 h (15.00 hours) TG concentration (day 1, 2·6 (SEM 0·3) MMOL/L v. DAY 24, 3·3 (sem 0·3) mmol/l; P<0·01) on the SUCROSE diet. Postprandial HOMA (i.e. incremental area under the curve (IAUC) glucose (mmol/l per min)×IAUC insulin/22·5 (mU/l per min)) median changes from day 1 to day 24 were −61, −43, −20 and +31 % for the HIGH-FAT, LOW-GI, SUCROSE and HIGH-GI diets respectively. The HIGH-GI percentage change was significantly different from the other three diets (P<0·001). Despite being advised to maintain an identical energy intake there was a significant weight change (−0·27 (sem 0·3) kg; P<0·02) on the LOW-GI diet compared with the SUCROSE diet (+0·84 (sem 0·3) kg). In conclusion the HIGH-FAT diet had a beneficial effect on postprandial glucose and insulin over time but it was associated with higher postprandial concentrations of TG and NEFA. Conversely the HIGH-GI diet appeared to increase postprandial insulin resistance over the study period.