Our previous study demonstrated that supplemental psyllium fibre increased cytoprotective heat-shock protein (Hsp) 25 levels in the intestinal cells of mice. Here, we examined the effect of psyllium fibre on colonic gene and protein expression and faecal microbiota in normal and colitic mice to improve the understanding of the preventive role of the supplement. DNA microarray analysis revealed that a 10 % psyllium fibre diet administered for 5 d up-regulated eleven extracellular matrix (ECM)-associated genes, including collagens and fibronectins, in normal mice. Acute colitis was induced using dextran sodium sulphate (DSS) in mice that were administered a pre-feeding 5 to 10 % psyllium fibre diet for 5 d. Psyllium fibre partially ameliorated or resolved the DSS-induced colon damage and inflammation characterised by body weight loss, colon shortening, increased levels of pro-inflammatory cytokines and decreased tight junction protein expression in the colon. Analysis of faecal microbiota using denaturing gradient gel electrophoresis of the PCR-amplified 16S rRNA gene demonstrated that psyllium fibre affected the colonic microbiota. Intestinal permeability was evaluated by growing intestinal Caco-2 cell monolayers on membrane filter supports coated with or without fibronectin and collagen. Cells grown on collagen and fibronectin coating showed higher transepithelial electrical resistance, indicating a strengthening of barrier integrity. Therefore, increased Hsp25 levels and modification of colonic ECM contribute to the observed psyllium-mediated protection against DSS-induced colitis. Furthermore, ECM modification appears to play a role in the strengthening of the colon barrier. In conclusion, psyllium fibre may be useful in the prevention of intestinal inflammatory diseases.

The present study investigated the LDL-cholesterol (LDL-C)-lowering effects of psyllium in Brazilian dyslipidaemic children and adolescents. A total of fifty-one individuals (6–19 years) with mild-to-moderate hypercholesterolaemia were evaluated by conducting a randomised, double-blind, placebo-controlled, parallel clinical trial. Over an 8-week trial period, the participants were randomly allocated to one of two groups (control: n 25 and psyllium: n 26) using a computer-generated random number sequence. Fasting blood samples, dietary records and anthropometric data were collected. Both groups were treated with the National Cholesterol Education Program Step 2 diet for 6 weeks before randomisation. After this run-in period, a daily supplement of 7·0 g psyllium was given to the intervention group, while an equivalent amount of cellulose was given to the control group. Statistically significant changes between the control and intervention groups over time were observed for total cholesterol (7·7 %; − 0·39 mmol/l; P= 0·003) and LDL-C (10·7 %; − 0·36 mmol/l; P= 0·01). None of the participants reported any aversion to the smell, taste, appearance or texture of psyllium. No serious adverse effects were reported during the study. In addition to causing a significant reduction in LDL-C concentrations, psyllium therapy was found to be both safe and acceptable for the treatment of hypercholesterolaemic children and adolescents.

Psyllium, a dietary fibre rich in soluble components, has both cholesterol- and TAG-lowering effects. Many studies have verified these actions using liver samples, whereas little information is available on the effects of psyllium treatment on other organs. The purpose of the present study was to evaluate the possible beneficial effects of psyllium. We investigated the gene expression profiles of both liver and skeletal muscle using DNA microarrays. C57BL/6J mice were fed a low-fat diet (LFD; 7 % fat), a high-fat diet (HFD; 40 % fat) or a HFD with psyllium (40 % fat+5 % psyllium; HFD+Psy) for 10 weeks. Body weights and food intake were measured weekly. After 10 weeks, the mice were killed and tissues were collected. Adipose tissues were weighed, and plasma total cholesterol and TAG blood glucose levels were measured. The expression levels of genes involved in glycolysis, gluconeogenesis, glucose transport and fatty acid metabolism were measured by DNA microarray in the liver and skeletal muscle. In the HFD+Psy group, plasma total cholesterol, TAG and blood glucose levels significantly decreased. There was a significant reduction in the relative weight of the epididymal and retroperitoneal fat tissue depots in mice fed the HFD+Psy. The expression levels of genes involved in fatty acid oxidation and lipid transport were significantly up-regulated in the skeletal muscle of the HFD+Psy group. This result suggests that psyllium stimulates lipid transport and fatty acid oxidation in the muscle. In conclusion, the present study demonstrates that psyllium can promote lipid consumption in the skeletal muscle; and this effect would create a slightly insufficient glucose state in the liver.

Endothelial dysfunction and increased arterial stiffness occur early in the pathogenesis of the metabolic syndrome and they are both powerful independent predictors of cardiovascular risk. A high-fibre diet has been correlated with lower BMI and a lower incidence of hyperlipidaemia, CVD, hypertension and diabetes. The present randomised, parallel-design study compared the effects of fibre intake from a healthy diet v. fibre supplement diets on blood pressure (BP) and vascular function over 12 weeks. Overweight and obese adults were randomised to one of three groups: control (with placebo), fibre supplement (FIB) or healthy eating group with placebo (HLT). Systolic blood pressure (SBP) was lower in the FIB group compared with the control group at week 6, but not at week 12. However, SBP was lower in the HLT group compared with control group at week 12. At week 6, the FIB group presented lower diastolic blood pressure and augmentation index compared with the control group, but this result did not persist to the end of the study. The present study did not show any improvements in BP or vascular function in overweight and obese individuals with psyllium fibre supplementation over 12 weeks of intervention. However, a healthy diet provided the greatest improvements in BP in overweight and obese subjects. Further research with hypertensive individuals is necessary to elucidate whether increased fibre consumption in the form of psyllium supplementation may provide a safe and acceptable means to reduce BP, vascular function and the risk of developing CVD.

Optimum levels and types of dietary fibre that provide the greatest beneficial effects on metabolic syndrome risk factors in overweight and obese individuals have yet to be determined in clinical trials. The present parallel design study compared the effects of fibre intake from a healthy diet v. a fibre supplement (psyllium) or a healthy diet plus fibre supplement on fasting lipids, glucose, insulin and body composition. Overweight/obese adults were randomised to either control (with placebo), fibre supplement (FIB), healthy eating plus placebo (HLT) or healthy eating plus fibre supplement (HLT–FIB). There was a significant increase in fibre intake in HLT–FIB, HLT and FIB groups up to 59, 31 and 55 g, respectively, at 12 weeks when compared to control (20 g). Weight, BMI and % total body fat were significantly reduced in FIB and HLT–FIB groups, with weight and BMI significantly reduced in the HLT group compared with control at 12 weeks. HLT–FIB and HLT groups had significant reductions in TAG and insulin compared with control at 6 and 12 weeks, and in insulin compared with the FIB group at 12 weeks. The HLT–FIB, HLT and FIB groups all had significant reductions in total cholesterol and LDL-cholesterol compared with control after 6 and 12 weeks. The present study demonstrated that simply adding psyllium fibre supplementation to a normal diet was sufficient to obtain beneficial effects in risk factors. However, a high-fibre diet consisting of a psyllium supplement plus fibre from a healthy diet provided the greatest improvements in metabolic syndrome risk factors.

Overweight and obesity is one of the risk factors for developing CVD. At present, very little is known about the acute effects of dietary fibre on lipids, glucose and insulin, resting energy expenditure and diet-induced thermogenesis in overweight and obese individuals. This study examined the postprandial metabolic effects of dietary fibre in overweight and obese men. Ten overweight and obese men consumed a mixed meal accompanied by either a high-fibre or low-fibre supplement on two separate visits, in a random order, 1 week apart. Two isoenergetic breakfast meals with similar composition were consumed by ten overweight/obese men. The meals contained either a low (3 g) or high (15 g) amount of fibre, low-fibre meal (LFM) and high-fibre meal (HFM) respectively. Analysis was carried out using paired t test and ANOVA. Serum TAG incremental area under the curve during 6 h of the postprandial period was significantly lower after the consumption of HFM compared with LFM. At the first hour of the postprandial period, plasma apo B48 concentration after consumption of HFM was significantly lower compared with LFM. The resting energy expenditure and diet-induced thermogenesis after both meals was similar during 6 h of the postprandial period. Collectively, these findings suggest that a single acute dose of dietary fibre in the form of psyllium supplement can decrease arterial exposure to TAG and modify chylomicron responses in the postprandial period.

Plantago ovata is the cultivated and economically important species in the monotypic genus Plantago. P. ovata is a short-stemmed annual herb, 10–45 cm tall. The species is generally an in-breeder. The seed husk of this plant is commonly called Psyllium or Isabgol (in Hindi), which is a very effective laxative. Other usages of Isabgol are in ice cream making, cosmetics, printing and finishing. The intake of husk also reduces blood cholesterol levels. Isabgol is commercially very important as its export earns India foreign exchange worth INR 2.5 billion (US$1=44 INR). The plant is cultivated on a large scale in western India. In Gujarat, it is cultivated in about 144,000 ha of land, yielding 720 kg/ha. P. ovata has a narrow genetic base, and the lack of variability is on account of low chromosome number, small chromosome size, presence of high heterochromatin in the chromosomes, low chiasmata frequency and low recombination index. The genome size of the species is ∼500 Mb. Different breeding methods, namely selection, hybridization, induced mutations, polyploidy and tissue culture, have been used for genetic improvement of this plant. Except selections, which have led to isolation of a few varieties, the results of other methods have not been encouraging. P. ovata has about 200 wild allies, some of which are medicinally important. These wild species constitute a rich resource of important genes, which if transferred to cultivated species could revolutionize the production of Isabgol. The present paper highlights various aspects of genetic diversity, cultivation and utilization of this important medicinal plant, and suggests the prospects of genetic manipulation.

Dietary fibre and fat affect colonic tumourigenesis and inflammation. Sphingomyelin metabolism may have implications for the pathogenesis of colonic tumours and ulcerative colitis. The present study examined the effects of psyllium and fat on the enzymes responsible for sphingomyelin metabolism and apoptosis in the colon. Mice were fed control, psyllium-containing (100 g/kg), high-fat (313 g/kg, 53 % energy as fat) or high-fat plus psyllium diets for 4 weeks. The activities of acid, neutral and alkaline sphingomyelinase (SMase), neutral ceramidase, and caspase 3, 8 and 9 in colonic mucosa were determined. The expressions of alkaline SMase and caspase 3 were examined. The psyllium-containing diet was found to increase significantly the activities of alkaline SMase and caspase 3 and decreased those of acid SMase and neutral ceramidase. The high-fat diet had opposite effects on these enzymes and attenuated the effects of psyllium. Western blotting showed that psyllium increased and high-fat decreased the levels of alkaline SMase and caspase 3 in colonic mucosa. The change in caspase 3 activity was positively correlated with that of alkaline SMase and negatively with acid SMase. No similar changes of acid and alkaline phosphatase activities in the colon or acid and neutral SMase activity in the liver were identified. In conclusion, colonic sphingomyelin metabolism and apoptosis were affected by psyllium and fat in an opposite manner. The results may have implications for colorectal tumourigenesis and inflammation.