Novel metabolic disturbances in marginal vitamin B6-deficient rat heart.

Vitamin B6 deficiency is associated with cardiovascular disease (CVD). Although plasma biomarkers have been proposed, no studies have yet directly profiled heart tissue, and the mechanisms have to be fully defined. Thus, in order to provide better insight into vitamin B6-deficient effects on cardiac functions, we sought to identify the metabolic profile in heart tissue consequent to change in dietary vitamin B6 levels by applying metabolomics. Heart tissues of rats fed a basal diet containing a marginal vitamin B6-deficient, vitamin B6-recommended or vitamin B6-supplemented level were analyzed by metabolomics analysis. Among over 500 detected metabolites, imidazole metabolites including carnosine, anserine, homocarnosine and histamine exhibited the highest decrease upon vitamin B6 deficiency (>-45%, P<.01), along with their precursors ß-alanine, γ-aminobutyric acid (GABA) and 1-methylhistidine. Ornithine was the only metabolite exhibiting an increased level in the vitamin B6-deficient group. Vitamin B6 deficiency significantly attenuated the activity of heart tissue glutamate decarboxylase (GAD), although there was undetectable activity of aspartate decarboxylase (ADC), suggesting that the involvement of vitamin B6 in imidazole metabolite synthesis occurs partly through GABA production by regulating GAD rather than through a straightforward ß-alanine production pathway via ADC in the heart. Notably, vitamin B6 deficiency significantly attenuated citric acid cycle metabolite levels, suggesting cardiac energy metabolism impairment. This study provides a new link between vitamin B6 and cardiac functions, in which marginal vitamin B6 deficiency impairs imidazole and energy metabolism in heart. This newly revealed cardiac metabolic profile may reveal novel molecular targets or foodstuffs for CVD prevention.

Beneficial Effects of Dietary Tempeh Prepared with Rhizopus stolonifer on Liver Function in Rats Fed with a High-Fat Diet.

The regional standard for tempeh established by the Codex Alimentarius defines the use of Rhizopus oligosporus, R. oryzae, and/or R. stolonifer as soybean tempeh starters. However, comparative studies on the functions of tempeh prepared with these Rhizopus species are scarce. In the present study, we examined the effects of dietary tempeh prepared with these three Rhizopus species using rats fed with a high-fat diet. Compared to the control diet, consumption of tempeh prepared with R. stolonifer significantly suppressed serum levels of aspartate transaminase, total bilirubin, and ammonium (indices of liver function). However, less or no suppression was observed with tempeh prepared with R. oligosporus or R. oryzae. Serum levels of triglyceride, total cholesterol, HDL cholesterol, and glucose were unaffected. Liver levels of free cholesterol, a parameter relating to liver injury, were significantly decreased by the three types of the tempeh examined; however, there was no difference in the free cholesterol levels among the tempeh groups. We conclude that the ingestion of tempeh prepared with R. stolonifer might have beneficial effects pertaining to the liver function in rats fed with high-fat diets.

Gender Difference and Dietary Supplemental Vitamin B6: Impact on Colon Luminal Environment.

Colon diseases can be affected by several factors such as gender difference and dietary supplemental vitamin B6 (B6). The nutritional status of B6 is affected by gender difference, leading us to hypothesize that gender difference affects colon luminal environment, which is dependent on B6 status. To investigate this hypothesis, we fed male and female rats a diet containing 1 mg, 7 mg, or 35 mg pyridoxine HCl/kg diet for 6 wk. We found significantly higher fecal mucin levels in female rats compared to those in male rats. Supplemental B6 significantly increased fecal mucins and was particularly profound in the female rats. The abundances of cecal and fecal Akkermansia muciniphila (mucin degrader) were unaffected. The fecal mucin levels were significantly correlated with colonic free threonine and serine and with gene expression of colon MUC16, implying that the combined effect of gender and dietary B6 on fecal mucins was mediated by the alteration in the levels of such amino acids and MUC16 expression. This study further showed the significant effects of gender difference on colonic free amino acids such as threonine, ornithine, asparagine/aspartate ratio, and glutamine/glutamate ratio, cecal and fecal Lactobacillus spp. levels, and colonic gene expressions of MUC16 and TLR8, the factors relating to colon health and diseases. Therefore, our findings suggest that gender difference and dietary B6 may have an impact on colon diseases by modulating these parameters.

Feeding of the water extract from Ganoderma lingzhi to rats modulates secondary bile acids, intestinal microflora, mucins, and propionate important to colon cancer.

Consumption of reishi mushroom has been reported to prevent colon carcinogenesis in rodents, although the underlying mechanisms remain unclear. To investigate this effect, rats were fed a high-fat diet supplemented with 5% water extract from either the reishi mushroom (Ganoderma lingzhi) (WGL) or the auto-digested reishi G. lingzhi (AWGL) for three weeks. Both extracts markedly reduced fecal secondary bile acids, such as lithocholic acid and deoxycholic acid (colon carcinogens). These extracts reduced the numbers of Clostridium coccoides and Clostridium leptum (secondary bile acids-producing bacteria) in a per g of cecal digesta. Fecal mucins and cecal propionate were significantly elevated by both extracts, and fecal IgA was significantly elevated by WGL, but not by AWGL. These results suggest that the reishi extracts have an impact on colon luminal health by modulating secondary bile acids, microflora, mucins, and propionate that related to colon cancer.