Long-term dietary intake influences the structure and activity of the trillions of microorganisms residing in the human gut, but it remains unclear how rapidly and reproducibly the human gut microbiome responds to short-term macronutrient change. Here we show that the short-term consumption of diets composed entirely of animal or plant products alters microbial community structure and overwhelms inter-individual differences in microbial gene expression. The animal-based diet increased the abundance of bile-tolerant microorganisms (Alistipes, Bilophila and Bacteroides) and decreased the levels of Firmicutes that metabolize dietary plant polysaccharides (Roseburia, Eubacterium rectale and Ruminococcus bromii). Microbial activity mirrored differences between herbivorous and carnivorous mammals, reflecting trade-offs between carbohydrate and protein fermentation. Foodborne microbes from both diets transiently colonized the gut, including bacteria, fungi and even viruses. Finally, increases in the abundance and activity of Bilophila wadsworthia on the animal-based diet support a link between dietary fat, bile acids and the outgrowth of microorganisms capable of triggering inflammatory bowel disease. In concert, these results demonstrate that the gut microbiome can rapidly respond to altered diet, potentially facilitating the diversity of human dietary lifestyles.

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Diet rapidly and reproducibly alters the human gut microbiome

https://www.thelancet.com/pdfs/journals/lancet/PIIS0140-6736(00)04046-0.pdf

Inflammation and cancer: back to Virchow?

The importance of the ratio of omega-6/omega-3 essential fatty acids.

http://envismadrasuniv.org/Physiology/pdf/Gut%20flora%20in%20health%20and%20disease.pdf

Gut flora in health and disease

Organismal life encounters reactive oxidants from internal metabolism and environmental toxicant exposure. Reactive oxygen and nitrogen species cause oxidative stress and are traditionally viewed as being harmful. On the other hand, controlled production of oxidants in normal cells serves useful purposes to regulate signaling pathways. Reactive oxidants are counterbalanced by complex antioxidant defense systems regulated by a web of pathways to ensure that the response to oxidants is adequate for the body's needs. A recurrent theme in oxidant signaling and antioxidant defense is reactive cysteine thiol–based redox signaling. The nuclear factor erythroid 2–related factor 2 (Nrf2) is an emerging regulator of cellular resistance to oxidants. Nrf2 controls the basal and induced expression of an array of antioxidant response element–dependent genes to regulate the physiological and pathophysiological outcomes of oxidant exposure. This review discusses the impact of Nrf2 on oxidative stress and toxicity and how...

/pdf/role-of-nrf2-in-oxidative-stress-and-toxicity-2utmvoa3ko.pdf

Role of nrf2 in oxidative stress and toxicity.

As a part of a program aimed to develop less toxic and more effective chemopreventive organoselenium compounds than inorganic selenium, we have evaluated benzyl selenocyanate (BSC) and its o-, m-, p-nitro and -methoxy isomers, o-, m-, and p-isomers of phenylenebis(methylene)selenocyanate (XSC), dibenzyl diselenide (DDS), and 2,2'-diselenobis[((N,N-dimethylamino)methyl)- benzene]bis(hydrochloride salt) (DSBDB) for their potential colon tumor inhibitory properties using azoxymethane (AOM)-induced colonic aberrant crypt foci (ACF), a preneoplastic lesion, in male F344 rats prior to preclinical efficacy study. In the first experiment, the effect of these agents administered during initiation and postinitiation periods of carcinogenesis was investigated. Male F344 rats were fed diets containing 8 ppm Na2SeO3 or 10 ppm of each BSC and its analogues, DDS and DSBDB or 20 ppm of each XSC analogue, two weeks prior to AOM (15 mg/kg body wt., once weekly for two weeks, s.c.) administration and during and until 8 weeks after AOM treatment. Formalin-fixed and methylene blue stained colons were scored for AOM-induced ACF using the light microscope. Taking body weight gains and multiplicity of 4 or more AC/focus, the inhibitory effects of Na2SeO3, o-, m- and p-methoxy-BSC, p-XSC and DDS were much greater than those of the other selenium compounds. In the second study, the effects of these agents when administered during the initiation or postinitiation periods were investigated. The results indicated that o-, m-, and p-methoxy-BSC, DDS and p-XSC significantly inhibited crypt multiplicity during the initiation period whereas o-, and p-methoxy-BSC, p-XSC and DDS suppressed crypt multiplicity during the postinitiation period. It is concluded that o-, and p-methoxy-BSC, p-XSC and DDS possess potential chemopreventive properties in colon cancer. Further studies are warranted to evaluated these agents for chemopreventive properties in preclinical efficacy studies.

Evaluation of organoselenium compounds for potential chemopreventive properties in colon carcinogenesis.

The geographic distribution of cancer of the colon, particularly its low incidence in Japan, its increase among Japanese immigrants to the United States, and the high rate of this disease among North Americans and most Western Europeans, indicate that environmental factors are of etiological significance in the development of this disease. Available evidence suggests an association of colon cancer to dietary factors, largely related to dietary fat intake. Studies in metabolic epidemiology have shown a correiation between dietary fat intake and the composition of intestinal micro-flora, and between the fecal bile acids and cholesterol metabolites. A significant association has also been established between the level of fecal anaerobic bacteria, bacterial β-glucuronidase activity, bile acid and cholesterol metabolites, and the risk of colon cancer among different populations. We also found that in the rat model, lithocholic acid and deoxycholic acid, which are present in high concentration in the stool of man, acted as tumor promotors to an established large-bowel carcinogen. It remains to be shown whether this established association is causative in nature.

The epidemiology of cancer of the large bowel.

This study was designed to investigate the cancer preventive activities of wheat bran (WB) oil. We studied the colon cancer preventive effects of WB oil and its subfractions in the Apc(min/+) mouse model, a recognized mouse model for human colorectal cancer, and used human colon cancer cell lines (HCT-116 and HT-29) to identify possible active fractions in WB oil. Our results showed that the oil fraction of WB was more active than the water fraction against the growth of human colon cancer cell lines and that 2% WB oil significantly inhibited the overall tumorigenesis by 35.7% (p < 0.0001) in the Apc(min/+) mouse model. The WB oil was further fractioned into nonpolar lipids and phytochemicals and the phytochemical fraction was fractionated into phytosterols and phytosterol ferulates, 5-alk(en)ylresorcinols, and unidentified constituents by normal phase silica gel column chromatography. Results on cell culture showed that the phytochemical fraction had a higher inhibitory effect on HCT-116 human colon cancer cells than that of WB oil, whereas the nonpolar lipid fraction had less growth inhibitory effectiveness. However, neither fractions showed a stronger inhibition than WB oil in the Apc(min/+) mouse model. The current results demonstrate, for the first time, the intestinal cancer preventive activity of WB oil. The active ingredients, however, remain to be identified.

Wheat Bran Oil and Its Fractions Inhibit Human Colon Cancer Cell Growth and Intestinal Tumorigenesis in Apcmin/+ Mice

Fecal constituents of a high-risk North American and a low-risk Finnish population for the development of large bowel cancer.

Background. Unresolved epidemiologic issues in large bowel cancer include reasons for changes in incidence rates, differences in epidemiology of cancer in the distal and proximal colon and rectal cancer, and the optimal fat and fiber levels for low rates. Methods. The authors examined questions of suitable procedures for the assessment of intake of specific key nutrients and mode of cooking. International data by site and nutritional factors were compared. Results. Fat and fiber intake in the United States, japan, and Finland related to differences in rates

Bandaru S. Reddy

Papers

Evaluation of organoselenium compounds for potential chemopreventive properties in colon carcinogenesis.

The epidemiology of cancer of the large bowel.

Wheat Bran Oil and Its Fractions Inhibit Human Colon Cancer Cell Growth and Intestinal Tumorigenesis in Apcmin/+ Mice

Fecal constituents of a high-risk North American and a low-risk Finnish population for the development of large bowel cancer.

Environmental dietary factors in colorectal cancer. Some unresolved issues.