Association Between Sulfur-Metabolizing Bacterial Communities in Stool and Risk of Distal Colorectal Cancer in Men

BACKGROUND & AIMS

Sulfur-metabolizing microbes, which convert dietary sources of sulfur into genotoxic hydrogen sulfide (H2S), have been associated with development of colorectal cancer (CRC). We identified a dietary pattern associated with sulfur-metabolizing bacteria in stool and then investigated its association with risk of incident CRC using data from a large prospective study of men.

METHODS

We collected data from 51,529 men enrolled in the Health Professionals Follow-up Study since 1986 to determine the association between sulfur-metabolizing bacteria in stool and risk of CRC over 26 years of follow-up. First, in a subcohort of 307 healthy men, we profiled serial stool metagenomes and metatranscriptomes and assessed diet using semiquantitative food frequency questionnaires to identify food groups associated with 43 bacterial species involved in sulfur metabolism. We used these data to develop a sulfur microbial dietary score. We then used Cox proportional hazards modeling to evaluate adherence to this pattern among eligible individuals (n = 48,246) from 1986 through 2012 with risk for incident CRC.

RESULTS

Foods associated with higher sulfur microbial diet scores included increased consumption of processed meats and low-calorie drinks and lower consumption of vegetables and legumes. Increased sulfur microbial diet scores were associated with risk of distal colon and rectal cancers, after adjusting for other risk factors (multivariable relative risk, highest vs lowest quartile, 1.43; 95% confidence interval 1.14-1.81; P-trend = .002). In contrast, sulfur microbial diet scores were not associated with risk of proximal colon cancer (multivariable relative risk 0.86; 95% CI 0.65-1.14; P-trend = .31).

CONCLUSIONS

In an analysis of participants in the Health Professionals Follow-up Study, we found that long-term adherence to a dietary pattern associated with sulfur-metabolizing bacteria in stool was associated with an increased risk of distal CRC. Further studies are needed to determine how sulfur-metabolizing bacteria might contribute to CRC pathogenesis.

Changes in growth performance, nutrient digestibility, immune blood profiles, fecal microbial and fecal gas emission of growing pigs in response to zinc aspartic acid chelate

Objective

This study was conducted to investigate the effect of zinc aspartic acid chelate (Zn-ASP) on growth performance, nutrient digestibility, blood profiles, fecal microbial and fecal gas emission in growing pigs.

Methods

A total of 160 crossbred ([Landrace×Yorkshire]×Duroc) growing pigs with an initial body weight (BW) of 25.56±2.22 kg were used in a 6-wk trial. Pigs were randomly allocated into 1 of 4 treatments according to their sex and BW (8 replicates with 2 gilts and 3 barrows per replication pen). Treatments were as follows: i) CON, basal diet, ii) TRT1, CON+0.1% Zn-ASP, iii) TRT2, CON+0.2% Zn-ASP, and iv) TRT3, CON+0.3% Zn-ASP. Pens were assigned in a randomized complete block design to compensate for known position effects in the experimental facility.

Results

In the current study, BW, average daily gain, and gain:feed ratio showed significant improvement as dietary Zn-ASP increased (p<0.05) in growing pigs. Apparent total tract digestibility (ATTD) of dry matter was increased linearly (p<0.05) in pigs fed with Zn-ASP diets. A linear effect (p<0.05) was detected for the Zn concentration in blood with the increasing levels of Zn-ASP supplementation. Lactic acid bacteria and coliform bacteria were affected linearly (p<0.05) in pigs fed with Zn-ASP diets. However, no significant differences were observed in the ATTD of nitrogen, energy and Zn. And dietary Zn-ASP supplementation did not affect fecal ammonia, hydrogen sulfide and total mercaptans emissions in growing pigs.

Conclusion

In conclusion, dietary supplementation with Zn-ASP of diet exerted beneficial effects on the growth performance, nutrient digestibility, blood profiles and fecal microbes in growing pigs.

Effect of bacteriophage supplementation on the growth performance, nutrient digestibility, blood characteristics, and fecal microbial shedding in growing pigs

A total of 144 ((Duroc×Yorkshire)×Landrace)) pigs with an average initial BW of 28.85±0.63 kg were used in this 6-wk growth trial. Pigs were randomly allotted to 1 of 4 treatments in a completely random block design. Each dietary treatment consisted of 9 replicate pens, with 4 pigs per replicate. Dietary treatments included: i) NC (basal diet), ii) PC (NC+apramycin 0.5 g/kg), iii) BPT1 (NC+bacteriophage 0.25 g/kg) and iv) BPT2 (NC+bacteriophage 0.5 g/kg). The inclusion of antibiotics and bacteriophages did not affect the (p>0.05) ADG, ADFI and G:F compared with the basal diet. Dietary antibiotics and bacteriophages supplementation led to a higher (p<0.05) DM digestibility than the NC treatment. Pigs fed the bacteriophage supplemented diet increased (p<0.05) the N digestibility compared with those fed NC treatment. Supplementation of antibiotics led to a higher (p<0.05) energy digestibility than the NC treatment. No difference (p>0.05) was observed in the RBC, WBC, lymphocyte concentration and fecal moisture among treatments. Pigs fed PC and BPT2 treatments reduced (p<0.05) the E. coli concentration compared with those fed NC treatment. The inclusion of BPT2 treatment led to a higher (p<0.05) lactobacillus concentration compared with NC and PC treatment. Dietary antibiotic and bacteriophage supplementation reduced (p<0.05) the Salmonella concentration compared with NC treatment. In conclusion, our study suggested that bacteriophage at the level of 0.5 g/kg could be used as an antibiotics alternative for growing pigs.

Evaluation of Houttuynia cordata and Taraxacum officinale on Growth Performance, Nutrient Digestibility, Blood Characteristics, and Fecal Microbial Shedding in Diet for Weaning Pigs

A total of 144 pigs ((Landrace×Yorkshire)×Duroc] with an average initial BW of 8.45±0.57 kg were used in a 5-wk growth trial. Pigs were randomly allocated to 4 treatments with 9 replications per pen in a randomized complex block design. Dietary treatments included: i) CON (basal diet), ii) ANT (CON+tylosin 1 g/kg), iii) H1 (CON+H. cordata 1 g/kg) and iv) T1 (CON+T. officinale 1 g/kg). In this study, pigs fed the ANT and T1 treatment had a higher (p<0.05) average daily gain (ADG) and gain:feed (G:F) ratio than those fed CON and H1 treatment. Dietary ANT and T1 treatment led to a higher energy digestibility than the CON group. No difference (p>0.05) was observed on the growth performance and apparent total tract digestibility with H1 supplementation compared with the CON treatment. The inclusion of ANT treatment led to a higher (p<0.05) lymphocyte concentration compared with the CON treatment. Dietary supplementation of herbs did not affect (p>0.05) the blood characteristics (white blood cell (WBC), red blood cell (RBC), IgG, lymphocyte). No difference was observed on (p<0.05) fecal microbial shedding (E. coli and lactobacillus) between ANT and CON groups. Treatments H1 and T1 reduced the fecal E. coli concentration compared with the CON treatment, whereas the fecal lactobacillus concentration was not affected by the herb supplementation (p>0.05). In conclusion, the inclusion of T. officinale (1 g/kg) increased growth performance, feed efficiency, energy digestibility similarly to the antibiotic treatment. Dietary supplementation of T. officinale and H. cordata (1 g/kg) reduced the fecal E. coli concentration in weaning pigs.