Middle Eastern diet increases gut microbiota diversity, shows benefit in cirrhosis
Diets with a high intake of vegetables, cereals, coffee, tea and fermented milk products like yogurt correlated with a higher diversity in the gut microbiome. In turn, a higher microbial diversity correlated with a lower risk for hospitalization among patients with cirrhosis, according to recently published data.
“We wanted to know why cirrhosis is so much more commonly a cause of death in some countries and why the disparities between populations exist,” Jasmohan S. Bajaj, MD, from the Virginia Commonwealth University, told Healio Gastroenterology and Liver Disease. “Specifically in the United States, cirrhosis as a cause of death is quite high, whereas it is not as high in some Middle Eastern countries like Turkey. We hypothesized that this could be because of the gut microbes and diet, which are clearly different in patients from these countries.”
To verify their hypothesis, Bajaj and colleagues enrolled 157 individuals from the U.S. who had compensated cirrhosis (n = 59), decompensated cirrhosis (n = 50) or were healthy controls (n = 48), and 139 individuals from Turkey who had compensated (n = 50), decompensated cirrhosis (n = 43) or were healthy controls (N = 46).
The enrolled subjects underwent a dietary evaluation with a food-frequency questionnaire and reported current medications and history of smoking and alcohol consumption. The researchers prospectively followed the patients with cirrhosis for nonelective hospitalization over 90 days.
Subjects from the U.S. had a significantly higher intake (P < . 05) of coffee (98 vs. 28), caffeinated (67 vs. 16) and other carbonated drinks (23 vs. 1), cereals (62 vs. 8), pork (104 vs. 0) and fish (81 vs. 59). The Turkish cohort consumed a diet approximating a complete Mediterranean diet and consumed significantly more (P < .05) tea (133 vs. 52), fermented milk products (121 vs. 29), rice (57 vs. 29), wheat bread (67 vs. 35), lamb (51 vs. 4) and chocolate (64 vs. 39) than those from the U.S.
Microbial diversity was significantly lower among U.S. subjects with decompensated cirrhosis compared with those with compensated cirrhosis and with controls, whereas diversity between the three groups was similar in the Turkish cohort. All three groups from the U.S. had lower microbial diversity compared with their Turkish counterparts.
According to Bajaj, Western studies have already shown that gut microbiota diversity reduces as liver disease worsens. In contrast, gut microbes that make endotoxins and harmful bile acids increase.
Subjects who consumed more tea (6.8 vs. 7.6; P < .0001), fermented milk products (6.8 vs. 7.8; P < .0001), vegetables (6.7 vs. 7.4; P = .05), eggs (6.9 vs. 7.5; P < .0001), wheat bread (7 vs. 7.7; P < .0001), rice (7.1 vs. 7.6; P = .012), chocolate (7 vs. 7.7; P < .0001), coffee (7.5 vs. 7.1; P = .05), and lamb (7.1 vs. 8; P < .0001) had higher microbial diversity. Subjects who consumed more caffeinated (7.4 vs. 7; P = .05) and decaffeinated carbonated drinks (7.3 vs. 6.5; P = .01), pork (7.5 vs. 6.8; P < .0001) and poultry (7.6 vs. 7.2; P = .04) had lower microbial diversity.
“Even though this research doesn’t directly prove it, fermented milk products in any case have been shown to improve outcomes in other diseases and yogurt has been shown to improve mental function in patients with minimal hepatic encephalopathy,” Bajaj said. “Coffee and tea have also been shown to improve outcomes in these patients. So, if someone can maximize their vegetable, coffee, tea and whole-grain cereal intake, not only would it be potentially beneficial for their cardiovascular health, it would be better in cirrhotic patients who are following the typical Western diet.”
The researchers observed a statistically higher number of all-cause hospitalizations (29 vs. 12; P = .016) and liver-related hospitalizations (25 vs. 10; P = .02) among the U.S. cohort compared with those in the Turkish cohort. Hospitalized patients had a significantly lower microbial diversity compared with the rest of the enrolled subjects (6.6 vs. 7.3; P = .02) and there was a significant correlation between diversity and time to hospitalization (r = 0.59; P < .0001) among those who were hospitalized.
Regarding future studies on gut microbiota and its effect on hepatic and overall health, Bajaj advised that information on a patient’s diet is as crucial as any demographic detail.
“When you’re studying gut microbial diversity, you have to know what your population is,” Bajaj concluded. “If your population eats a healthy diet, the gut microbial diversity may respond to that rather than the underlying disease process. That is why the diet has to be perfectly controlled during microbiota studies.” – by Talitha Bennett
Disclosure: Bajaj reports the study was funded partly by a VA Merit Review and by the Turkish Association for the Study of the Liver.