The rise in obesity in the US has led to an increase in fatty liver disease, including in children. Now a new study out of Texas A & M finds that a common compound in vegetables may help combat fatty liver disease.
The research, published in Hepatology, showed how indole, a natural substance found in gut bacteria and cruciferous vegetables like cabbage, kale, cauliflower and Brussels sprouts can help control non-alcoholic fatty liver disease, a.k.a. NAFLD. The study also looked into how indole could lead to new treatment or prevention of NAFLD.
Chaodong Wu, M.D., Ph.D., a Texas A&M AgriLife Research Faculty Fellow and principal investigator for the study states, “Based on this research, we believe healthy foods with high capacity for indole production are essential for preventing NAFLD and are beneficial for improving the health of those with it. "This is another example where altering the diet can help prevent or treat disease and improve the well-being of the individual."
How indole helps NAFLD
NAFLD happens when the liver accumulates fat. This can be related to poor quality diet including excessive intake of saturated fats or simple sugars. If left untreated, NAFLD may lead to chronic liver disease including cirrhosis or cancer of the liver.
Multiple factors are implicated with NAFLD. It is 7 to 10 times more common in obese individuals than in people of a normal weight. Obesity is associated with bodily inflammation. Macrophages, type of white blood cells that fight infection, drive inflammation. This inflammation worsens damage to the liver in those with liver disease.
The progression of fatty liver disease (positive or negative) is also impacted by gut bacteria. Gut bacteria make several different compounds, indole being one of them. This compound made from the amino acid tryptophan, has been found by clinical dietitians and nutrition scientists as having probably preventive and therapeutic benefits in those with NAFLD.
The anti-inflammatory and cancer-fighting benefits of indole-3-carbinol found in cruciferous vegetables have also been noted by the National Cancer Institute.
An extensive and multi-level research study on fatty liver disease
To help find indole’s effect on liver inflammation and possible benefits to people with NAFLD, the research study examined the effect of concentrations of indole on people, animal models, and individual cells. It looked into the extent to which indole helps in NAFLD, utilizing previous data on gut bacteria, intestinal inflammation, and inflammation of the liver. It also used data on how indole improves fatty liver in animal models.
The effects of indole were also investigated on those with fatty livers. Qifu Li, a physician at Chongqing Medical University in China lead the clinical research on Chinese subjects. There were 137 participants in the study. Researchers found that those with a higher BMI typically had lower levels of indole in their blood. In addition, levels of indole in subjects considered clinically obese were much lower than those considered lean. Those with lower levels of indole had higher levels of fatty deposits in their liver.
Li believes that the results of his study will likely impact other ethnicities, though ethnic background could have an influence on populations of gut bacteria and concise levels of metabolites. The research team utilized a low-fat diet in animal models compared to a group fed a high-fat diet to model the effects of NAFLD. Gianfranco Alpini, M.D., a study collaborator and former professor of Texas A&M Health Science Center notes "The comparisons of animal models fed a low-fat diet and high-fat diet gave us a better understanding of how indole is relevant to NAFLD." Fat accumulation and inflammation of the liver can be modified through the use of indole in animal models with NAFLD. The impact of indole on individual cells was also studied by the research team.
Indole acts on intestinal cells in addition to reducing fat in liver cells, which send out molecular signals that reduce inflammation., according to Shannon Glaser, M.D., a professor of Texas A&M Health Science Center. Future studies are indicated to investigate the complex relationship between NAFLD, indole and the gut.
Wu believes that foods that impact indole production or medications that model its effect could be novel therapies for prevention and treatment of NAFLD. He hopes to collaborate on future research with clinicians and food scientists to study which foods modify gut microbiota and increase production of indole.
Dietitians working with individuals with NAFLD can suggest the following:
- Lose weight if overweight or obese. This may aid in reducing inflammation in the liver.
- Cut back on total fat and saturated fat, which can accumulate in liver tissue.
- Reduce excess sugar from the diet, especially simple sugars from soda, sweetened tea, sports drinks, candy, high fat desserts, etc. These are associated with obesity and fat accumulation in the liver.
- Increase intake of cruciferous vegetables including cabbage, broccoli, cauliflower, kale, and Brussels sprouts
- Avoid alcohol and medications that impact liver function.
By Lisa Andrews, MEd, RD, LD
- Linqiang Ma, Honggui Li, Jinbo Hu, Juan Zheng, Jing Zhou, Rachel Botchlett, Destiny Matthews, Tianshu Zeng, Lulu Chen, Xiaoqiu Xiao, Giri Athrey, David Threadgill, Qingsheng Li, Shannon Glaser, Heather Francis, Fanyin Meng, Qifu Li, Gianfranco Alpini, Chaodong Wu. Indole Alleviates Diet?induced Hepatic Steatosis and Inflammation in a Manner Involving Myeloid Cell PFKFB3. Hepatology, 2020; DOI: 10.1002/hep.31115
Stephanie Ronco has been editing in a professional capacity for the past 10 years. In addition to her work as an editor, Ronco has also served as a ghostwriter and writing tutor. A voracious reader, Ronco loves watching language evolve and change. When she’s not delving into her latest project, Ronco can be found teaching acting classes, performing in community theater, or sailing with her husband.