NAFLD: Can Liver Fat Be Helped by Probiotics?

NAFLD is an acronym for nonalcoholic fatty liver disease. It is defined as a chronic condition with more than 5 to 10% of extra fat in the liver. Some amount of fat is normal, but the amounts in nonalcoholic fatty liver disease can lead more serious diagnoses of NASH (nonalcoholic steatohepatitis, meaning liver inflammation) and cirrhosis (scarring in the liver which can lead to liver failure). Not only is liver failure a possibility with uncontrolled liver cirrhosis, but liver oxidative stress increases the risk of hepatocellular carcinoma, malignant liver cancer.

It used to be thought that only alcoholics got fatty livers. Now we know better. As a matter of fact, you may have it and not even know it. Based on the Dallas Heart Study report, 31% of US adults are affected by it. A study on the US pediatric population reported a prevalence of 12.5% among children. Other countries do not fare much better.

Children with biopsy-proven NAFLD have been shown to be more sedentary and consume a Western diet, characterized by high levels of total fat, saturated fat and refined sugar, when compared to both obese and lean peers without liver disease.

The prevalence of nonalcoholic fatty liver disease is rapidly rising, and is becoming a worldwide public health problem. Three of the biggest risk factors are:

  1. Obesity. In patients with severe obesity undergoing bariatric surgery, the occurrence of NAFLD can exceed 90% and up to 5% of patients may have unsuspected cirrhosis (scarring of the liver).
  2. Type 2 diabetes. A study of patients with Type 2 diabetes using ultrasound showed a 69% prevalence of NAFLD.
  3. Dyslipidemia, dysregulation of blood fats. High serum triglyceride levels and low serum HDL levels are very common in patients with NAFLD.

Other causes of fatty liver can include excessive alcohol consumption, Hepatitis C, some medications, Wilson’s disease, congenital metabolism defects, Reye’s syndrome and others. However, in westernized societies, obesity is a common cause.

Weight loss of 3-5 % has been associated with a reduction of hepatic steatosis while weight loss of greater-than-or-equal-to 5-7 % was correlated with resolution of NASH in some studies. Greater reductions in weight loss (greater-than-or-equal-to 10 %) may improve hepatic fibrosis. So the first thing to do to help resolve nonalcoholic fatty liver disease is to lose weight.

How is NAFLD Diagnosed?

You cannot self-diagnose. Ultrasound, MRI (magnetic-resonance imaging) and liver biopsy are the three most common ways to diagnose nonalcoholic fatty liver disease. All three procedures can be expensive and cumbersome. Since fibrosis, or thickening and scarring, of the liver can lead to more advanced liver disease, the determination of the degree of liver fibrosis is helpful to know.

A few non-invasive methods to identify advanced fibrosis in patients with nonalcoholic fatty liver disease include the NAFLD Fibrosis Score (NFS), Enhanced Liver Fibrosis (ELF) panel and transient vibration-controlled transient elastography (VCTE).

A late-2015 study showed that the NFS is the most cost-effective method for diagnosing fibrosis risk among older adults with nonalcoholic fatty liver disease. The NFS is based on six variables (age, BMI, hyperglycemia, platelet count, albumin, AST/ALT ratio) that are easily obtained from a physical exam and routine blood test. It is calculated using a published formula.

Some medical practitioners say that you can use blood tests as markers for fatty liver, but blood markers can be within normal ranges in patients with NAFLD and NASH. Also, blood test liver panel markers can be high for reasons other than fatty liver. However, if your liver blood panel results are high and you have any risk factors for nonalcoholic fatty liver disease, it is best to proceed with more sensitive diagnostic tests, or at least have the NFS done, to see if your liver has fibrosis, or thickening and scarring, and start taking better care of your liver.

Although prescription medications are often prescribed to patients with fatty liver or suspected fatty liver, there are many diet and lifestyle interventions which can be helpful. As you might have guessed, an intervention with probiotics is one of those.

What is the NAFLD-Probiotics Connection?

If you’ve read my book, Probiotics: How to Use Them to Your Advantage, newsletters, or website pages on other conditions, you know that what happens in the gastrointestinal (GI) tract does not necessarily stay confined to the GI tract. A gut-liver-adipose tissue axis contributes to NAFLD.

Gut microbiota can influence this axis in many negative ways, and the particulars of what we know about that are too detailed to describe on this page since the focus is on probiotics. To summarize, by influencing gut microbiota for the better, probiotics can work to overcome this negativity via reduction of endotoxins and exotoxins. This reduction improves liver enzymes, insulin resistance and most importantly, anti-inflammatory markers. 

Probiotics can also maintain the health of the small intestine intestinal barrier, which in turn helps with proper absorption of nutrients to protect the liver from overload. For example, a 2018 study by C. Jang et al. in the journal Cell Metabolism showed that, in mice, the small intestine converts approximately 90% of small amounts of dietary fructose into glucose, lactate, and glycerate, saving the liver the task of doing that. High amounts of fructose contribute to NAFLD.

Which Probiotics Show Promise for NAFLD?

In a 2014 randomized, double-blind, placebo-controlled clinical pilot study trial, 52 patients with nonalcoholic fatty liver disease were supplemented twice daily for 28 weeks with either a probiotic capsule or placebo. The capsules contained 200 million CFU of 7 species of lactic acid bacteria: Lactobacillus casei, Lactobacillus rhamnosus, Streptococcus thermophilus, Bifidobacterium breve, Lactobacillus acidophilus, Bifidobacterium longum, and Lactobacillus bulgaricus. The capsules also contained an undisclosed amount of FOS (fructooligosaccharide).

Both groups were instructed to follow and energy-balanced diet and engage in physical fitness. It should be noted that part of the dietary guidelines included 20-30 grams of fiber per day. Improvements in hepatic fibrosis, liver enzymes, and inflammatory markers were the study objectives.

At the end of the study, the blood marker alanine aminotransferase (ALT) decreased in both groups, but more significantly in the probiotics group. There were also significant differences in AST, GGT, C-reactive protein, TNF-alpha, NF-kB and fibrosis scores between the 2 groups.

A total of 400 million CFU is really a small amount compared to dosages used in other studies, yet beneficial effects were seen in this small pilot trial.

In another pilot trial, 28 patients diagnosed with NAFLD via liver biopsy were analyzed in a double-blind, randomized clinical trial for 3 months. Participants received either 500 million CFU of Lactobacillus bulgaricus and Streptococus thermophilus or a placebo. In the probiotics group, ALT, AST and GGT levels all decreased, whereas those markers remained unchanged in the placebo group.

In another study, 66 patients were randomly assigned to either Bifidobacterium longum with an undisclosed amount of fructooligosaccharides (FOS) plus lifestyle modifications or lifestyle modifications alone for 24 weeks. At the end of study, compared to the lifestyle modification group, the combination treatment group experienced significant reductions in TNF-alpha, C-reactive protein, AST, insulin resistance and beta-cell function HOMA scores, liver fat accumulation, and the nonalcoholic fatty liver disease score.

In yet another study, 22 nonalcoholic fatty liver disease patients and 20 alcoholic liver cirrhosis (AC) patients were compared with 36 Hepatitis C virus (HCV)-positive patients with chronic hepatitis, 20 without (CH) and 16 with (CC), liver cirrhosis. All groups received 3-month treatment with VSL#3, 450 billion CFU, 2 packets twice per day. In the nonalcoholic fatty liver disease and AC groups, VSL#3 significantly improved plasma levels of MDA and 4-HNE (both markers of oxidative stress), whereas TNF-alpha, IL-6, and IL-10 improved only in AC patients. No similar effects were observed in HCV patients, but routine liver damage tests showed improvement at the end of treatment in all groups.

Can Probiotics Help Your NAFLD?

As with many conditions, there isn’t just one probiotic capable of helping this liver condition. More studies with probiotics and liver diseases are sure to be published in the future.

Cleaning up your gut, including using probiotics, is an easy way to reduce the negative effects of the gut microbiota on liver health, as well as other aspects of health. If you have or suspect you have nonalcoholic fatty liver disease, please consult with a qualified medical professional to have your situation assessed first, and consider nutrition therapy to help with your necessary dietary and lifestyle improvements and choice of probiotic supplement.

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