A recent prospective study (M Markova, O Pivovarova, et al. Gastroenterol 2017; 152: 571-85) showed that among individuals with nonalcoholic fatty liver disease (NAFLD) and type 2 diabetes that a diet high in protein (animal or plant) reduced liver fat over a 6 week period.
Among 37 participants, body fat and intrahepatic fat were detected with MRI and spectroscopy, respectively. Protein was increased to 30% of the diet. Fat was reduced to 30% and carbohydrates to 40% of diet composition. .
- With a high animal protein diet, liver fat was reduced by 36%. In the high plant protein diet group, liver fat was reduced by 48%.
- Theses changes were unrelated to change in body weight. However, these changes were correlated with down-regulation of lipolysis and lipogenic indices.
Some of the findings may be limited to older patients as this cohort was older than 60 years of age. In the pediatric population, the dietary factor that has been linked most closely to NAFLD has been fructose, mainly in sugar-sweetened beverages (R Patusco et al. Top Clin Nutr 2017; 32: 27-46 -thanks to Ben Gold for this reference).
My take: This study shows improvement in liver fat with increased protein/reduced dietary fat. While this study indicates that dietary modification is important in treating NAFLD, the optimal dietary intervention (eg. higher protein, lower sugar, lower fat) remains uncertain.
- When Will MRI Obviate the Need for a Liver Biopsy in Pediatric NAFLD?
- Concise Review: Fatty Liver in Pediatrics
- Reaching Consensus on Bariatric Intervention in Children and Adolescents
From MedicalNewsToday – a summary of a recent Hepatology study by Jeffrey B. Schwimmer, MD and colleagues.
Excerpts from http://www.medicalnewstoday.com/releases/289088.php along with image.
“In this study, the researchers compared a new MRI technique to the standard liver biopsy method of assessing fat in the liver. To do this, the team enrolled 174 children who were having liver biopsies for clinical care. For each patient, the team performed both MRI-estimated PDFF and compared the results to the standard pathology method of measuring fat on a liver biopsy.”
“The team found a strong correlation between the amount of liver fat as measured by the new MRI technique and the grade of liver fat determined by pathology. This is an important step towards being able to use this technology for patients. Notably, the correlation was influenced by both the patient’s gender and the amount of scar tissue in the liver. The correlation between the two techniques was strongest in females and in children with minimal scar tissue.”
“Depending on how the new MRI technology is used, it could correctly classify between 65 and 90 percent of children as having or not having fatty liver tissue.”
“… However, further refinements will be needed before this or any other MRI technique can be used to diagnose NAFLD in an individual child.“
I am not sure of the origin of the expression “what is a dog going to do if it catches a bus?” However, I am reminded of this expression after reading a recent article about nonalcoholic fatty liver disease (J Pediatr 2014; 164: 707-13).
This retrospective study, “Histologic Abnormalities in Children with Nonalcoholic Fatty Liver Disease with Normal or Mildly Elevated Alanine Aminotransferase Levels,” analyzed 91 children (5-18 years) with suspected NAFLD who had normal or mildly elevated ALT values from 12 U.S. medical centers. They obtained liver biopsy specimens within 180 days of the ALT measurement and compared them from 392 children with elevated ALT.
When reading this title, one has to wonder, how did they select these children for this study? First of all the authors used two NASH CRN databases with 483 children. The reasons for NAFLD evaluation at entry in the current study included symptoms of liver disease in 22%, identification during evaluation of another illness in 38%, routine physical exam (41%), and other causes in 6%. At one point, elevated ALT was evident in 74% and radiographic evidence of steatosis in 55%.
The authors conclude that “liver biopsy specimens from children with NAFLD with normal or mildly elevated ALT levels show significant histological abnormalities, including advanced fibrosis…measurement of ALT may underestimate liver injury in NAFLD.” Yet, while it is true that ALT values may not have adequate sensitivity for liver injury, the authors deploy some circular logic; when one understands the selection of these patients, it comes as no surprise that some had advanced liver findings on biopsy. If one identifies an abnormal liver on ultrasound and confirms this on liver biopsy, this is targeting a population whose findings are not generalizable.
Outside of a research study, how does one decide which patients will benefit from a liver biopsy? This study does not offer any clarity.
And, if one identifies more cases of NAFLD, what is one to do? Besides weight loss (which should be recommended already in the majority), there are no other proven treatments. The associated editorial (pgs 684-86) reminds the reader to use appropriate normative values for ALT (<25.8 U/L for boys and <22.1 U/L for girls). In the study’s discussion, the lack of consensus among expert recommendations is acknowledged. Furthermore, in those who have recommended frequent screening with ALT values in obese children, the authors note that “evidence of the utility and cost-effectiveness of this approach is still lacking.”
Another study in the same issue (J Pediatr 2014; 164: 699-706) suggests a possible link between obstructive sleep apnea (OSA) and more advanced liver histology in NAFLD. This was a cross-sectional study with only 25 patients (88% Hispanic, mean age 12.8 years). The authors speculate that nighttime hypoxemia triggers oxidative stress and may induce further liver injury. 53% of those with OSA had stage 2 or higher fibrosis compared with only 10% of those without OSA.
Bottomline: NAFLD occurs in a lot of children and a normal or mildly elevated ALT does not exclude more severe disease. OSA may be either an epiphenomenon or a causative factor for more severe NAFLD findings.
Related blog posts:
This large case series of 35 children indicates that Magnetic Resonance Elastography (MRE) may be quite useful to assess hepatic fibrosis as well as steatosis (J Pediatr 2014; 164: 186-8).
The study (2011-2012) included 27 patients with nonalcoholic fatty liver disease (NAFLD); 22 of this group had probable or definite nonalcoholic steatohepatitis (NASH). Other diseases included progressive familial intrahepatic cholestasis (type 2), autoimmune sclerosing hepatitis, Wilson disease, glycogenic hepatopathy (due to type 1 diabetes), and other liver conditions. All of the patients in the study had undergone liver biopsy as well.
The authors showed that MRE had a high accuracy to detect significant fibrosis and may be better suited for severely obese patients. At the cutoff they identified, the sensitivity was 88% and the specificity 85% for detecting significant fibrosis.
In severely obese patients, alternative imaging techniques, namely transient elastography and acoustic radiation force imaging have higher technical failure rates. The authors note that at their institution, more than 100 MRE studies have been completed (including many without liver biopsies); thus far, only two morbidly obese patients failed completion. In addition, the authors state that this limited study costs about twice that of an ultrasound.