AIM: To assess nutrition, physical activity and healthful knowledge in obese children with biopsy-proven non-alcoholic steatohepatitis (NASH or NA) compared to children without liver disease.

METHODS: Children with biopsy-proven NASH comprised the NASH group. Age, sex and ethnicity matched control groups consisted of obese (OB) and lean (CO) children with no liver disease. Subjects were administered the School Physical Activity and Nutrition Survey and one blood draw was obtained.

RESULTS: Fifty-seven patients were enrolled with a mean age of 12.1 ± 2.1 years, and all were Hispanic. Even though the OB and NA had a similar increased body mass index (%), 35% of the NA group always read nutrition labels compared to none in the OB (P < 0.05), and more NA children felt their diet is “less healthy”. NA consumed the least amount of fruits with only 25% having ≥ 1 fruit/d vs 45% in OB and 64.7% in CO (P < 0.05 NA vs CO). Only 15% of NA subjects performed light exercise vs 35% and 59% of OB and CO groups, respectively (P = 0.02). The mean physical activity score was lowest in the NA group (P < 0.05). Amongst the subjects with NASH, we found that 100% of patients with grade 2 or 3 fibrosis had a sedentary score > 2 compared to only 63.6% of those with grade 1 or no fibrosis (P < 0.05).

CONCLUSION: Children with NASH had increased se-dentary behavior, decreased activity, and fruit intake. Larger studies may determine the benefit of changing these behaviors as treatment for NASH.

The prevalence of obesity is increasing in epidemic proportions in both adults and children. This has tripled from 1980 for the age group 6 to 19 years, with national health and nutrition examination survey (NHANES) reporting 17.4%-18.8% of children being obese[1]. The evidence is clear; obese children become obese adults. In fact, obese 10 to 14 years old adolescents are more than 20 times more likely to become obese adults[2]. This is unfortunate, since obesity is associated with metabolic syndrome, which has been reported in up to 50% of severely obese children[3], and other obesity-associated diseases, such as fatty liver disease.

As the epidemic of childhood obesity progresses, it is predicted that the prevalence of non-alcoholic fatty liver disease (NAFLD) and non-alcoholic steato-hepatitis (NASH or NA) will also increase[4]. NAFLD is an umbrella term that includes simple steatosis and simple steatosis with the presence of lobular inflammation. These two forms of NAFLD are generally considered to be non-progressive. Once a patient has portal inflammation, ballooning degeneration of hepatocytes or fibrosis the patient has the type of NAFLD that has been shown to be progressive, or NASH. A diagnosis of NAFLD may be made when the patient has elevated liver enzymes in combination with radiography demonstrating fatty infiltration in the liver. NAFLD is now considered to be the most common cause of chronic liver disease in the pediatric population[5]. Studies using non-invasive techniques have been performed worldwide and have shown that NAFLD may be present in up to 77% of obese children[6]. Schwimmer et al[7] recently reported a population-based study where 13% of all children had biopsy-proven NAFLD and 3% had NASH.

The pathogenesis of the development of NAFLD is not completely understood. In 1999, Day and James[8] published the current theory “the two hit hypothesis”. The first “hit” is believed to be the development of steatosis, while the second “hit” leads to the progression to inflammation, necrosis and fibrosis. Oxidized by-products are harmful adducts that can cause liver injury, resulting in subsequent fibrosis[9]. Day[10] has subsequently pointed out that genetic factors influence the host response to endotoxin, oxidative stress, and severity of steatosis and that environmental factors, such as a diet high in saturated fat or low in antioxidant vitamins, influence the host’s susceptibility to fatty liver disease.

There are still no approved pharmacological therapies for NAFLD/NASH. Therefore, current management is based upon the presence of associated risk factors and aims to improve an individual’s quality of life, thus reducing NAFLD-associated morbidity and mortality. Today, lifestyle intervention (diet and exercise) is the treatment of choice for NAFLD/NASH. Significantly high levels of serum triglycerides, glucose, insulin, alanine aminotransferase (ALT), increased body mass index (BMI) and waist circumference (central adiposity) are all possible clinical features of pediatric NAFLD, which suggests that interventions on these variables can help to treat fatty liver, as well as to prevent progression to NASH[11]. On the other hand, resolution of histological abnormalities revealed by liver biopsy is, at this time, the main target of NASH treatment[12]. Studies on pediatric subjects have shown that moderate weight loss can improve BMI and serum levels of ALT, and reduce fatty liver infiltration and necro-inflammation, although no change has been demonstrated in degree of fibrosis[13].

One way to assess a child’s diet and physical activity is the School Physical Activity and Nutrition (SPAN) questionnaire[14], which was developed as a surveillance instrument to measure physical activity, nutrition attitudes, and dietary and physical activity behaviors in children and adolescents. This tool can assess many dietary and physical behaviors over the 24 h prior to questionnaire administration. The food behaviors measured by this instrument include recall of certain foods from the previous day. This type of short-term recall is better for children because their cognitive skill has not developed sufficiently to estimate averaging and frequency as found in a traditional food frequency questionnaire[15]. It has been validated and found to be reproducible[16,17].

We hypothesize that there are differences in the dietary behaviors, physical activity and healthful knowledge between obese children who develop NASH and obese and lean children with no evidence of liver disease. These differences would be of greater clinical relevance when examined in subjects who share a similar genetic background and who are affected most frequently by NASH, i.e., being of Hispanic origin. Therefore, identifying those potential environmental differences may have important implications which may guide us towards treatment and possibly even prevention of this condition in the future.

To test the hypothesis that there are differences in the dietary and physical activity habits between obese children with NASH and obese and lean children with no evidence of liver disease, we enrolled 57 children between the ages of 8 and 16 years into this pilot study. We categorized them into three different groups: the “NA” or NASH group which included 20 obese children with biopsy-proven NASH, the or obese control group (OB) which included 20 obese children with no evidence of liver disease, and the or lean control group (CO) which included 17 lean children with no evidence of liver disease.

Our pilot study demonstrates clear differences in dietary behaviors, physical activity and healthful knowledge between lean healthy children, obese children with no evidence of liver disease and obese children with NASH. One potential caveat to our study is that we didn’t obtain a liver biopsy to confirm the absence of NAFLD in the CO and OB groups. However, given the invasive nature of liver biopsy and normal transaminases in these subjects, it would be unethical to perform this procedure on children with no other clinical indication. Hence, in order to minimize this possibility, we excluded any child with a history of liver disease of any sort, history of elevated ALT or ALT > 40 U/L on the day of the study visit.

We performed this study in a cohort of Hispanic children; this must be taken into account when considering generalizing this to the population as a whole. Ogden et al[19] recently reported that the highest rate of obesity in children of all age groups was among teenage African American girls followed by Hispanic boys and girls of all ages with Hispanic males having the highest percentage of obesity compared to white and African American males[20]. Additionally, the role of gender, race and ethnicity has been described in a population based study on NAFLD by Schwimmer et al[21], where they noted that obese adolescent boys were six times more likely to have fatty liver compared to obese adolescent girls. This study also supported the observation that NAFLD is more common in Hispanic adolescents compared to other ethnicities, with Hispanic ethnicity making a child five times more likely to have NAFLD than an African American child[7]. Given the prevalence and severity of obesity and NAFLD in Hispanic children, our study population provides a unique insight into this population.

In our cohort, all subjects were Hispanic, and 74% of them were males. This male:female ratio is similar to Schwimmer’s report of 82% of children with NASH being male[7]. There were no differences between the 3 groups in regards to age and sex; however, there were clear differences between the groups in regards to their fasting glucose and insulin levels - findings that are consistent with previous studies (e.g., Louthan et al[22] and Vos et al[23] studies). Evidence supports the concept that a trio of obesity, dyslipidemia, and insulin resistance play an important role in the pathogenesis and severity of NASH in children, and we found that children with NASH had an increase in HOMA-IR and a decrease in QUICKI when compared to the obese and lean control groups[19,22,23]. The NA and OB groups had a significantly higher level of triglyceride (TG) and lower level of high-density lipoprotein (HDL) when compared to the lean control subjects. Those values were comparable to the values from other studies such as Viva La Familia study by Butte et al[24] and Quirós-Tejeira et al[25], as the mean HDL in our NA subjects was 43.85 ± 9.7 (in Viva La Familia; HDL: 46.6 ± 0.5 mg/dL) and mean TG was 140.3 ± 81.4 (in Quirós-Tejeira et al[25]; TG for boys: 157.2 ± 86.9 mg/dL and for girls: 145.0 ± 71.7 mg/dL).

Recent studies have shown that the majority of Hispanic mothers of overweight children may not perceive their children as being overweight[26-28] . In another study by Mikhail et al[29] both children and parents underestimated the child’s body fat with parents’ estimates being slightly, but not significantly, better (unpublished data). Similarly, we found that only half of the NA children found themselves heavier than their classmates; however, the majority of them had tried and/or are currently trying to lose weight.

Interestingly, even though the NA and the OB groups had the same mean BMI % (98%), similar proportions reported feeling heavier than their classmates, and a similar percentage had tried or are currently trying to lose weight, the NA and OB groups had notable differences in their healthful knowledge. For example about one third of the NA children read food labels on a regular basis compared to none in the OB group, and more NA than OB children recognized that their diets are “less healthy”. This finding may be attributed to the fact that the NA children had multiple physician’s visits including seeing a specialist (i.e., a hepatologist), and had undergone multiple blood draws and a liver biopsy for obesity-related health issues, while the OB group were recruited generally during their well-child visit, through Baylor Pediatric Residents Primary Care clinics at Texas Children’s Hospital. Therefore, the NA subjects may have a heightened sense that their diet is not as healthy as it should be and may truly be reading food labels on a more regular basis.

A growing body of evidence supports that oxidative stress may play a vital role in the development of NASH[30,31]. Intake of antioxidants may help prevent the occurrence of this disease and antioxidant vitamin supplementation studies have been performed[13,32,33]. In our study, there were no differences between the three groups in regards to their daily intake of a vitamin pill to explain a difference in their antioxidant intake; however, we noted that the NA group had the lowest intake of fruits per day while the CO group had the highest intake. Fruits are rich in antioxidants[34-36], and this difference in fruit intake between the groups may give insight into why some obese Hispanic children develop NASH while others do not.

In an analysis of NHANES looking at whole grain consumption and weight status, it was found that women consuming at least one serving of whole grain had a significantly lower mean BMI and waist circumference than women with no whole grain consumption[37]. In another study done in the United Kingdom, it was found that a higher intake of whole grains (about three servings per day) was associated with lower BMI and central adiposity[38]. Nicklas et al[39] have found that consuming ready-to-eat cereal at breakfast was associated with improved weight and nutrient adequacy in African American children. Surprisingly, in our study there were no differences between the 3 groups in regards to having breakfast or cereal intake. This, however, may be due to the small sample size in our pilot study.

While differences between the 3 groups were noted in respect to vigorous activity, it was even more notable in regards to light exercise, with only 15% of the NA subjects performing light exercise for at least 30 min on the prior day, compared to one third and almost two thirds of the OB and CO groups, respectively. While we have not evaluated for patatin-like phospholipase domain-containing protein 3 (PNPLA 3) variants in our study subjects, it has been recognized that PNPLA 3 variants have been associated with NASH, especially in Hispanics. Johansson, et al[40] reported that PNPLA 3 mutations were associated with decreased light physical activity. This highlights the need for studies to evaluate PNPLA 3 mutations in children with NASH.

Amongst the subjects with NASH, we found that all patients with advanced fibrosis had a sedentary score > 2 compared to less than two thirds of those with grade 1 or no fibrosis. Realizing that this was a one-time study visit, we can not be certain as to where our subjects are in regards to the natural history of disease progression. However, in a study out of Italy by Nobili et al[41], children with NASH who improved their BMI, partially by increased exercise, decreased the degree of liver injury. This could explain the above finding in our study.

In conclusion, both genetic and environmental factors play major roles in the development of NASH and determine why only a minority of obese, insulin resistant individuals progress from simple steatosis to inflammation and fibrosis[10]. This pilot study aimed to use a validated tool, the SPAN questionnaire, to asses the role of specific environmental factors such as diet and physical activity in pediatric NAFLD. Our results suggest that pediatric hepatologists should consider counseling children with NASH regarding the potential benefits of decreasing sedentary behavior, increasing light activity level, and increasing fruit intake. We conclude that future studies identifying environmental factors involved in pediatric NASH may help target therapeutic measures and preventative measures.