Uncover the hidden health "liver" disturbance of fat babies: non-alcoholic fatty liver disease!

Author: Wu Jingfang, deputy chief physician of China Rehabilitation Research Center

Reviewer: Li Xuemei, Chief Physician, China Rehabilitation Research Center

In recent years, with the improvement of living standards and changes in dietary structure of Chinese residents, the problem of overweight and obesity among children in my country has become increasingly serious. According to the "Report on the Nutrition and Chronic Disease Status of Chinese Residents (2020)", the overweight and obesity rates of children aged 6 to 17 in my country reached 11.1% and 1.9%, respectively. The detection rate of non-alcoholic fatty liver disease (NAFLD) in obese children is as high as 50% to 80%. The prevalence of non-alcoholic fatty liver disease has increased year by year. It has become the main cause of chronic liver disease in Chinese children and a serious public health problem affecting children's health. As a parent, how can you take good care of your children's health?

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1. Only when we know the harm of non-alcoholic fatty liver disease will we pay attention to it

1. What is non-alcoholic fatty liver disease in children?

Non-alcoholic fatty liver disease in children refers to a clinical syndrome in which chronic fat deposition in the liver affects more than 5% of liver cells in children under the age of 18 years, excluding alcohol consumption and other clear pathogenic factors. The disease spectrum includes non-alcoholic fatty liver (NAFL), non-alcoholic steatohepatitis (NASH) and its related cirrhosis and hepatocellular carcinoma.

In 2023, the United States and the European Association for the Study of the Liver jointly proposed to rename non-alcoholic fatty liver disease to fatty liver disease associated with metabolic dysfunction. They believe that "non-alcoholic" cannot accurately reflect the essential characteristics of non-alcoholic fatty liver disease, and fatty liver disease associated with metabolic dysfunction can better highlight the importance of metabolic function, but it is easily confused with fatty liver caused by genetics. Therefore, non-alcoholic fatty liver disease is still used.

2. Why should we control non-alcoholic fatty liver disease?

If children develop mild fatty liver and then non-alcoholic fatty liver disease, if not discovered, diagnosed and treated in time, it may develop into cirrhosis and even cause hepatocellular carcinoma. Once cirrhosis develops, 30% to 40% of children will die within 10 years. If non-alcoholic fatty liver disease in children is not actively prevented and controlled, the risk of serious cardiovascular and cerebrovascular events such as diabetes, chronic kidney disease and stroke in adulthood will be significantly increased. Therefore, early identification and prevention of non-alcoholic fatty liver disease in childhood is the core link in preventing the chronicity of liver disease and is of great significance to reducing the medical burden in adulthood.

2. What are the causes of non-alcoholic fatty liver disease in children?

(1) Obesity factor: The etiology of non-alcoholic fatty liver disease is very complex, but obesity is an independent risk factor for non-alcoholic fatty liver disease in children.

(2) Gender and age factors: Boys and older children have a higher risk of developing non-alcoholic fatty liver disease than girls and younger children, which may be related to the protective effect of estrogen on metabolic pathways such as fat synthesis and browning of adipose tissue in the body. As people age, the rates of overweight and obesity increase, indicating that the accumulation of obesity over time may be the cause of non-alcoholic fatty liver disease.

(3) Factors during pregnancy: As the obesity rate among adults increases, pregnant women face increasing problems of obesity and insulin resistance, which may lead to gestational diabetes, affect fetal development, and increase the risk of non-alcoholic fatty liver disease.

(4) Intestinal flora imbalance: Cesarean section, dietary conditions and frequent use of antibiotics may cause intestinal flora imbalance in infancy and increase the risk of non-alcoholic fatty liver disease.

(5) The combined effects of environment and genetic polymorphisms: Obesity and exposure during pregnancy may lead to epigenetic changes in the fetus, increasing the risk of non-alcoholic fatty liver disease.

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3. What are the clinical characteristics of non-alcoholic fatty liver disease?

Most children with non-alcoholic fatty liver disease are overweight or obese. They are generally asymptomatic when the disease occurs. Occasionally, they complain of non-specific symptoms such as right upper abdominal pain, dull pain in the liver area, or upper abdominal distension and pain. Severe non-alcoholic fatty liver disease may cause jaundice, loss of appetite, nausea and vomiting. One-third of children have elevated blood pressure when diagnosed, and blood tests for aspartate aminotransferase and alanine aminotransferase are elevated, with the elevation of alanine aminotransferase being more obvious.

4. What are the evaluation indicators and testing methods for non-alcoholic fatty liver disease in children?

(1) Physical test: age, gender, height, weight, body fat percentage, waist/hip ratio, etc.

(2) Blood indicators: blood sugar, blood lipids, liver function tests, etc. Alanine aminotransferase is a biomarker recognized both domestically and internationally for screening non-alcoholic fatty liver disease, so it is recommended to fast when going to the hospital for treatment.

(3) Imaging examination: The most commonly used screening tool is abdominal ultrasound to check for fatty liver. Magnetic resonance imaging proton density fat fraction examination can also be used, but the cost is relatively high, the examination time is relatively long, and the children sometimes do not cooperate.

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(4) Liver biopsy: Liver biopsy confirming fatty degeneration of hepatocytes ≥5% is the gold standard for diagnosing non-alcoholic fatty liver disease. However, liver biopsy is an invasive examination and is not suitable for routine examinations in children.

2. What are the effective methods to prevent non-alcoholic fatty liver disease in children?

A healthy lifestyle and scientific diet are the most effective ways to prevent and treat non-alcoholic fatty liver disease in children.

1. Adjustment of dietary structure

Three meals a day should be eaten at regular times and in fixed quantities. Breakfast, lunch, and dinner should account for 30%, 40%, and 30% of the total energy for the day, respectively. Do not eat too fast, chew slowly, and each meal should be controlled within 20 to 30 minutes. Eat more foods rich in calcium, iron, and vitamin D to ensure the child's bone development and the absorption of iron and calcium in the body.

2. Adjustment of daily activities

Reduce static activity time and limit the use of electronic screens (TV, mobile phones) to no more than 2 hours a day, because long-term sitting will increase the accumulation of calories; in terms of exercise, it is recommended that healthy children aged 6 to 17 years old ensure at least 30 to 60 minutes of medium- and high-intensity aerobic exercise (such as jogging, skipping, ball games and swimming, etc.) every day, 3 to 5 times a week, and combine resistance exercise, 2 to 3 times a week. Go to bed before 22:00 at night.

Aerobic exercise can effectively reduce liver and visceral fat and improve insulin sensitivity. Resistance exercise can improve weight loss, reduce fat, improve cardiovascular function, and improve insulin sensitivity. However, given the physical development characteristics of children and adolescents, the principle of gradual progress should be followed when choosing the amount and intensity of exercise.

3. Grow taller without gaining weight

Parents should be alert to changes in their children's weight and waist circumference as early as possible to ensure that children grow taller but not fatter. Weight gain should be actively controlled because a 3% to 5% weight loss can improve fatty changes, and a 7% to 10% weight loss can improve abnormalities in liver enzymes and histology.

3. Can non-alcoholic fatty liver disease be treated?

In terms of treatment, there are currently no approved drugs for the treatment of non-alcoholic fatty liver disease in children. Both domestic and international guidelines recommend: Strengthening lifestyle intervention as the first-line treatment for non-alcoholic fatty liver disease in children. Most children can eliminate the cause of the disease, reduce weight, and achieve reversible fatty changes in the liver through lifestyle changes. Therefore, parents can formulate a reasonable diet structure, total dietary calories and exercise for their children, arrange their children's work and rest time reasonably, actively control their weight, and avoid obesity and overweight. For children who are already overweight or obese, it is recommended that parents make an observation index chart for their children. This chart allows children to record daily changes and let them see their own progress, which is conducive to building confidence in weight loss; it can also be used for communication between doctors and patients in order to improve individualized diet and exercise plans.

In short, prevention of non-alcoholic fatty liver disease is better than treatment. Only when families and society work together can children have a healthy body.