A high omega-3 and low omega-6 essential fatty acid diet improves insulin sensitivity in obese children and adolescents with non-alcoholic fatty liver disease (NAFLD), recent studies report. 

Remarkably, the high omega-3, low omega-6 fat diet reduced liver fat by 25.8% and improved insulin sensitivity without causing weight loss. Insulin sensitivity was increased due to the increased removal of excess insulin. 

These studies suggest that dietary changes may be more effective than drugs for treating NAFLD in children and adolescents with obesity. And unlike some drugs currently used to treat NAFLD, diet may also improve lipid profiles and insulin sensitivity in these children. 

The first study, “A low omega-6 to omega-3 PUFA ratio (n-6:n-3 PUFA) diet to treat fatty liver disease in obese youth,” was published in The Journal of Nutrition. The second study, “A low n-6 to n-3 polyunsaturated fatty acid ratio diet improves hyperinsulinaemia by restoring insulin clearance in obese youth,” was published in Diabetes, Obesity and Metabolism.  

The rates of obesity in children, adolescents and young adults are increasing dramatically worldwide. On World Obesity Day, the World Health Organisation (WHO) reported that 340 million adolescents and 39 million children worldwide are obese (WHO, 2022). Notably, obesity is a strong risk factor for non-alcoholic fatty liver disease (NAFLD) – a disease that occurs when fat builds up in the liver. 

Besides causing liver damage, NAFLD disrupts chemical processes in the body, causing insulin resistance, glucose intolerance and impaired pancreas function, raising the risk of prediabetes and type 2 diabetes. Scientists have established that unhealthy diets containing excess energy, refined sugar and saturated fat with low fruit and vegetable intake raise the risk of NAFLD, insulin resistance and type 2 diabetes. Recent studies further show that low intake of omega-3 fatty acids and overconsumption of omega-6 fatty acids promotes NAFLD and insulin resistance.

In the current study, scientists investigated if eating a low omega-6, high omega-3 fatty acid diet could reduce insulin resistance and liver fat in children and adolescents with NAFLD. 

A total of 17 children and adolescents with obesity and NAFLD were recruited from the Yale Paediatric Obesity Clinic in the United States. All participants were given a high omega-3, low omega-6 diet rich in fish, nuts and seeds without dietary supplements for 12 weeks. Before and after the 12-week diet, the participants underwent an oral glucose tolerance test (OGTT), during which their plasma glucose, and insulin levels were measured. Their liver fat, whole-body fat, abdominal fat, lipid profile, pancreas function, insulin sensitivity, production, and clearance rates were also measured. 

The cohort’s median age was 13 years, and 65% were female. In total, 41% were Caucasian, 12% African American and 47% Hispanic. After 12 weeks, participants reduced their liver fat by 25.8% despite maintaining the same weight. Remarkably, around one-third of the participants reduced their liver fat to normal levels. Overall, participants reduced their triglycerides by 21.9%, low-density lipoprotein (LDL, bad) cholesterol by 3.28% and improved insulin sensitivity by 26.3%. 

“This study has shown, to our knowledge for the first time, that a nonpharmacologic, food-based dietary intervention high in n-3 and low in n-6 PUFA [polyunsaturated fatty acids] intake improves fatty liver disease in obese adolescents, and restores liver fat content to normal in one-third of participants, in the absence of weight loss. The observed improvements in lipids, lipoprotein concentrations, and insulin sensitivity at the end of the study demonstrate a beneficial impact of a low n-6:n-3 PUFA ratio diet on both diabetes and cardiovascular disease risk factors,” the researchers wrote. 

In a secondary analysis, the researchers found that the high omega-3 and low omega-6 fatty acid diet improved insulin sensitivity by removing excess circulating insulin before and after meals. Participants with worse insulin resistance at the start of the study showed the greatest improvements in insulin sensitivity by the end of the study. 

“Our findings show that a eucaloric dietary intervention high in n-3 and low in n-6 PUFA compared with the ratio of a typical Western diet, can reduce hyperinsulinaemia by increasing fasting and post-load insulin clearance in obese youth with NAFLD, in the absence of weight loss,” they wrote. 

“The beneficial effects of the low n-6:n-3 PUFA ratio diet on insulin clearance and sensitivity were more evident in adolescents at increased metabolic risk, characterised by impaired insulin clearance, beta-cell function, and glucose tolerance,” they added. 

The researchers highlighted some limitations of the study, including the small number of participants and the short study duration. 

Still, the study “showed that a 12-week low n-6: n-3 PUFA ratio diet improves hyperinsulinaemia by increasing fasting and post-load insulin clearance insulin-resistant obese youth, in the absence of significant changes in body weight, glucose tolerance, and average insulin secretion.”

“This study supports the concept that nutritional interventions might be most effective in ameliorating the metabolic phenotype of youth with NAFLD providing additional benefits to dyslipidaemia and insulin resistance not present in some drugs for treating NAFLD,” the researchers wrote.

Although this study could be conducted in a small number of children and adolescents with NAFLD, larger, long-term studies are needed to understand the effectiveness of high omega-3 and low omega-6 diets on fatty liver and related diseases. 

REFERENCES

1. World Health Organisation. (2022) World Obesity Day 2022 – Accelerating action to stop obesity. Available from: https://www.who.int/news/item/04-03-2022-world-obesity-day-2022-accelerating-action-to-stop-obesity. Accessed: 25 April 2022.