Mediterranean Diet Reduced Liver Fat by 39% in NAFLD

SAN FRANCISCO – The Mediterranean diet is superior to the low-fat diet for decreasing hepatic fat and increasing insulin sensitivity in patients with nonalcoholic fatty liver disease, based on a randomized crossover study conducted in Australia.

After just 6 weeks on the Mediterranean diet, the 12 patients studied had significant improvements in a range of metabolic measures, such as a greater than one-third decrease in hepatic triglyceride content. In contrast, they had no such improvements after 6 weeks on the low-fat diet.

©Dušan Zidar/Fotolia.com

"The Mediterranean diet treats the underlying pathophysiology of NAFLD; this diet shows promise as a dietary recommendation for NAFLD," first author Dr. Marno C. Ryan said in her presentation of the results at the annual meeting of the American Association for the Study of Liver Diseases. "However, this is a small, highly controlled study, and larger, longer-term studies are needed to confirm these findings."

Importantly, the Mediterranean diet was also well received. "All of our patients enjoyed it, a lot more than the low-fat diet. Our dietitian actually was personally involved in preparing a lot of the meals, and she followed certain techniques that are required to do the slow cooking, etc., so the food was very tasty," she explained, noting that a larger trial would require more patient training in food preparation.

Also, cost might be a barrier for some patients in following the Mediterranean diet, acknowledged Dr. Ryan, a physician with St. Vincent’s Hospital in Melbourne. "Olive oil was a concern, and fish was as well. We did provide patients with money, approximately $80 a week, for that."

The investigators are now planning a similar but larger, less well controlled study in which patients will be followed for 2 years and will have liver biopsy at the beginning and end, she said.

Dr. T. Jake Liang, president of the AASLD and chief of the liver diseases branch at the National Institute of Diabetes and Digestive and Kidney Diseases in Bethesda, Md., pointed out that roughly 2%-3% of the U.S. population has NAFLD. That number is likely to increase, he said, given that two-thirds of the population is now overweight.

These new findings are "interesting; further long-term study is warranted," he said in a press conference. "Obviously, if we can prevent and treat a disease with a diet, that’s probably better than any drugs we can develop."

Insulin resistance is implicated in the pathogenesis of NAFLD as well as the other components of metabolic syndrome, such as abdominal obesity and dyslipidemia, Dr. Ryan said, giving some background for the study. "Therefore, any therapeutic strategies directed toward NAFLD should also encompass potential benefits for these associated features." To be eligible for the study, patients needed to be nondiabetic, with biopsy-proven NAFLD with fibrosis classified as less than F3 in extent, and to consume fewer than two servings of alcohol daily. The cohort had an equal sex distribution, a mean body mass index of 32 kg/m², and a mean hepatic triglyceride content of 11%.

The patients were randomized to start the study with either the Mediterranean diet or the low-fat, high-carbohydrate diet currently recommended for patients with NAFLD. They ate one diet for 6 weeks, returned to their own diet for 6 weeks as a washout, and then went on the alternate diet for 6 weeks. The aim was to change diet without inducing weight loss, since that can be a confounding factor, Dr. Ryan noted.

All patients received dietary instructions, weekly rotating menus, and approximately 70% of the meals needed for the study diets. They underwent testing – lab assays of fasting blood samples, a 3-hour euglycemic clamp study, and liver imaging and spectroscopy – before and at the end of each 6-week study period.

"This diet shows promise as a dietary recommendation for NAFLD."

Patients lost only small amounts of weight on the two diets, an average of 1 kg on the Mediterranean diet and 2.4 kg on the low-fat diet, a nonsignificant difference, Dr. Ryan reported.

The main results showed that the Mediterranean diet was associated with a 39% reduction from baseline in hepatic triglyceride content. This was determined via magnetic resonance spectroscopy after adjustment for weight loss (P = .001). There was a similar reduction in hepatic fat fraction measured by volumetric magnetic resonance imaging (P = .006).

The Mediterranean diet was also associated with improvements in insulin sensitivity as determined from reductions in homeostasis model assessment–insulin resistance, or HOMA-IR (P = .008) and fasting insulin levels (P = .003), and an increase in the glucose infusion rate on the euglycemic clamp study (P = .09).

In contrast, the low-fat diet was not associated with significant changes from baseline in any of these measures. "Interestingly, the serum insulin concentration actually increased across the 6-week period of the low-fat diet, presumably in response to the higher carbohydrate intake," she noted.

The sequence of the diets did not influence the study’s overall findings, according to Dr. Ryan. Neither diet significantly improved serum levels of liver enzymes, which were elevated at baseline.

When the two diets were directly compared with each other, the Mediterranean diet bested the low-fat diet in terms of changes in hepatic triglyceride content (P = .03), insulin levels (P = .008), and glucose infusion rate for the euglycemic clamp study (P = .03).

Dr. Ryan and Dr. Liang reported that they had no relevant conflicts of interest.

SAN FRANCISCO – The Mediterranean diet is superior to the low-fat diet for decreasing hepatic fat and increasing insulin sensitivity in patients with nonalcoholic fatty liver disease, based on a randomized crossover study conducted in Australia.

After just 6 weeks on the Mediterranean diet, the 12 patients studied had significant improvements in a range of metabolic measures, such as a greater than one-third decrease in hepatic triglyceride content. In contrast, they had no such improvements after 6 weeks on the low-fat diet.

©Dušan Zidar/Fotolia.com

"The Mediterranean diet treats the underlying pathophysiology of NAFLD; this diet shows promise as a dietary recommendation for NAFLD," first author Dr. Marno C. Ryan said in her presentation of the results at the annual meeting of the American Association for the Study of Liver Diseases. "However, this is a small, highly controlled study, and larger, longer-term studies are needed to confirm these findings."

Importantly, the Mediterranean diet was also well received. "All of our patients enjoyed it, a lot more than the low-fat diet. Our dietitian actually was personally involved in preparing a lot of the meals, and she followed certain techniques that are required to do the slow cooking, etc., so the food was very tasty," she explained, noting that a larger trial would require more patient training in food preparation.

Also, cost might be a barrier for some patients in following the Mediterranean diet, acknowledged Dr. Ryan, a physician with St. Vincent’s Hospital in Melbourne. "Olive oil was a concern, and fish was as well. We did provide patients with money, approximately $80 a week, for that."

The investigators are now planning a similar but larger, less well controlled study in which patients will be followed for 2 years and will have liver biopsy at the beginning and end, she said.

Dr. T. Jake Liang, president of the AASLD and chief of the liver diseases branch at the National Institute of Diabetes and Digestive and Kidney Diseases in Bethesda, Md., pointed out that roughly 2%-3% of the U.S. population has NAFLD. That number is likely to increase, he said, given that two-thirds of the population is now overweight.

These new findings are "interesting; further long-term study is warranted," he said in a press conference. "Obviously, if we can prevent and treat a disease with a diet, that’s probably better than any drugs we can develop."

Insulin resistance is implicated in the pathogenesis of NAFLD as well as the other components of metabolic syndrome, such as abdominal obesity and dyslipidemia, Dr. Ryan said, giving some background for the study. "Therefore, any therapeutic strategies directed toward NAFLD should also encompass potential benefits for these associated features." To be eligible for the study, patients needed to be nondiabetic, with biopsy-proven NAFLD with fibrosis classified as less than F3 in extent, and to consume fewer than two servings of alcohol daily. The cohort had an equal sex distribution, a mean body mass index of 32 kg/m², and a mean hepatic triglyceride content of 11%.

The patients were randomized to start the study with either the Mediterranean diet or the low-fat, high-carbohydrate diet currently recommended for patients with NAFLD. They ate one diet for 6 weeks, returned to their own diet for 6 weeks as a washout, and then went on the alternate diet for 6 weeks. The aim was to change diet without inducing weight loss, since that can be a confounding factor, Dr. Ryan noted.

All patients received dietary instructions, weekly rotating menus, and approximately 70% of the meals needed for the study diets. They underwent testing – lab assays of fasting blood samples, a 3-hour euglycemic clamp study, and liver imaging and spectroscopy – before and at the end of each 6-week study period.

"This diet shows promise as a dietary recommendation for NAFLD."

Patients lost only small amounts of weight on the two diets, an average of 1 kg on the Mediterranean diet and 2.4 kg on the low-fat diet, a nonsignificant difference, Dr. Ryan reported.

The main results showed that the Mediterranean diet was associated with a 39% reduction from baseline in hepatic triglyceride content. This was determined via magnetic resonance spectroscopy after adjustment for weight loss (P = .001). There was a similar reduction in hepatic fat fraction measured by volumetric magnetic resonance imaging (P = .006).

The Mediterranean diet was also associated with improvements in insulin sensitivity as determined from reductions in homeostasis model assessment–insulin resistance, or HOMA-IR (P = .008) and fasting insulin levels (P = .003), and an increase in the glucose infusion rate on the euglycemic clamp study (P = .09).

In contrast, the low-fat diet was not associated with significant changes from baseline in any of these measures. "Interestingly, the serum insulin concentration actually increased across the 6-week period of the low-fat diet, presumably in response to the higher carbohydrate intake," she noted.

The sequence of the diets did not influence the study’s overall findings, according to Dr. Ryan. Neither diet significantly improved serum levels of liver enzymes, which were elevated at baseline.

When the two diets were directly compared with each other, the Mediterranean diet bested the low-fat diet in terms of changes in hepatic triglyceride content (P = .03), insulin levels (P = .008), and glucose infusion rate for the euglycemic clamp study (P = .03).

Dr. Ryan and Dr. Liang reported that they had no relevant conflicts of interest.

SAN FRANCISCO – The Mediterranean diet is superior to the low-fat diet for decreasing hepatic fat and increasing insulin sensitivity in patients with nonalcoholic fatty liver disease, based on a randomized crossover study conducted in Australia.

After just 6 weeks on the Mediterranean diet, the 12 patients studied had significant improvements in a range of metabolic measures, such as a greater than one-third decrease in hepatic triglyceride content. In contrast, they had no such improvements after 6 weeks on the low-fat diet.

©Dušan Zidar/Fotolia.com

"The Mediterranean diet treats the underlying pathophysiology of NAFLD; this diet shows promise as a dietary recommendation for NAFLD," first author Dr. Marno C. Ryan said in her presentation of the results at the annual meeting of the American Association for the Study of Liver Diseases. "However, this is a small, highly controlled study, and larger, longer-term studies are needed to confirm these findings."

Importantly, the Mediterranean diet was also well received. "All of our patients enjoyed it, a lot more than the low-fat diet. Our dietitian actually was personally involved in preparing a lot of the meals, and she followed certain techniques that are required to do the slow cooking, etc., so the food was very tasty," she explained, noting that a larger trial would require more patient training in food preparation.

Also, cost might be a barrier for some patients in following the Mediterranean diet, acknowledged Dr. Ryan, a physician with St. Vincent’s Hospital in Melbourne. "Olive oil was a concern, and fish was as well. We did provide patients with money, approximately $80 a week, for that."

The investigators are now planning a similar but larger, less well controlled study in which patients will be followed for 2 years and will have liver biopsy at the beginning and end, she said.

Dr. T. Jake Liang, president of the AASLD and chief of the liver diseases branch at the National Institute of Diabetes and Digestive and Kidney Diseases in Bethesda, Md., pointed out that roughly 2%-3% of the U.S. population has NAFLD. That number is likely to increase, he said, given that two-thirds of the population is now overweight.

These new findings are "interesting; further long-term study is warranted," he said in a press conference. "Obviously, if we can prevent and treat a disease with a diet, that’s probably better than any drugs we can develop."

Insulin resistance is implicated in the pathogenesis of NAFLD as well as the other components of metabolic syndrome, such as abdominal obesity and dyslipidemia, Dr. Ryan said, giving some background for the study. "Therefore, any therapeutic strategies directed toward NAFLD should also encompass potential benefits for these associated features." To be eligible for the study, patients needed to be nondiabetic, with biopsy-proven NAFLD with fibrosis classified as less than F3 in extent, and to consume fewer than two servings of alcohol daily. The cohort had an equal sex distribution, a mean body mass index of 32 kg/m², and a mean hepatic triglyceride content of 11%.

The patients were randomized to start the study with either the Mediterranean diet or the low-fat, high-carbohydrate diet currently recommended for patients with NAFLD. They ate one diet for 6 weeks, returned to their own diet for 6 weeks as a washout, and then went on the alternate diet for 6 weeks. The aim was to change diet without inducing weight loss, since that can be a confounding factor, Dr. Ryan noted.

All patients received dietary instructions, weekly rotating menus, and approximately 70% of the meals needed for the study diets. They underwent testing – lab assays of fasting blood samples, a 3-hour euglycemic clamp study, and liver imaging and spectroscopy – before and at the end of each 6-week study period.

"This diet shows promise as a dietary recommendation for NAFLD."

Patients lost only small amounts of weight on the two diets, an average of 1 kg on the Mediterranean diet and 2.4 kg on the low-fat diet, a nonsignificant difference, Dr. Ryan reported.

The main results showed that the Mediterranean diet was associated with a 39% reduction from baseline in hepatic triglyceride content. This was determined via magnetic resonance spectroscopy after adjustment for weight loss (P = .001). There was a similar reduction in hepatic fat fraction measured by volumetric magnetic resonance imaging (P = .006).

The Mediterranean diet was also associated with improvements in insulin sensitivity as determined from reductions in homeostasis model assessment–insulin resistance, or HOMA-IR (P = .008) and fasting insulin levels (P = .003), and an increase in the glucose infusion rate on the euglycemic clamp study (P = .09).

In contrast, the low-fat diet was not associated with significant changes from baseline in any of these measures. "Interestingly, the serum insulin concentration actually increased across the 6-week period of the low-fat diet, presumably in response to the higher carbohydrate intake," she noted.

The sequence of the diets did not influence the study’s overall findings, according to Dr. Ryan. Neither diet significantly improved serum levels of liver enzymes, which were elevated at baseline.

When the two diets were directly compared with each other, the Mediterranean diet bested the low-fat diet in terms of changes in hepatic triglyceride content (P = .03), insulin levels (P = .008), and glucose infusion rate for the euglycemic clamp study (P = .03).

Dr. Ryan and Dr. Liang reported that they had no relevant conflicts of interest.