PNPLA3 rs738409 (I148M) variant is associated with hepatic liver accumulation and chronic liver diseases including non-alcoholic fatty liver disease. It has been shown that obesity augments genetic risk but studies investigating the interaction of PNPLA3 rs738409 risk variant and diet are scarce. The aim is to investigate the effect of dietary fat quality modification in participants with different variants of the PNPLA3 gene (rs738409). The primary outcome is the change in liver fat measured by magnetic resonance imaging in the randomized controlled 12-week dietary intervention trial.
Non-alcoholic fatty liver disease (NAFLD) is the most common liver disease worldwide. The composition of the diet, especially quality of dietary fat, contributes to the susceptibility to hepatic lipid accumulation. Saturated fatty acids (SFA), but not polyunsaturated fatty acids (PUFA) increases intrahepatic triglycerides with and without concomitant weight gain. Therefore, the modification of dietary fat quality is the key dietary approach for the prevention of NAFLD. PNPLA3 rs738409 (I148M) variant is associated with hepatic liver accumulation and chronic liver diseases including NAFLD. It has been shown that obesity augments genetic risk but studies investigating the interaction of PNPLA3 rs738409 risk variant and diet are scarce. Therefore, the aim is to investigate the effect of dietary fat quality modification (high unsaturated fat vs. high SFA) on liver fat and lipid and glucose metabolism in participants with different variants (CC or GG) of the PNPLA3 gene. The investigators will conduct the randomized controlled 12-week dietary intervention trial in participants with different homozygous PNPLA3 variants (CC or GG). The primary outcome of the intervention is in the amount of liver fat measured by nuclear magnetic resonance imaging (MRI). Altogether 140 homozygous participants (PNPLA3 rs738409 CC and GG) will be recruited from the Metabolic Syndrome in Men (METSIM) study. The inclusion criteria include BMI \< 35 kg/m2 and age \< 75 years. The main exclusion criteria include diabetes, acute illness, or current evidence of acute or chronic inflammatory or infective diseases. Dietary guidance in the intervention group is based on the Nordic and Finnish nutrition recommendations with an emphasis on the quality of dietary fat. The aims for the intake of fatty acids will be SFA \< 10 % of energy intake (E%) and mono- and polyunsaturated fatty acids (UFA) \>2/3 of the total fat intake. The diet of the control group corresponds to the average nutrient intake in the Nordic countries, i.e. the intake of SFA about 15 E% and the proportion of UFA about 50 % of total fat intake.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
PREVENTION
Masking
DOUBLE
Enrollment
99
Dietary guidance in the intervention group is based on the Nordic and Finnish nutrition recommendations with an emphasis on the quality of dietary fat. The aims for the intake of fatty acids will be SFA \< 10 % of energy intake (E%) and mono- and polyunsaturated fatty acids (UFA) \>2/3 of the total fat intake. The key food products such as vegetable oil-based spread, liquid margarine and canola oil are provided to the participants. The participants are recommended to use fat free (e.g. milk, sourdough milk and yogurt) and low fat (e.g. cheese ≤ 17%) dairy products and low-fat meat, poultry, and fish as well as natural nuts and seeds.
The control diet corresponds to the average nutrient intake in the Nordic countries, i.e. the intake of SFA about 15 E% and the proportion of UFA about 50 % of total fat intake. The participants of the control group will get butter-based spread for bread and cooking. They are recommended to use semi-skimmed milk (1,5 %), normal fat yogurt (\~2%), normal fat cheese (\~24-35 %) and avoid consumption of vegetable oils. They are allowed to eat a portion of fish and nuts once a week.
Institute of Public Health and Clinical Nutriton
Kuopio, Finland
Liver fat
The primary outcome is the change in liver fat measured by magnetic resonance imaging
Time frame: 12 weeks
Hepatic condition monitored by ultrasound
The hepatic condition will be monitored by ultrasound
Time frame: 12 weeks
Hepatic condition monitored by elastography
The hepatic condition will be monitored by elastography
Time frame: 12 weeks
Hepatic condition monitored by calculated indexes
The hepatic condition will be monitored by calculating and comparing Fibrosis-4 index, NAFLD Fibrosis Score, hepatic steatosis index, the fatty liver index and NAFLD liver fat score.
Time frame: 12 weeks
Glucose metabolism
Changes in glucose metabolism (oral glucose tolerance test, 0, 30 min and 2 h samples)
Time frame: 12 weeks
Serum lipid profile
Concentrations of total cholesterol, LDL cholesterol, HDL cholesterol and triglycerides
Time frame: 12 weeks
Inflammatory markers
Serum circulating concentrations of high-sensitivity C-reactive protein
Time frame: 12 weeks
Plasma metabolomic profile
Mass spectrometry based metabolomics analysis
Time frame: 12 weeks
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Plasma lipidomic profile
Mass spectrometry based lipidomics analysis
Time frame: 12 weeks
Gut microbiota
The DNA/RNA of gut microbiota will be extracted and collected for high throughput metagenomics and metatranscriptomics to observe changes in type and composition of gut microbiota.
Time frame: 12 weeks
Fatty acid composition of plasma lipid fractions
Fatty acid composition of plasma phospholipids, cholesteryl esters and triglycerides
Time frame: 12 weeks