The study, published in Clinical Nutrition, suggests that four weeks of supplementation with whey protein may significantly reduce the markers of fatty liver disease in obese women by reducing the amount of fat inside liver cells. The research found that whey protein improved key markers of blood lipid profiles – an important risk marker for heart disease.
“This preliminary, uncontrolled study therefore suggests that a high protein diet may, in the long term, reduce the risk of non-alcoholic steatohepatitis [fatty liver disease] and of cardio-vascular disease in obese patients,” said the researchers, led by Murielle Bortolotti from University of Lausanne.
According to the authors, the incidence of fatty liver disease (hepatic steatosis) is frequently increased in obese patients, and is considered as the hepatic (liver associated) component of the metabolic syndrome.
The disease is closely associated with the metabolic complications of obesity, such as insulin resistance, impaired glucose tolerance, and dyslipidemia (abnormally high levels of blood lipids).
Previous research has suggested that high protein intake may improve fatty liver disease.
The amount of fat inside liver cells (known as intra-hepatocellular lipid concentrations – IHCL) in subjects fed a short term high fat diet has been previously shown to be reduced again through increasing dietary protein intake.
Such findings suggest that high protein intakes may have beneficial effects for fatty liver disease (FLD) patients.
“We therefore hypothesized that increasing the dietary protein intake in the same range as that which reduced IHCL in high-fat fed subjects would also reduce IHCL concentrations in obese patients,” wrote the authors.
To test this hypothesis, Bortolotti and colleagues studied the effects of 4 weeks supplementation with 60 grams per day (3 x 20 gram doses) of whey protein in eleven obese, non diabetic females.
The whey protein was a commercial whey protein (WheyProtein94) supplied by Sponser of Switzerland
At baseline all obese patients had a BMI ranging between 30.9 and 52.4 kg/m2 (average BMI of 37.6 for the group), and IHCL concentrations ranging between 1.9 and 20.5 percent of liver volume.
The group was – on average – reported to have significant baseline insulin resistance as measured by a homeostatic model assessment (HOMA) insulin sensitivity score of 2.77
The authors reported that four weeks of supplementation with whey protein led to a significant decrease in IHCL of 21 percent, whilst fasting plasma triglyceride was observed to decrease by 15 percent, and total plasma cholesterol concentration decreased by over 7 percent.
Insulin sensitivity, as indicated by the HOMA index, was not found to be greatly changed with whey protein supplementation.
Bortolotti and her co workers noted that the IHCL reduction was not accompanied by visceral fat volume or total liver volume or with important changes in body weight or body fat mass.
“This therefore indicates that the improved IHCL and plasma triglyceride profiles were to be attributed to an effect of protein rather than to changes in body composition,” they said.
The researchers concluded that whey protein supplementation improves markers of fatty liver disease and plasma lipid profiles in obese non diabetic patients, without adverse effects on glucose tolerance.
“While a high protein diet may also have adverse effects, the present study did not hint at adverse renal effects. Further studies will however be needed to evaluate the optimal amount and sources of dietary proteins intake,” they said.
Source: Clinical Nutrition
Published online ahead of print, doi: 10.1016/j.clnu.2011.01.006
“Effects of a whey protein supplementation on intrahepatocellular lipids in obese female patients”
Authors: M. Bortolotti, E. Maiolo, M. Corazza, E. Van Dijke, P. Schneiter, A. Boss et al
Trial Number: NCT00870077, ClinicalTrials.gov