A recent study published by the American Society for Nutrition discovered that individuals with non-alcoholic fatty liver disease (NAFLD) may require higher doses of vitamin D in order to correct vitamin D deficiency.
NAFLD is the accumulation of fat cells within the liver, resulting in chronic liver inflammation and scarring. This is a common condition, affected up to 100 million individuals within the United States. The characteristics of this condition are very similar to liver damage caused by heavy alcohol use, but in cases of NAFLD, the causes are generally unknown. However, some lifestyle factors such as obesity, diabetes and high blood pressure have been associated with occurrence of NAFLD.
While this condition cannot be cured, it can be easily managed. However, left untreated, NAFLD can lead to more severe liver damage. The spectrum of NAFLD can include the following:
- Hepatic steatosis (HS): Buildup of fat within the liver
- Nonalcoholic steatohepatitis (NASH): Severe inflammation of the liver
- Cirrhosis: Buildup of scar tissue on the liver
- Liver failure.
Currently, lifestyle modifications are the only treatment recommended to control the progression of NAFLD.
Research has shown a strong relationship between vitamin D status and NAFLD progression and severity. Additionally, animal studies have found that sufficient vitamin D status may prevent the occurrence of NAFLD. Now, researchers are beginning to look at the effect of correction of vitamin D deficiency on NAFLD outcome. However, research has yet to determine the dosage required to enable NAFLD patients to reach sufficient vitamin D levels (40-80 ng/ml). Therefore, researchers from this study decided to analyze the efficiency of 2,000 IU (50 mcg) vitamin D3 on this population.
The researchers included a total of 42 adults with NAFLD who were considered to be vitamin D deficient (<30 ng/ml). All participants were given 2,000 IU per day for six months. Additionally, basic evaluations measuring BMI, evaluating medical history and disease severity were administered to all participants. Serum blood draws were taken in order to determine vitamin D status and some metabolic markers at baseline and at the conclusion of the study. At the end of the study, patients were divided into two groups based off of their response to the vitamin D supplementation. Individuals with vitamin D levels >30 ng/ml were considered responders, and individuals with vitamin D levels <30 ng/ml were considered nonresponders. Responders and nonresponders were compared during analysis of the study.
This is what the researchers found:
- Average serum 25(OH)D concentration at baseline was 21.7 + 6.4 ng/ml.
- By the end of the study, a total of 26 individuals were considered nonresponders and 16 were considered responders.
- Nonresponders had a greater fat mass and lower fat-free mass scores compared to responders (p < 0.001).
- Nonresponders had higher disease severity scores than nonresponders, indicating a greater disease severity (p = 0.02).
- Baseline 25(OH)D concentrations were inversely correlated with disease severity scores (p = 0.044).
- Secondary outcomes, including several metabolic markers that reflect insulin resistance and liver function, were significantly improved in the responder group compared to the nonresponder group (p = 0.02 and p < 0.01, respectively).
- Diagnosis of NAFLD and initial high HOMA-IR scores, indicating higher insulin resistance, were independent predictors of lack of response to supplementation (p = 0.008 and p = 0.002, respectively), but baseline vitamin D status was not.
The researchers concluded:
“This prospective, observational study of cholecalciferol supplementation in a select cohort of well-characterized NAFLD patients with vitamin D deficiency [plasma 25(OH)D
<30 ng/mL] showed that the currently used regimen of 2000 IU/d for 6 mo is insufficient, and higher doses may be necessary in the majority of patients with NASH”
As always, the strengths and limitations of this study should be addressed. While the long study duration was favorable, the population size was relatively small. Additionally, the participants were given the responsibility of self-supplementation, which could have led to a decreased compliance rate, therefore accounting for lack of supplementation response. The researchers called for randomized controlled trials using at least 4,000 IU (100 mcg) to help individuals on the spectrum of NAFLD increase their vitamin D levels.
Peterson, R. Researchers discover lack of response to vitamin D supplementation in individuals with non-alcoholic fatty liver disease. The Vitamin D Council Blog and Newsletter, 8/2017.