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Liver fat did not independently increase atherosclerosis risk in healthy individuals

A recent study indicated an association between liver fat and subclinical carotid atherosclerosis in healthy participants, but the association was not independent of BMI or waist circumference.

The study included 492 healthy participants enrolled in the Multicultural Community Health Assessment Trial between 2004 and 2005. Demographic information, body composition and cardiovascular risk factors were assessed, and a follow-up was performed 5 years later. At that time, liver fat (LF) was measured via CT and subclinical atherosclerosis was determined via carotid intima media thickness (IMT) and total area (the sum of IMT and plaque areas) was indicated by carotid ultrasound. BMI and waist circumference (WC) also were recorded.

Negative correlations were observed between liver fat as measured by Hounsfield units (HU) and BMI, age, WC and body fat percentage (P<.05 for all). Mean HU values were different between participants of normal weight (24.9 kg/m2 or lower) and overweight (25.0-29.9 kg/m2) and obese participants (30 kg/m2 or higher) (P<.001). Values decreased significantly as WC increased (P<.001). Investigators also noted that participants with a higher body fat percentage had lower HU values (P<.001).

Average IMT and total area were negatively associated with mean liver HU after adjusting for factors including age, sex, ethnicity, tobacco use, education and income (P=.015 for IMT and P=.047 for total area). Further adjustment for BMI (P=.581 for IMT; P=.161 for total area) and WC (P=.956 for IMT; P=.335 for total area) eliminated this association, while adjustment for body fat percentage did not (P=.034 for IMT; P=.043 for total area).

“The results of our study indicate that increasing LF is associated with subclinical carotid atherosclerosis in a healthy population,” the researchers concluded. “However, this association was not independent of simple anthropometric measures demonstrating that in this population, increasing levels of LF do not exacerbate the risk for subclinical atherosclerosis beyond that identified by BMI or WC.

“Our results may suggest that, at low levels of LF accumulation, there is limited additional risk for atherosclerosis, and that substantially greater amounts … of LF may be needed for an independent effect to be recognized.”