s Diet Outpacing Pills in Driving Down US Lipid Levels?

Patrice Wendling

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HYATTSVILLE, MD — Declines in total cholesterol, triglycerides, and LDL cholesterol observed around the new millennium continue their downward march in US adults, with the sharpest drops surprisingly seen in those not on lipid-lowering drugs, in a National Health and Nutrition Examination Survey analysis^[1].

“It will be important to understand what’s driving these trends, and our study doesn’t get at the why question, but the finding that adults not taking cholesterol-lowering medications had steeper declines over the past 4 years than adults taking these medications is a clue that the drops are not being driven by the increased use of these medications alone,” principal investigator Dr Asher Rosinger (Centers for Disease Control and Prevention, Hyattsville, MD) told heartwire from Medscape.

Instead, he said, “we think one possible reason, especially over the past 4 years, includes the removal of trans-fatty acids from foods.”

Food manufacturers have been required to include trans-fat–content information on food nutrition labels since 2006, but the FDA balked at an all-out ban on artificial trans fat in processed foods in 2013.

In 2015, however, the FDA gave food manufacturers 3 years to remove partially hydrogenated oils, the primary dietary source of artificial trans fat in processed foods. These efforts have paid off, with an estimated 78% reduction in consumer trans-fat consumption between 2003 and 2012, according to the federal agency.

The new study, published online in JAMA Cardiology, used eight 2-year cross-sectional cycles between 1999–2000 and 2013–2014 in the National Health and Nutrition Examination Survey to examine trends in total cholesterol in 39,049 adults aged 20 years or older, triglycerides in 17,486 adults, and LDL-C in 17,096 adults.

Overall, between 1999–2000 and 2013–2014 age-adjusted arithmetic mean total cholesterol declined from 204 to 189 mg/dL, geometric mean triglycerides from 123 mg/dL to 97 mg/dL, and arithmetic mean LDL-C from 126 mg/dL to 111 mg/dL (P for all <0.001).

Age-Adjusted Mean Lipid Levels in US Adults

TC=total cholesterol

TG=triglycerides

“What really surprised us was the magnitude of the declines, especially with triglycerides,” Rosinger said. “Between 1999 and 2010, there was a cumulative decline of 13 mg/dL, but then between 2011–2012 and 2013–2014, so over the past 4 years, it declined another 13 mg/dL, essentially a doubling of that previous decline.”

He suggested that again, the removal of trans fats in foods may explain the observed trends in triglycerides.

“With increased interest in triglycerides for cardiovascular health, the continued drop of triglycerides, LDL-C, and TC levels at a population level represents an important finding and may be contributing to declining death rates owing to coronary heart disease since 1999,” Rosinger and his colleagues write.

One of the strengths of the study is that it used 16 years of data from a nationally representative sample, but one of the limitations is that this is cross-sectional data so it was not possible to follow specific individuals over time nor address causality, he said.