Campesterol Test

Campesterol is a type of phytosterol, a plant-based compound that closely resembles cholesterol in structure. Unlike cholesterol, which your can body produces, campesterol is made only by plants and enters your system entirely through food. Common sources include vegetable oils, nuts, seeds, and whole grains.

Once in the digestive tract, campesterol is taken up using the same absorption pathway as cholesterol. Both compounds are incorporated into micelles (fat droplets) and transported into intestinal cells via a protein called NPC1L1 (Niemann-Pick C1-Like 1). Because they share this entry point, blood levels of campesterol reflect how efficiently your intestines absorb sterols overall, including cholesterol.

After entering the intestinal cell, cholesterol is packaged into lipoprotein particles called chylomicrons and released into the lymphatic system, which eventually drains into the bloodstream. Campesterol can follow the same route, but unlike cholesterol, which is needed for hormones and cell structure—the body has no use for it. To prevent buildup, the majority of campesterol is pumped back out into the gut by specialized transporter proteins called sterolin. As a result, only ~5% of dietary campesterol reaches the blood, compared to ~50% of dietary cholesterol.

Even though only a small amount of campesterol enters circulation, its blood levels are proportional to overall sterol absorption activity. This makes it a valuable indirect marker of cholesterol absorption:

• High campesterol suggests your intestines are absorbing sterols more efficiently than normal, including cholesterol. In these cases, medications like ezetimibe, which blocks the NPC1L1 transporter, can be particularly effective in reducing cholesterol absorption.
• Low campesterol usually indicates normal or low sterol absorption. If your LDL-C or ApoB remains high despite low campesterol, it points to internal overproduction of cholesterol by the liver, which is typically managed with statins that block cholesterol synthesis.

To get a fuller picture of cholesterol metabolism, campesterol is often measured alongside beta-sitosterol, another plant sterol with a nearly identical absorption pattern. If one is elevated, the other usually is too, reinforcing the conclusion of high sterol absorption. A third marker, cholestanol, may also be included to confirm the pattern.