November 3, 2012

postheadericon Shaking Hands with Cholesterol

Cholesterol is the Dr. Jekyll and Mr. Hyde of the nutrition world. This fat-like substance is both essential for your healthy body and potentially hazardous to your heart.

Making the most of cholesterol’s Jekyll-like good characteristics while counteracting its Hyde-like bad impulses can be a delicate but not impossible balancing act. The task begins with understanding how and where cholesterol does its good work and how and where it can cause problems. Begin your mission, in the true scientific spirit, at the beginning.

Where cholesterol comes from

Yes, you get some cholesterol from food, but the curious fact is that most of the cholesterol in your blood and body tissues is produced right in your very own liver. Your liver uses the proteins, fats, and carbohydrates in food to manufacture and churn out about 1 gram (1,000 milligrams) of cholesterol a day.

How cholesterol travels around your body

Whether your cholesterol comes from food or your liver, it travels through your bloodstream in particles called lipoproteins, a name derived from lipos (the Greek word for “fat”) and protos (Greek for “first” or “most important”).

The fatty substances in lipoproteins include cholesterol and triglycerides, the most common fatty substance in the human body (more about triglycerides in the section “Focusing on Other Blood Baddies”). The proteins that combine with fats to produce lipoproteins are called apolipoproteins, often abbreviated as apo.

Lipoproteins develop through five distinct phases as they mature into the particles that carry cholesterol around your body:

  • Phase 1: Chylomicrons
  • Phase 2: Very low-density lipoproteins (VLDLs)
  • Phase 3: Intermediate-density lipoproteins (IDLs)
  • Phase 4: Low-density lipoproteins (LDLs)
  • Phase 5: High-density lipoproteins (HDLs)

How does a chylomicron become a VLDL, then an IDL, then an LDL, and finally, maybe, an HDL? The following roadmap marks the route.

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