Question: What is lympth? And why are lipids the only organic biomolecules that travel via lympth?

Eva Rath answered on 20 Jun 2023:

Lymph is a colorless fluid that is formed when blood fluid (called plasma) exits blood vessels. The lymph is then between tissues and cells, the so-called interstitial space, until it enters lymph vessels. The main lymph vessel merges with a big blood vessel in the chest, and lymph and blood are blended again.
Immune cells travel with the lymph, along with molecules and cellular debris too large to be collected by veins and capillaries. Lymph nodes act as “filtering stations” in the lymphatic system. In this way, the lymphatic system acts like a dish washer cleaning the body.
Unlike other nutrients, lipids in chylomicrons cannot be absorbed directly into the blood from the gut because chylomicrons are simply too large to be taken up by the tiny blood capillaries that line it; it would simply clog them up. For comparison: diameter of a chylomicron: 500 – 1.000nm; molecular size of glucose: roughly 1 nm; length of an amino acid: 0.4 – 1nm. Instead, chylomicrons enter the lymphatic system and are flushed into big blood vessels. Membrane proteins on cells take up lipids from the chylomicrons, which slowly “shrinks” them until there’s just a small part of the chylomicron left (a remnant). Chylomicron remnants are taken up and recycled in the liver.