Fig. 1

The absorption, transportation and uptake of vitamin K are lipids dependent. Green leafy vegetables are the primary dietary sources of phylloquinone. Different forms of exogenous vitamin K2, such as MK-4 found in chicken, MK-7 found in natto, and MK-9 found in chicken, are classified based on the length of the side chain. SR-BI, CD36, NPC1L1 and ABCG5/ABCG8 play a primary role in facilitating the intestinal transport of phylloquinone and cholesterol. The absorption of vitamin K and cholesterol is facilitated by SR-BI, CD36 and NPC1L1 protein, while the efflux of vitamin K and cholesterol out of cells is controlled by ABCG5/ABCG8. These mixed micelles are absorbed by intestinal epithelial cells and processed into chylomicrons that contain both apoA and apoB-48. Upon entering the blood, chylomicrons acquire additional apolipoproteins, including apoC and apoE from HDL. Lipoprotein lipase (LPL), found in the capillaries of muscle and adipose tissues, can cleave, and remove triglycerides from chylomicrons, leading to the formation of smaller remnants capable of re-entering circulation. The liver preferentially absorbs phylloquinone for the carboxylation of coagulation factors, whereas MK-4 is primarily transported to the pancreas and brain. In these organs, MK-4 may exhibit anti-inflammatory and neuroprotective effects through its binding to Gas 6 receptors. MK-7 is transported to the bone and kidneys where it regulates the functions of OC and MGP in calcium metabolism and vascular health. By Figdraw