The whitish moon shape of the nail bed is really important and fragile part of the nail and you must be incredibly careful around it.
That white part is called lunula (small moon-Latin), and is sensitive a lot. Lunula is the visible white half moon shape on the nail and if it’s damaged the nail is deformed!
But, in case you damage the nail or have some surgery on it, or the nail falls off due to injury, surprisingly the lunula is intact. Sometimes, the eponychium the thick skin layer cuticles around the fingernails and toenails can cover the lunula even fully.
In the alternative medicine, lunula was believed to present some secrets and information of our health. Like for example, Chinese traditional medicines stated that lunula or lack of it is anemia or malnutrition, whitish pale or bluish lunula is maybe diabetes. If it is reddish or with red spots it might be heart problems for example.
Now, lacking the lunula or having a really small one is a sign of bad digestion or indigestion and that is due to bad metabolism or too many toxins.
Source and Image Source: fhfn.org