(Question) Are vertical lines on the nails a sign of nutritional deficiency?

The vertical lines on the nails seem really old.

If you look it up on the internet, the first thing that comes up is aging, but it's something I've had since I was young.

The process of aging now accounts for some part, but I don't think it's the fundamental cause for me.

There is a deficiency in nutrition and mild chronic disease.

I think that consuming less protein is a form of nutritional deficiency.

I admit it. So these days, I try to take better care of myself with more meat and eggs.

It seems difficult to make the nails look good again.

I am taking other supplements as well as multivitamins.

What is lacking in the vertical lines of the nails?