Toenail yellows soft what causes

Toenail color yellow and soft, is likely to be caused by insufficient nutrient intake. But also do not rule out pathological factors, mainly affecting blood circulation of lung disease; nail is the farthest part from the heart, so there must be normal blood supply; when showing cor pulmonale, caused by distal blood supply deficiency, it will show the nail thickening situation. And onychomycosis, this kind of disease, often most or all nail thickening involved.