Subclinical deficiency is a condition in which a nutritional deficiency that is capable of having an effect on an individual’s health is not severe enough to produce typical deficiency signs and symptoms. Subclinical deficiency is discovered only by biochemical changes and it can change to clinical deficiency if it is not treated.
this is because the blood flow slow through the capillaries to allow gaseous exchange. Plus the pressure is higher in capillaries because the diameter of the capillaries is smaller than arterioles