what makes the liver so great...

LONG LIST
So what makes liver so wonderful? Quite simply, it contains more nutrients, gram for gram, than any other food. In summary, liver provides:

An excellent source of high-quality protein
Nature’s most concentrated source of vitamin A
All the B vitamins in abundance, particularly vitamin B12
One of our best sources of folic acid
A highly usable form of iron
Trace elements such as copper, zinc and chromium; liver is our best source of copper
An unidentified anti-fatigue factor
CoQ10, a nutrient that is especially important for cardio-vascular function
A good source of purines, nitrogen-containing compounds that serve as precursors for DNA and RNA.