The liver, which makes protein and stores glucose, vitamin B12 and iron, helps get nutrients to your body by processing all foods—carbohydrates, protein and fat—into glucose that can be used throughout your body.
Glucose is a fancy name for a specific and common sugar…yup, everything is turned to sugar. Iron stores in the liver are great enough for most people that iron supplements are not usually needed, except in people with iron deficiency anemia, which is the most common nutritional deficiency worldwide.
The liver also serves as the initial source of glucose when you rush the hot dog stand at halftime since the sugar in your blood provides only 10 minutes of energy. It then does double duty to break down the nitrates from that hot dog in the detox function. This, by the way, is the reason you don't burn fat immediately when you start exercising—your body is using the fuel that's stored as glucose in the liver first.