If a patient has a medical condition that causes his cells to absorb fewer than normal molecules, this patient would likely feel very tired oxygen oxygen fiber fiber starch starch protein protein

oxygen

Explanation:

The medical condition described here is anaemia. It is a blood cell disorder whereby the red blood cell doesn't function properly and hence doesn't carry enough oxygen to the tissues. This is usually caused when ones body is deficient of iron.

The symptoms that may occur to such patients are weakness, fatigue, headache and pale skin.

Based on the explanation, the answer is oxygen