I found this fascinating article while researching coenzyme A. Basically some foods such as offals, small fish and beans and legumes have high amounts of the nucleotides your body needs to make DNA and RNA . By eating these nucleotides it is a more efficient way of the body putting together these molecules than making them from scratch. Other foods like sugars, refined flours, oils have none.
It seems to me a good reason why the whole food diet and Weston Price diet is effective. Studies show athletes fed these food cope better with the stress of exercise. When the gut is injured or immune system activated the body may not be able to produce enough so by eating foods with these building blocks already complete it helps the body ‘s repair to be more efficient.