Whether generating proteins from amino acids or creating sugar for cells to feed on, nucleotides and nucleic acids are everywhere in nature. Nucleic acids also form the patterns of life in their most popular form, DNA. As such, nucleic acids can be found in several foods which spring both from plant and animal matter.
Beef has played a central role in the western diet for hundreds of years. This is because beef is common, nutritious and packed full of energy. Most nucleic acids synthesize protein and that is what beef is full of. In fact, all meats are high in protein and contain a number of different types of nucleic acids (from DNA to RNA and TRNA). Beef is one of the most protein-rich foods, holding up to 7 grams of protein per ounce. This means that beef has more nucleic acid than most other foods eaten today.
While there have been several contradictory reports on the healthfulness of eggs in a diet, the fact that eggs are another major source of nucleic acid is not in dispute. Eggs are a logical source of nucleic acid, since they are designed to provide food for gestating life. All life needs energy to thrive, but new life needs energy simply to begin existing. Again, this means protein and eggs have 6.3 grams of it. More than just chock full of nucleic acids, eggs have just the kind of amino and nucleic acids needed by humans. Because of this, an egg is 90 percent digestible (normal foods are 50 to 70 percent digestible); so, we get more out of eating an egg than most other foods.
Beans carry many of the same protein-creating nucleic acids as meat and poultry and while beans may not carry as many nucleic acids per ounce as a cut of beef or an omelet, they may do it better. In fact, beans have the ability to purify the enzymes involved in creating nucleic acids, making them more potent and concentrated. A study in the "Journal of Biological Chemistry" found that mung beans contained enzymes that were up to 50 times "cleaner" than those found in beef.
Even mushrooms have nucleic acid. While mostly in the form of DNA, mushrooms also have a number of nucleic and amino acids which create protein. Shitake mushrooms have the highest nucleic acid content (and the most protein).