Myths & Facts Series : Nucleotides

Editor(s): Myths & Facts Series Vol.1 , 2012

Summary

The easiest description of Nucleotides would be that they are organic molecules which serve as the basic building block of nucleic acids such as DNA and RNA. However, there are various myths associated with them and these common myths have been discussed in this issue of NNI publication. The most commonly prevalent myths about Nucleotides have been decoded here and facts have been presented to support the arguments. The myths have been elucidated in simple words and proven with substantial scientific backing. Five prominent myths have been broken and a list of references has been included at the end for clarifications.

Let’s look at some nucleotides myths. Endogenous supply of nucleotides is sufficient for optimal functioning of tissues. Though the fact about it clearly says that synthesis of nucleotides is a metabolically costly process, particularly in rapidly dividing tissues such as lymphoid and intestinal tissues, which require them for the synthesis of nucleic acids. Hence it is more efficient to use already formed nucleotides. An exogenous source of nucleotides, such as a dietary supplement, could optimize the tissue function by sparing the cost of de novo or salvage synthesis. Barankiewicz and Cohen demonstrated that the activation of T-lymphocytes causes a rapid increase in the synthesis of nucleotides, which are required immediately because of an increase in energy metabolism and later as precursors for the synthesis of nucleic acids. Perignon JL, et al., reported that lymphocytes have limited capacity to salvage pyrimidines, and suggested that rapidly dividing lymphoblasts have a greater need for pyrimidine nucleotides

Another one such myth is that nucleotides are equally distributed in the cells of the human body but the nucleotides fact is that the concentration of nucleotides varies in diff¬erent tissues, adenine compounds predominate in RBC, uridine and other nucleotides are more prominent in the liver, the concentrations of RNA are higher than those of DNA in all cells, the former being 1000 times more concentrated than DNA and relatively constant whereas DNA concentration varies with the stage of the cell cycle.

One nucleotides myth says that the amount of nucleotides present in cow’s milk is similar to that in human milk. In-fact human milk has a diff¬erent nucleotide profile from that of cow's milk. Human milk is particularly rich in cytidine and adenosine monophosphates while cow's milk predominantly has orotate, a by-product of pyrimidine catabolism. And therefore, un-supplemented cow's milk based commercial formulae have significantly lower levels of nucleotides than human milk.

Another myth is that regulatory committees do not recommend addition of nucleotides to infant formula. Nucleotides fact is that European Society of Paediatric Gastroenterology, Hepatology and Nutrition (ESPGHAN) recommends addition of nucleotides at a maximum total content of 5 mg/100 kcal as well as maximal levels of 2.5 mg/100 kcal CMP, 1.75 mg/100 kcal UMP, 1.5 mg/100 kcal AMP, 0.5 mg/100 kcal GMP, and 1.0 mg/100 kcal IMP.