Nutrition and DNA Methylation: How Dietary Methyl Donors Affect Reproduction and Aging

Methylation is a biochemical process involving the addition of methyl groups to proteins, lipids, and nucleic acids (both DNA and RNA). DNA methylation predominantly occurs on cytosine and adenine nucleobases, and the resulting products—most frequently 5-methylcytosine and N6-methyladenine epigenetic marks—can significantly influence gene activity at the affected genomic sites without modifying the DNA sequence called nucleotide order. Various environmental factors can alter the DNA methylation pattern. Among these, methyl donor micronutrients, such as specific amino acids, choline, and several B vitamins (including folate, pyridoxine, thiamine, riboflavin, niacin, and cobalamin), primarily regulate one-carbon metabolism. This molecular pathway stimulates glutathione synthesis and recycles intracellular methionine. Glutathione plays a pivotal role during oocyte activation by protecting against oxidative stress, whereas methionine is crucial for the production of S-adenosyl-L-methionine, which serves as the universal direct methyl donor for cellular methylation reactions. Because local DNA methylation patterns at genes regulating fertility can be inherited by progeny for multiple generations even in the absence of the original disrupting factors to which the parent was exposed, and DNA methylation levels at specific genomic sites highly correlate with age and can also be passed to offspring, nutrition can influence reproduction and life span in a transgenerational manner.