Maternal intake of dietary methyl donors during the first trimester of pregnancy modulates the risk of developing childhood asthma at age 7, according to a new study. Methyl donors are nutrients involved in a biochemical process called methylation, in which chemicals are linked to proteins, DNA, or other molecules in the body. This process is involved in a number of important functions in the body, and dietary intake of methyl donors has been shown to affect the risk of developing a number of diseases, including heart disease and cancer.