[1] Ziegler joined the National Cancer Institute (NCI) in 1979, was tenured in 1987, and has served most recently as a senior investigator in the epidemiology and biostatistics program.

[1] Her early work helped characterize the role of vegetables and fruits, individual carotenoids, folate and one-carbon metabolism in cancer etiology.

[1] In addition, she has conducted a number of breast cancer studies with emphasis on anthropometry, diet and endogenous hormones and growth factors.

[1] Ziegler collaboratively developed an international pooled analysis of circulating vitamin D concentrations in relation to risk of colorectal and breast cancer.

[1] Ziegler applied her training in chemistry and biochemistry to the development of new and improved methods for measuring various hormones and nutrients in epidemiologic studies.