Matthias Rath is a controversial German physician who worked with and published two articles discussing the possible relationship between lipoprotein and vitamin C with Pauling.[20][21] He is an active proponent and publicist for high-dose vitamin C. Pauling's and Rath's extended theory states that deaths from scurvy in humans during the ice age, when vitamin C was scarce, selected for individuals who could repair arteries with a layer of cholesterol provided by lipoprotein(a), a lipoprotein found in vitamin C-deficient species.[22]