A connection between under active thyroid (hypothyroidism) and cancer is that the lymph fluid becomes "thicker" and other tissues also thicken. This makes it more difficult for the fluid to flow, resulting in cellular oxygen starvation, nutrient starvation, buildup of acidic waste products, and edema (swelling). Some doctors suggest that increased viscosity of the lymph due to hypothyroidism is a factor in all chronic illness. For example, see Solved: The Riddle of Illness, by Stephen Langer, MD et al. (Drinking an abundance of water also thins the body fluids, allowing them to flow and penetrate more easily. See also our page on zeta potential and blood coagulation).