However, we're talking about cellular hydration, the water inside the cells themselves. It is accompanied by positive nitrogen balance, protein synthesis, and growth hormone release, equivalent to useful levels even in older people. Cellular hydration also results in a reduction of cell acidity, reduced auto-immune response, increased fat burning, DNA repair, and increased resistance to viruses. As a result the cell becomes more sensitive to free radicals and more susceptible to viruses and auto-immune diseases. Virtually all symptoms of aging are the result of cellular dehydration accompanied by free radical damage.
Most scientists accept the free radical theory of aging.
The free radicals enter our bodies, damage our cells, as well as damage the replication of DNA so that our cells don't replicate properly. They replicate in this damaged way and our bodies can become more and more damaged as we grow older, until we eventually die as a result. You know, some older people die of things like common colds because their immune systems have been so badly damaged by free radicals over a lifetime. For cellular hydration, you need low surface tension bodily fluids. If you drink a lot of water that has a very high surface tension, like tap water, you're not going to get the hydration needed.