The Lipid Regimen

Abstract

In the early phase of tissue aging, the turnover rate of metabolic processes is slowed down to a level that cannot cope effectively with external stress, as can the young tissue. At this phase, the continuous accumulation of serum lipids (e.g., cholesterol and sphingomyelin) in cell membranes is not fully compensated for by fluidity homeostasis (Sinensky, 1974) and a progressive decrease in membrane fluidity takes place. This phase is therefore characterized by changes in lipid composition, mostly increase in cholesterol and sphingomyelin, while the population of proteins and other functional entities remains to a large extent unaffected. Table 1 summarizes changes in membrane lipid composition of various tissues with age, all of which correlate with decrease in fluidity. It seems that these changes precede the decline in the overt physiological functions and in some way induce it. The lipid regimen is based on the supposition that restoration of normal membrane fluidity in aging cells, notably neurites, can rectify deteriorated physiological, as well as behavioural patterns which are characteristic of aging.