How much total saturated do we need? During the 1970s, researchers from Canada found that animals fed rapeseed oil and canola oil developed heart lesions. This problem was corrected when they added saturated fat to the animals diets. On the basis of this and other research, they ultimately determined that the diet should contain at least 25 percent of fat as saturated fat. Among the food fats that they tested, the one found to have the best proportion of saturated fat was lard, the very fat we are told to avoid under all circumstances!
However, aging is seen as a progressive failure of homeodynamics–systemic preservation of homeostasis , involving genes for maintenance and repair, stochastic events leading to molecular damage and molecular heterogeneity, and chance events determining the probability of death. Since complex and interacting systems of maintenance and repair comprise the homeodynamic space of a biological system, aging is considered to be a progressive shrinkage of homeodynamic space mainly due to increased molecular heterogeneity. [ citation needed ] In 2013, a group of scientists defined nine hallmarks of aging that are common between organisms with emphasis on mammals: genomic instability, telomere attrition, epigenetic alterations, loss of proteostasis , deregulated nutrient sensing, mitochondrial dysfunction, cellular senescence, stem cell exhaustion, and altered intercellular communication.