“As we’ve seen, science is only recently discovering that both fat and cholesterol are severely deficient in diseased brains and that high total cholesterol levels in late life are associated with increased longevity.24 The brain holds only 2 percent of the body’s mass but contains 25 percent of the total cholesterol, which supports brain function and development. One-fifth of the brain by weight is cholesterol! Cholesterol forms membranes surrounding cells, keeps cell membranes permeable, and maintains cellular “waterproofing” so different chemical reactions can take place inside and outside the cell. We’ve actually determined that the ability to grow new synapses in the brain depends on the availability of cholesterol, which latches cell membranes together so that signals can easily jump across the synapse. It’s also a crucial component in the myelin coating around the neuron, allowing quick transmission of information. A neuron that can’t transmit messages is useless, and it only makes sense to cast it aside like junk—the debris of which is the hallmark of brain disease. In essence, cholesterol acts as a facilitator for the brain to communicate and function properly.”