Essentials: Using Salt to Optimize Mental & Physical Performance

Welcome to Huberman Lab Essentials, where we revisit past episodes for the most potent and actionable science based tools for mental health, physical health, and performance. I'm Andrew Huberman, and I'm a professor of neurobiology and ophthalmology at Stanford School of Medicine. Today, we are going to discuss salt, also referred to as sodium. Salt has many, many important functions in the brain and body. For instance, it regulates fluid balance, how much fluid you desire and how much fluid you excrete. Salt also regulates your appetite for other nutrients, things like sugar, things like carbohydrates. We all harbor small sets of neurons. We call these sets of neurons nuclei, meaning little clusters of neurons that sense the levels of salt in our brain and body. There are a couple brain regions that do this, and these brain regions are very, very special. Special because they lack biological fences around them that other brain areas have, and the those fences, or I should say that fence, goes by a particular name, and that name is the blood brain barrier or BBB. Most substances that are circulating around in your body do not have access to the brain, in particular large molecules can't just pass into the brain. The brain is a privileged organ in this sense. However, there are a couple of regions in the brain that have a fence around them, but that fence is weaker. And it turns out that the areas of the brain that monitor salt balance and other features of what's happening in the body at the level of what we call osmolarity at the concentration of salt reside in these little sets of neurons that sit just on the other side of these weak fences. And the most important and famous of these for the sake of today's conversation is one called OVLT. OVLT stands for the organum vasculosum of the lateral terminalis. The neurons in that region are able to pay attention to what's passing through in the bloodstream and can detect, for instance, if the levels of sodium in the bloodstream are too low, if the level of blood pressure in the body is too low or too high, and then the OVLT can send signals to other brain areas, and then those other brain areas can do things like release hormones that can go and act on tissues in what we call the periphery in the body, for instance, have the kidneys secrete more urine to get rid of salt that's excessive salt in the body. So let's talk about the function of the OVLT and flesh out some of the other aspects of its circuitry, of its communication with other brain areas and with the body in the context of something that we are all familiar with, which is thirst. Have you ever wondered just why you get thirsty? Well, it's because neurons in your OVLT are detecting changes in your bloodstream, which detect global changes within your body, and …