Dr. Andrew Huberman, Ph.D. is a Professor of Neurobiology and Ophthalmology at Stanford University School of Medicine. His lab focuses on neural regeneration, neuroplasticity, and brain states such as stress, focus, fear, and optimal performance.
Andrew Huberman discusses the role of salt (sodium) in the nervous system and the key role it plays in health and mental & physical performance. He reviews how to determine how much salt your body needs and pros and how to optimize salt intake and supplementation.
Host: Andrew Huberman (@hubermanlab)
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Neurons activated in the gut are activated when sugar, fatty acids, and amino acids are present
Nerve cells (specifically called neuropod cells) in the gut are collecting information about what’s there and send that information up to the brain via the vagus nerve
Neuropod cells sense nutrients, particularly sugar, which activates areas of the brain that cause you to seek out more of that food
The selective preference for seeking out sweet foods occurs even if you can’t taste the food and it is injected straight into the gut
The gut can detect the difference between sweet things that contain calories and things that do not (artificial sweeteners)
We have salt receptors that fire action potentials when salt is detected
The closer foods are to their innate taste (without processing), the more quickly you can hone in on salt appetite and salt needs
Fluid balance: salt regulates how much fluid you desire and how much you excrete
Salt appetite: you crave salty things when salt stores are low and avoid salt when stores are high
Nutrient appetite: salt regulates appetite for sugar, carbohydrates, and other nutrients
Scientifically, table salt and sodium are not the same things – one gram of table salt contains 388 mg of sodium
We have neurons in the brain that sense the levels of salt in our brain and body
The blood-brain barrier prevents substances from entering the brain unless those substances are very small or required for brain function – but there are special areas (organum vasculosum of the lamina terminalis; OVLT) that monitor salt and osmolarity sense contents of blood and salt levels
OVLT detects changes to salt levels in bloodstream and sends signaling cascades accordingly – thirst, regulation of blood pressure, kidney function, secretion of salt
Types of thirst: (1) osmotic thirst (concentration of salt in the bloodstream); (2) hypovolemic thirst (thirst related to drop in blood pressure)
The cascades are set off for concentrations of both high and low sodium in the blood
Osmotic and hypovolemic thirst are not just about seeking water – they’re also about seeking salt which can help retain water
Sodium engages the action potential, which is the firing of electrical signals by neurons
If you ingest too much water (this requires A LOT of water), you will actually kill yourself because you’ll disrupt the body’s ability to communicate, brain, and neurons
It’s a complicated, highly contextual balance between hormones, salt, and fluid
The kidneys are responsible for retaining and releasing substances in the body such as glucose, amino acids, urea, uric acids, salt, potassium, etc.
Very general mechanism: blood enters the kidney and responds to hormonal signals to make mechanical or chemical changes to retain or release substances accordingly
Your urine is filtered blood!
Vasopressin: anti-diuretic which prevents urination by increasing permeability of distal tubes
Water follows salt: the kidney holds on to water in the body when it needs salt
When estrogen levels are high, there’s water retention
Blood pressure is in part regulated by sodium intake and sodium balance
An increase in sodium could help combat symptoms of low blood pressure
Historically, we’ve been taught that a high salt diet may be consequential for brain function
However, high salt diets are likely related to other unhealthy factors like processed foods, poor balance of carbohydrate and fat, etc.
A high salt diet can have detrimental health consequences – but – a very low salt diet can also have deleterious health events
Some reports point to the idea that diets with more salt than we previously thought necessary, may actually be protective if you find your sweet spot (not too high, not too low)
Read more: Urinary Sodium and Potassium Excretion and Risk of Cardiovascular Events
Read more: Dietary Sodium and Health: How Much Is Too Much For Those With Orthostatic Disorders?
People tend to adapt to certain levels of salt and fluid intake
There’s a direct relationship between the stress system (glucocorticoid system) and the salt craving system
Bringing sodium in the body counteracts or resists stressors in our lives
If sodium is too low, our ability to combat stressors is impaired
If you’re feeling anxious, slightly increasing sodium intake can stabilize blood pressure and ability to lean into stressors and challenges
Additional sodium intake is naturally stimulated by stress
Sodium and potassium work closely together in the body
Recommended ratios of sodium to potassium vary widely
Diet is an important contextual element to your ideal sodium-potassium ratio
Low carb dieters excrete more water so lose sodium and potassium at a higher rate and may need to adjust dietary intake accordingly
If you are time-restricted eating or fasting you may want to consider increasing electrolytes if you ingest caffeine since caffeine is a diuretic
Rule of thumb: for every ounce of caffeine, drink 1.5x as much water with a touch of sodium
There’s some evidence that supplementing with magnesium malate can reduce muscle soreness
Mangesium threonate may promote transition into sleep and cognitive function
Magnesium bisglycinate is an alternative for magnesium threonate as far as the transition to sleep, but no studies have been done on cognitive function
Magnesium citrate is an effective laxative
Recommended book:The Salt Fix: Why the Experts Got It All Wrong–and How Eating More Might Save Your Life by Dr. James DiNicolantino