Salt.
It doesn't get much attention lately as the most that is said about it is usually
just to eat less of it.
But is that always the best advice?
A March 1940 paper by Lawson Wilkins in Baltimore describes the case of a child who, starting
from 11-months of age, had a very unusual craving for salt.
In a letter responding to questions regarding their child's special appetite, the parents
explained how the child would throw up almost everything except for mother's milk; at
the advice of a doctor, the parents tried giving the child crackers.
He threw those up too... but soon he started just licking all the salt off the crackers
and then would ask for more.
Once the boy figured out what was in the salt shaker, the mother said he refused to eat
anything unless the salt shaker was also on the table.
He ate plain salt by dipping his finger into it and bringing it to his mouth.
It was estimated that the child was eating an extra teaspoon of plain table salt a day
in addition to his foods already being saltier than his parents'.
Based on weight, the adult equivalent of that would be about 20 to 30 extra grams of salt
per day.
American dietary guidelines by the way, advise people to limit their daily salt intake to
a maximum of only 5.75 grams.
Later it was found out that this massive craving for salt wasn't just a quirk of the palate,
the child's body was urging him to get what it needed.
He was admitted to the hospital at age 3 and unfortunately after only 7 days on the hospital's
low salt diet, he suddenly died.
The final paragraph of this paper says "A boy aged 3 1/2 years with deficient adrenal
cortical tissue, manifesting various symptoms of adrenal insufficiency, had a marked craving
for salt.
...it would seem that this boy, by increasing his salt intake kept himself alive for at
least two and one half years."
As this case illustrates, we can't live without enough salt, but of course healthy
people can survive on far less than what this child needed.
In 2005, the US federal government's dietary guidelines set a maximum limit for sodium
at 2,300 milligrams, or about 5.75 grams of salt per day - this is about as much sodium
as is much is in just one and a half large dill pickles.
It was estimated that reducing Americans intake of salt by half a teaspoon a day (about 2.8
grams) would prevent 92,000 heart attacks and save the country $20 billion in health
care related costs.
Their logic behind this is relatively straightforward: "In large amounts, sodium pulls fluid from
the body's tissues and into the blood which raises the blood volume and the heart pumps
harder.
The result: high blood pressure.
Chronic high blood pressure stresses the heart and arteries leading to heart disease.
So, less salt should mean less disease.
Now, Hypertension is currently at an all time high - 1 in 3 Americans have it.
But is salt to blame?
Dietary salt intake used to be far higher than it is now, mainly out of necessity.
Before the industrial era, salt was the most common and effective food preservative.
As Mark Kurlansky points out in "Salt: A World History," we know that the salt intake
in Europe was very high at least from the 1500's when it was as much as 40 to 100
grams, thanks to foods like salted fish.
This amount would be like consuming the entire contents of one to two two-ounce salt shakers
like you'd see in a diner.
If these massive quantities of salt were causing hypertension induced heart disease, then people
at the time must not have cared much about ...sudden death.. considering the first report
of heart disease didn't occur until the mid 1600s.
Then, from the early 1800's until the end of World War 2, western societies consumed
between 15 and 17 grams of salt per day - Based on military archives' data.
"After World War II, when refrigeration began to displace salt as the main means of
food preservation, salt consumption in the U.S. dropped dramatically to about half that
rate, or nine grams (1.8 teaspoons) per day and, based on twenty-four hour urinary sodium
data, has remained flat for the last fifty years."
So, despite this historically low and steady salt intake, prevalence of hypertension is
now three times as high as it was in the first half of the 1900s.
So, salt intake is "still" high according to health guidelines, but this doesn't explain
how hypertension keeps going up while salt consumption stays steady.
The South Koreans eat a wide variety of salty foods with the easiest example being kimchi-
cabbage and other vegetables preserved in salt and spices.
Kimchi is eaten at literally every meal.
The average South Korean consumes around 4000mg of sodium per day, almost twice as much as
the US dietary guidelines recommend.
Despite this, South Korea has the lowest rates of coronary heart disease in the world, according
to 2014 data from the World Health Organization.
In fact, the data from a September 2015 paper funded by the Korea Food Research Institute
shows that the quartile groups that consumed the most sodium had the lowest rates of hypertension,
coronary heart disease and stroke.
This has been dubbed "The Korean Paradox."
And, as Dr. James DiNicolantonio points out: "you could swap out Korea for any one of
thirteen other countries and get a lot more "paradoxes" regarding high salt intakes."
In his very thorough book "The Salt Fix," Dr. DiNicolantonio makes the case that reducing
salt intake is not only unnecessary but potentially harmful to health.
Salt has several very important functions: It's needed by the heart to pump blood properly,
it's needed by the stomach to facilitate digestion, and it is necessary for bone formation
and bone strength.
It's a key component in cell-to-cell communication and the optimal transmission of nerve impulses
to and from organs like the heart and brain.
As is explained in The Washington Manual's Endocrinology Subspecialty Consult, at particularly
low sodium levels, "patients may present with neuropsychiatric signs and symptoms,
ranging from muscular weakness, headache, lethargy, ataxia and psychosis to cerebral
edema, increased intracranial pressure (ICP), seizures, and coma."
On the other side of the spectrum, consuming particularly large quantities of salt can
of course have terrible consequences.
According to a 1913 article, "in the Chekiang province, and probably in other provinces
of China, the drinking of a saturated solution of salt [was] a common mode of committing
suicide."
People would down an entire pint to pint and a half of saturated salt solution- they usually
drank the brine used for pickling cabbage.
But for it to kill someone, all this salt had to be consumed very quickly in order to
overcome the powerful filtration ability of the kidneys.
This is why 16th century Europeans could consume so much salt- while 100 grams of salt is a
massive amount, it can be simply processed by the kidneys if ingested at a normal pace.
So, if humans had to consciously restrict their salt intake in order to stay healthy,
this would suggest that our regulating systems like the kidneys aren't very powerful at
all, but our history suggests otherwise.
In order for our cells to work properly, systems had to develop that could regulate the concentration
of salt and other components of our blood and extracellular fluid.
The kidneys of course are very important in this respect.
Considering cells can't survive outside a narrow range of electrolyte levels in the
extracellular fluid, the ability to retain salt and at the same time excrete excess salt
is very important.
Mammals who get their food from the sea such as the sea lion, sea otter, walrus, and polar
bear, ingest large amounts of salt.
But The salt content of their blood is not very different from that of terrestrial mammals.
From our perspective at least, these animals' "kidneys must be able to excrete massive
quantities of salt."
But, the basic physiology of the kidneys is the same in humans.
Through the process of osmoregulation, the water and sodium levels in our body are constantly
balancing each other out.
If the blood sodium levels drop too low, water from the blood will enter our tissues to maintain
this balance.
When there's an increase in sodium in the blood, the kidneys simply excrete the excess
into our urine.
As is explained in the book the Salt Fix: "If our blood and fluid levels of sodium get
high, we start reabsorbing less salt from the kidneys and absorb less salt from the
foods we eat--the liver can signal the intestine to reduce sodium absorption.
And If sodium begins to accumulate, our bodies also tend to harmlessly shunt excess sodium
to the skin or organs."
In fact, a 1979 paper authored by Friedrich Luft and colleagues, described an experiment
where they gave people with normal blood pressure various amounts of sodium, going as high as
around 87 grams of salt.
They found that "The urinary sodium excretion approached the total sodium intake at each
level."
Their bodies were simply excreting these excess loads of salt, to the point that they were
able to excrete ten times a normal sodium intake, up to 86 grams of salt per day.
Dr. DiNicolantonio points out that these kinds of capabilities "suggest that the human
body is well adapted to handle salt overload-but not salt deficit."
So, If it's easier for the body to handle excess salt rather than insufficient salt,
we should expect to have data showing higher rates of mortality from lower salt intake.
Well, this data is available.
A 2014 article in The New England Journal of Medicine analyzed the Mortality and Cardiovascular
Event rates of 102,000 people assessed for urinary sodium and then followed them for
3.7 years.
The article concluded that "An estimated sodium intake between 3 grams and 6 grams
per day was associated with a lower risk of death and cardiovascular events..."
But, what's important is that the adverse effects to health increase much more rapidly
when you are under this range rather than above it.
As you go over 6 grams of sodium, about 15 grams of salt, the health risk does start
to rise but it rises much more gradually.
Based on the data here, eating six times as much salt as is recommended by the US dietary
guidelines would pose less of a risk to your health than actually following the guidelines.
Animals have a very strong innate drive to acquire salt specifically- just like they
would go to great lengths to acquire water or food when thirsty or hungry.
Elephants will uproot entire trees to get at the salty soil under the roots, gorillas
will chew on rotting wood to eat the salty microbes and some animals will drink urine
due to its sodium content.
But these efforts pale in comparison to what humans have done for salt.
Mark Kurlansky's book Salt: A World History is a 449 page testament to this.
As he shows, Salt-seeking drove civilization, built empires and won wars.
Romans established every major city near a saltworks and for some time roman troops were
paid in salt; Britain lost control of its American and Indian colonies when it lost
control of their salt supplies.
Kurlansky states, "The history of the Americas is one of constant warfare over salt.
Whoever controlled salt was in power."
When salt is freely accessible, people across many populations tend to consistently consume
between 3000 and 4000 milligrams of sodium per day.
In America, the country infamous for reckless eating habits, from 2011 to 2012 the average
daily sodium intake was only 3600 milligrams.
This suggests that the body will push people to acquire salt, but in accordance with their
actual needs for the mineral.
In a 1936 paper titled "Experimental sodium chloride deficiency in man," through 7 days
of sweating and sodium-free diets, subjects became sodium deficient.
"The participants reported that they experienced extreme, unquenchable thirst.
One participant reported that he experienced a longing for salt and often went to sleep
thinking about it.
...With regard to mood-related symptoms, subjects reported a loss of appetite, anhedonia, difficulty
concentrating, excessive fatigue, and a general sense of exhaustion."
A 1995 study at Johns Hopkins University School of Medicine was done on a group of Chronic
Fatigue Syndrome patients.
Patients were encouraged not to restrict sodium intake and were given the drug fludrocortisone,
which causes the body to retain sodium.
76% of the patients "reported a favorable response to [this] therapy by manifesting
reduced CFS symptoms and improved clinical signs…"
Especially noteworthy was the observation that the patients also improved scores on
a test of general well-being that likely reflected improved mood.
at the conclusion of the study, it was learned that 61% of the Chronic Fatigue Syndrome patients
had voluntarily imposed low sodium diets upon themselves.
As the 17th century Chinese scientist and encyclopedist Song Yingxing said: "[there
are] in the world five tastes…
A man would not be unwell if he abstained for an entire year from either the sweet or
sour or bitter or hot; but deprive him of salt for a fortnight, and he will be too weak
to tie up a chicken…"
Craving for salty foods is surely not indicative of salt being "addictive", but just shows
that the body has an impressive ability to drive you to consume what it needs.
A 1928 study in the American Journal of Diseases of Children found that When very young normal
children were given free access to a variety of natural foods to choose by themselves,
they selected foods that facilitated normal growth and development.
There was even one child with Rickets caused by vitamin deficiency that continued to take
large amounts of straight cod liver oil over a period of 101 days.
After the deficiency symptoms disappeared, so did his craving for cod liver oil.
The reason humans in general are hovering around an intake of 3 to 4 grams of sodium
per day, despite the world health organization and US government urging them to cut their
salt intake down to lower than 2.3 grams a day, is probably because their bodies are
pushing them to acquire the amount that is best for them.
As mentioned earlier, a sodium intake of 3 to 6 grams (about 7 to 15 grams of salt) seems
to be an ideal range for most people.
However, if you are losing more salt from sweating alot or being on a low carbohydrate
diet, this range may be shifted upwards to say 4 to 7 or 5 to 8 grams of sodium or more.
Now, there's still a several points about specifically why lowering salt intake stresses
the body, contrary to conventional health advice.
So stick around, I'll be covering the science behind this another time.
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