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A few weeks ago, I wrote a post here on PDN, called “Paleo Diet: Does Salt Deserve Its Bad Reputation?”, which covered Chris Kresser’s initial post addressing the ins and outs of human salt consumption. I promised that I’d also comment on the follow-up posts, and now it’s time to follow through with that. Chris is still promising one final article on salt, and I’ll report on that when it is posted in the near future.
On April 13th, Chris published “Shaking up the Salt Myth: The Human Need for Salt”, then on April 20th 2012, Chris released an article entitled “Shaking up the Salt Myth: The Dangers of Salt Restriction”, and then on April 27th 2012, Chris released “Shaking up the Salt Myth: When Salt Reduction May Be Warranted”. I figured that I’d cover the basics of each of the articles here for you, but please make sure you read the whole enchilada over on Chris’ blog.
The Paleo Diet And Salt
“Physiological roles of salt in the human body
Despite its recent bad press, there is no doubt that an adequate intake of salt in the human diet is required to maintain good health. The Institute of Medicine recommends that healthy adults consume 1500 mg of sodium, or 3.8 grams of salt, to replace the amount lost daily on average through sweat and urination. (5) (Ironically, this recommendation is almost double the amount theoretically consumed by Paleolithic man.) The minimum physiological requirement of sodium simply to sustain life has been estimated to be 500 mg of sodium per day. (6)
Sodium is a vital nutrient. It’s a major component of extracellular fluid, and is essential for maintaining the volume of the plasma to allow adequate tissue perfusion and normal cellular metabolism. (7) Because sodium is used as an extracellular cation, it is typically found in the blood and lymph fluid. The maintenance of extracellular
fluid volume is an important physiologic function of the sodium in the body, particularly in regards to cardiovascular health.”
“Evidence about human salt consumption
The human body has adapted complex physiological mechanisms in order to prevent blood pressure fluctuations in response to these variations in sodium intake. Not surprisingly, epidemiological data has revealed an average sodium intake range of 2400 mg to 5175 mg of sodium per day in developed cultures. (17) Certain isolated groups in areas such as Brazil, Papua New Guinea, and rural African communities have been found to live on sodium intakes of as little as 1150 mg per day. However, despite finding generally low blood pressure in these remote communities, the little evidence that exists on these low salt societies suggests shorter life expectancy and higher mortality rates.”
“As we can see, there is an enormous range in the daily dietary sodium intake of various cultures around the world, ranging from quite low (1150 mg) to fairly high (5175 mg). Additionally, we know that the healthy kidney is capable of adjusting to fluctuating levels of sodium in the diet in order to maintain fluid homeostasis. Finally, we know that hunter-gatherer and Paleolithic diets were very low in sodium, and that salt was rarely, if ever, added to food. Therefore, it would seem that limiting salt in the diet to those levels recommended by the AHA and USDA would not have any significant consequences, and would be an ideal dietary choice when mimicking the diet of our ancestors. However, evidence is mounting to the contrary: a low-salt diet may actually lead to serious health consequences and higher overall mortality, particularly in conditions like heart disease and diabetes.”
“Serious health consequences of long-term salt restriction
While salt-induced hypertension is typically blamed as a cause of heart disease, a low salt intake is associated with higher mortality from cardiovascular events. A 2011 study in the Journal of the American Medical Association demonstrates a low-salt zone where stroke, heart attack and death are more likely. (3) Compared with moderate sodium excretion, there was an association between low sodium excretion and cardiovascular (CVD) death and hospitalization for coronary heart failure. These findings demonstrate the lowest risk of death for sodium excretion between 4 and 5.99 grams per day.”
“Why is the government still recommending salt restriction?
Conventional healthcare experts have been recommending salt restriction ever since the 1970s, when Lewis Dahl established “proof” that salt causes hypertension. (17) In his research, he induced high blood pressure in rats by feeding them the human equivalent of over 500 grams of sodium a day; 50 times more than the average intake in the western world. (18, 19, 20) Dahl also invoked evidence that cultures consuming higher levels of salt tend to have higher blood pressure than those who consume less salt. (21)”
“In short, there is a healthy range of salt consumption for most people. When eating a whole foods diet, most people tend to consume an appropriate amount of salt simply due to an innate preference for saltiness. In fact, the consumption of salt around the world for over two centuries has remained in the range of 1.5 to three teaspoons per day, which appears to hold the lowest risk for disease. (25)
Our bodies may have a natural sodium appetite through which our ideal salt intake is regulated. By following a whole foods, Paleo diet, and eliminating processed foods, excess sodium in your diet will be drastically reduced. Thus, you can be confident in following your own natural taste for salt when adding it to your food during preparation. In other words, there are few reasons to deprive yourself of salt!”
“Salt intake with impaired renal function
For those who have high blood pressure, there is evidence that some hypertensive individuals have inherited salt sensitivity, thought to be caused primarily by impaired sodium transport in the kidney. (1) Our understanding of the salt-sensitivity mechanisms is still underdeveloped, but we do know that certain individuals are far more sensitive to fluctuations in dietary salt. Those individuals with this trait will have a significant blood pressure response to a high salt intake, and would likely benefit from reducing their intake of salt. However, it is thought that potassium intake can greatly impact these effects, and may even eliminate salt sensitivity symptoms. (2, 3) In fact, salt sensitivity is dose-dependently suppressed when dietary potassium is increased within its normal range, so these individuals may benefit more from including ample potassium rather than limiting sodium.”
“High sodium intake may cause excess calcium excretion
Additionally, those who are prone to kidney stones may need to reduce their salt intake, as high sodium excretion also leads to a higher level of calcium excretion in the urine. (6) Again, evidence on this topic is mixed, but it has been demonstrated that excess sodium intake is associated with increased urinary excretion of sodium and calcium, and subjects who consumed the highest levels of sodium tended to have the greatest urinary calcium excretion. Higher calcium excretion may lead to kidney stone formation, particularly if fluid intake is inadequate.”
“Other minerals important for controlling blood pressure
There has been much research into the other dietary minerals that may play a role in blood pressure. The evidence has been mixed on whether certain minerals, particularly supplemental minerals, reduce blood pressure or risk for cardiovascular disease. However, epidemiological and anthropological data suggest that a diet high in certain minerals, such as potassium, magnesium, and calcium, may be beneficial in reducing high blood pressure.”
“Take home message? Use your own judgment!
Ultimately, the amount of salt required for good health is based on individual needs, health status, and genetic predisposition to salt sensitivity. The evidence for salt restriction, even for those with cardiovascular or renal disease, is mixed and often times inconclusive. It’s important to remember that the data regarding sodium intake has been from populations typically eating a standard American diet, and it’s unknown whether salt intake would demonstrate any detrimental effects in a population eating a potassium, magnesium, and calcium rich whole foods Paleo diet. These are important points to consider when deciding how much salt to include in your own diet.”
Isn’t that typical, that the answer to the question, “how much salt does my body need?” is basically, “it depends!”. I hear that a lot recently, but for good reason. After all, if anyone tries to give you some of those good old “one size fits all” answers to pretty much any question related to human physiology, diet or health, you should definitely run the opposite direction. It’s not as simple as one recommendation for all of human kind…..it’s truly different for every person and every situation.
The Paleo Diet And Salt
Stay tuned for Chris’ next and presumably last installment, where he is going to talk about his recommendations for the types of salt and their applications.
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Barry Cripps is a Paleo-based, Certified Nutrition and Wellness Consultant, who operates out of Bowling Green, Kentucky.
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