I like reading articles by Chris Kresser. He holds a masters in science and is a licenced acupuncturist who believes in functional medicine. I hold him in the same regard as Mark Sisson in terms of his unbiased scientific approach to various health related topics.
I’ve summarised the main findings below – which are very eye opening and fly in the face of the outdated position we are taught with regards to salt consumption:
An adequate intake of salt in the human diet is required (by the majority of individuals) to maintain good health.
It is needed to maintain cardiovascular health via its role as a component in extracellular fluid.
It also plays a part in the nervous system.
It plays a part in the production of Hydrochloric Acid (HCL) in the digestive juices which is needed to digest food and destroy pathogens in the stomach.
Too little sodium in the diet causes hyponatremia – brain swelling, coma, congestive heart failure, and cardiovascular collapse. Animals such as horses will seek out sodium to prevent hyponatremia (this is why owners buy “salt licks” for horses and ponies).
The kidney can compensate for any abrupt increase in dietary salt via extra sodium excretion to match the dietary intake. Therefore, healthy people are generally able to adapt to a wide range of salt intakes without a significant change in blood pressure.
Conversely a significant increase in renin and aldosterone (via our renin-angiotensin-aldosterone hormonal system) is a symptom of sodium insufficiency (to low sodium) and has been shown to occur as salt intake drops below 1.5 teaspoons per day (which interestingly is below the US recommended daily allowance of salt).
The renin-angiotensin-aldosterone hormonal system which regulates blood pressure does however rely on adequate potassium intake (minimum intake of 4700mg – but our ancestors consumed at least 10,500 mg per day of potassium). Most westerners are consuming very low levels of potassium – in USA: 3200 mg per day for Men and 2400 mg per day in women.
The theory is that we are not getting enough potassium in our modern diet which may explain the population wide increase in high blood pressure (hypertension). “…Dietary potassium has been demonstrated to dose-dependently counter the pathophysiological effects associated with modern dietary excess of salt, including salt-sensitivity, a likely precursor of hypertension. Therefore, dietary potassium intake, in addition to the sodium to potassium ratio, may play a crucial role in the development of those diseases typically associated with a simple excess of sodium in the modern diet…”
Around the world salt intake generally ranges from 2400mg to 5175 mg per day. There are some outlier cultures who survive on as little as 1150 mg per day and have lower blood pressure but also generally lower life expectancy!
There seems to be little correlation between salt intake alone and high blood pressure. In some of the culture’s studied – higher salt consumption seems to suggest longer life expectancy – “…a low-salt diet may actually lead to serious health consequences and higher overall mortality, particularly in conditions like heart disease and diabetes…, a low salt intake is associated with higher mortality from cardiovascular events… the lowest risk of death for sodium excretion [is] between 4 and 5.99 grams per day…”
Summarising salt consumption levels – there is a “healthy range of salt consumption” for most people (see below for the very few people where dietary salt should be reduced). The consumption of salt around the world for over two centuries has remained in the range of 1.5 – 3 teaspoons per day – “…which appears to hold the lowest risk for disease…”
There are certain individuals who would benefit from reducing their daily salt intake:
Those with impaired renal function have a higher sensitivity to salt. These individuals are sensitive to a high daily salt intake and it can cause a significant blood pressure response.
Those who are prone to kidney stones should also reduce salt intake – “…high sodium excretion also leads to a higher level of calcium excretion in the urine…”
For the same reason as above – those individuals with osteoporosis may benefit from low salt intake too. “…Increased losses of calcium in the urine, particularly in the context of low dietary calcium, could be problematic for those at risk for low bone density…”
If high blood pressure is of concern to you – there is evidence within “…epidemiological and anthropological data [to] suggest that a diet high in certain minerals, such as potassium, magnesium, and calcium, may be beneficial in reducing high blood pressure…”
What type of salt to consume is an interesting query just as much as which ones you should avoid:
We should avoid table salt deficient of trace minerals “…and commonly contains undesirable additives such as anti-caking agents like sodium silicoaluminate or sodium ferrocyanide… avoiding table salt is a good idea, though care must be taken to ensure adequate iodine intake from other sources once iodized table salt has been removed from the diet…”
Dead Sea Salt should be avoided as it contains a high level of Bromide and can lead to Bromide Toxicity.
If consuming regular sea salt worries you due to the pollution in modern day oceans “…there are salts produced from ancient geological oceans, like Real Salt from Utah beds or Himalayan pink salt, which would not have the same level of pollution as salt from much of the world’s oceans…” These are generally better choices as they are purer forms of salt.