Few dictates of modern medicine could be considered more sacrosanct than the prohibition of excess salt intake in our daily diets. For more then five decades every medical student has had the principle of dietary salt reduction drummed into his or her heads. Salt was the bane of human health, the poison that created hypertension, congestive heart failure, stroke, renal failure and contributed to the death of untold millions of people in the western society. At least so it seemed.
Three articles in the 08/14/2014 New England Journal of Medicine raise serious questions about the validity of that heretofore established principle of medical therapeutics.
Two of the articles utilized urinary sodium and potassium excretion as a surrogate for dietary intake to examine impact on blood pressure, mortality and cardiovascular events overall. A third article applied a Bayesian epidemiologic modeling technique to assess the impact of sodium intake on cardiovascular mortality.
The first two articles were unequivocal. Low sodium intake, that is, below 1.5 to 2 grams per day was associated with an increase in mortality. High sodium intake that is, greater than 6 grams per day, was also associated with an increase in mortality; but the middle ground, that which reflects the usual intake of sodium in most western cultures did not pose a risk. Thus, the sodium intake associated with the western diet was safe. What is troubling however is the fact that very low sodium diets, those promulgated by the most established authorities in the field, are in fact hazardous to our health.
It seems that every day we are confronted with a new finding that refutes an established dogma of modern medicine. I have previously written blogs on the intake of whole milk or consumption of nuts, both of which were eschewed by the medical community for decades before being resurrected as healthy foodstuffs in the new millennium. One by one these pillars of western medicine have fallen by the wayside. To this collection, we must now add the low-salt diet.
Thomas Kuhn in his 1962 book, The Structure of Scientific Revolutions, stated that a new paradigm would only succeed if a new one arises that can replace it. Perhaps these large meta-analyses will serve that purpose for sodium intake and health. One can only wonder what other medical sacred cows should now be included in these types of inquiries?
As a researcher in the field of human tumor biology and purveyor of the EVA-PCD platform for prediction of chemotherapy drug response and oncologic discovery, I am intrigued but also encouraged, by the scientific community's growing ability to reconsider its most established principles as new data forces a re-examination of long held beliefs. It may only be a matter of time before more members of the oncologic community re-examine the vast data supporting the predictive validity of these Ex Vivo Analyses and come to embrace these important human tumor phenotypic platforms. At least we can hope so.