Thursday, September 27, 2012

Salt Taste, Part 3

NaCl is an easy additive for the cook to use, as it is a cheap and convenient way to increase liking; therefore from a cooks perspective it is like magic powder, add NaCl to a food and the food becomes more palatable.  To health advocates NaCl is a slow working poison, added to foods in excess, slowly killing the population via myriad disease conditions.
If salt is a poison then why are we allowed to use it as a food ingredient?  The answer lies in the rate we consume NaCl, and if you over-consume there are consequences (to help with quantities mentioned in this article, 5g NaCl is equivalent to 1 teaspoon).  It is calculated that human species evolved with intakes of 1.8g NaCl/day, in comparison we now consume >9g NaCl/day, with approximately 75% of intake coming from processed foods.  As a result there has been a 400% increase in NaCl consumption during recent human history.  The excess consumption of NaCl is the source of the problem identified by health advocates who have suggested an adequate intake of between 1.2-2.3 g NaCl, and an upper limit of approximately 6 g NaCl for chronic disease prevention.  It is important to note that it is the Na or sodium portion of NaCl that is implicated in the adverse health effects, but for simplicity, I will continue to use NaCl.
Evidence that excessive NaCl intake has an adverse effect on blood pressure regulation is well established, as is the relationship between raised blood pressure and cardiovascular disease.  In a confusing twist, the link between NaCl intake and cardiovascular disease is more tenuous, but we presume that chronic excessive NaCl intake increases blood pressure, which in turn increases incidence of vascular diseases. It is reported that approximately 30% of Australians are diagnosed with high blood pressure (hypertension) and for every known case of high blood pressure it is believed that there is one case that goes undiagnosed.  
Excessive NaCl consumption is a big problem, to illustrate the effect excessive NaCl consumption has on public health, consider this; a 3g/day reduction in dietary NaCl would have the same effect on rates of heart disease as a 50% reduction in tobacco use, and a 5% reduction in body-mass index among obese adults.  Also, a 5 g/day increase in dietary NaCl is calculated to increase the risk of stroke by 13-32% and heart disease by 50-61%, with the higher risk associated with overweight/obese individuals.  Excessive NaCl intake has also been linked to gastric cancer via enhancing H.Pylori colonisation, and decreased bone density by increasing calcium loss from bones.  There have also been suggestions of a link between NaCl intake and obesity with an increase in dietary NaCl inducing thirst resulting in an increase of the amount of high kilojoule drinks consumed, consequently leading to excess energy intake.  The potential health benefits from reducing sodium are staggering and hard to believe more is not done to reduce NaCl levels in the food supply. But…. there is, of course, conflicting data and an investigation of NaCl intake over the past 50 years suggests NaCl intake has been stable.  Yet rates of cardiovascular disease have declined over the same period. Such inconsistency do not mean excess NaCl intake is harmless, it just means there are other factors involved in vascular diseases that have influenced disease rates.
NaCl intake seems a little like Russian Roulette, there is a chance that the bullet (NaCl) may not be in the chamber, but is it worth the risk when the only benefit appears to be better tasting food?  Perhaps the only effective way to have population based reduction in salt intake is government regulation, targeted to the foods that contribute most to salt intake – bread, processed meats.  That way all food manufacturers must adhere and no one manufacturer will have a competitive advantage by adding more salt.  This will strike stern opposition from food manufactures because……. That is for Part 4.

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