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.

Saturday, September 8, 2012

Salt Taste Part 2

Why is NaCl, according to some cooks, the most important ingredient when cooking?  The reason is simple, added NaCl has a positive influence on liking and preference for foods.  And it is not just due to saltiness, although saltiness is one component. Apart from savoury foods where it appears naturally complementary, it is also added to caramel, chocolate and foods we associate with another taste, sweet.  Perhaps it is the subtleness of small amounts of salt in sweet foods we like, maybe the sharp contrast when you taste a some NaCl in a sweet food, or maybe it is something else.
When two compounds with different taste qualities are mixed a number of interactions may occur including suppression of bitterness by NaCl. NaCl also enhances sweetness at low concentrations, and through NaCl effect on bitterness, sweetness maybe further enhanced.  NaCl also has the ability to enhance aromas associated with sweetness (we like them) and suppress aromas associated with bitterness (we don’t like them).  In this situation, adding NaCl to a food has created saltiness, increased sweetness and sweetness associated aromas, all aspects of food that we like.  NaCl has also decreased bitterness and bitterness associated aromas, thereby reducing the negative aspects of food and also increasing our liking of food.  You start to appreciate the wisdom of Heston Blumenthal’s statement – but there is even more. NaCl also acts as a preservative and water binding agent in processed meats and influences on the texture of foods such as breads.
When you have one compound with so many positive influences on the flavour of food, and is cheap, convenient to use, and not acutely toxic, all this adds weight to being the cooks most useful ingredient.  In a way I agree with Heston Blumenthal, NaCl is the most useful ingredient for the cook, just as the hammer is the most useful tool for the builder.  Using an analogy, a builder (or handy person) faces a problem, the hammer is close by, the hammer becomes the solution; it is low tech, easy to use and it may work. The same happens with NaCl in the kitchen, perhaps it becomes the ingredient that is the solution to everything, it is at hand and easy to add some NaCl to every dish, at every stage of production. The accumulation of NaCl in a food adds up and there begins another problem. Much of the added sodium is trapped within the food matrix and unavailable to fulfill its role in taste, it becomes taste invisible (this will come up in Part 4 of salt).  Yet when the food is swallowed and the food matrix broken down, the NaCl is adsorbed and available for physiological function.
After consideration and remembering the old nutrition mantra, ‘everything in moderation’, I would qualify the Blumenthal statement that ‘salt is the most important ingredient for the cook’, by saying NaCl is the easiest ingredient a cook can use to increase liking of a dish. It is a process similar to delayed gratification, using excessive NaCl in the dish you are preparing may (not will) increase the liking of the dish, but the excess sodium may also cause detrimental health effects in a few years.  The evidence that we consume excessive sodium which is associated with many detrimental health effects.  That is for Part 3.