Take it with a Pinch of Salt

The media is rife with advice on nutritional health, yet such reports often offer conflicting views. So how do we know what to believe?

One of the latest health stories to hit the news marks the re-emergence of the salt saga. Too much salt is widely believed to be a bad thing, with high levels known to lead to high blood pressure, which in turn can result in an increased risk of disorders such as heart disease. Yet, salt is also an essential component of our diets, and a recent study published in the Journal of the American Medical Association (JAMA) suggests that increased sodium intake may actually increase cardiovascular health. Inevitably, these conflicting views lead to confusion about which stance to take on the issue.

The fact is, like all things, moderation is the key. Government recommendations for salt intake suggest that adults should consume no more than 6g per day, but it is worth remembering that this only applies to healthy individuals. Indeed, the results of the JAMA report were only applicable to those who were already in good shape, and conceded that people with high blood pressure could control the condition with a low-sodium diet. At the other end of the spectrum, some people have to increase their salt intake to aid fluid retention, helping to control heart problems which arise as a result of dehydration. The human body is amazingly adept at self-regulation, able to extract what it needs from our diet, and discarding the remainder in urine. Ahem. So if your kidneys are able to excrete unneeded sodium, why is excess salt a problem? The answer lies in the excess that the body is unable to remove — this accumulates in the bloodstream, causing fluid to be retained and forcing the heart to work harder to pump that extra volume across the body.

Now for the chemistry. Every cell in the human body contains salt which is an electrolyte essential for human life. An electrolyte is a solution which contains ions (charged atoms), allowing electrical conductivity. It is this property which allows sodium to facilitate the production of electrical signals in the brain and muscles — without these signals, we wouldn’t be alive. So don’t cut out the salt completely!

On a lighter note, salt is undoubtedly a fantastic enhancer of our gastronomic experience. Salt is one of the five sensations that our taste buds are able to detect; the others are bitter, sweet, sour, and umami (yes, really!), and it is the combination of these sensations that contributes to our perception of taste. The human tongue contains thousands of individual taste buds, each consisting of clusters of taste receptors, which are able to transmit chemical signals to the brain. Each taste bud lasts for approximately 10 days — we all know the feeling of tastelessness after burning your tongue on a hot curry!

Although excess salt can lead to long-term health problems, this pales into insignificance when you consider consuming 1 gram of salt per kilogram of body weight. This amount of sodium chloride, known as the lethal dose, is sufficient to kill a human. Although vital for life, as the saying goes, too much of a good thing can kill you!

David Milner

One Comment
  • Jason
    23 August 2011 at 12:58
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    Whilst this article is essentially valid, I would like to point out some subtle inaccuracies. For example, the taste receptors do not transmit chemical signals to the brain but convert chemical stimuli into electrical stimuli which then travels to the brain via the nervous system. Also, the lethal dose description is inaccurate. One gram of sodium chloride is the lethal dose required to kill 50% of the population(LD50). There can be a range of lethal doses (depending on the percentage of the population that are killed).

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