The problem with the Western diet is not one of deficiency, but one of excess. We get too much of a good thing – too many calories, too much of the wrong kind of fat, and too much salt. As a result obesity, diabetes, and hypertension are growing health problems.

There also does not appear to be an easy solution – voluntary diets founded primarily on will power are notoriously ineffective in the long term. Add to that is the marketplace of misinformation that makes it challenging for the average person to even know where to apply their (largely ineffective) will power.

It can be argued that this is partly a failure, or an unintended consequence, of market forces. Food products that provide cheap calories and are tasty (sweet, fatty, or salty) sell well and provide market incentives to sell such products. Consumers then get spoiled by the cheap abundance of tempting foods, even to the point that our perspective on appropriate portion sizes have been super-sized.

It may be counter argued that there is a market for healthful foods, but it seems that this creates the incentive to claim that food is healthful with marketing gimmicks rather than to make food for which there is good scientific evidence that they improve health.

And so the public is faced with claims that products are “all natural” when this term is not regulated and there is no evidence to support this notion that “natural” by any definition is necessarily healthful. Low fat foods are made palatable by adding sugars, and low sugar foods are kept tasty by adding fat.

All of this has led to the conclusion that systemic fixes are necessary to address what is becoming and increasing public health problem of diet-related diseases. The first round of regulations dealt with transparency – providing the consumer with accurate and complete information on food labels so that they cna make informed choices. If we gauge success by public health outcomes, this strategy has not succeeded.

So governments, who are also increasingly conscious of the cost of health care, are experimenting with other options. New York City has famously declared War on Fat and has passed laws to limit the use of trans fat. Now the Big Apple has added salt to their 10 most wanted list.

According to the New York City Department of Health:

The New York City Health Department is coordinating a nationwide effort to prevent heart attacks and strokes by reducing the amount of salt in packaged and restaurant foods. Americans consume roughly twice the recommended limit of salt each day – causing widespread high blood pressure and placing millions at risk of heart attack and stroke. This is not a matter of choice. Only 11% of the sodium in our diets comes from our own saltshakers; nearly 80% is added to foods before they are sold.

How do these claims hold up to the evidence. I found a reference that states that over 75% of salt intake is from processes food and restaurants – which is close to the 80% figure quoted above.

Do Americans really get twice the recommended salt intake? Here is a comprehensive review of salt intake around the world, suggesting that Americans get close to three times the daily recommended about (which is about 65 mmol/day or 1.5 grams – Americans get about 165 mmol per day).

What about the core claim – that salt intake causes increased risk of hypertension, cardiovascular disease, and stroke? Well, this is a trickier question – as are all epidemiological questions. My review of reviews suggests that there is a growing consensus that increased salt intake does correlate with an increased risk of vascular disease. However, increased salt intake also correlates with obesity, which may be at least partly responsible for this increase.

The more important question, however, is this – does reducing salt intake reduce high blood pressure and/or the risk of vascular disease? Here the answer seems to be a qualified yes. Salt reduction reduces blood pressure, but only a little. However, most of these studies are short term. Longer term studies are still needed. Some reviews claims that salt reduction – with or without a reduction in blood pressure, in hypertensive and normotensive people – reduces cardiovascular risk. Meanwhile, other reviews claim the evidence is inconclusive on long term effects.

Conclusion

As usual, the medical and regulatory communities are tasked with making sense out of chaos – with implementing bottom-line recommendations in the face of inconclusive evidence. While there remains legitimate dissent on the role of salt in vascular health, the current consensus is something like this:

- Most of the world, including Americans and those in industrialized nations, consume more salt than appears to be necessary.

- In the US most of that salt comes from processed or restaurant food (while in other countries, like Japan, most salt intake is added while cooking).

- There is a plausible connection between excess salt intake, hypertension, strokes and heart attacks.

- There is evidence to suggest that reducing overall salt intake will reduce the incidence of these health problems, but the evidence is not yet conclusive and longer term and sub-population data is needed.

Given all this it seems reasonable (from a scientific point of view – and ignoring the role of political ideology) to take steps to reduce the amount of salt in processed and restaurant food, while continuing to study the impact of such measures. But we also have to consider unintended consequences. Part of the reason salt is added to processed food is because it helps preserve it – give it a longer shelf life. People also develop a taste for salty food, and a sudden decrease in salt content may be unsatisfying, leading people to seek out higher salt foods. But these are technical problems that can be addressed.

It should also be noted that salt requirements and tolerance may vary considerably from individual to individual – based upon genetics, and certainly underlying diseases. Therefore recommendations from one’s doctor should supercede any general recommendations for the population.

In any case it seems that the War on Salt has begun. I only hope this is a war we choose to fight with science.