It is white, inexpensive, tasty and one of the most vital ingredients in the food industry – salt. Besides being a key taste ingredient and a natural bitter suppressor, salt is a critical component of a great array of products, including meat and meat products, cheese, fish, fermented and canned vegetables, bread and biscuits.

The role of salt in food processing has been known for centuries. Its ability to reduce water activity in products, resulting in a limitation of microbial spoilage and pathogenic bacteria, has made it a historic agent for the conservation of foods, before refrigeration even existed.

For some time now, however, salt has been in the spotlight for its ill effects on global health. With high blood pressure and cardiovascular diseases rising among adults and children, leading nutritionists, scientists and politicians have been urging the food industry to reduce their use of salts in the production of food.

Many companies have acquiesced to the pressure of politics and health authorities and lowered sodium chloride in their products or settled on using salt substitutes. However, some believe that the conclusions drawn from the studies are not as clear-cut as previously assumed, highlighting the nutritional value of the white ingredient once again.

Low-sodium pressure

"National salt and sodium reduction strategies have been adopted in the US, Canada, Europe, Australia, as well as China and India."

When US researchers discovered in the 1970s that very high doses of salt raised blood pressure in rats, research started booming. It was not long before scientists worldwide concluded that too much salt was bad for humans too. One of the earliest studies on salt and health is the 1988 InterSalt, which surveyed more than 10,000 adults globally, and found a connection between a high salt intake, high blood pressure and hypertension.

In the past few years, governments have begun to act on the results of the ever-increasing numbers of studies supporting this notion. National salt and sodium reduction strategies have been adopted throughout the US, Canada, Europe, Australia, as well as China and India.

The UK is leading the way and has urged food producers to reduce sodium across a wide range of food products. In the US, political leaders such as New York’s Mayor Michael Bloomberg and First Lady Michelle Obama, have started a country-wide effort to cut salt in food by 25%, also supported by the Institute of Medicine.

It was not long before food companies also started reacting to this pressure. In 2010, 16 major producers including Mars Foods, Heinz, Kraft and Unilever joined forces in the US as part of the National Salt Reduction Initiative (NSRI) to cut sodium in restaurants and packaged foods by 25% to 2015. Food giants Cargill, Nestlé, General Mills, PepsiCo and Campbell’s have since announced that they would also cut sodium content in their global food production.

Dangerous salt?

Organisations such as the US-based Salt Institute however believe that most of the studies supporting risks of a high salt intake are insufficient and very much misleading. They claim the nutritional value outweighs all health concerns. The organisation’s vice president of science and research Morton Satin explained that alternative peer-reviewed science shows that inadequate salt levels in the diet can lead to insulin resistance, cognition loss and congestive heart failure.

"The Salt Institute believes that public health establishment has been duplicitous and abusive to consumers," said Satin, who calls himself the salt guru. "All the publications relating to the number of lives and healthcare costs saved are bogus and would not hold up a minute in any public forum, but because the public health institutions command such attention this nonsense is believed."

Indeed, it seems that independent scientific evidence that supports a higher salt intake than current national guidelines propose is gaining significance. In July 2011, the much-regarded Cochrane Library published a report saying they found no evidence that reducing salt intake lowers the risks of developing a heart disease or dying prematurely, even if it would lead to slight reductions in blood pressure.

"There have been a number of Cochrane reports stating that population-wide salt reduction is not warranted, plus many more peer-reviewed publications that state it is a dangerous strategy," claimed Morton Satin. "Based on the available science we believe that salt reduction is a very bad idea."

The UK-based Salt Association agreed and said that experts are "totally polarised in their views […and] that the balance of credibility supports salt consumption as an essential part of the diet."

Salt substitutes

Morton Satin said the debate is not just about selling a few pounds of salt. With food salt only taking up a small percentage of the 250 million tons of annual global production, plus about 5% of the volume of salt sold in the US, the industry has seen no impact of the anti-salt campaign in food. The real problem would be that the recommended levels of sodium consumption are too low, leading to a diet that is inadequate in other nutrients, which would be a "false and dangerous recommendation."

"Salt has been an essential component of the human diet since we first crawled out of the sea."

"If it were ever possible for the food industry to make acceptable products at the low levels that are recommended, they would in all likelihood end up being blamed for making consumers ill," he explained.

According to the Salt Association, food manufacturers will continue to be dependant on salt and even sodium substitutes will be unlikely to replace it. Attempts to develop sodium substitutes without the ‘unhealthy’ aftertaste have many been made. Cargill Salt has for instance developed several solutions for reducing salt and sodium. One of them is SaltWise, a direct salt substitute that reduces sodium levels by 25%-50% in products, including meat and poultry applications.

In late 2011, US functional ingredients producer Nu-Tek introduced potassium chloride, able to lower the amount of sodium required in baked goods by 30%. This could be particularly interesting for the production of hamburger buns, with no variations in texture, flavour and appearance or any negative effects on the bun production process.

Both the Salt Association and Morton Satin from the Salt Institute in the US, however, believe that replacing a natural ingredient with synthetic chemicals is not the right thing to do.

"Salt has been an essential component of the human diet since we first crawled out of the sea," said a spokesperson for the Salt Association. "Some potential substitutes have not been exposed to human consumption in the concentrations or the same length of time and some experts question their safety and the long-term carcinogenic effects."

Changing the taste

"There have been a number of Cochrane reports stating that population-wide salt reduction is not warranted."

A completely different approach has now been developed at the Nottingham University’s School of Biosciences, where scientists discovered a way to measure how humans register saltiness of crisps. According to research leader Ian Fisk, this could lead to a new way of producing snack foods with significantly less salt.

"Salt is released in a two-step process that is driven by mixing (chewing and release from the crisp) and diffusion (transfer across the saliva across the receptors on the tongue)," Fisk explained.

The ‘salt burst’ from crisps is only released into the mouth 20 seconds after chewing begins, which means the food may have already been swallowed before the majority of the salty taste is detected. The researcher’s aim now is to develop a series of technologies that speed up the delivery of salt to the tongue. This would mean less salt is needed to get the same amount of taste.

"All my work in this area has one focus, to reduce the total amount of sodium consumed whilst not impacting the consumer experience," said Fisk. He hopes technical innovations will be developed so far that salt could be fully replaced by substitutes one day, even though he is not sure if consumers would want that. In fact, there is some evidence that consumers are making up for the loss of salt in manufactured goods by adding it at the table, as surveys in the UK have shown.

The row between scientists supporting a low-sodium diet and experts claiming the nutritional value of salt is definitely set to go on. It seems the variety of choices is the way to go. Campbell’s for instance is already putting more salt back into all its Select Harvest soups, after consumers stopped buying the reduced-salt version. The food industry’s challenge here is to continue to use high-quality salt – be it in low-sodium or regular food – and to keep a close eye on new studies as they emerge.