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Should salt come with a health warning?

Food giants say we don't need to cut salt intake. But studies suggest such advice should be taken with a pinch of ... er ... cynicism. By Janette Marshall

Janette Marshall
Monday 29 July 1996 23:02 BST
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"The worst thing was eating potatoes without salt - absolute murder," recalls David Green, 65, who gave up salt five years ago on his doctor's orders because of his high blood pressure. "But you soon get used to it, and once you have, foods containing salt taste awful. At home, I eat a no-salt bread, and when we were on holiday recently, I ate ordinary bread at the hotel. I said 'Oh, my God - salt!' It was inedible. You don't realise how much salt is in food until you cut down."

It seems we have developed an almost irresistible attraction to salt - an innate appetite which can be traced, researchers believe, to the Stone Age, when it was in short supply, and humans and other animals were driven to find it in salty water or rocks containing sodium.

But this appetite poses a major risk to health, particularly as we hit middle age. Specialists are convinced that a diet high in salt causes high blood pressure, a disorder that is suffered by one third of people over 60, which costs the NHS about pounds 300m a year in drugs, and which is a risk factor for the two big killers - coronary heart disease and stroke. In a report published in the Lancet last week, a high-salt diet is also linked to the "demineralisation" of bone and the rising incidence of osteoporosis as well as asthma and stomach cancer. Doctors are recommending a reduction in average salt intake from 10g to 5g daily.

It's of little use to throw away the salt cellar or reduce salt in cooking - some 80 per cent of our salt intake comes from processed foods, ranging from crisps and canned carrots to sausages and baked beans. In some processed foods, the concentration of salt is similar to that of seawater, but we're so used to it that we don't notice. Like tobacco in the 1960s, it looks as though salt could become the health battleground of the next decade, with doctors fighting for regulation of salt in food on one side and the big battalions of the salt industry on the other.

The latest findings, from the "Intersalt" study of 10,000 people in 32 countries, were published earlier this year in the British Medical Journal and provide the strongest evidence yet of a link between excess sodium and higher-than-average blood pressure, suggesting that the effect increases with age.

"Man evolved needing to conserve salt, which was in short supply. Now we eat too much and our bodies have not evolved to get rid of excess sodium," says Graham MacGregor, professor of cardiovascular medicine at St George's Hospital Medical School London."In primitive societies, salt intake is up to 100 times less than in the UK."

Professor MacGregor is a founder member of Cash (Consensus Action on Salt and Hypertension), a group of doctors who want to see a reduction in salt in processed food. He explains: "Food manufacturers do a fantastic job on convenience and choice, but we need to convince the more reasonable among them that the evidence against a high-salt diet is overwhelming and persuade them to gradually reduce the amount they add to our food."

The Intersalt findings are, ironically, the result of pressure from the food industry for a re-analysis of data previously published in 1988. Unfortunately for the industry, the re-analysis came up with an even stronger correlation between salt intake and high blood pressure than the previous study.

The Food and Drink Federation, representing food and drink manufacturers, and the Salt Institute, the trade organisation of salt producers based in Virginia, argue that although individuals with hypertension might need to reduce salt intake, the majority of the "normotensive" population do not. "There is no scientific consensus to demonstrate a benefit of dietary sodium restriction for the entire population," claims the FDF.

Specialists take issue with this, arguing that it isn't just those with "high" blood pressure who need to cut down on salt, pointing out that the majority of strokes occur in people with so-called normal blood pressure for their age."Normal" Western blood pressure is in fact wildly abnormal," says Professor Peter Sleight from the Department of cardiovascular medicine at Oxford University and a member of Coma, the government's Committee on Medical Aspects of Food Policy, which in its 1994 report recommended a reduction in salt intake to 6g daily.

"The current 'debate' fuelled by the food industry is similar to the false debate about smoking in the 1960s when the tobacco industry got some doctors to say there was no link with cigarettes as a cause of lung cancer, or the prolonged debate over cholesterol and heart diseases in the UK. The failure to act on these, and currently on salt, has been the cause of a lot of deaths in this country."

Apart from its effect on blood pressure, salt has other adverse effects such as fluid retention. "The average person has the equivalent of a couple of bottles of mineral water sloshing around inside them because of excess salt intake, which translates to around two kilos in weight," says Professor MacGregor. "Excess salt also aggravates osteoporosis, asthma and stomach cancer and contributes to stroke independently of high blood pressure."

Salt and sodium-based food additives are attractive to food processors because they allow water to be bound into sausages, and other meat and fish products, which increases weight, and therefore profit. Salt also makes you thirsty, which is why giant food conglomerates that produce both (salty) fast foods and soft and fizzy drinks are reluctant to reduce salt levels. It is used in junk foods as a cheap filler, giving flavour to what might otherwise be unpalatable.

The food industry's final bastion of defence is to say that it is only following customer preference and that, as far as salt goes, there is a level below which the customer will not tolerate. Nutritionist for Heinz, Nigel Dickie, says: "We present soups with differing levels of salt for tasting but there is a threshold below which customers do not like the taste." But Professor MacGregor points out that taste receptors for salt are dependent on intake. "If gradual reductions are made, it would not be noticeable. What previously tasted 'normal' would in time become distastefully salty."

Not all the news is bad, though. The food industry is changing, albeit slowly - it just needs a few carrots. In the 1980s, the salt content of bread was reduced by 25 per cent to just under 2 per cent - a move made by big bakeries in return for "healthy eating" logos endorsed by the then Health Education Council. Sainsbury's and Tesco both offer 'healthy eating' brands of bread containing 0.8 per cent salt and are trialing even lower salt breads. In the last decade, Heinz has reduced the amount of salt in baked beans by 15 per cent and tomato soup by 17 per cent (although these still cannot be said to be low-salt foods). Manufacturers are diversifying into low-salt products - but they cost more because better, more flavoursome ingredients are needed.

The British government's strategy for health, Health of the Nation, gives no target for dietary salt reduction, despite the recommendations for a reduction from its own committee of experts, thanks to some powerful lobbying from the food industry. But many believe that in the long term, government regulation of salt in food is inevitable. Perhaps Britain should look to Finland, where government intervention to set salt levels in some foods, together with voluntary changes by the food industry, has led to an overall reduction in salt intake. Over the last 20 years, Finland has gone from the country with the second highest death rates from heart disease and stroke in the developed world to second lowest, while Britain remains near the top of the league table. "Strokes and coronary heart disease are down 60 per cent in middle-aged people," says Professor Heikki Karppanen, from Helsinki University. This is the most dramatic change in the whole world."

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