Nov 1, 2004 | Features

Unsound Science?

The Food Standards Agency’s £4m slug-led campaign to persuade us all to cut our salt consumption has met with strong criticism. Here, Peter Sherratt of the Salt Manufacturers’ Association puts the case for caution.

YOU would expect a government-backed campaign that seeks to change the nation’s diet to be based on hard, unassailable facts. Yet the Food Standards Agency (FSA) is spending £4m ($7.2m) on encouraging us to cut our salt intake when, in reality, the science that under- pins it is unsound.

While these concerns could be discounted as coming from the industry that supplies salt, they are shared by a significant body of independent expert opinion in the UK and internationally. Tony Heagerty of the University of Manchester (and president of the European Society of Hypertension), says: ‘We do not have any long-term outcomes information as to whether a sustained restriction of salt in the diet would actually lead to a reduction in stroke and heart disease. It has by no means been demonstrated by a dietetic intervention of any substance whatsoever.’

Instead of ‘dietetic intervention’, the FSA is basing its campaign on inconclusive and contradictory papers. One of these is the Department of Health’s National diet and nutrition survey, published earlier this year. The latest in a series of surveys, it investigated the nutritional status of a national sample of adults and found ‘no correlation between systolic blood pressure and urinary sodium’.

The FSA’ s campaign relies heavily on the 1988 Inter- salt study, which looked at the sodium excretion and blood pressure of more than 10 000 people at 52 med- ical centres around the world. Forty eight of those cen- tres confirmed that sodium was not related ‘to median blood pressure or prevalence of high blood pressure’, while ‘body mass index and heavy alcohol intake had strong, significant independent relations with blood pressure in individual subjects’.

Since 1995, 10 studies in the US showed lower sodium diets do not produce health benefits in the gen- eral population. This year, a coalition of six medical groups in Canada rejected a recommendation for uni- versal salt restriction, choosing instead to make lifestyle recommendations for reducing blood pressure such as exercising, eating a balanced diet, and stress management. The Medical Journal of Australia reviewed various Western salt studies and concluded that ‘more information of an objective nature is required before we admonish whole populations to restrict dietary sodium intake’.

So why is the UK government forging ahead with the campaign? Its direction has been swayed by one very forceful anti-salt lobby — Consensus Action on Salt and Health (CASH). Founder Graham Macgregor has co- written a report on the effect of salt reduction on blood pressure. However, a University of York review that appears on the National Health Service’s own website claims that ‘the authors appear, on balance, to have overemphasised’ a vital section of the report — ‘the estimation should be regarded as a hypothesis or sug- gestion for further investigation’.
Such caution is echoed time and again. An independ- ent review of the evidence by the prestigious Cochrane Collaboration earlier this year found that ‘further evalu- ations to assess effects on morbidity and mortality out- comes are needed for populations as a whole and for patients with elevated blood pressure’.

What the government has failed to recognise is that salt is an essential mineral. The figurehead for the cam- paign, a character called Sid the slug — whose family apparently died from eating salt — carries a potentially very damaging message. It could even create a long-term irreparable fear and phobia in the younger audience.

We all have about a cupful of salt (250g) in our bodies to keep us alive. The sodium helps maintain fluid in our blood cells and transmits electrical impulses between muscles, nerves and the brain. The chloride is essential to food digestion. Normal, healthy individuals do not need to reduce their salt intake because the kid- neys filter salt that is not essential, and it is excreted. Yet the Department of Health and Food Standards Agency repeatedly insist that salt is deadly.

For those with high blood pressure, the Salt Manufac- turer’s Association (SMA) agrees that medical advice on diet may be advisable. The recent National Institute for Clinical Excellence (NICE) report advocates the use of modern, effective drugs, rather than salt restriction.

For other groups, reacting to blanket advice to cut salt consumption could be harmful. Ingo Füsgen from the department of geriatrics at the University of Witten- Herdecke in Germany presented evidence to the Euro- pean geriatrics congress in Vienna that up to 10% of older people suffer from subacute sodium deficiency. A low-salt diet can also cause problems with blood vol- ume in the unborn child, which in turn can increase the mother’s own blood pressure.

We suggest that a risk assessment is crucial to pro- tect potentially vulnerable population groups. The minister for health, Melanie Johnson, confirmed in a written reply to the House that no such assessment had been carried out. This would be unacceptable in the case of introducing a new drug, but apparently not so when changing the diet and nutritional intake of an entire nation.

The FSA is spending £4m on its salt awareness cam- paign. But the cost of the study we are proposing would be relatively insignificant. The SMA has even offered to contribute. We believe it would provide much needed certainty on an issue that is of great importance to the population.

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