The UKs advertising watchdog has ruled that the FSA was untruthful to claim that a family reduced their blood pressure after eating less salt.
A nutritionist challenged the Food Standard Agencys anti-salt advertising campaign, which asserted that "after four weeks on the Salt Challenge, the Keytes ... look and feel better and have lowered their blood pressure."
The nutritionist believed it was unlikely all the family members had reduced their blood pressure.
In addition, he felt that the claim misleadingly suggested that reduced salt intake alone was responsible for the reported drops in blood pressure, whereas the higher intake of potassium as a result of increased fruit and vegetable consumption was probably the primary causal factor.
The FSA told the Advertising Standards Agency (ASA) that the campaign, which included an advert that centred on the Keyte family and told how their health improved when they reduced their salt intake, was part of an extensive public information campaign on salt consumption and its impact on health.
The agency said that it contracted a professionally qualified dietician, through the British Dietetic Association, to check the accuracy of the claims in the ad against the original data. They said the ad was a case study rather than a scientific research study and was always portrayed as such.
After checking through their data however, the FSA accepted that not all the family had lowered their blood pressure. They agreed that the ad misleadingly implied the whole family lowered their blood pressure as a result of reduced salt intake and that those claims were not supported by the evidence.
The ASA ruled that the advert breached clauses in the Committee of Advertising Practice code on social responsibility, substantiation and truthfulness, but welcomed the FSA's acknowledgement that the claim was misleading.
The ruling comes at a bad time for the FSA, which was hoping to capitalise on Salt Awareness Week, which runs from 29 January to 4 February, to raise awareness of excessive salt consumption. Europeans still consume far too much salt, most of which still comes from processed food.
The UK government for example estimates that processed foods, from soups and sauces to breakfast cereals and snacks, contribute about 75 per cent to people's salt intakes.
But there is evidence that awareness of the need to reduce salt consumption has increased. There has been a noticeable shift away from salt in recent years - according to market analyst Mintel, the salt sector in the UK has seen sales fall 13 per cent from 23 million in 2000 to about 20 million in 2005.
Table and cooking salt have been the main casualties, losing 15 per cent and 17 per cent of volume sales respectively between 2003 and 2005. In contrast, sea/rock salt and low sodium alternatives have increased, but between them they account for just 20 per cent of the total salt market, not enough to stem the decline.