Many are also given cows’ milk, which has higher levels of salt than breast or formula milk, as their main drink despite recommendations that it should not be used in this way until babies are at least one year old. High levels of salt can damage developing kidneys, give children a taste for salty foods and establish poor eating practices that continue into adulthood and can result in health problems later in life.

These are the latest findings from researchers at the University of Bristol based on almost 1,200 participants in the Children of the 90s study and just published online by the European Journal of Clinical Nutrition.

The researchers found that the majority of infants were first introduced to solids around 3-4 months, with the mean salt intake for the highest group at eight months more than double the maximum recommendation for that age group (400mg sodium per day up to 12 months). Infants in this top group often consumed cows’ milk as a main drink, which has a higher sodium content  at 55mg per 100g than breast (15mg per 100g) or formula (15-30mg per 100ml) milk. They also ate three times the amount of bread compared to the lowest group, and were given salty flavourings such as yeast extract and gravy.

In the UK, the majority of salt consumed by individuals is added to food during manufacturing, with a relatively small proportion added during cooking or at the table and current intakes in both children and adults are far higher than NICE (National Institute for Health and Clinical Excellence) guidelines.

Speaking about the findings, Dr Pauline Emmett and Vicky Cribb, the nutritionists who conducted the research, said: "These findings show that salt intakes need to be substantially reduced in children of this age group. Infants need foods specifically prepared for them without added salt, so it is important to adapt the family diet. 

"This research suggests that clear advice is needed for parents about what foods are suitable for infants. This should be given to all parents and carers and should include the important advice not to use cows’ milk as a main drink before 12 months of age."

They added that: "Given that three-quarters of salt in the diet comes from processed adult foods, successful salt-reduction strategies can only be achieved with the co-operation of the food industry. Manufacturers have a responsibility to reduce the salt content of food products. This process has already started in UK but much more needs to be done. If this study were repeated today it is likely that there would be some improvement but not enough to safeguard the health of all babies."’

The researchers studied three-day dietary records (completed by the mothers) of 1,178 8-month-old infants born in 1991/92 and involved in the Children of the 90s study at the University of Bristol. Infants were categorised into four groups of increasing salt intake.

Paper: Cribb VL, Warren JM and Emmett PM. 'Contribution of inappropriate complementary foods to the salt intake of 8-month old infants'. European Journal of Clinical Nutrition 2011; doi: 10.1038/ejcn.2011.137