Salt is one of the main human tastes and is known to be a strong driver of food selection in adults. In nutrition, salt principally refers to sodium chloride, but can also include the similarly tasting potassium chloride that is also used in food manufacturing. The human preference for salt is likely largely innate, but evidence suggests that at least some of the desire to consume salty food may be learned in early life. For example, researchers1 have investigated the salty preference of infants under 6 months old to assess the way that salt taste may be learned. Responses to 0.17 and 0.34 mol sodium chloride solutions in water were assessed in a double-blind manner. The acceptance of a salty taste was measured by the amount of salt ingested, and this was investigated in relation to exposure to dietary starch, which is a rich sources of sodium for infants.
Infants that had been previously exposed to starchy foods, and therefore had dietary experience of sodium chloride, showed a stronger acceptance for salty foods than infants with no prior exposure. In contrast, fruit exposure in infants showed no association with salt acceptance. This suggests that salt preference may be related to the early exposure of salt containing foods. Exposure to salty foods at 6 months of age resulted in an increased likelihood of salt consumption at pre-school age, including the eating of plain salt and licking salt off foods. The plasticity of the brain in early life may therefore allow modification on innate salt preference resulting in greater salt acceptance in later life. However, it is unclear if this results from a response to sodium or a response to the salty taste. While sweet and bitter tastes develop at birth, salt taste therefore appears to occur developmentally.
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