DEFINING COOKING SALT INTAKES FOR PATIENT COUNSELING AND POLICY-MAKING

The role of salt (NaCl) in the development of high blood pressure has been a matter of debate, however, the Intersalt Study showed that sodi um (Na) intake in various areas of the World is related to the slope o f blood pressure with age. Accurate amounts of the total salt intake o r that coming from a particular source are needed, both, for physician s who need to consider the salt intake of their patients and for publi c health workers who are in charge of the implementation of public hea lth programs where salt is used as a carrier of other nutrients. An an alysis of the literature suggests that exaggerated values for total sa lt intakes have often been obtained from indirect estimates; discretio nary salt use, i.e. home-cooking salt has invariably been overestimate d. A method is described for measuring the contribution of cooking sal t to total salt intake since it is a confusing area where inappropriat e methods have been used to assess its contribution. The method descri bed is based on the use of small amounts of lithium carbonate fused wi th NaCl. Validation experiments were undertaken to determine the natur ally occurring lithium (Li) in a number of foods including fresh, froz en and tinned vegetables, and the use of Li tagged salt for cooking ve getables and for direct use in cooked foods. We also assessed whether Li was taken up proportionally with Na into foods during cooking. In g eneral vegetables contained variable but only small amounts of Li exce pt aubergine and spinach, and Li was taken up proportionally with Na i n a variety of vegetables. Results showed that 36,35 and 21% of the sa lt added during cooking was recovered in carrots, runner beans and pot atoes respectively, the rest being discarded in the cooking water. Thi s suggest that about a third of salt added during the cooking of veget ables will be ingested by the household. Attempts to rely simply on th e total use of household salt supplies will clearly exaggerate, marked ly, the true intake of individuals.