Reducing dietary salt intake and preventing iodine deficiency: towards a common public health agenda

Public health advocates coordinate programs to reduce salt intake and prevent iodine deficiency

After decades working in parallel, public health advocates for dietary salt reduction and those seeking to achieve the elimination of iodine-deficiency disorders through salt iodisation have harmonised their agendas.

The World Health Organization (WHO) promotes reducing dietary salt intake as a cost-effective strategy to reduce the burden of non-communicable diseases,1 but it also recommends universal salt iodisation to prevent and control iodine-deficiency disorders. Parallel implementation of both policies could be counterproductive.2 However, a meeting convened by the WHO and the George Institute for Global Health, in collaboration with the International Council for the Control of Iodine Deficiency Disorders Global Network (ICCIDD–GN), in Sydney in March 2013, agreed on a new approach to consolidate the two agendas. Technical experts came together with WHO representatives to discuss the potential for maximising the impact of dietary salt reduction and iodine-deficiency elimination programs through improved coordination.3

High salt intakes are a primary cause of high blood pressure, one of the main risk factors for heart attack, kidney disease and stroke, which are leading causes of death and disease worldwide. Member states of the United Nations endorsing the global monitoring framework and voluntary global targets for the prevention and control of non-communicable diseases at the United Nations World Health Assembly in 20134 agreed to achieve a 30% reduction in population salt intake by 2025. Working with the food industry to reduce the amount of salt added to processed foods and restaurant meals, campaigns to change consumer behaviour and efforts to improve the food environment through work in schools and the workplace will be the cornerstones of these efforts.5

Iodine-deficiency disorders are another major global health problem; they cause impaired cognitive development, reduced intelligence quotient (IQ), congenital anomalies, cretinism, and endemic goitre and other thyroid conditions. It is estimated that 1.9 billion people worldwide remain at risk of insufficient iodine intake. The WHO, United Nations Children's Fund (UNICEF) and the ICCIDD–GN recommend an intake of 150 µg iodine daily for non-pregnant, non-lactating adults and 250 µg daily for pregnant and lactating women. Food-grade salt is the primary vehicle for dietary iodine fortification and is preferred because the technology is simple, iodine levels in salt can be easily monitored, salt consumption is mostly stable throughout the year, and salt is affordable. The estimated annual cost attributable to iodine-deficiency disorders in the developing world is $36 billion with just $0.5 billion required to deliver effective salt-iodisation programs.6

The public health goals of salt reduction and salt iodisation can both be achieved if the concentration of iodine in salt is increased as salt intake is reduced. The inherent challenge that salt will continue to be viewed as healthful for the iodisation program may remain, but can be overcome by full implementation of the universal salt iodisation strategy such that all salt used in both human and animal foods is iodised so that notionally ‘‘healthy'' iodised salt does not have to be sought out by the population.

To date, dietary salt-reduction efforts and iodine-deficiency disorder elimination programs have largely operated independently. Improved coordination between programs will help to ensure consistent messaging, enhance implementation and reduce costs for monitoring. Both programs are also based on multistakeholder engagement, including close links with the food industry and civil society. Specific areas for future coordination of the two programs were identified as: policy development; research, monitoring and evaluation; and advocacy and communication.

It was proposed that the WHO and UNICEF would lead the development of the coordinated program, working with ICCIDD–GN, the World Health Organization Collaborating Centre on Population Salt Reduction at the George Institute for Global Health in Sydney and other technical advisers. The priority action will be to encourage national governments to develop strategies that ensure universal salt iodisation, reduce population salt consumption, and track levels of salt and iodine intake such that both sets of public health goals are achieved.

The Sydney forum was the last in a series of WHO meetings to provide countries with tools to reduce population salt intake. The collaborative program of work on salt reduction and iodine-deficiency elimination is the final plank in the strategy. A series of regional initiatives have since been held, and iodine levels are now being monitored as part of several national dietary salt-reduction projects. The coordinated approach has also been incorporated into the “SALT Toolkit” currently being developed by the WHO to provide practical advice to support countries to achieve the new global salt-reduction targets.

In 2009, we saw the introduction of mandatory iodine fortification of salt in bread in Australia to help solve the problem of re-emerging iodine deficiency.7 While this is a step in the right direction and has already corrected iodine deficiency in children and adults, although not in pregnant women, it will not detract from ongoing salt-reduction efforts in Australia. The fortification of all food-grade salt with iodine (universal salt iodisation) would be the most effective approach to ensuring that the benefits of fortification reach at-risk groups in Australia while remaining in harmony with initiatives to reduce dietary salt intake.8