BENEFITS OF SALT REDUCTION IN SOUTH AFRICAN FOOD
This article is a citation from the editorial in SA Cardiology and Stroke Journal, April/May 2013, with approval from René Bosman of Media24.
KRISELA STEYN1, VASH MUNGAL-SINGH2, EDELWEIS WENTZEL-VILJOEN3, KAREN HOFFMAN4, MELVYN FREEMAN5
Chronic Disease Initiative for Africa, University of Cape Town
Heart and Stroke Foundation of South Africa
Centre of Excellence for Nutrition, North-West University
School of Public Health, University of Witwatersrand
Medical Research Council/Wits Rural Public Health and Health Transitions Research Unit (Agincourt), University of the Witwatersrand
The deleterious effect of high salt intake on blood pressure is irrefutable. High salt intake is also associated with gastric cancer and osteoporosis. Data to support the association between sodium and hypertension were generated from animal studies, ecological studies, feeding studies, cohort studies, randomised controlled trials and meta-analyses of such trials. Globally hypertension accounts for 62% of strokes and 49% of heart attacks1,2,3.Norman et al. estimated that hypertension accounted for 9% of all deaths in people 30 years and older in 2000 in South Africa (SA). Of these, 50% of strokes, 42% of ischaemic heart disease, 72% of hypertensive heart disease and 22% of other cardiovascular burden were attributable to high blood pressure4.
Two studies in the United States modelled the impact of salt reduction on population health. Palar and Sturm estimated the effect of salt intakes according to the World Health Organisation (WHO) recommendation of 5g salt per day. Such a decrease would result in an estimated11 million fewer people tobe hypertensive and that 18 billion US dollar less would be spent on health care5. Bibbins-Domingo et al. showed that even if the reduction was as little as 3g of salt intake per day, the number of new cases of coronary heart disease will decrease by 60 000 to 120 000, stroke by 32 000 to66 000 and myocardial infarctions 54 000 to 99 000. Such an intervention would be cost-saving even if only a modest reduction of 1g salt per day were achieved gradually between 2010 and 2019. Reduction of salt intakewould be more cost-effective than using medications to lower blood pressure in all persons with hypertension6.In most populations similar benefits have been predictedif a mean reduction of 1g salt intake per day can be achieved. Salt reduction of 1g per day can save 6000 lives and can prevent a further 6000 non-fatal strokes and heart attacks each year 7.
Global initiatives to reduce salt
In most countries in the world 5 to 18 g of salt per person per day are consumed, which is more thanthe physiological requirement,and has prompted a global movement to support countries to reduce the salt intake of their populations8.Asariaet al. showed that salt reduction is at least as cost-effective as tobacco control9.For this reasonsalt reduction has been identified as a priority intervention and is listed as a cost-effective intervention in non-communicable disease (NCD) prevention10.These influences put salt reduction firmly on the agenda of the UN High-level Meeting on the Prevention and Control of Non-communicable Diseases held in September 2011. At the meeting the WHOwas taskedto develop a global monitoring framework, voluntary global targets and a Global Action Plan for 2013 to reduce the impact of NCDs globally. The target of globally reducing salt intake by 30%, as part of the overall NCD recommendations, was recommended at the WHO Executive Board meeting in January 2013. Once this recommendation was adopted by the member states,all the WHO member states will be in a position to act on high salt intakes in their countries.
Sources of dietary salt in South Africa
Until about 15 years ago very little attention was paid to the amount of salt consumed by South Africans and its impact on their health.Accurately measuring salt intake is challenging, because the gold standard to ascertain salt intake isto measure sodium in all urine passed by a person during a 24 hour period. Conducting such a study in large population studies is not an easy task and few such studies have been conducted in free living populations. In 2005 Charlton et alpublished data on salt intakes of 300 people in Cape Town11. This showed that people of African descent consumed 7.8 g salt per day, while people of mixed race ancestry consumed 8.5g salt and people of European descent had the highest intake at 9.5 g of salt per day.
From a range of nutrition surveys conducted between 1982 and 2010 foods contributing most to salt intake in South African populations were identified.One of the staple foods, namely bread,was the food that contributed the most to salt intake (between 40 -50% of total salt intake). It turned out that South African bread has a remarkably high salt content. Other foodstuffs that contribute significantamounts of saltare meat products like sausage and pies, margarines, gravy and soup powders, meat and vegetable extracts and products containing sodium monoglutamates. These products contribute significantly to the diets of South African low-income groups12.
The benefit of salt reduction in South Africa
These findingspointed to the importance to study the effects of food with less salton blood pressure, especially in low-income groups. Charlton et al. conducted a randomised controlled trial in LangaTownship in Cape Town with the assistance of leading food producers in South Africa12. They manufactured low-sodium versions of six foods, including low-sodium bread,margarine, soup cubes, soup powders, a low-sodium table salt and maas (sour milk) to increase calcium intake. Consumption of the healthier foods compared to the usual commercially produced food significantly reduced blood pressure over an 8-week period.
As salt in South Africa is fortified with iodine a concern has been expressed that salt intake of 5 g or less a day may lead to insufficient iodine intake in geographical areas with low iodine levels. Charlton et al. assessed this and concluded that a salt intake to 5g per day of iodinated salt will not lead to iodine deficiency.13
An economic evaluation of lowering the salt content of bread, soup mix, seasoning and margarine was recently performed in SA. It is estimatedthat by decreasing the salt content in fourfoods by 0.85g/day, the distribution of systolic blood pressure in the South African population would be lowered and would result in 7400 fewer deaths due to cardiovascular disease, as well as 4300 fewer non-fatal strokes per year14. These changes would save SA R300 million annually in direct hospital costs. Stroke is one of the top chronic conditions in terms of cost because of its associated disability. However, the cost saving due to prevention of stroke was not estimated.It was estimated that one-third of the lives saved would be from premature mortality in the under 60 age group.
South African initiatives to reduce salt
The National Department of Health (NDOH)considered the data from international and South African studies,as well as the international movement towards the reduction of salt in food.Theyinitiated aconsultation process withacademics, representatives of the foodindustry and non-governmental organisations such as the Heart and Stroke Foundation of SA. Furthermore, international experts on salt reductionvisitedSA to advise on the process. Guidelines on desirable levels of salt in six groups of foods, from UK, Australia and the USA were consulted to ascertain the target levels of salt agreed to in those countries. A questionnaire was distributed to food industry members and the results showed that about half of the large food industryproducers of products high in sodium preferred to have regulated salt reductions rather than voluntary salt reduction. This is fortuitous as an Australian studyshowed thatmore health gains was seen through mandatory legislative changes on food containing salt than through voluntary changes15. The Minister of Health published draft regulations (R533: 11 July 2012) in the Government Gazette to add to regulations pertaining to the Foodstuffs, Cosmetics and Disinfectants act (act 54 of 1972)16. These draft regulations show how salt will be decreased in certain foodstuffsover a period of several years. These include regulations for the salt content in bread, breakfast cereals, margarines and fat spreads, savoury snacks, processed meats and raw-processed meat sausages, dry soup and gravy powders and stock cubes. Extensive feedback were received over the three months period for comments and the draft regulations were reviewed and adapted to enable a gradual reduction of salt in the identified foods to achieve the required levels well before 2020. The final regulations relating to the reduction of sodium in foodstuffs and related matters were published on 20 March 201317.
It is clear that regulation is only one aspect of the process to ensure an adequate salt reduction strategy for SA. The issue of discretionary salt addedduring domestic food preparation and at the table will require an active and intense public education initiative which is currently being planned in collaboration with the NDOH and the SA Heart and Stroke Foundation. Health professionals and members of the Nutrition Society can play an important role in this initiative.
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