IS IT TIME TO REDUCE SALT IN SOUTH AFRICAN FOOD? KRISELA STEYN DEPT OF MEDICINE, UCT CHRONIC DISEASES INITIATIVE IN AFRICA

IS IT TIME TO REDUCE SALT IN SOUTH AFRICAN FOOD? KRISELA STEYN DEPT OF MEDICINE, UCT CHRONIC DISEASES INITIATIVE IN AFRICA

INTERSALT STUDY OBSERVATIONAL STUDY IN 52 COUNTRIES CONDUCTED IN THE 1980s 10 079 PERSONS IN 52 COUNTRIES FOUND AN ASSOCIATION BETWEEN DIETARY SODIUM IN TAKE (MEASURED BY URINARY SODIUM EXCRETION) AND BLOOD PRESSURE INTERSALT RESEARCH GROUP. BMJ 1988;297(6644):319-328.

RECOMMENDED INTAKE FOR SODIUM AND POTASSIUM SODIUM INTAKE (NaCl) RECOMMENDED LEVEL OF DIALY INTAKE SALT 5.8g = SODIUM 2.3g SODIUM 1.5g (65mmol/l) SALT 5g ORGANISATION USA IOH (2004) WHO SALT 6g Number of countries POTASSIUM INTAKE POTASSIUM 4.7g (120mmol/l) IOH (2004)

High salt and low potassium intake in South Africans Urinary Na equates to a salt intake of: Black = 7.8 g/day Coloured = 8.5 g/day All groups exceed WHO guidelines of White = 9.5 g/day < 5 g salt/d Urinary K equates to a potassium intake of: Black = 55.6 mmol/day Coloured = 54.3 mmol/day White = 61.9 mmol/day (Charlton et al., 2005) No groups meet JNC 6 guidelines of >= 90mmol/d

Contribution of foods to Na intake Black (N = 110) White (N = 103) Bread (white) 22.3 % Bread (brown) 40.5 % 17.3 % Boerewors 4.2 % Meat pie 3.4 % Soup powder 2.9 % Margarine (brick) 2.9 % Polony 2.5 % Maas 2.4 % French fries 2.2 % Milk (full cream) 2.1 % Bread (white) 15.2 % Bread (brown) 25.2 % 5.7 % Bread (WW) 4.2 % All Bran Flakes 4.2 % Cornflakes 3.1 % Vienna sausage 2.6 % Boerewors 2.4 % Sausage - pork 1.9 % Cheese - cheddar 1.8 % Pizza 1.7 % Bread/cereals food group: 48.6 % (black) and 45.9 % (white) total salt intake. (Charlton et al., 2005)

SALT INTAKE IN URBAN DEVELOPING SA COMMUNITY AIMS: 1) To compare the Na and K intake (ascertained by 24h urinary Na and K excretion) with recommended daily allowance (RDA) of intake 2) To asses the Na and K intake in patients with diagnosed and treated HPT Maseko et al. Cardiovasc J of Southern Afr 2006;17:186-191

METHODS Random sample of 483 people of African ancestry for genetic HPT studies 291 Participants had 3X 24hour urinary Na and K determinations BP was measured by means of mercury sphygmomanometer 5 times. Mean calculated 31% were patients with hypertension of these 67% had been diagnosed and being treated Maseko et all Cardiovasc J Southern Afr.2006;17:186-191

RESULTS 82% OF PARTICIPANTS HAD NA EXCRETION EQUVALENT TO NA INTAKE ABOVE THE RDA OF 65MMOL/DAY 100% OF PARTICIPANT HAD K EXCRETION EQUAVALENT TO K INTAKE BELOW THE RDA OF 120MMOL/DAY. Maseko et al Cardiovasc J Southern Africa 2006;17:186-191

COMPARRISON OF HIGH NA INTAKE AMONG GROUPS OF PARTICIPANTS % Above RDA % Above RDA 80% 84% 73% HPT undiagnosed HPT on Rx Normotensive Maseko et al Cardiovasc J Southern Afr. 2006;17:186-191

CONCLUSION PEOPLE OF AFRICAN ANCESTRY IN JHB CONSUMED MORE SALT AND LESS POTASSIUM THAN RECOMMENDED THE RDA RECOMMONDATION REGARDING NA AND K INTAKE TO NOT TRANSLATE INTO CLINICAL PRACTICE IN URBAN DEVELOPING COMMUNITIES IN SOUTH AFRICA Maseko et al Cardiovasc J Southern Afr.2006;17;186-191

He and MacGregor.J Human Hypertension 2002;19:761-770

He and MacGregor J Human Hypertens 2002;16:761-770

Cook et all. BMJ, Publishhed 20 April 2007

Other intervention trials of sodium restriction in hypertensives Cutler et al.(1997) - Meta-analysis of 23 RCTs. Median reduction of 74mmol Na (4.3 g salt) per 24h: - 4.9 mmhg (Systolic BP) - 2.6 mmhg (Diastolic BP). Geleijnse et al.(2003) - Meta-analysis of 40 RCTs. Median reduction of 77mmol Na (4.4 g salt) per 24h: - 5.2 mmhg (Systolic BP) - 3.7 mmhg (Diastolic BP).

150 mmol/d Intervention simulated DASH diet for high Na arm of the DASH- Sodium study Urinary excretion (mmol/d) DASH study Low salt group Na 156 - K 74.5 72.8 Mg 4.03 3.86 Ca 3.64 2.15

Projected effect of dietary salt reduction on future CVD. CHD policy model is a computer-simulation, state-transition (Markov cohort)model of the incidence and prevalence of CHD and or the mortality and costs associated with CHD in USA residents 35 years and older. Subgroup models : black/nonblack populations. Compared 3gm salt, treatment of HPT patients in ALLHAT study Bibbins-Domingo et al. NEJM 21st January 2010

3gm of salt in USA population projected to reduce annual rates of new cases of: CHD 60 000 and 120 000 Stroke 32 000 and 66 000 MI 54 000 and 99 000 All cause mortality 44 000 and 92 000 Blacks benefitted more than others Women benefitted more from stroke reduction Bibbins-Domingo et al. NEJM 21st January 2010

Projected Annual Reductions in CV Events in the USA Given a Dietary Salt Reduction of 3 g per Day in Black Men, Black Women, Nonblack Men, and Nonblack Women, According to Age Group Bibbins-Domingo et al NEJM 21st January 2010

It is projected that a reduction of 3gm of salt intake per day in the USA population will reduce annual health care costs between $10 billion and $24 billion Bibbinns-Domingo et al. NEJM 21st Jaunary 2010

Even a reduction of 1gm of salt intake per day in the population of the USA will be more cost-saving than treating all the people with hypertension in the USA Bibbin-Domingo et al. NEJM 21st January 2010

WHAT EVIDENCE IS THERE THAT SALT CONSUMPTION CAN BE REDUCED AND IMPACT ON BP IN AFRICA?

A randomised controlled trial of the impact of dietary manipulation of Na, K, Ca and Mg on blood pressure in hypertensive South Africans Charlton KE, 1 Steyn K, 1 Levitt NS, 2 Peer N, 1 Jonathan D, 1 Gogela T, 1 Roussouw K, 1 Gwebushe N, 3 Lombard CJ. 3 Chronic Diseases of Lifestyle 1 & Biostatistics Units 3, Medical Research Council and Diabetes and Endocrine Unit, University of Cape Town. 2

Objective To investigate the impact of an 8-week feeding study (in which sodium intake is decreased, and potassium, magnesium and calcium intake is increased) on blood pressure in mild to-moderate hypertensive black South Africans.

Intervention and control diets Control Intervention Salt (4 g/day) Sasko Sam bread Rama margarine Regular stock cubes Regular soup mixes 500 ml cooldrink/day Solo (4 g/day) Reduced salt bread Reduced salt margarine Reduced salt stock cubes Reduced salt soup mixes 500 ml maas/day

ation content of trial bread (mg/100g Control Experimental Recipe Lab Recipe Lab Median % change (Lab values) Sodium 531 490 330 343-30.6 % Potassium 213 213 402 213 +64.7 % Magnesium 71 57 150 87 +69.5 % Calcium 132 146 211 166 +36.2 % 24 repeated lab analyses, March 04 - July 05 (CSIR, CVAC, WW, CSIR labs)

% Change in cation content of experimental foods Na K Mg Aromat -57.1 % + 7 221 % + 7 900 % Soup mix -20.7 % + 1 200 % +1 132 % Beef stock cube -34.9 % + 9 487 % -21.1 % Rama brick margarine -32.5 % Regular variety not analysed by laboratory

Diastolic BP (mmhg) Systolic BP (mmhg) 140 138 136 134 132 130 128 126 124 122 84 82 80 78 76 Control Low salt 0 2 4 6 8 10 Intervention (week) Change in BP (Pre to Post) Systolic BP Between-diet difference (mean (SE)) = -6.19 (2.63) mmhg (P<0.05) Diastolic BP Between-diet difference (mean (SE)) = -0.59 (1.22) mmhg

Change in 24-hr Ambulatory BP Mean difference between diets (SE) P value Total Systolic BP Total Diastolic BP Wake Systolic BP Wake Diastolic BP -4.53 (2.27) 0.050* -2.49 (1.34) 0.066-5.14 (2.40) 0.036* -2.66 (1.46) 0.072

% subjects % subjects % subjects % subjects Acceptability of products 100 90 80 70 60 50 40 30 20 10 0 87.5 77.5 5 Bread 17.5 5 Prefer Same Dislike 7.5 100 90 80 70 60 50 40 30 20 10 0 90 Salt/Solo 22.5 2.5 2.5 75 Prefer Same Dislike 7.5 Low Salt Control Low Salt Control 100 90 80 70 60 50 40 30 20 10 0 92.5 Margarine 10 7.5 5 87.5 Prefer Same Dislike 2.5 100 90 80 70 60 50 40 30 20 10 0 95 85 Aromat 5 10 Prefer Same Dislike 5 Low Salt Control Low Salt Control

Conclusions Replacement of 6 commonly consumed food items with reduced Na alternatives for 8 weeks resulted in a systolic BP reduction of 6.2 mmhg in older black hypertensives. No change in diastolic BP observed. Results have far-reaching public health implications for cardiovascular risk reduction.

COUNTRIES THAT HAVE INTRODUCED SALT REDUCTION PROGRAMMES FINLAND, JAPAN AND MOST RECENTLY UK BY MEANS OF ENLISTING HELP OF THE FOOD INDUSTRY, EITHER VOLUNTARILY OR ENACTING LEGISLATION MARKED REDUCTIONS IN BP. AUSTRALIA, CANADA, IRELAND AND THE NETHERLANDS HAVE INITIATED STEPS TO REDUCE SALT INTAKE WORLD ACTION ON SALT AND HEALTH (WASH) STARTED IN 2005.

THE UNITED KINGDOM HAS REDUCED THE SALT INTAKE BY 10% OVER 4 YEARS FROM 9.5g to 8.6g per day

RECENT GLOBAL INITIATIVES 2010 INSTITUTE OF MEDICINE (USA) REPORT: STRATEGIES TO REDUCE SODIUM INTAKES IN THE UNITED STATES IN 2009 TEN GLOBAL FOOD COMPANIES GAVE WHO THE ASSURANCE THAT THEY WILL IMPROVE THE QUALITY OF THE PRODUCTS, INCLUDING REDUCING THE SALT CONTENT.

SALT INTAKE IN SOUTH AFRICA AVERAGE SALT INTAKE DETERMINED BY URINARY SODIUM EXCRETION 8.1 GRAM PER DAY RECOMMENDATION < 5 GRAM PER DAY

DISCRETIONARY SALT INTAKE SOUTH AFRICA - BETWEEN 33%-46% DEVELOPED COUNTRIES - BETWEEN 15%-25%

IN SOUTH AFRICA A HEALTH PROMOTION CAMPAIGN MAY BE NECESSARY TO REDUCE DISCRETIONARY ADDITION OF SALT IN FOOD PRERATION. A GRADUAL REDUCTION OF SALT CONTENT IN FOODS ALLOWS THE POPULATION TO ADAPT EASILY TO LOWER SALT CONTENT WITHOUT

IMPACT OF SALT REDUCTION IN SA Reductions in salt in bread, margarine, soup mix and flavoured seasoning (Charlton) will reduce salt intake by 0.85 grams per day. Lowering the sodium content of these foods would reduce the population distribution of systolic blood pressure. This will result in 7,400 fewer deaths due to CVD and 4,300 less non-fatal strokes per year than in 2008. (Bertram etal SAMJ in press)

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