Sodium Recommendation 2005 Dietary Guidelines for Americans (DGA) recommendation: <2,300 mg/day. http://www.health.gov/dietaryguidelines/dga2005/document/pdf/DGA2005.pdf “Specific populations” recommended to limit intake to 1,500 mg/day: Hypertensives Blacks Middle-aged (40) or older Americans “Specific populations”: 70% of American adults. Average intake: 3,466 mg/day. Source: Ayala C, et al. Application of lower sodium intake recommendations to adults—United States, 1999–2006. MMWR Morb Mortal Wkly Rep. 2009;58(11):281–283.
Canadian Best Practice Recommendations for Stroke Care, updated 2008 2.1 Sodium: The recommended daily sodium intake from all sources is the Adequate Intake by age. For persons 9-50 years, the Adequate Intake is 1500 mg. Adequate Intake decreases to 1300 mg for persons 50-70 years and to 1200 mg for persons > 70 years. A daily upper limit of 2300mg should not be exceeded by any age group. See www.sodium101.ca for sodium intake guidelineswww.sodium101.ca CMAJ 2008;179(12 Suppl):E1-E93 #2.1
Recommendations for Adequate Sodium Intake by Age AgeSodium Intake per Day (mg) 0-6 months120 7-12 months370 1-3 years1000 4-8 years1,200 9-50 years1,500 50-70 years1,300 > 70 years1,200 CMAJ 2008;179(12 Suppl):E1-E93 #2.1
High Blood Pressure: Major Component of Chronic Disease Risk Proportion of incidence due to high blood pressure ( Systolic >115 mmHg) Stroke 70-75% Congestive Heart Failure 50% Ischemic Heart Disease 25% Renal Failure 20% High blood pressure is the leading cause of mortality worldwide Lancet 2006 367:1747
Sharp increase in sodium consumption: Source: Briefel and Johnson (2004) for 1971-2000 data; NHANES for 2003-2006 data.
Main sources are commonest foods: USDA Major Food Categories Source: CDC NHANES unpublished data.
Hypertension Detection and Management in Thailand 2005 (>15 years) 3 rd NHES 2005.
A few are meeting the target daily intake: Met the 2005 DGA Recommendation All Adults9.6% <2,300 mg/day Recommended18.8% ≤ 1,500 mg/day Recommended5.5% With hypertension5.9% Aged 40 years and older without hypertension 5.1% Black, aged 20–39 years5.7% Source: CDC NHANES unpublished data.
Many purchasers do buy “Low Salt”: Frequency of Buying “Low Salt” Items by Gender AlwaysOftenSometimesRarelyNeverDon’t Shop for Food All11.7%12.8%22.8%17.3%27.0%8.4% Male Female 10.5% 12.8% 11.4% 14.0% 19.9% 25.4% 16.0% 18.5% 27.8% 26.3% 14.4% 2.9% SOURCE: NHIS unpublished data. 47.3% of all shoppers
Thank You CDC Sodium Web Page: http://www.cdc.gov/dhdsp/library/sodium.htm http://www.cdc.gov/dhdsp/library/sodium.htm The findings and conclusions in this presentation are those of the author and do not necessarily represent the official position of the Centers for Disease Control and Prevention. For More Information:
A Brief History… The Yellow Emperor’s Classic of Internal Medicine written in China over 2,000 years ago notes*: “Hence if too much salt is used for food, the pulse hardens” *Veith, I. (Translator) U of California Press, 2002. For millions of years daily sodium intake < 400 mg/day - genetically programmed level Recent change to 3-4,000 mg/day - a major physiological challenge
Salt: Increasing the Pressure High sodium fluid retention B.P. Kidneys excrete sodium fluid retention B.P. Prolonged high sodium intake may reset thresholds set by kidneys. Kidneys are less able to remove sodium as we age. Genes (14) responsible for Mendelian forms of hypo- or hypertension are all involved in renal sodium handling. Low dietary potassium renal sodium retention B.P. Signaling pathway in vasculature responds to sodium but does not regulate basal B.P. ( Nat. Med. 2008 14:64 ). Mechanisms by which dietary sodium increases arterial pressure are not fully understood
Sodium and Blood Pressure Animal studies Human Genetic Studies Epidemiological Studies Migration studies Interventional Studies Treatment Studies Evidence:
Animal Studies Chimps: 2 groups of 13 (age 5-18y) Control group usual veg. & fruit diet, low Na +,high K + Intervention group fed increasing amounts of salt over 84 weeks *Nature Med 1995; 1:1009-16 InterventionChange in mean B.P. vs. controls 5g/d 19 weeks+12 mmHg (systolic) 10g/d 3 weeks, 15g/d 36 weeks+26 mmHg 15g/d 26 weeks+33 mmHg 0g/d 20 weeksControl levels Similar study (127 chimps) finds effect of Na + on B.P. persists over 2 year time course (Circulation 2007 116:1563).
Treatment Study: DASH Sodium Control diet - low in fruit, veg and dairy, fat content typical of US DASH diet - high in fruit, veg and low-fat dairy, reduced fat content Consume diet for consecutive 30 day periods in random order at each of 3 levels of salt NEJM 2001; 344:3-10 InterventionChange in mean B.P. vs. control (systolic) Control dietDASH diet 9g/d saltControl level- 6 mmHg 6g/d salt- 2 mmHg- 7 mmHg 3g/d salt- 7 mmHg- 9 mmHg -7 Randomized 412 adults (mixed B.P. status, racial groups, sexes) to: -7 (NT) -11(HT)
Blood Pressure and Stroke 30% reduction in risk 10 mmHg 35% strokes*65% strokes* Based on trial data n =190,000 Stroke 2004 35:1024 *Registry data
Blood Pressure and Stroke Clinical cut-off points do not reflect continuous relation between B.P. and health outcomes “Normotensives” get strokes too – key is to reduce population risk! 10 mmHg reduction in systolic B.P. reduces individuals stroke risk by >30% Mean systolic B.P. reductions of 5-10 mmHg are potentially achievable by reducing sodium consumption. -7
Sodium (salt) in our Diet Natural ~15% Discretionary ~15% Manufactured food processing ~70% Adequate Intake* 1,500 mg/d (3.8 g salt) Tolerable Upper Intake* 2,300 mg/d (5.8 g salt) Reference Standard** 2,400 mg/d (6.1 g salt) 3,000 – 4,000 mg/d (8-10 g salt) Health Minimum 180 mg/d *Health Canada. Dietary Ref. Intake Reports **2003 labeling legislation
Public Health Impact ~3,500 mg/day (current) ~1,500 mg/day (AI) Decrease hypertension prevalence by 30% (CJC 2007 23:437) Prevent 30 premature deaths per day from Stroke and IHD, ~15% all CV events (CJC 2008 24:497) Likely positive impact on obesity, osteoporosis, stomach cancer, kidney disease, asthma, etc… BP ~5 mmHg
Sodium in our Food: Hard to Avoid Food (CCHS 2004 data)% Pizza, sandwiches, subs, burgers, hot dogs*19.1 Soups7.4 Pasta5.7 Liquid milk products4.0 Poultry and poultry dishes3.8 Potatoes3.4 Cheese3.2 Cereals3.0 *Breads14.0
Sodium in our Food: Why? $ Cheap way to boost flavor, texture and shelf life of poor quality foods $ Salt and sodium phosphates increase water binding capacity of meat products $ Salty snacks make you thirsty! $Food – (fiber, nutrients, flavor) + (salt, sugar, fat) = $$Processed food
Sodium in our Food: Would we miss it? Taste buds are used to high salt levels As salt levels are gradually reduced taste buds become more sensitive Studies have shown that it only takes a few weeks to enjoy food with less salt and reveal subtle flavors