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Salt, Sodium and Blood Pressure

Salt, Sodium and High Blood Pressure 

  • Sodium is a major contributor to high blood pressure and as intake of the mineral goes up, so does the risk of stroke, heart attack, kidney damage, stomach cancer, and osteoporosis.
  • Since sodium accounts for 40% and chloride 60% in the salt, 6g of table salt contains 2.4g of sodium and 3.6g of chloride. Sodium content in commonly used measures of salt is given in Table 122A. Aim to eat less than 1,500 mg of sodium (or ½ tsp salt) per day.

Table 122 A. Sodium Content in Commonly Used

Measures of Salt

Salt measure Sodium content
1/4 teaspoon salt  600 mg sodium
1/2 teaspoon salt  1200 mg sodium
3/4 teaspoon salt  1800 mg sodium
1 teaspoon salt  2400 mg sodium
1 teaspoon baking soda  1000 mg sodium

 

  • High blood pressure is the second leading modifiable cause of death, accounting for 54% of all stroke and 47% of all coronary events worldwide. In the US alone, blood pressure accounted for 350,000 preventable US deaths annually.1                           
  • In clinical trials, the participants who consumed the least sodium had the greatest reduction in blood pressure. Significantly, people who started the study with normal blood pressure also saw their blood pressure go down with lower sodium intake.  
  • The relation between blood pressure (BP) and adverse health outcomes is direct and progressive with no evidence of a threshold; that is, the risk of cardiovascular disease (CVD), stroke, and end-stage kidney disease increases progressively throughout the range of usual blood pressure starting at a level of >115/75 mm Hg.1 The CVD risk doubles for every 20 point increase in systolic and 10 point increase in diastolic blood pressure.2
  • Modest reductions in dietary salt could substantially reduce cardiovascular events and medical costs and should be a public health target.3 For example, reducing dietary salt by 3 g (1200 mg sodium) per day in the US is projected to reduce the annual number of new cases of coronary artery disease by 60,000 to 120,000, stroke by 32,000 to 66,000, and heart attacks by 54,000 to 99,000 and to reduce the annual number of deaths from any cause by 44,000 to 92,000.3
  • A regulatory intervention designed to achieve a reduction in salt intake of 3 g per day would save 194,000 to 392,000 quality-adjusted life-years and $10 billion to $24 billion in health care costs annually.1, 3

Sodium Intake in the US and UK

  • Men, in particular are putting their health at risk by eating more salt than women. In the United Kingdom (UK) men are eating the equivalent of 365 pints of salt in a lifetime. Men, on average, eat over 2g more salt a day than women and are less aware that salt can damage their health.
  • Men also have a higher blood pressure than women, particularly at a younger age, are less likely to have their blood pressure measured and take action to reduce it when it is raised, or take blood pressure lowering drugs.
  • The UK has had an active nationwide salt reduction program since 2003. Nevertheless, intakes remain well above the maximum recommended limit of 6 g/d.4 In the UK, sodium reduction targets have been set for a large number of processed food categories.
  • A study of 44,372 food products in the UK revealed that the largest contributors to sodium purchases were table salt (23%), processed meat (18%), bread and bakery products (13%), dairy products (12%), and sauces and spreads (11%). More than one-third of sodium purchased (37%) was accounted for by 5 food categories: bacon, bread, milk, cheese, and sauces.
  • For some food groups (bread and bakery, cereals and cereal products, processed meat) market leaders have higher sodium (18-35% higher) contents than the category mean.
  • The targeting of sodium reduction in a small number of food categories and focusing on products sold in the highest volumes could lead to large decreases in sodium available for consumption and therefore to gains in public health.4 See Table 121 A.

 

Table 121A.Selected Foods with High Sodium Content4(in mg/100g)

Sauces and Spreads 1090-1286
Snack Foods 739
Processed Meats 590
Bacon 1298
Sliced Ham 939
Processed Vegetables 195
  • Comparisons with similar data from Australia shows that for most food groups the unweighted mean sodium content of Australian foods are 50-80% higher than those in the UK. 4
  • In the American diet, about 80 percent of salt comes from processed or prepared foods — 35 percent of that in cereals, breads and pastries. The hidden places of salt in our diet are in breads and cereals, canned foods and condiments, and of course fast foods. Most of the salt that we eat is not from our salt shaker, but salt that is already added in food that we eat.
  • Americans’ salt consumption has been shaped in part by changes in eating habits as people consume more processed foods, dine out more frequently, and prepare fewer meals from basic, raw ingredients in the home.
  • Any meaningful strategy to reduce sodium intake population-wide must involve the efforts of food manufacturers, food processors, and restaurant industries, a strategy that is being successfully implemented in other countries.

Salt Intake and Teenagers

  • Teenagers eat more salt each day — more than 9 grams (3,800 milligrams of sodium) — than any other age group. The American Heart Association and Indian Council of Medical Research recommend no more than 1,500 milligrams of sodium (65 mmol/d) per day for most Americans. (2020 AHA goal).5 Small decreases in salt consumption among teens could reduce high blood pressure, heart disease, and stroke in adulthood.
  • The enormous benefit of reducing the salt intake in teenagers was recently reported. Reducing the salt in the teenage diet from an average of 9 grams to 6 grams (1 teaspoon or 2500 mg sodium) would get teenage boys and girls to appropriate levels of salt intake and reduce the systolic blood pressure by 2.4 mm Hg.
  • An apparently miniscule reduction in blood pressure in all teenagers would lead to a 44-63% decrease in the number of teenagers and young adults with high blood pressure (380,000 to 550,000) as well as a 30-43% decrease in the number of adults with high blood pressure at ages 35 to 50 (2.7 to 3.9 million).
  • As teenagers reach the age of 50 years, other health benefits of reducing salt intake are shown in Table 123A.
Table 123A.Long Term Health Benefit of Reduced Salt Intake in Teenagers by the Time they are 50 Years of Age
Percent reduction Absolute number
7 to 12% in coronary artery disease 120,000 to 210,000
8 to 14% reduction in heart attacks 36,000 to 64,000
5 to 8% reduction in stroke 16,000 to 28,000
5 to 9% reduction in death from any cause 69,000 to 120,000
Less salt in teenagers’ diet may improve heart health in adulthoodAmerican Heart Association Meeting Report – Abstract 18899/P2039 Co-authors are: Pamela Coxson, Ph.D.; Tekeshe Mekonnen, M.S.; David Guzman, M.S.; and Lee Goldman, M.D., M.P.H. abstract

 

  • Processed foods and fast foods, pose high salt hazards to families and teens. Pizza is the biggest culprit of salt for teens according to data from the National Center for Health Statistics. Researchers say food manufacturers should continue to reduce salt levels in their products.
  • Manufacturers should continue to reduce salt in their foods in cooperation with local, state, and federal regulatory agencies. Many major companies have already joined the National Sodium Reduction initiative and have voluntarily agreed to work to lower the salt content that is already added to processed and prepared foods.

Sources

1. Appel LJ, Frohlich ED, Hall JE, et al. The importance of population-wide sodium reduction as a means to prevent cardiovascular disease and stroke: a call to action from the American Heart Association. Circulation. Mar 15 2011;123(10):1138-1143.

2. Chobanian AV, Bakris GL, Black HR, et al. The Seventh Report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure: the JNC 7 report. Jama. 2003;289(19):2560-2572.

3. Bibbins-Domingo K, Chertow GM, Coxson PG, et al. Projected effect of dietary salt reductions on future cardiovascular disease. N Engl J Med. Feb 18 2010;362(7):590-599.

4. Ni Mhurchu C, Capelin C, Dunford EK, Webster JL, Neal BC, Jebb SA. Sodium content of processed foods in the United Kingdom: analysis of 44,000 foods purchased by 21,000 households. Am J Clin Nutr. Dec 29 2010.

5. Lloyd-Jones D. M., Hong Y, Labarthe D, et al. Defining and setting national goals for cardiovascular health promotion and disease reduction: the American Heart Association’s strategic Impact Goal through 2020 and beyond. Circulation. Feb 2 2010;121(4):586-613.

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