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Diets

Does Salt Cause High Blood Pressure?

Salt adds flavor and provides sodium, an essential element in our diet.  In a world of scarcity, humans had no need to limit their sodium intake.  In a world of plenty, our natural inclinations mean we must be wary of consuming too much sodium – especially in the form of added salt.

While sodium is available in many foods, it is usually a challenge to meet our dietary need without supplemental salt.  Today, the need for sodium and salt for supplemental sodium is well understood.  The question is, how much of this tasty food additive is enough and how much is too much for good health.

Because food labels usually show sodium content rather than salt content, estimating the equivalent salt per serving can be confusing.  For now, just be aware that salt is only about 40% sodium.

For most of early human history, people are believed to have consumed about ¾ of a gram of sodium per day or the equivalent of about 2 grams of salt.  During the hunter-gathering period of Paleolithic times, sodium intake may have risen to 1 gram per day (about 2.5 grams of salt) from diets that are believed to have been about 50% meat and 50% plants. In these hunter-gather diets, most sodium in the diet came from meats.

As society changed and agriculture developed, meat consumption decreased. To compensate, it became necessary to supplement food with added salt.  In some regions, the scarcity of supplemental dietary salt turned salt into a precious commodity of commerce.  Today, dietary sodium consumption per person has increased to an average of 3.5 grams per day in the United States.  For some, consuming 9-12 grams per day is not unusual. At 12 grams per day, that’s a 24 fold increase in salt consumption since ancestral times.

In modern times, increased salt intake has been implicated as a cause of high blood pressure that can lead to cardiovascular disease that in turn causes 62% of cerebrovascular disease and 49% of ischemic heart disease.  Interestingly, this is not a new discovery.  The effects of excessive dietary salt on blood pressure were documented by a Chinese medical doctor living in 2500BC.

For reasons that are not fully understood, the effect of salt on blood pressure varies.  Some people have little increase in blood pressure despite high levels of salt consumption.  In younger people, salt often has little effect on blood pressure. As we get older the effect of salt on blood pressure usually becomes greater.

            Around the world, health organizations in different countries recommend different amounts of salt in the diet.  The World Health Organization recommends a reduction in dietary salt to less than 5 grams per day.  In the United States, the CDC and the, United States Department of Agriculture (USDA) recommendation is for less than 2.3 grams of sodium per day.  The American Heart Association (AHA) recommendation is for less than 1.5 grams of sodium per day.

            While these recommendations differ, be aware that USDA recommendations are typically biased by what people might do if encouraged verse what a cardiologist would tell you is best for your health.  In fairness to USDA, reaching the AHA recommendation on the Standard American Diet (SAD) would be impossible.

            In recent years, studies about the effects of salt in the diet have been published with conflicting findings.  As you might expect, most studies about diets are short-term and often raise more questions than they answer.  Still, certain trends have been observed.   In general, people who have high blood pressure, diabetes, kidney problems, are African-American or over age 50 need to read food labels for sodium content and choose wisely to decrease their sodium intake.  For more about the source of these controversies read “A Pinch of Controversy Shakes Up Dietary Salt.

The difference between Sodium and Salt?

            Sodium in its pure form is a soft, silvery-white, highly reactive metal represented by the symbol ‘Na.’ Fortunately, we are unlikely to encounter sodium in its pure form except in a laboratory situation.  What we need for nutrition is compounds containing sodium that the body can extract sodium from. Naturally occurring plant-based foods contain small amounts of sodium and usually insufficient amounts for good health.  To meet the body’s need, minerals containing sodium must supplement the diet.  The supplement of choice is usually the common salt called Sodium Chloride (NaCl) which is 40% sodium (Na) and 60% chloride (Cl).  While there are many compounds that contain sodium, not all have chemical properties that make the sodium in them available during the digestive process.  Fortunately almost everyone gets enough sodium from salt.  Unfortunately, the trend toward consumption of highly salted processed foods has raised daily salt consumption to unhealthy levels for anyone consuming processed foods or frequently eating out.

Recommended Dietary Salt

            Given that most sodium in our diet comes from the common salt called Sodium Chloride you may be wondering how much salt is needed to supplement the diet with 2,300 milligrams of sodium.  The answer depends on the brand of salt used. One teaspoon of common table salt typically contains 2,325 milligrams of sodium whereas one teaspoon of kosher salt has roughly 1,800 milligrams.  The lower sodium content per teaspoon of Kosher salt, sea salts and many gourmet salts is due to their larger and hence less compact crystals.  By weight, all salts have very close to the same amount of sodium.  Reading labels is the key to knowing how much sodium you consume from a teaspoon of salt.

Most foods disclose the amount of sodium (naturally occurring and added). It’s only when you add salt that you might need to know the type of salt to compute the total sodium. If math challenged, you will be pleased to know that online calculators can make short work of the salt to sodium conversions.

While many packaged food products taut their salt-free nutritional qualities, it’s the total sodium from all foods that make the important difference.  If looking for a low sodium alternative then join me for a beautiful morning walk. My morning walks feature salt free crystal clear water.

Nancy Neighbors, MD

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Tips for Lowering Sodium at the Supermarket

  • Buy fresh, frozen (no sauce), or no salt added canned vegetables.
  • Use fresh lean meat, rather than canned or processed meats.
  • When available, buy low sodium, lower sodium, reduced sodium, or no salt added versions of products.
  • Limit your use of sauces, mixes, and “instant” products, including flavored rice and ready-made pasta.
  • Compare nutrition facts labels on food packages for Percent Daily Value or amount of sodium in milligrams.
  • If salineor salt solution has been added then choose another brand.

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Tips for Lowering Sodium While Eating Out

            Restaurant foods are a major source of sodium in most Americans’ diets, so it pays to take a few minutes to find out what’s in the food you’re eating. Planning ahead also can help you find restaurants that have information on sodium levels in the foods they serve. To reduce your sodium when you are eating out at a restaurant:

  • Check online for nutritional information before you go if you are eating at a chain restaurant or fast-food outlet. Some independent restaurants also post this information on their Web sites.
  • Ask your server for information about the amount of sodium in your food. Sometimes this information is printed on the menu.
  • Request that no salt be added to your food.
  • Beware of hidden sources of sodium such as sauces and dressings, and ask for these toppings on the side.

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Salt Facts

  • Sodium serves as an important nutrient in the body and helps nerves and muscles to function correctly. It is also involved in the auto-regulation of the water and fluid balance of the body.
  • High salt diets have been linked to diabetes, heart disease, and other health problems that can result from the condition known as metabolic syndrome.
  • High dietary salt intake presents a major challenge to the kidneys.
  • The cardiovascular system is vulnerable to adverse effects from excessive sodium.
  • At extremes, low salt intake health complication can arise including the risk of death.
  • A reduction of 1.2 grams of salt per day could reduce heart attacks and strokes by 150,000 per year in the United States.
  • Most table salt has been purified with trace minerals removed and iodine as additives.
  • Sea salt is often sold as a tastier and healthier option.  Unfortunately, the trace minerals are seldom listed which leaves the health value unknown. 

By Nancy Neighbors, MD

... Dr. Neighbors provides a blend of traditional family medicine and evidence-based lifestyle medicine in Huntsville, Alabama. When indicated, lifestyle change is recommended as the first line of therapy.

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