Sodium and Hypertension

Table of Contents

Resources

Wikipedia articles:

Salt and sodium:

Medical topics:

Other resources on Salt & Sodium

The US Food and Drug Administation (FDA) Guidance on salt.

Canada Department of Heath (Health Canada):

The US Department of Agriculture (USDA) 2020-2025 Dietary Guidelines.

The American Heart Association (AHA):

Nutrients, Food Components

The widest data is found in the US Deparment of Agriculture Agricultural Research Service’s FoodData Central (“USDA FDC”) which can search 5 data sets called

  • Foundation Foods,
  • Standard Reference Legacy Foods,
  • Human Research Center Food and Nutrient database for Dietary Studies (“FNDDS Survey Foods”),
  • Branded Foods,
  • Experimental Foods.

It may be necessary to repeat searches in each set. The American government does not collect or test samples except for the FNDDS Survey Foods. The government requires tests from accredited services at a manufacturer or distributor’s expense in most instances.

Other countries, including Canada have data sets on products offered for sale in those countries. The data comes from manufacturers or hired services. Government or independent testing is limited.

Hypertension

Blood Pressure

Western medical science credits the idea that blood, rather than the “humours” postulated by classical and medieval Greek, Roman, Arabic, and middle Eastern writers, circulated through the body by vessels from and to the heart to William Harvey, in 1628. The stethoscope was invented produced early in the 19th century. Measurement of blood pressure started late in the 19th century with the invention of the sphygnomanometer. In 20th century medical practice:

Blood pressure is one of the vital signs … that healthcare professionals use in evaluating a patient’s health.

Wikipedia, Blood Pressure, September

Measurement involves

  1. restricting blood flow in the brachial artery, a major artery in the upper arm,
  2. releasing it and
  3. using a sphygnomanometer to measure the pressure.

Modern devices use an inflatable cuff on the arm to restrict the flow. The units of measurement are millimeters of mercury (abbreviated mmHg),derived from the original mercury column sphygnomanometer. Systolic pressure is the maximum pressure during one heartbeat. Diastolic pressure is the minimum pressure between two heartbeats. The normal blood pressure of a healthy adult is 120 mmHg systolic and 80 mmHg diastolic, written as 120/80, read aloud as 120 over 80. General observations:

“… the average blood pressure, age standardized, since 1975 to the present, at approx. 127/79 in men and 122/77 in women, although these average data mask significantly diverging regional trends.”

… in many older people, systolic blood pressure often exceeds the normal adult range”.

….

Blood pressure fluctuates from minute to minute and normally shows a circadian rhythm over a 24-hour period, with highest readings in the early morning and evenings and lowest readings at night. Loss of the normal fall in blood pressure at night is associated with a greater future risk of cardiovascular disease and there is evidence that night-time blood pressure is a stronger predictor of cardiovascular events than day-time blood pressure. Blood pressure varies over longer time periods (months to years) and this variability predicts adverse outcomes. Blood pressure also changes in response to temperature, noise, emotional stress, consumption of food or liquid, dietary factors, physical activity, changes in posture (such as standing-up), drugs, and disease. The variability in blood pressure and the better predictive value of ambulatory blood pressure measurements has led some authorities, such as the National Institute for Health and Care Excellence (NICE) in the UK, to advocate for the use of ambulatory blood pressure as the preferred method for diagnosis of hypertension

Wikipedia, September 2022, Blood Pressure

Some meaurement methods are superior to others but more expensive and time consuming for health care providers and patients.

In hospital settings, nurses use automated meters. Automated meters are also used in ambulatory measurement. Home automated meters are available for people to measure and record their blood pressure. Automated meters inflate a cuff, detect when blood flow through the limb has paused, take readings, release the cuff, record and display blood pressure and pulse.

In theory, devices are calibrated regularly and reliably. Home devices, in theory are self-calibrating.

Readings play a major role in the diagnosis and treatment of hypertension. The AHA’s classification of 5 bands of BP readings sets out a guide followed by most physicians.

In modern practice, a physician may use

  • a stethosope to listen to the artery to check for sounds of blood flow and an aneroid sphygnomanometer, or
  • an automated meter.

Measurement is complicated by environmental and psychological factors. Health care professionals recognize white coat hypertension which is studied in reference to the effect of being monitored in a clinical setting but generally trust the devices.

General

Hypertension (AHA stage 2, above) is a medical condition in which the blood pressure in the arteries is persistently elevated – systolic blood pressure is elevated (>140 mmHg) with a normal diastolic blood pressure (<90 mmHg). Isolated systolic hypertension may present a health concern. This is called elevated by the AHA or prehypertension in some material. Where those readings (140/90) appear twice, a medical doctor can diagnose hypertension. Doctors often prescribe medications to reduce blood pressure to levels under 140/90. Medical care is often dedicated to managing medications and adverse side-effects. The medications have adverse side-effects. ACE inhibitors (e.g.), can cause persistent dry coughing, among other things. Calcium channel blockers (e.g. Amlodypine) often cause peripheral edema.

Hypertension … is a long-term medical condition in which the blood pressure in the arteries is persistently elevated. High blood pressure usually does not cause symptoms. Long-term high blood pressure, however, is a major risk factor for stroke, coronary artery disease, heart failure, atrial fibrillation, peripheral arterial disease, vision loss, chronic kidney disease, and dementia. Hypertension is a major cause of premature death worldwide.

High blood pressure is classified as primary (essential) hypertension or secondary hypertension. About 90–95% of cases are primary, defined as high blood pressure due to nonspecific lifestyle and genetic factors. Lifestyle factors that increase the risk include excess salt in the diet, excess body weight, smoking, and alcohol use. The remaining 5–10% of cases are categorized as secondary high blood pressure, defined as high blood pressure due to an identifiable cause, such as chronic kidney disease, narrowing of the kidney arteries, an endocrine disorder, or the use of birth control pills.

Blood pressure is classified by two measurements, the systolic and diastolic pressures, which are the maximum and minimum pressures, respectively. For most adults, normal blood pressure at rest is within the range of 100–130 millimeters mercury (mmHg) systolic and 60–80 mmHg diastolic. For most adults, high blood pressure is present if the resting blood pressure is persistently at or above 130/80 or 140/90 mmHg. … Ambulatory blood pressure monitoring over a 24-hour period appears more accurate than office-based blood pressure measurement.

Wikipedia, September 2022, Hypertension

It is common for the diagnosis of hypertension to be made upon by readings taken by machine.

Treatment

Lifestyle changes and medications can lower blood pressure and decrease the risk of health complications. Lifestyle changes include weight loss, physical exercise, decreased salt intake, reducing alcohol intake, and a healthy diet. If lifestyle changes are not sufficient, then blood pressure medications are used. Up to three medications taken concurrently can control blood pressure in 90% of people. The treatment of moderately high arterial blood pressure (defined as >160/100 mmHg) with medications is associated with an improved life expectancy. The effect of treatment of blood pressure between 130/80 mmHg and 160/100 mmHg is less clear …

….

The first line of treatment for hypertension is lifestyle changes, including dietary changes, physical exercise, and weight loss. Though these have all been recommended in scientific advisories, a Cochrane systematic review found no evidence for effects of weight loss diets on death, long-term complications or adverse events in persons with hypertension.The review did find a decrease in body weight and blood pressure.Their potential effectiveness is similar to and at times exceeds a single medication. If hypertension is high enough to justify immediate use of medications, lifestyle changes are still recommended in conjunction with medication.

Dietary changes shown to reduce blood pressure include diets with low sodium, the DASH diet (Dietary Approaches to Stop Hypertension), and plant-based diets. … There is evidence from randomized, double-blind, placebo-controlled clinical trials that Hibiscus tea consumption significantly reduces systolic blood pressure (-4.71 mmHg, 95% CI [-7.87, -1.55]) and diastolic blood pressure (-4.08 mmHg, 95% CI [-6.48, -1.67]). Beetroot juice consumption also significantly lowers the blood pressure of people with high blood pressure

Increasing dietary potassium has a potential benefit for lowering the risk of hypertension. The 2015 Dietary Guidelines Advisory Committee (DGAC) stated that potassium is one of the shortfall nutrients which is under-consumed in the United States. However, people who take certain antihypertensive medications (such as ACE-inhibitors or ARBs) should not take potassium supplements or potassium-enriched salts due to the risk of high levels of potassium.

Wikipedia, September 2022, Hypertension

In the short run, drinking alcohol increases blood pressure for a short period after consumption. One drink will raise blood pressure for about two hours. Long term regular drinking contributes to hypertension, The causation is still under discussion. A modern (2014) paper says:

… the mechanism through which alcohol raises blood pressure remains elusive. Several possible mechanisms have been proposed such as an imbalance of the central nervous system, impairment of the baroreceptors, enhanced sympathetic activity, stimulation of the renin-angiotensin-aldosterone system, increased cortisol levels, increased vascular reactivity due to increase in intracellular calcium levels, stimulation of the endothelium to release vasoconstrictors and loss of relaxation due to inflammation and oxidative injury of the endothelium leading to inhibition of endothelium-dependent nitric oxide production. Loss of relaxation due to inflammation and oxidative injury of the endothelium by angiotensin II leading to inhibition of endothelium-dependent nitric oxide production is the major contributors of the alcohol-induced hypertension. For the prevention of alcohol-induced hypertension is to reduce the amount of alcohol intake. Physical conditioning/exercise training is one of the most important strategies to prevent/treat chronic alcohol-induced hypertension on physiological basis. The efficacious pharmacologic treatment includes the angiotensin-converting enzyme (ACE) inhibitors or angiotensin II type 1 receptor blockers (ARBs) which have antioxidant activity and calcium channel blockers.

Abstract, Husain, Ansari, Ferder; Alcohol-induced hypertension: Mechanism and prevention 6 World J. Cardiol. 245 (2014)

Abstention by long term regular drinkers can reduce blood pressure readings during the period of absention. Studies:

Sodium

Salt

Salt is found as a crystaline solid, or in solution in water. Salt can be mined from mineral deposits, or extracted from seawater by evaporation.

Salt is chemically described as sodium chloride. One molecule of salt has one atom of sodium (Na) and one atom of chlorine (Cl). Salt crystals dissolve in water.

Salt molecules consumed by living organisms becomes use in extracellular fluid and interstitial fluid.

Sodium – nutrient and hazard

Sodium is an element, an alkaline earth metal in Group 1, in the periodic table. In living organisms, salt is separated into sodium cations (positively charged ions) and chlorine anions. Before industrial food processing manufactured other products made with sodium, humans consumed animals and plants, or salt, to acquire sodium. Most plants consume little salt, but animals require sodium. Sodium is a vital nutrient in all animals, including humans:

Sodium ions play a diverse and important role in many physiological processes, acting to regulate blood volume, blood pressure, osmotic equilibrium and pH.

Wikipedia, Sodium in Biology, September 2022

Sodium is the primary cation in extracellular fluids in animals and humans. Sodium ions pass into cellular fluid by the enzyme in the cell walls known as the sodium-potassium pump.

The adequate intake for sodium is 1,200 to 1,500 milligrams per day. On average, people in the United States consume 3,400 milligrams per day, an amount that promotes hypertension. As salt contains about 39.3% sodium by mass, the safe upper limit for sodium is under 1 teaspoon per day. 1 tsp of table salt weighs 5.7 grams, and contains 2,240 mg. of sodium.

Salt was a vital substance to preserve and store food for centuries. It was not believed to be harmful until medical research was conducted in the 20th century.

Most salt for cooking is processed to standard sized crystals sold as table salt. It is the standard presentation of the salt sold in grocery stores for household use in cooking and baking. The crystals are small enough to fit the holes in a salt shaker, and dissolve in water including in the amounts used to mix bread dough in industrial bakeries. Table salt is treated with anti-caking agents. Depending on manufacturer and brand, it may be treated with or without iodine and other chemicals.

Kosher salt is a table salt with slightly larger crystals, and normally not treated with chemicals other than anti-caking ingredients.

Sea salt may have crystals of varying sizes, some of which may not dissolve and distribute uniformly during cooking and baking.

Humans became habituated to salt. During the industrialization of food processing, yhe food industry used salt to mask the changes to the taste of food that was processed in canneries, and began to use salt as flavour enhancer to increase the sales of processed foods. The food industry resists reducing the use of sodium in the preparation of packaged foods and restaurant meals. It markets some salty items as traditional foods. Its lobbyists and lawyers disputes the harms of salt. The food industry argues that

  • consumers make informed decisions (the argument tobacco companies and drug companies used to defend their profit from the sale of addictive harmful products), and
  • manufacturers have the right to use salt and marketing to sell products.

Food (Nutrition) Facts labels

Manufacturers are required to disclose facts to the USDA in the USA, and to disclose facts to persons purchasing packaged foods with a label on the package headed “Nutrition Facts”.

Sodium is listed in the Food/Nutrition facts labels in milligrams; (.001 or 1/1000 of a gram). Sodium is also stated as a % of the national recommended daily allowance (usually the USDA RDA) in a stated amount called a serving, as defined by the manufacturer. It is usually given as a volume and often also as a weight measured in grams.

There are regulations in the USA requiring chain restaurants to disclose sodium content on menus and in some instances tag the content with health risk logo that may alert consumers. These regulations are resisted by restaurants and manufacturers, by lobbying, occasional litigation, obscurity, equivocation and evasion. The Canadian CBC Network covered sodium in restaurant food in Canada in its television/streaming program Marketplace‘s episode Putting takeout to the test: the shocking amount of sodium in some restaurant meals (Season 50, Episode aired January 6, 2023) – Text for internet article, with link to YouTube video.

I have put sodium content of several food items in a table at the end of this post that I can alter without changing the rest of this post.

Salt Free Foods

Some manufacturers have produced salt free foods and brought them to market, and abandoned them for unknown reasons.

In British Columbia, Canada, the Thrifty’s grocery stores (now part of the retail group that manages the Sobeys stores) sold a store brand of no sodium whole wheat bread. It wasn’t good but it appeared to sell. The store stopped offering it during the pandemic, in about 2020.

Becel (an Upfield brand) packaged a low sodium margerine spread for several years. It disappeared in 2019. Becel’s other margerine spreads generally have about 70 mg. of sodium per 2 tsp. of margerine spread. Becel/Upfield does not post Nutrition Facts on the Web (it complies with the law and has Nutition Facts labels on it product tubs and wrappers. Becel/Upfield promotes Becel margerine spreads as healthy plant based oil products. Becel still manufactures a salt free margerine, sold in blocks. It is not spreadable.

Some zero salt products available before 2020 fell victim to supply chain problems or disappeared for retail stores during the pandemic

Salt Sensitivity

The journal Hypertension published Salt Sensitivity of Blood Pressure; A Scientific Statement From the American Heart Association in Volume 68, No. 3 in September 2016 which argued for the existence of a physiological trait by which the blood pressure of some members of the population exhibits changes parallel to changes in salt intake.

Physicians in most places do not diagnose salt sensitivity.

Physicians in most places diagnose hypertension on the basis of blood pressure readings, and treat it by prescribing anti-hypertensive medication and testing patients periodically. A few countries cover the cost of prescribed medications under health insurance or drug cost insurance.

Baking

Salt used in baking yeasted or yeast-leaving bread to flavour bread and to affect the formation of gluten. It is a normal ingredient in recipes and formulas for yeasted bread, as I discuss in my post Sodium in Bread.

Baking Soda

Baking soda, also known as sodium bicarbonate is used in baking as a chemical leaving agent. It is also used as an ingredient in manufacturing baking powder. It is not uncommon for baking recipes to use both baking powder and baking soda. Baking soda has some other uses in cooking, and several other uses.

There is a sodium free baking soda substitute called Ener-G Baking Soda Substitute, manufactured by Ener-G Foods Inc., and available for sale online.

Baking Powder

Baking powder is a chemical leavening agent used in baking, made with baking soda. There is a sodium free baking powder substitute called Featherweight, manufactured by Hain Pure Foods, and available for sale online

Sodium in Food Table

This table does not include food products used in baking including salt. That information is in a table embedded in the post for baking ingredients

The column headings list the items, in groups. The column headings identify the item and

  • the Food/Nutrition Facts Unit (“serving”) size (“LabelUnit”), normally set by the manufacturer;
  • the weight or mass (metric, in grams) of the Unit or the volume (metric in milliters), as stated by the mfr., in the Food Facts label;
  • for some items, a realistic amount (“RA”) used in a recipe by volume and by weight (metric, in grams);
  • the sodium (“Na”) in the RA, by weight, in milligrams. If no RA is given, the Na is per Unit;
  • the potassium (“K”) in the RA, by weight, in milligrams. If no RA is given, the Na is per Unit.

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