This article discusses dietary salt needs, the history of salt use and why its use should be studied to further investigate links to cardiovascular disease. The author cites a potential study on salt intake aimed at determining the unhealthy consequences of high salt intake and closes by reviewing recent studies suggesting that too much salt in the diet can lead to a variety of cardiovascular problems, including high blood pressure and the potential for heart attack or stroke.
For years, medical experts have called for a randomized clinical trial to investigate dietary salt’s links not only to high blood pressure but to heart attack or stroke. Without such trial, there will always be conjecture, but not evidence, regarding the health impact of the use of salt in the diet. Now, leading researchers have recently proposed conducting a very large study aimed at tracking table salt's effect on the health on incarcerated volunteers. The study, which aims at controlling how much salt is included in participants diets, may end decades of scientific disagreement over the benefits and/or risks in using salt. Although conducted with volunteers, the trial may, however, face ethical concerns should it be detrimental to prisoner's health as using prison inmates as study subjects has always been controversial.1
Indeed, history is full of horror stories about clinical tests in the US and other using incarcerated study subjects, often involuntarily. For example, in the early 1940s prisoners were deliberately infected with malaria for study purposes. In 1946, hundreds of prisoners Guatemala were deliberately exposed to syphilis. In the 1950s, inmates were infected with hepatitis. Between 1965 and 1966, approximately 75 prisoners at Holmesburg prison in Pennsylvania were exposed to high doses of dioxin, the main poisonous ingredient in Agent Orange.2
When (and if) the ethical issues are settled, the large salt study under consideration will be conducted through a pilot project involving volunteer prisoners aged 55 and over. This limited study would be followed by a large trial lasting about five years and involving 10,000 to 20,000 volunteer inmates in the same age group. The purpose of both studies would be to investigate the effects of dietary salt.
Why study salt?
Sodium chloride (salt) has been used for millennia. Yet, most people have a poor understanding about salt’s effect on health or the history of its use. The hunger for salt is influenced by its taste, cultural cooking practices and social customs. Sodium, which the body cannot manufacture, is an essential element needed for proper fluid balance, nerve transmission, and muscle contraction. Salt, along with potassium, calcium and magnesium play a vital role in regulating blood pressure. There have been a number of claims that reducing dietary sodium (which represents 40 percent of the salt molecule) is crucial to our well-being; however, some studies report that too much salt in the diet is also a health hazard. The majority of scientific findings suggest that most Americans should cut back on their sodium intake because sodium is responsible for most cases of high blood pressure, the leading risk factor for heart attack, stroke and kidney failure. Today, one in three adults is afflicted by high blood pressure, but of those only half have it under control. Another third of adults have blood pressure higher than normal, although not yet in the “high” blood pressure range. Poor high blood pressure treatment remains a serious contributor to heart disease and deaths.3
Many factors are responsible for having an excess of salt in our diet. Unfortunately, there is an innate response that drives a human to seek and ingest salt containing foods and fluids and this means many of us have a daily salt intake in excess of physiological requirements. However, the majority of salt added to our foods does not from our own salt shakers. It is added by commercial food and drink processors and restaurants.4
How much salt is recommended?
The recommended daily intake for healthy American adults is only 2300 milligrams of sodium per day or the amount in about 1 1/8 teaspoons of salt. This information will be provided in the new nutrition facts labeling, scheduled to take effect beginning in mid-2018 until January 2021. Currently, the average American consumes more than 3400 mg per day. That amount is often found in a single restaurant meal. According to a report in the New England Journal of Medicine, an average reduction of just 400 milligrams of sodium a day could save 28,000 lives and $7 billion in healthcare costs yearly.5 Cutting back could be fairly simple—avoid processed meats, buy low sodium or sodium free products, such as soups and condiments, and use less salt when cooking at home.
A Brief History of Salt and its use
Until modern times, salt provided the principal way to store food. Salt has the ability to preserve, protect against decay, and to sustain life. On every continent, once human beings began cultivating crops, they began looking for salt to add to their diet. How they learned of this need is a mystery. Another development that created the need for salt began when animals were raised for meat rather than killing wild ones. Animals, like humans, need salt.
Almost no place on earth is without salt. Until the twentieth century, salt was desperately searched for, traded for, and fought over. Homer referred to salt as a “divine substance.” Plato described it as especially dear to the gods.
Oh, and the Egyptians used salt in the mummification process.
For thousands of years, salt represented wealth. Many governments taxed it to raise money for wars. Soldiers and workers were paid in salt. The Latin word for salt was “sal,” and the "salt money" given to soldiers was called “salarium.” Salarium later became used for the regular pension or salary paid to soldiers. An excellent book entitled "Salt: A World History," written by Mark Kurlansky, provides a remarkable story about salt and how it influenced the establishment of trade routes and cities, provoked and financed wars, secured empires, and inspired revolutions.6 Salt may have as many as 14,000 uses, including for manufacturing pharmaceuticals, melting ice in the winter, fertilizing agricultural fields, making soap, softening water and drying textiles. It has even been used to treat dyspepsia, sprains, sore throats and earaches.
While the historical aspects of salt may make interesting reading, its use as part of our physical well-being is much more important. Reducing the intake of salt appears to be a prudent dietary consideration in the management of high pressure. Few risk factors are as important to health. High blood pressure is second only to smoking as a preventable cause of heart attacks and strokes. Heart disease remains the leading killer of Americans. Under new guidelines, high blood pressure will be defined as 130/80 millimeters of mercury, or greater for anyone with a significant risk of heart attacks or stroke. The previous guidelines defined high blood pressure as 140/90.7 The first number describes the pressure on blood vessels when the heart contracts, and the second refers to pressure when the heart relaxes between beats. To calculate your risk of heart trouble, contact your physician and use the online calculator sponsored by the American College of Cardiology. The calculator will ask for your blood pressure and cholesterol measurements.8 This online health tracker website (https://ccccalculator.ccctracker.com/) can help safeguard your health.
Despite its historical value and physiological beneficial properties, too high a salt intake has been determined to be detrimental to one’s health. However, consensus as to how much is too much has been lacking. The difficulty stems from an inaccurate means of estimating sodium intake, and because sodium levels can fluctuate throughout the day. An accurate measure of a person's sodium intake requires a full 24 hour sample. In addition, sodium consumption may change from day-to-day. A new study assessed sodium intake in multiple ways, using the average of multiple, non-consecutive urine samples. The study included nearly 3000 individuals with pre-hypertension and a direct linear relationship between increased sodium intake and increased risk of death.9 This information, together with the proposed inmate study, may provide further evidence of a direct cause-and-effect relationship between salt intake, blood pressure, and any cardiovascular consequences. Until then, we should all heed advice from major health organizations and cut back on sodium for the sake of our well-being.
- Kolata G. “The ideal subjects for a salt study? Maybe Prisoners. New York Times. 4 June 2018.
- Reiter K. “Experimentation in Prisoners: Persistent Dilemmas in Rights and Regulations. California Law Journal. 2009 Vol 97 Issue 2:501-566.
- Brody JE. “Clearing up the Confusion About Salt. New York Times. 20 November 2017.
- Op cit 3.
- Kotchen TA, et al. “Salt in Health and Disease: A Delicate Balance. NEJM. 2013; 368 (13):1229-37.
- Kurlansky M. ”Salt: A World History.” Penguin Books. New York, 2002.
- Welton PK and Carey RM. “The 2017 Clinical Practice Guideline for High Blood Pressure. JAMA. 20 November 2017.
- Rabin CR. “Am I at high risk for a heart attack? New York Times. 24 November 2017.
- Feng JH, et al. “Errors in Estimating Usual Sodium Intake by the Kawasaki Formula Alter its Relationship With Mortality: Implications for Public Health. International Journal of Epidemiology. 2018; DO 10.1093/ije/dyy114.
About the Author
Max Sherman is a retired regulatory professional. He has contributed to Regulatory Focus for more than two decades and is the author of the recently published book entitled "Eclectic Science and Regulatory Compliance: Stories for the Curious." The book contains 36 essays, most of which appeared in Regulatory Focus. In 2012, RAPS published "From Alzheimer's to Zebrafish: Eclectic Science and Regulatory Stories." He is also the editor of the first (2015) and second (2018) editions of "The Medical Device Validation Handbook." He may be contacted at firstname.lastname@example.org.
Cite as: Sherman M. “Salt: Needed, Widely Used, Often Misunderstood.” Regulatory Focus. August 2018. Regulatory Affairs Professionals Society.