Lawrence Solomon: Shake the salt

The sodium-is-dangerous theory is itself a danger.

Are you worried about congestive heart failure? Liver or kidney failure? Chronic fatigue? Pneumonia? Blood vessel health? Alzheimer’s or the loss of other cognitive abilities? Do you experience muscle cramps or have high cholesterol? Perhaps you suffer from Gitelman’s syndrome or Type-2 diabetes, low libido or insomnia. Maybe your glucose metabolism isn’t what it should be.

If any of these medical conditions applies to you, then maybe you should ask yourself if you’re getting enough salt in your diet. These and numerous other conditions — some of them potentially fatal — could be triggered or exacerbated by a diet low in sodium.

We hear a lot from governments about the dangers to our health of consuming sodium. Governments are also subjecting us to an increasing array of sodium-related regulations, much of it geared to protecting those suffering from hypertension, a condition associated with heart attacks. This sodium-is-dangerous theory (it is only a theory because no proof for it has yet materialized) is credible and worth considering. But before the government’s regulatory apparatus expands, it and we should consider the far-reaching danger in cutting back on our salt, a danger that — ironically — fully applies to those who suffer from hypertension.

Only one controlled study has been conducted of hypertensive patients on a low-sodium diet. Its results, involving some 3,000 patients in the 1990s, showed the opposite of what most expected: The more sodium the patients consumed, the less likely they were to suffer from heart attacks. The 25% of male patients who consumed the least sodium experienced more than four times as many heart attacks as the 25% of male patients who consumed the most sodium (women did not show a statistically significant relationship). The study, published in Hypertension, a publication of the American Heart Association, was conducted by a research team from the Department of Epidemiology and Social Medicine at the Albert Einstein College of Medicine in the Bronx and the Cardiovascular Center at Cornell University Medical College in New York.

The gold standard in medical research is the randomized clinical trial, which randomly assigns participants to different treatments. To date, such trials have rarely occurred in the study of low-sodium diets, with only one involving patients suffering from heart failure.

These high-risk patients were found to be at higher risk still when following a low-sodium regimen, says a 2009 study in the American Journal of Cardiology. In contrast, those who consumed normal levels of sodium were less likely to be rehospitalized, less likely to experience the neurohormonal activation associated with heart failure, less likely to suffer from renal dysfunction and less likely to die.

Most studies of sodium and heart disease point to highly complex relationships. In one of the largest studies, involving some 11,000 participants, sodium intake was shown to benefit cardiovascular health. In a follow-up study that disaggregated the data, however, large differences turned up among the 28% who were overweight. Unlike the other 72%, the overweight fared poorly when they increased their salt consumption, experiencing more deaths from coronary heart disease, from cardiovascular disease, and more deaths overall.

Other studies show sodium interrelates with the type of diet, with environmental factors, and with our genetic makeup. African Americans are thought to be salt-sensitive. The Kuna Indians, who live in the San Blas Islands off Panama, may be salt-insensitive.  When studied in the 1940s, these islanders were found to consume little salt and to have normal blood pressure. Fifty years later, with ready access to salt, these islanders’ salt consumption resembled that of North Americans yet they continued to have normal blood pressure. The blood pressure of those Kuna who emigrated to the mainland of Panama and ate as much salt as their island cousins, however, now resembled that of other Panamanians. How diet, genetics and environmental factors conspire with sodium to produce their results remains a mystery.

We know, however, that in this mystery sodium plays a commanding role, and yet a precarious one. Our bodies run on electricity, with electrolytes transmitting electrical signals to the central nervous system, muscles, the brain and other organs. The body’s chief positive electrolyte is the sodium ion that results when salt (NaCl) dissolves into its sodium (Na+) and chlorine components (Cl-). Sodium also controls the fluids in our body, regulating our blood pressure and the pressure inside and outside our cells to prevent their collapse or explosion. In performing its service to us, sodium must also maintain itself in precise balance within the body, calling up replenishments by making us crave salt or by expelling any surplus through our urine.

Put another way, our bodies cannot function efficiently, or at all, if their use of sodium is compromised. Because sodium has such far-reaching effects on nearly all bodily functions, its abuse can — and does — trigger any number of medical conditions.

When governmental health authorities attempt to regulate sodium, knowing next to nothing about the science, they are endangering our lives as well as well as our lifestyles. The human body regulates sodium. One regulator is enough.

Second in a two-part series, click here for part one.

Lawrence Solomon
Financial Post
May 1, 2010

Sources for this column:

Fluid and Electrolyte Balance

Salt and geographical mortality of gastric cancer and stroke in Japan.

Can Dietary Sodium Intake Be Modified by Public Policy?

Intersalt: an international study of electrolyte excretion and blood pressure. Results for 24 hour urinary sodium and potassium excretion

Reducing Dietary Sodium: The Case for Caution

Medium term effects of different dosage of diuretic, sodium, and fluid administration on neurohormonal and clinical outcome in patients with recently compensate   heart failure.

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