What is “The Salt Fix” and why should you care?

During my nutrition education, I was educated to believe that excessive consumption of salt leads to hypertension. This seemed to make intuitive sense at the time. I associated salty foods with processed foods such as french fries and fried chicken. Therefore, I conflated the deleterious effects of processed foods with salt. However after digging into the science a bit deeper, I have come to realize that salt may not be as bad as I originally thought. In fact, we may need to be consuming more to achieve optimal health.

The Salt Fix is a book written by Dr. James DiNicolantonio, a Cardiovascular Research Scientist and Doctor of Pharmacy at Saint Luke’s Mid American Heart Institute in Kansas City, Missouri. He has published over 200 scientific papers in the medical literature. The Salt Fix is about why our preconcieved notions about salt are wrong. According to Dr. James DiNicolantonio, salt intake is in fact not the driver of hypertension. Sugar and processed carbs are. In this book review, I will go over Dr. DiNocolantonio’s main points and my thoughts as to why I think the concepts of this book are important.

What is salt and why is it important?

Salt is an essential nutrient composed of sodium and chloride. Essential nutrient means that we must consume it in order to live. Without consuming salt, we would be dead. Sodium is needed for many functions in the body including:

• maintenance of optimal blood in the body
• by the heart to pump blood
• digestion
• cell-to-cell communication
• bone formation and strength
• prevention of dehydration.

When dissolved into water, Na+ is the main positively charged electrolyte and Cl- is the main negatively charged electrolyte in our blood. They have the highest concentration in our blood compared to any other electrolyte. 99% of the electrolyte concentration of our body consists of Na+ and Cl-.

Our bodies have the same mineral concentration of NaCl (salt) as the ocean. In order for us to survive outside the ocean, we evolved to develop salt regulating systems such as skin, adrenal glands and kidneys to maintain a specific concentration. Without a specific concentration of these essential nutrients, we die.

“Compared to the dramatic changes in the form, structure, and function of organs that occurred during vertebrate evolution, the fact that the electrolyte makeup of the extracellular fluid has generally remained constant suggest that salt balance is an evolutionary adaptation.”

The Salt Fix by Dr. James DiNicolantonio, p. 17

Our hypothalamus, a part of our reptilian brain, both receives and transmits signals that drives us to drink water and obtain salt.

Our adrenal glands produce hormones that also regulate our salt balance. During times of stress, our adrenal glands produce cortisol that causes a release of sodium from our skin to help us have more energy. Aldosterone is another hormone produced from the adrenal glands that helps us reabsorb salt from the kidneys when sodium in the blood is low.

Our kidneys work hard to maintain a certain salt balance. 70% of the basal energy expended by the kidneys is used to reabsorb salt. On average, the kidneys filter between 3.2 to 3.6 lbs of salt per day. This is 150x the amount of salt we consume daily. We are told that 2,300mg of salt is too high but our kidneys filter this much every 5 minutes. The amount of salt we consume is a drop in the bucket compared to what the kidneys deal with.

History of salt consumption

Humans have been consciously mining salt for at least 8,000 years. Salt mining started in China but spread to other parts of the word such as Egypt, Jerusalem, Italy, Spain and Greece. These countries also traded salty foods such as fish, fish eggs, olives and cured meats. Here are some interesting facts about our history of salt consumption and it’s correlation with heart disease:

• The average Roman consumed about 25g of salt (10mg of sodium) per day.
• 16th century Europeans consumed about 40g of salt (16mg of sodium) per day. 18th century Europeans consumed 70g of salt (28mg of sodium) per day.
• 1500s in Europe, people consumed about 40-100g of salt per day. First report of heart disease did not occur until the mid-1600s.
• Overall, consumption of salt was at least 2-10x more than today.
• At least 14 countries consume a higher salt diet but have lower rates of CVD (coronary vascular disease).
• Japan, France and South Korea have some of the lowest rates of death due to coronary artery disease
• The average Korean eats 4,000mg of salt per day.
• In one Korean study, the group that consumed the most sodium had a 13.5% lower prevalence of hypertension compared to the group consuming the lowest amount of sodium.
• US Army rations are a good reflection of our previous salt intake. The army rations of the War of 1812, the Mexican War and Civil War included 18 grams (7,200 mg sodium) per day.
• Compared to the 1900s, hypertension if about 3x as high despite salt intake being the same.
• History of hypertension in the US:
  • Early 1900s, 5-10% of the population
  • 1939 in Chicago- 11-13% of the population
  • 1975- 25% of population
  • 2004- 31% of population
  • 2014- 1 in 3 Americans have hypertension

Taking into account these historical facts, we can intuit that hypertension is probably not predominantly driven by excessive salt intake. Why does our government tell us to restrict our salt intake? What is the evidence for this recommendation?

The salt-blood pressure hypothesis

Since the 1977 Dietary Goals, Americans have been told to restrict our salt consumption. This stems from the “salt-blood pressure hypothesis” that has been theorized since the 1900s. The theory is that when we eat more salt, we get more thirsty. Increased thirst leads to drinking more water. This leads to us retaining water to dilute the saltiness of the blood.

However when we look at the actual data, there is little to support this theory. We have only been able to show a slight increase in blood pressure with increased salt intake in SOME people. We have extrapolated this data to an entire population, not considering the potential harms of severe salt restriction. According to Dr. James DiNicolantonio, 80% of people with normal blood pressure, 75% of people with prehypertension and 55% of people with hypertension are not sensitive to the blood pressure raising effects of salt. In one systematic review of eight randomized controlled trials looking at salt restriction of greater than 6 months, there was a decrease in blood pressure by only -1.3mmHg in people with normal blood pressure and -2.9 mmHg in people with hypertension. Studies have consistently shown that during a true blood volume expansion, it takes 75 minutes for blood pressure to increase. That is more than enough time for the kidneys to excrete excess salt and water.

Clearly, lowering salt intake is not the most effective lever to pull to reduce blood pressure. What may be a better tool? What is the root cause of hypertension?

What raises blood pressure? Sugar!

According to Dr. James DiNicolantonio, there is a stronger correlation between sugar intake and hypertension compared to sodium intake. Here is a brief history of Americas sugar consumption throughout the years:

• 1776- 4 lbs per person per year. Equivalent to 1 tsp of sugar in coffee per day
• 1909-1913- 76 lbs per person per year.
• 1950- 100 lbs per person per year.
• Increase of 30 fold from 1776-2002.

As previously stated, out salt intake has not increased in recent years and has dropped 2-3 X less than previous centuries. Therefore, sugar is more strongly correlated with our increase in hypertension, not salt. Lets look into why that may be!

How sugar may increase blood pressure

It has been know for some time now that people with diabetes are more likely to develop high blood pressure. The reason being is that many diabetics have hyperinsulinemia, meaning they have chronically high insulin. Insulin is a hormone excreted from the pancreas that shuttles sugar out of the blood stream into cells. When it is high all the time, insulin resistance can develop which leads to diabetes. 80% of people with hypertension have insulin resistance.

Why would chronically high insulin lead to hypertension? Insulin stimulates the reabsorption of sodium in the kidneys. Rather than excreting the normal amount of sodium in the urine, the kidneys reabsorb sodium when insulin is high. This constant reabsorption of sodium causes high blood pressure.

Another way in which sugar increases risk of developing hypertension is through a rise in cortisol. Cortisol is a hormone excreted out of our adrenal glands when we are stressed. Excess cortisol in the body has been known to increase hypertension in those with certain conditions such as Cushings Syndrome, chronic renal failure and hypertension. One way in which cortisol increases risk of hypertension is through causing insulin to rise. Again insulin signals to the kidneys to reabsorb sodium. If sodium is constantly being reabsorbed and never released, this can result in high blood pressure.

Weight reduction has also been shown to reduce blood pressure. In one study, 25 obese people were randomized to either eat a normal sodium intake of 2,760 mg of sodium per day or a low sodium intake of 920mg per day. Both groups consumed a reduced calorie diet. Both groups blood pressure fell equally with the weight. Weight loss also reduces insulin in the body, therefore reducing the reabsorption of sodium, decreasing blood pressure.

So we now know that sodium is an essential nutrient. We also know now that sodium is not as influential on raising blood pressure as we previously thought. Why should we consume a certain amount of salt? What are the consequences of a low salt diet?

Consequences of a low salt diet

There are many potential consequences to consuming a low salt diet. When we do not consume an adequate amount of salt, our body activates rescue systems to retain water and salt. The body responds to low salt intake by increasing substances such as renin and aldosterone along with noradrenalin and adrenalin to reabsorb salt and maintain proper blood volume. However there are consequences to chronically activating these systems. One consequence is increased heart rate. Increased heart rate increases our risk of developing heart disease by putting more pressure on the arteries and decreasing the amount of oxygenated blood that gets into the heart.

Sodium is necessary for proper blood volume. When intake is low, blood volume is reduced. Studies have shown a decrease in blood volume by 10 to 15 % on a low sodium diet. Low blood volume can lead to problems with the cardiovascular and central nervous system, thermoregulation issues, metabolic abnormalities and heat stroke.

Low sodium in the blood (hyponatremia) is a very serious condition. In fact, it is the most common electrolyte abnormality. 65% of cases are cause by gastrointestinal disorders. In the elderly, hyponatremia is over 31 X as prevalent as hypernatremia. Mild hyponatremia puts you at high risk of cardiovascular events. Symptoms of hyponatremia include anorexia, cramping, nausea, vomiting, headache, irritibaility and disorientation. Neurological symptoms such as seizures, coma and brain damage can also occur. Hyponatremia can be caused by many conditions such as medications, diseases and overexercising in the heat. Hyponatremia is not usually caused simply by under consuming salt. Again this is because the body has systems in place to increase sodium reabsorption and maintain normal sodium levels. However it is interesting to examine the dire consequences of low blood sodium. It demonstrates just how essential this nutrient is.

So if low sodium diets are so dangerous, how much salt should we be consuming to maintain optimal health?

How much salt should we be consuming?

Optimal range is between 3-6 grams per day (1 1/3 to 2 2/3 tsp of salt). The only people who should be limiting their salt intake are people who have diseases that make them especially sensitive to the negative effects of sodium on their blood pressure. Listed below are the exceptions:

• Hyperaldosterosim
• Cushings Disease
• Liddle Syndrom

People with these conditions have hormonal disregulation, preventing sodium from properly excreting from the body. For the rest of us, the body is very good at excreting excessively consumed salt or storing it in the skin and organs.

Listed below are conditions in which one should be consuming MORE salt. The conditions listed below deplete the body of sodium, increasing our need to consume more:

• Overconsumption of sugar
  • Leads to kidney problems causing salt wasting
• Chronic diseases like hypothyrodism, adrenal insufficiency & congestive heart failure.
• Antidepressant and anti-psychotic medications
  • Cause hyponatremia by triggering over secretion of antidiuretic hormone, leading to water retention. This dilutes sodium in the blood.
• Diuretic medications
  • Loss of water and sodium from kidneys
• Over consumption of coffee.
  • Coffee acts as a natural diuretic, flushing water and salt from the kidneys.
• Intense exercise
  • Depletes the body of sodium through sweat.
• Low carb and intermittent fasting diets.
  • These diets dramatically reduce insulin in the body, causing more sodium to be excreted.
• Traumatic events (burns, trauma, hemorrhage)
  • Injured regions draw in more water to aid in healing process. Less fluid is available to other areas. An increase in sodium would help carry fluid throughout the body.
• Hyponatremia (low sodium in blood) treatment.
  • Most cases are caused by gastrointestinal disorders but are also caused by certain medications and diseases. Low sodium in the blood is the most common electrolyte abormality.
• Diarrhea
  • Cause loss of fluid and sodium

As stated earlier, in most conditions, the kidneys are very good at excreting any excessive salt. But there are many conditions that deplete the body of salt, prompting us to increase our intake to help our body work its best. Proper salt intake allows out body to have proper blood circulation. This is important so that our cells can receive the oxygen and nutrients they need to work their best. Overall, in my perspective, the benefits of adequate salt intake very much outweigh the potential side effect of a slight increase in blood pressure.

Summary, my thoughts

The Salt Fix had a profound effect on shifting my perspective on salt’s effect on blood pressure. Sure, salt may raise blood pressure in SOME genetically susceptible people. However this effect is a lot less than one would assume. Additionally most people do not experience a rise in blood pressure and some people even see an increase! Our bodies are very capable of excreting excessively consumed sodium. The side effects of limited salt intake could be potentially dangerous as the body has to activate rescue systems such as renin aldosterone along with norepinephrine and epinephrine to reabsorb salt. Over activation of these systems can result in increased heart rate, increasing our risk of heart disease. The very thing we are trying to prevent with a low salt diet! A more effective lever for reducing blood pressure is reducing intake of sugar/ refined carbs and weight loss. Reducing our consumption of sugar/refined carb and reducing weight reduces insulin. A decrease in insulin reduces sodium retention, causing blood pressure to reduce naturally. Adequate salt intake is necessary for adequate blood flow, maintaining adequate blood in the body, cell-to-cell communication and carrying out electrical impulses.

If you are on a low carb or fasting diet, excessively exercising or on certain medications (SSRIs), you may benefit from adding a little more salt to your diet. If you have further questions about this, feel free to reach out to me or check out Dr. James DiNicolantonio’s Book. Thanks for checking out my page!