LOW SALT–TWO VIEWS
Dr. Pinna says:
The Japanese saw, in millions of people, that too much sodium was causing hypertension and strokes. The Japanese now restrict their sodium intake.
Low Salt Diets May Be Harmful
By Dr. Mirkin
“A new study from Belgium found that low-salt diets increase the risk of death from heart attacks and strokes and do not prevent high blood pressure (JAMA, May 4, 2011). The investigators found that the less salt people ate, the more likely they were to die of heart disease.
3,681 middle-aged Europeans with normal blood pressure and no heart disease were followed for 7.9 years. The researchers measured urine excretion of salt to prove how much salt each person took in. Virtually all salt intake during a day can be measured by how much salt ends up in the urine.
This study is one of the first to measure a person’s salt intake directly, rather than using dietary history which is not very dependable. However, Dr. Walter Willett of Harvard thinks that the study is flawed because investigators based their findings on a single measurement of sodium collected at the start of the study.
How Could a Low-Salt Diet cause Heart Attacks?
We know that salt restriction can raise blood sugar and insulin levels, while salt loading lowers them (American Journal of Hypertension, July 2001).
* A low-salt diet can cause salt deficiency which blocks insulin receptors.
* This prevents the body from responding to insulin.
* This causes the pancreas to release huge amounts of insulin.
* High levels of insulin constrict arteries leading to the heart to cause heart attacks.
Salt Deficiency Can Cause the Side Effects of Diabetes
Blocked insulin receptors:
* prevent insulin from removing sugar from the bloodstream to cause
* high blood sugar levels.
* This causes sugar to stick to cells.
* Once sugar is stuck on a cell, it can never get off, and is eventually converted to a poison called sorbitol that destroys the cell, to cause all the side effects of diabetes: blindness, deafness, dementia, heart attacks, stokes, impotence, nerve damage and so forth.”
Dr. Pinna says:
That was Dr. Mirkin reacting to one study. Here is the reaction from the Centers for Disease Control (CDC):
JAMA Study on Salt: The CDC Response
By Carol Peckham and Peter A. Briss, MD, MPH
“On May 4, 2011 JAMA published a study in which 3600 participants were followed for a median of 7.9 years. Higher salt intake was associated with an increase in systolic blood pressure but not in diastolic blood pressure. In addition, cardiovascular deaths increased with decreasing amounts of sodium excretion in the urine. Needless to say, this study has garnered wide coverage among consumers and the professional press.
For a response to this study, Medscape interviewed Peter A. Briss, MD, MPH, Medical Director, National Center for Chronic Disease Prevention and Health Promotion, US Centers for Disease Control and Prevention (CDC), Atlanta, Georgia.
Medscape: How would the CDC address the evidence in this study within the context of previous studies that suggested reducing salt intake would save money and lives?
Dr. Briss: In any scientific area, there are going to be degrees of conflicting results and evidence from studies with stronger and weaker designs.
This particular paper had certain methodologic issues that complicated its interpretation. It does not do much in our view to change the long-standing collective body of evidence demonstrating that lower sodium intake is associated with better cardiovascular health and higher sodium intake is associated with high blood pressure and its complications.
We believe that we know enough to take action now.
Medscape: Can you describe any of the actual specific limitations or flaws in the study?
Dr. Briss: This study had a number of limitations that are concerning to us.
First, the study population was small and there were few cardiovascular events.
Second, this study focused on people who were about 40 years of age and much younger than the age group who experiences most cardiovascular morbidity and mortality.
Third, important data were missing or were incomplete. For example, a number of people were lost to follow-up.
Fourth, the measurement of sodium intake may have been inaccurate. Sodium intake varies considerably from day to day, and a single 24-hour urine measurement may not give you a complete picture. In addition, the urine volumes and urine creatinine suggest that some of the people who were categorized in the low-sodium group may have had incomplete urine collection.
Finally, there were differences between the groups that were not limited to their sodium intake. For example, people in the low-sodium group had more smoking and lower educational levels. Those could have confounded the study’s results.
Medscape: What advice would you offer clinicians whose patients would like to use this study as an excuse to maintain a high salt intake or increase their existing intake? What would they say to these patients?
Dr. Briss: In this context they should tell their patients to take the study with a grain of salt, but otherwise they should work to limit their intake. Patients should be told that this study has some challenges that complicate its interpretation. It doesn’t do much or anything to change what we previously knew that too much salt is bad for you.
Medscape: In what specific population or group is salt reduction specifically important?
Dr. Briss: The people for whom salt reduction is most important are people who are older than 50 years of age; are African American; or who already have high blood pressure, diabetes, or chronic kidney disease. These groups taken together make up the majority of American adults.
Medscape: Are there any specific populations in whom salt reduction is known to be harmful?
Dr. Briss: There are very few cases in which salt reduction below the currently recommended levels might be problematic: for example, people who participate in heavy physical activity in hot environments or people with certain diseases, such as cystic fibrosis. These issues are not very common, however.
Medscape: Is there anything else that you’d like to say?
Dr. Briss: Only, again, that too much salt intake is a really important contributor to high blood pressure, which in turn leads to heart disease and stroke, which are the first and third leading causes of death in the United States. Reducing these intakes would have health benefits. We believe that there’s enough evidence to take action now.”
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Filed Under: Blood Pressure • Food • Health
I do believe that not enough salt can be bad, since it’s necessary for immune system function and managing neurotransmitter levels. I There were a little too many flaws in that study, though. Not only does it greatly weaken it by having the test subjects only 40 years old when they started, but I read somewhere that a lot of the people who died also had prexisting conditions like being a heavy smoker. Just because this study was done with some sketchy science doesn’t mean that their hypothesis is invalid, though. I went on a low salt diet for a couple years and I noticed that my anxiety and ocd symptoms were through the roof (even though i was on fluoxetine already). I read somewhere that the DSV-V is going to add salt in a list of things as a predisposing factor to ocd. Most sites these days even include this in their definitions already, ie. http://www.anxiety.org/disorders/ocd