The going theory (assumption?) in our society is that salt is bad for your health. From what I understand, it’s definitely bad if you have a pre-existing condition like high blood pressure. But is it bad for you-- even in large amounts-- if you don’t have a health condition? Or does its bad rap come from people mistakenly assuming negative health consequences based on its effects on people with health problems?
Well, depends on how much salt you’re talking about.
A “low salt diet” seems to be nessesary only for a small % of the population that have that pre-existing condition, (there are some who are are susceptable to such a condition but could trigger it).
A LOT too much salt isn’t good for you, in general, of course.
This is exactly the point I’m trying find evidence to support. Everyone says that a high salt diet is “obviously” is bad for you. But is it true? What is the evidence to corroborate this? Is it more a conditioned belief than a scientific fact?
The National Academies published a report covering salt consumption in 2004.
Report Sets Dietary Intake Levels for Water, Salt, and Potassium
It goes on to mention that people at special risk of high blood pressure are more sensitive to salt than the general population.
So… is that stating a direct, causal relationship?
Too much- like a half pound- could poison you, that’s what I meant.
There is a lot of debate about a diet that is just plain "high in salt’.
The concept that the long-term regulation of blood pressure is dependent on the kidney’s handling of sodium is generally accepted in the medical community, but the precise role that salt in the diet plays remains controversial. The Dietary Approches to Stop Hypertension (DASH) sodium study confimed that reducing salt intake improved blood pressure in people with normal blood pressure or high blood pressure, in men and women, and in people of different racial heritage. As compared with the control diet with a high sodium level, the DASH diet with a low sodium level led to a mean systolic blood pressure that was 7.1 mm Hg lower in participants without hypertension, and 11.5 mm Hg lower in participants with hypertension.
Now, as to the question of who appears to benefit from sodium restriction: the strongest evidence is for people who are or have any one of the following:
- already have high blood pressure
- are at least 50 years old
- are black
- have renal disease
So, a healthy 50+ year old probably should try to keep their salt intake down, because evidence suggests a high salt diet will raise their blood pressure and put them at risk of strokes and heart disease over the long term.
But doesn’t this also say that if you are a healthy any year old, already consuming a “high” salt diet and you do not have high blood pressure, there is no reason to cut back on salt?
And what physiological changes would make it okay for a healthy 25 year old to have a high-salt diet but not a 50 year old?
We need a nephrologist to wade in on this, or a cardiologist. I am a doctor, but this is not my area of specialization.
My understanding is that in general as we get older, blood pressure has a tendency to rise because one’s arteries become less elastic (more stiff), which means that your heart has to pump harder to overcome the resistance of these more rigid pipes. Salt intake also contributes to higher blood pressure, particularly as we age, because higher chronic salt intake results in increased blood volume (another determinant of blood pressure). So, if you are trying to avoid developing high blood pressure, current guidelines recommend keeping one’s salt intake low (among other things). On the other hand, if you are willing to wait to develop high blood pressure and then try to see if you can reverse it by non-drug methods including reducing your salt intake (and then drugs if that doesn’t work), it’s your body and you can choose to take that risk.
I should direct your attention to the web publication of the AHA , Dietary Electrolytes & Blood Pressure , which is a little old (1998) but goes through some of the evidence linking salt intake and blood pressure . From chimpanzee data, as quoted from that site: “the addition of NaCl (5, 10, and then 15 g/d) to the chimpanzee’s usual diet (a fruit-and-vegetable diet low in NaCl and high in potassium) over 20 months results in significant and progressive elevations of blood pressure. After 84 weeks of added NaCl, relative to both baseline values and a control group, mean systolic and diastolic blood pressures increased by 33 mm Hg and 10 mm Hg, respectively. This increase was completely reversed within 6 months of cessation of the high NaCl intake. Animal studies (as well as limited epidemiological and clinical observations) suggest that diets high in NaCl may also have deleterious cardiovascular consequences independent of blood pressure, eg, cerebral arterial disease and stroke, left ventricular hypertrophy, renal vascular disease, and glomerular injury.” * In other words, even if it doesn’t increase your blood pressure, diets high in salt may put you at increased risk for damage to your brain, heart, and kidney.*
-The 25 year old’s kidneys can handle a high salt load better than a more elderly person’s kidneys, so that’s probably why this is less of an issue in a healthy 25 year old. in the short term. Under normal circumstances, age has no effect on the ability of the individual to maintain normal extracellular fluid volume and blood volume. However, the mechanisms responsible for regulating fluid balance are impaired in the elderly and the aging kidney has a decreased ability to dilute and concentrate urine. An elderly person’s kidneys take longer to clear out a salt load than his younger counterpart’s would. (For the details of the physiologic changes to the kidney with age, we really need to get a nephrologist to expound on this.)