So what's the deal with salt? You know you need some of it, but
everywhere you see advertising and headlines telling you to eat less of
it. You might have salt cravings but you feel guilty indulging in them
because you've heard from everyone, the government to personal trainers
to your mother-in-law, that salt is bad for you. The way headlines
sound, you'd get the impression that eating a bag of chips will raise
your blood pressure enough to have a stroke right then and there! I once
had an 11-year old sit next to me, watch me salt my scrambled eggs and
ask me if didn't I know that salt was bad for me! So let's see what's
actually accurate amongst all the headlines, advertising, special
interests, and advice.
Like all the topics I've written about, it's not that simple to say
salt is "good" or bad". One thing to keep in mind is that salt is so
vital for human health that "sal" is the basis of the word "salary"
because people used to be paid in salt. Sodium and chloride are both
vital minerals, used for nerve transmission/impulse conduction, fluid
balance, and muscle contraction. Not having enough sodium will cause
hyponatremia, a life-threatening condition that happens when someone
sweats out too much sodium, or drinks too much water, and upsets the
fluid balance.
Salt is a prime determinant for taste in food (along with fat) and
80% of the salt we consume is in processed foods, making it difficult to
avoid. The message promoted by both the National Heart, Lung, and Blood
Institute (NHLBI) and the National High Blood Pressure Education
Program (NHBPEP), a coalition of 36 medical organizations and six
federal agencies is that everyone, not just people will hypertension,
would benefit from a daily intake of 2400 mg or sodium (6 grams of salt,
or about 1 teaspoon) per day, which is 4 grams less than our current
average. The problem lies in the fact that the research does not
conclusively show that a reduction helps with blood pressure and
actually shows that low levels could lead to health problems. "You can
say without any shadow of a doubt," says Drummond Rennie, a JAMA editor
and a physiologist at the University of California, "that the NHLBI has
made a commitment to salt education that goes way beyond the scientific
facts."
One of the first studies that showed how diet lowered blood pressure was
a Duke University clinician who, in the 1940's, showed he could
successfully treat hypertension with a low-salt, peaches-and-rice diet.
If patients' hypertension didn't improve, Kempner said it showed,
protestations notwithstanding, that the patient had clearly fallen off
the diet. It was cited for decades as evidence that low sodium diets
could treat hypertension, but there are a couple of very large problems
that were conveniently overlooked — Kempner's diet was also low in
calories and fat, as well as high in potassium, and those are all
factors that are also known to lower blood pressure.
A major problem with some of the biggest studies involving salt are
that they are epidemiological studies, which are known for showing a
correlation and not actual causality. As I mentioned in my article "That
Study Is Wrong: The Truth About Research", epidemiologists even suspect
their own studies and call it a "pseudoscience". In this particular
field, it would be fair to say that there is so much bias that
researchers will not consider research that doesn't support their own
position, and combined with the tendency to cite research, accurate or
not, creates a case that looks as if a position has more "evidence" than
it actually does. For example (and there are many), in 1991, a 14-page
epidemiological study was printed in the British Journal of Medicine,
concluding that the salt-hypertension link was "substantially larger"
than previously thought. That same year, researcher John Swales, former
director of research and development for Britain's National Health
Service, dissected the study so completely that no one at the European
Society for Hypertension's conference was left unclear by how shoddy the
research was. And yet 2 years later, that same paper was cited
repeatedly by the U.S. NHBPEP as compelling evidence to reduce sodium
intake. In fact, Swales repeats this thought in a paper in 2000, saying,
"Reviews biased by the inclusion of nonrandomized studies exaggerate
the apparent blood pressure fall… Nevertheless, citation analysis shows
that they are quoted much more frequently than rigorous reviews reaching
more negative conclusions. This appears to be the result of an attempt
to create an impression of scientific consensus."
Here's the first thing: there ARE some people for whom salt it
problematic, but there is no test for "salt sensitivity" and even the
condition itself is not fully clarified. It may be related to race (one
study saw an association with African-Americans), or gender, or age, as
well as a possible genetic link. However, because you cannot predict who
is salt-sensitive, we're left with creating generalized recommendations
that may not actually benefit sensitive individuals, but may also harm
the rest of the population.
So how does lowering salt intake cause harm? Let us count the ways,
starting with cardiovascular disease. While hypertension is often blamed
as a cause for heart disease, low sodium has been directly linked
multiple times to increased cardiovascular deaths, and another 2011
study confirmed this. In fact, this last study also saw that sodium
levels didn't predict hypertension, and that any association between
blood pressure and sodium didn't actually translate into less morbidity
or better survival.
Low salt diets also increase cholesterol and triglycerides in the
blood. In fact, people with Type 2 diabetes are more likely to die
prematurely on a low-salt diet, due to cardiovascular disease. A
Harvard study showed that low-salt diets were linked to an immediate
onset of insulin resistance. And yet doctors are consistently
recommending salt restriction diets to diabetics.
In studies with the elderly, sodium restriction can be especially
damaging. It has been shown that low salt intake leads to more falls
and broken hips, and decreased cognitive abilities. Hyponatremia (too
low sodium) is commonly found in geriatric patients , and yet it is
repeated ad nauseum that older people should be lowering their salt
intake.
You may not realize this, but this is not necessarily new
information. There have been articles in the New York Times about the
dangers of low salt intake and the research supporting it in 2010 and
again in 2013.
Sodium intake hasn't changed much in decades, and that certainly
seems to stand true in research: in studies measuring urinary sodium
excretion, spanning 5 decades, over 30 countries, and over 50,000
subjects, the normal range of sodium excretion is 3,500 mg/day. This
last study also points out that renin-angiotensin-aldosterone system
(RAAS) is a protective mechanism to PREVENT the loss of sodium. As
sodium is clearly the backbone of extracellular fluid, ensures adequate
blood volume, arterial pressure and ultimately organ perfusion, to make
recommendations below 2760 mg/d (which activates the RAAS reaction)
assumes that basic biology is being ignored, and that lowered intakes
are not harmful (and clearly there is plenty of research showing this).
McCarron et al. (2009) saw in this 26-year study that since sodium can't
be stored, it is tightly regulated by the body, regardless of how much
is in the diet, and "that public health initiatives designed to lower
intakes of this nutrient by altering the food supply are destined to
fail."
What IS true is that little to no distinction is being made between
the salt in processed foods and what is found naturally in fresh foods
or what you might add at the table. The main sources of sodium in the
U.S. diet are grain mixtures (mainly pasta, breads and rolls), and
processed meats like frankfurters, sausages and lunch meats. This would
be why the famous DASH diet (Dietary Approaches to Stop Hypertension)
with it's emphasis on generous amounts of fresh fruit, vegetables and
dairy is effective for lowering blood pressure — it is simply removing
most sources of processed foods. It's also considered by many to be a
preferable alternative to across-the-board sodium restriction.
Which is also exactly what is seen in research — studies that looked
at fresh food, cooked at home, (with salt added for flavor) saw no
impact on blood pressure but people who ate out frequently, and ate
processed foods regularly had a much higher incidence of hypertension.
If hypertension is a concern, it would be good to also boost potassium,
as inadequate potassium will still cause hypertension, even if eating a
low-sodium diet. Potassium is so available in foods that you can't
really get it as a supplement — and, you guessed it, it's highest in
fresh foods like leafy greens, bananas, avocados, melons, mango and
prunes. Additionally, weight loss and reduction of alcohol intake are
known to be extremely effective at reducing blood pressure.
The current U.S. recommendations are 2,300 mg/day. The American Heart
Association would prefer that everyone consume as little as 1,500
mg/day, clinging to antiquated research long since disproven. In fact,
in light of the overwhelming evidence, the Department of Health and
Human Services will be revising the sodium guidelines in 2015. In the
meantime, bring back your common sense about food, and avoid "quick
fixes" with store-bought food and eat as much fresh food and food that
YOU prepared as often as you can. And hand this article to your
mother-in-law the next time she makes a comment as you are salting your
eggs!
The more appropriate conclusion would be that since controls (study
subjects without prostate cancer) and prostate cancer patients have
nearly identical plasma phospholipid levels of omega-3 fatty acids, it
is not likely that an association between fatty acids and prostate
cancer can be identified in this study. Other dietary and lifestyle
factors are likely to be involved. Consider that prostate cancer is rare
in Inuit Eskimos, who consume a traditional diet that includes
extremely large amounts of omega-3 fatty acids. 
