OH! Magazine - Australian Version June 2014 (Australian Version) | Page 14

( Nutrition )

but additionally randomised participants
to eat foods with high, moderate or low
levels of sodium for 30 days. The result
– lowering sodium intake lowered blood
pressure and the lowest blood pressure
was seen in those following the DASH
diet and the lowest intake of sodium.
Since so many of the positive studies
have been criticised for being too short,
in 2005 the highly regarded Cochrane
Collaboration published a review of trials
lasting at least 4 weeks. The conclusions
were that lowering salt intake lowered
blood pressure in both hyper- and
normotensives. Even so, the debate
continues as others have shown that after
six months or so the benefits to blood
pressure are lost. What is not clear is
whether this occurs as a result of
physiological adaptations or as a result of
increasing non-compliance with a low salt
diet over time.
The bottom line is, as well we know from
weight loss diets, it is incredibly difficult to
change what we habitually eat over the long
term. The focus of scientific arguments and
in messages to the public has centred on
the relationships between salt, blood
pressure and cardiovascular disease.
However, a high salt intake has several
other detrimental effects in the body:
• The more salt you eat, the more
calcium you excrete in your urine.
This puts you at risk of both kidney
stones and osteoporosis.
• Many Asian countries, including
Japan, have a high incidence of
stomach cancer and this is thought to
relate to their high salt intake. (Soy,
oyster and fish sauces are all extremely
high in salt.)
• A high salt intake can exacerbate fluid
retention since increased cellular
sodium results in an increased uptake
of fluid.
• Finally a high salt intake is thought to
aggravate, although not cause,
asthma.

So can a low salt intake be harmful?
The critics of the anti-salt message
claim that it can be. When sodium intakes
come down, what’s called the renin14

JUNE 2014 ( OH! MAGAZINE )

angiotensin system kicks in, in part to
preserve sodium levels in the blood. High
renin (and therefore angiotensin II) in the
blood has been linked to cardiovascular
disease. So the question has been raised
that if we lower blood pressure through
lowering our salt intake, are there other
detrimental factors that outweigh this
benefit? The anti-salt supporters say that
increased renin is not a concern in the
context of modest salt reduction
recommendations and very low sodium
intakes would almost never occur in
people eating varied diets.

So how do we interpret this ongoing
debate?
Well if we strip away the complicated
scientific arguments and use our common
sense to think instead about how humans
would have eaten before modern
industrialised life, this may provide
answers. In the average Western diet,
some 75 per cent of the salt we eat
comes from processed, pre-packaged
foods that we buy. None of these foods
were available a few generations ago,
never mind back in the days of huntergatherer man. Surely this alone tells the
tale.
Unravelling and understanding the
complex relations between diet and
health is supremely difficult and no
matter which dietary aspect we care to
look at, there are almost always conflicting
results, if only because as soon as you
change one aspect of a diet, other
changes are unavoidable.

However the one resounding message
is that eating more fresh whole foods and
fewer processed food is better for our
health. The fact that this lowers salt
intake may or may not explain part of the
benefit. For example, compare two meals;
a popular fast food outlet burger or a
grilled fillet steak with steamed veggies.
The former has an estimated 1,284mg of
sodium, 13 times the 98mg found in the
fresh food meal! While we do need some
sodium in our diet, it is quite clear that
modern diets provide way in excess of our
requirements and I for one find it
exceedingly hard to believe that
encouraging people to eat less can do us
anything but good.

So what are my recommendations?
If you know you have high blood
pressure the overwhelming weight of
evidence suggests you would do well to
cut down on salt. In addition, all of us
should eat fewer processed foods and
eat more fresh whole foods. But if you
enjoy a sprinkle of salt on your poached
egg, then go ahead and enjoy it without
guilt. This way you control how much
salt is in your diet, and not the food
manufacturers, and you will reap the
rewards of all the many other benefits to
be found in such a diet. And remember,
maintaining a healthy weight, stopping
smoking and taking up regular exercise
remain the big three in the fight against
chronic disease. Don’t let the arguments
for and against salt divert you from the
big picture.