March 9, 2001
Not So Salty!
A high-salt diet can be hazardous to your health
By Eleanor Gilman
is a well-publicized link between excess salt and hypertension,
or high blood pressure. But did you know that consuming too much
salt can increase your risk for other diseases as well?
"High-salt diets can cause a lot of health problems," explains
Jiang He, M.D., Ph.D., associate professor of epidemiology at
the Tulane University School of Public Health and Tropical Medicine.
High-salt diets can increase the risk of a variety of conditions,
including stomach cancer, cataracts, and osteoporosis. "It damages
parts of the body through different mechanisms, but salt tastes
good, so people in modern society eat a lot of it," explains Dr.
Salt and stomach cancer
Diets high in salt are thought to increase the risk of stomach
cancer, according to researchers at the American Institute for
Cancer Research, which reviewed 17 studies analyzing salt consumption.
"Excess salt destroys many of the cells lining the stomach.
When these cells are replaced, excessive cell division increases
the risk of cancer," says Pelayo Correa, M.D., Boyd Professor
of Pathology at Louisiana State University. "Salt can also play
a role in the prevalence of gastritis associated with Helicobacter
pylori, a source of infection that may result in stomach cancer."
Packaged food found in the aisles of American grocery stores
may contain as much as salt as foods commonly found in Portugal,
Japan, and parts of China and Latin America -- where salt-preserved
foods are most popular and stomach cancer rates are the highest.
"The higher the salt intake, the higher the risk for stomach cancer,"
explains Dr. Correa. "When people reduce their salt intake, their
risk of stomach cancer drops."
Salt and cataracts
A clear relationship also exists between high salt intake and
posterior subcapsular cataract, the most serious type of cataract
among older people. Australian researchers who studied nearly
3,000 people found that those who consumed the most salt -- an
average of 3,164 milligrams per day -- had approximately twice
the risk of this disabling condition as did those with the lowest
intake of salt intake -- an average of 1,273 milligrams per day.
"Higher sodium levels in the blood could interfere with the level
of sodium inside the lens," explains Robert G. Cumming, M.D.,
Ph.D., associate professor of epidemiology at the University of
Sydney and lead author of the study.
The Australian study supports the findings of both an human study
that found an association between high sodium intake and increased
risk of cataract extraction, and an animal study that showed that
high sodium intake caused cataract formation. Sodium restriction
in the animals led to the reversal of early cataracts.
Most people eat more salt than the recommended daily
allowance of 2,400 milligrams. In fact, average salt
intake is around 20 times as much as our bodies require.
Given that cataracts are the leading cause of blindness worldwide,
it seems prudent to consider the Australian researchers' suggestion
that a reduction in salt consumption may help prevent cataracts
in older adults.
Salt and osteoporosis
Yet another relationship has been noticed between salt intake
and osteoporosis. Studies on both humans and animals have shown
that excess salt intake increases the loss of calcium through
the urine. "Every 2,300 milligrams of sodium excreted by the kidney
pulls 20 to 60 milligrams of calcium out with it," says Randi
Wolf, Ph.D., epidemiologist and research assistant professor at
Columbia University. That's bad because "the calcium that shows
up in urine comes from breakdown of bone," says Wolf.
If calcium intake is adequate, the body can compensate for higher
sodium intake by increasing absorption of calcium from the gastrointestinal
tract. But if you lose more calcium than you take in, your body
leeches calcium from your bones, increasing your risk for osteoporosis.
Shaking the Salt Habit
If you're like most people, you probably eat too
much salt. But other than hiding the salt shaker,
what can you do to cut down? Melanie Polk, a registered
dietician and director of nutrition education at the
American Institute for Cancer Research, offers these
labels carefully for ingredients containing sodium
(like monosodium glutamate), and notice the amount
of sodium in a serving. A serving of soup containing
1,100 milligrams of sodium is providing almost half
the recommended daily salt allowance of 2,400 milligrams.
your intake of processed foods, fast foods, salted
snack foods, mixes that contain salt, and high-sodium
prepared frozen dishes.
lots of fruits and vegetables -- prepared without
salt. Not only will you decrease your sodium intake;
you will also reduce fats and calories and add protective
nutrients and compounds.
seasoning food with herbs and spices instead of
following recipes, note the amount of salt required.
If it seems like too much, cut the amount in half
or omit the salt entirely.
eating out, request that dishes be served without
salt. If that isn't possible, order foods that are
lower in salt. Ask for gravy and salad dressing
on the side.
"If you stick to the recommended intake of sodium (no more than
2,400 milligrams per day) and consume adequate calcium (1,200
milligrams per day for people over 50), you will probably be protected,"
says Dr. Wolf. "But if you consume more than the recommended sodium
intake, you may need to up your calcium consumption."
The obesity factor
Since high blood pressure is a strong risk factor for coronary
heart disease and stroke, it makes sense that a high-salt diet,
implicated in high blood pressure, increases the risk of cardiovascular
disease. For those who are overweight, a high-salt diet can be
especially dangerous, according to Tulane University researchers.
They found that high sodium intake is significantly associated
with increased stroke incidence and with death from stroke, coronary
heart disease, and cardiovascular disease in people who are overweight.
The long-term study involved 14,000 participants over a 19-year
"Overweight people retain more sodium and are more sensitive
to the effect of sodium on blood pressure," says Dr. He, lead
author of the study.
Researchers say they are troubled by the prevalence of obesity
in the United States; they recommend that overweight patients
lose weight and reduce sodium intake. "But people who have trouble
losing weight can lessen their risk of cardiovascular disease
by reducing their salt intake," says Dr. He. "Reducing sodium
by about 6 grams [6,000 milligrams] a day could reduce mortality
from stroke by 47 percent and heart attack by 31 percent."
Salt and your diet
Most people eat more salt than the recommended daily allowance
of 2,400 milligrams. In fact, average salt intake is around 20
times as much as our body requires.
Where does the excess salt in our diet come from? Foods in their
natural state contain little salt. Most salt people consume comes
from manufactured foods -- like breakfast cereals, rice mixes,
and processed meat. Twenty to 30 percent of salt is added during
cooking or while eating.
Reports from experts concerned with diet and cardiovascular disease
or diet and chronic diseases find that lower salt consumption
is best; only two out of 70 United States experts who have recently
studied the issue disagree. But until food manufacturers are persuaded
to lower the salt content in their products, it's up to consumers
to be cautious about their salt intake.
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