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March 9, 2004
We are all born liking a sweet
taste, perhaps to stimulate a desire for breast milk, which
is naturally sweet, or ripe
edible fruit. These foods are excellent sources of nutrients
that support growth and good health. Indeed, as the American
Dietetic Association points out in a new position paper on
sweeteners, "By increasing palatability of nutrient-dense foods/beverages,
sweeteners can promote diet healthfulness."
For example, for
a child who refuses to drink milk, the addition of sweet chocolate
powder can enhance consumption of this health-promoting food.
Likewise, a little sugar added to a high-fiber cereal can encourage
the consumption of a food that lowers cholesterol and promotes
good digestion.
But as with any substance prone to overuse,
sweeteners can also work against us. Modern manufacturing has
introduced a plethora of sweetened products that are less than
nutritious and that could contribute to weight gain and ill
health because their sweetness encourages overconsumption.
The consumption of added caloric sugars has soared in the last
half-century, despite the introduction and undeniable popularity
of artificial (i.e. non-nutritive) sweeteners that supply few,
if any, calories.
According to the findings of the latest national
nutrition survey, from 1988 to 1994, the average daily intake
of added sugar varied from 40 to 120 grams a day, or 160 calories
to 480 calories, or an average of 21 percent of daily calories.
The World Health Organization recommends half that amount,
and my guess is that consumption is considerably higher today,
given readily observed changes in the marketplace.
There is
no direct evidence that caloric sweeteners by themselves increase
the risk of obesity. But there is also no question that in
the United States and throughout the world, rates of overweight
and obesity are increasing because people are consuming more
calories than they expend, even as their intake of several
essential nutrients declines. This suggests that people are
eating and drinking more calorically dense but nutrient-deficient
foods, many if not most because they are sweet.
Perhaps the
best example of this phenomenon is the carbonated soft drink
sweetened with high-fructose corn syrup. Such beverages contribute
nothing but sweet calories and water and have replaced nutrient-rich
milk and fruit juices in the diets of millions of Americans,
especially adolescents and young adults.
The consumption of
high-fructose corn syrup has skyrocketed 4,000 percent since
the early 1970's. By 2000, per capita annual consumption of
the sweetener in this country exceeded 62 pounds, while consumption
of cane and beet sugars decreased just 35 percent, from 100.5
pounds to 65.6 pounds per capita. That represents an annual
net gain of 27 pounds of sugar in the average American diet.
Sugar's Health Effects
No responsible nutrition expert suggests
abandoning all foods and drinks that contain added sugars,
caloric or otherwise. But in seeking to satisfy the desire
for sweetness, it helps to know what effects the various sweeteners,
natural and artificial, can have on health.
Each gram of sugar,
whether sucrose (table sugar, a combination of glucose and
fructose from sugar cane or sugar beets) or pure fructose (fruit
sugar), supplies four calories, the same as a gram of starch
or protein. A teaspoon of sugar provides about 16 calories.
Both sugars can promote tooth decay.
In most people, the small
intestine contains enzymes to foster the digestion of all natural
sugars, but absorption rates vary. Fructose can by itself be
malabsorbed and may cause diarrhea in young children who consume
large amounts of apple juice or fructose-sweetened drinks.
Other sweeteners called polyols — sorbitol and mannitol, for
example — are also less than fully absorbed and can cause diarrhea
in consumers of any age. Lactose, the milk sugar, can also
cause gastrointestinal upset in people who lose their ability
to produce the enzyme lactase.
Fructose can blunt feelings
of satiety and thus may foster overconsumption of calories.
Fructose and, to a lesser extent, sucrose can also raise blood
levels of harmful L.D.L. cholesterol. Even though the two sugars
raise blood levels of glucose, neither has been found to increase
the risk of developing diabetes, unless, of course, they result
in excess weight gain.
Despite the widespread belief that sugar
promotes hyperactivity in children, researchers have not found
support for that. Although animals seem to undergo brain changes
that suggest a kind of addiction to sugar, that has yet to
be clearly demonstrated in people.
Safety of Sweeteners
In
the American market, five non-nutritive sweeteners contain
no calories or a negligible amount, despite being much sweeter
than sucrose. They are saccharin products like Sweet'N Low,
200 to 700 times as sweet as sugar; aspartame substitutes like
Nutrasweet and Equal, 160 to 200 times as sweet; acesulfame-K
sweeteners like Sunett, 200 times as sweet; sucralose products
like Splenda, 600 times as sweet; and neotame, 8,000 times
as sweet. The sweeteners produce little or no effect on blood
sugar.
Aspartame, a popular artificial sweetener used at the
table, in diet sodas and in more than 6,000 foods, personal
care products and pharmaceuticals can be hazardous in large
amounts to people with an inherited metabolic disorder, phenylketonuria.
The American Medical Association says consumption by normal
people is safe and not associated with any adverse health effects,
not migraine headaches, depression or epilepsy. Reports of
allergic reactions have not been supported by careful studies,
a report by the American Dietetic Association states.
Saccharin
remains the leading artificial sweetener. Eight million pounds
a year find their way into foods, tabletop packets, beverages
and personal care products. A previous link to cancer in laboratory
animals has not stood the test of further research, and saccharin-containing
products no longer warn of such an effect.
Sucralose, which
is derived from sugar that is chemically changed to limit the
body's ability to absorb it, has been tested in 110 studies
in people and found free of cancer risk, reproductive damage
or neurological harm. It has also been found to be safe for
people with Type 2 diabetes. Granular sucralose can be used
instead of table sugar in desserts and baked goods.
"Non-nutritive
sweeteners could improve dietary quality if consumers were
to use energy savings for consumption of nutrient-dense foods," the
dietetic association concluded. This has the potential to improve
nutrient intake by people who want to lose or control weight
and by elderly people, who typically need and consume fewer
calories.
"Non-nutritive sweeteners could also increase the
palatability of fruits and vegetables that have less desirable
sour or bitter qualities," the report noted.
The bottom line
from the association is that sweeteners are O.K. when consumed
in a reasonable amount and context.
"Sweeteners can add to
the pleasure of eating and can assist consumers in improving
the quality of the diet if selected in appropriate quantities
and in forms that are high in micronutrients," the report concluded.
In other words, once again, it is the dose that makes the poison.
© 2004 The
New York Times Company
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