Removing most of the sugar from a
child's diet can immediately improve health, even if the diet still contains
the same amount of calories and carbohydrates as before, a new study suggests.
Researchers put a group of 43
obese kids on a nine-day diet that severely restricted sugar intake, but
replaced added sugars with starchy foods to maintain the children's intake of
calories and carbs.
That diet caused immediate
reductions in their high blood pressure and improvement in their blood sugar
and cholesterol levels, the investigators found.
"Every aspect of their
metabolic health got better, with no change in calories," said study
author Dr. Robert Lustig, a pediatric endocrinologist at UCSF Benioff Children's
Hospital in San Francisco.
"This study definitively shows that sugar is metabolically harmful not
because of its calories or its effects on weight. Rather, sugar is
metabolically harmful because it's sugar."
The finding raises serious
concerns about the health effects of sugar, and calls into question the
longstanding belief that "a calorie is a calorie is a calorie,"
regardless of its food source, said Dr. Jeffrey Mechanick, director of
metabolic support in the division of endocrinology, diabetes and bone disease
at Mount Sinai Icahn School of Medicine in New York City.
"It's an important study
that adds to the weight of evidence, and really calls out for us to examine the
fact that eating patterns, and what a healthy eating pattern is for the American
public, are as important as total caloric intake," said Mechanick, who is
president-elect of the American College of Endocrinology and a past president
of the American Association of Clinical Endocrinologists.
For the study, researchers
recruited kids aged 8 to 18 who were obese and had at least one other chronic
metabolic problem, such as high blood pressure, elevated cholesterol levels or
signs of insulin resistance.
The study only involved black and
Hispanic kids, because of their higher risk for certain conditions associated
with metabolic syndrome, such as high blood pressure and type 2 diabetes.
The researchers provided the
study participants with nine days of food, including all snacks and drinks.
The menu was crafted to be
kid-friendly, but restricted foods loaded with added sugars such as high-sugar
cereals, pastries and sweetened yogurt.
All of the foods -- which
included turkey hot dogs, potato chips and pizza -- came from local
supermarkets, and researchers provided starchy carbs from foods such as bagels,
cereal and pasta to replace the carbs that normally would have come from sugary
treats.
The end result: kids consumed the
same amount of carbs, but their total dietary sugar intake dropped from 28
percent to 10 percent.
The children were given a scale
and told to weigh themselves every day. If they started to drop weight
drastically, they were given more low-sugar foods so that weight loss could be
discounted as a factor in any positive health effects that might occur.
After just nine days on the
sugar-restricted diet, virtually every aspect of the participants' metabolic
health improved without a huge change in weight.
Blood pressure began to move
toward normal, and levels of triglycerides and LDL ("bad")
cholesterol decreased. Fasting blood glucose went down by 5 points, and insulin
levels were cut by a third, the findings showed.
"We took kids who are sick
and we made them healthy," Lustig said. "We didn't completely reverse
it, but within 10 days we went a very long way in reversing their metabolic
dysfunction, with no change in calories and no change in weight."
Other studies have shown that
sugar can have bad metabolic effects outside of promoting weight gain through
additional calories, Lustig said.
The sugar contained in foods is
made up of two simple sugars called glucose and fructose, and studies have
found that fructose can promote cellular aging, he said.
Fructose also acts directly upon
the reward system in a person's brain, causing them to crave more sugar.
"The more sugar you get, the more you want," Lustig said.
These findings show that people
would do well to follow dietary guidelines that already encourage them to limit
sugar intake and eat more fruits and vegetables, Mechanick said.
However, he noted that the study involved
only a handful of kids over a short amount of time, and needs to be replicated
in a larger group.
"It's an important study to
file along with the total weight of evidence," Mechanick said.
"Obviously, it's going to need to be corroborated in a different setting
and a different population."
The study was published online
Oct. 27 in the journal Obesity.
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