Fructose, the natural
sugar found in fruit and corn, has raised many an eyebrow because of its effect
on weight. But all fructose might not be equal. There’s the fructose that you
get in whole fruit, and then there’s the fructose that’s formulated into a
sweetener for food products like soda, which has been linked to health
problems, including healthy cholesterol levels and reduced insulin sensitivity.
But experts say that
the fruit sugar in whole fruit is not to blame for these health issues. In
fact, the U.S. Department of Agriculture recommends several healthy diet plans
to help adults with weight, all of which suggest eating 2 to 21/2 cups of fruit
daily. However, only about 42 percent of U.S. adults eat that much. In
contrast, Americans consume an average of 200 to 250 calories a day from sweet beverages,
some of which contain fructose and might be real weight-gain causing culprits.
“If we got the sugar
and high-fructose corn syrup out of our diet, you could eat all of the fruit
you wanted or could afford,” says George Bray, MD, chief of the division of
clinical obesity and metabolism at the Pennington Biomedical Research Center in
Baton Rouge, La., and the author of a detailed review of the impact of fructose
on heart disease risk factors published in Current Atherosclerosis
Reports. “It takes a lot of fruit to get much fructose. You have to squeeze
several oranges and mince up several apples to get a glass of juice.”
Fructose and Your Liver
Although you might
hope that fruit sugar would be solely good for the body, fructose does have
some unique adverse effects when consumed in excessive amounts, says Brenda M.
Davy, PhD, RD, an associate in the Laboratory for Eating Behaviors and Weight
Management at Virginia Tech in Blacksburg, Va.
Here’s why. Our diet
has three basic sugar sources: fructose from fruits; glucose from fruits and
starchy foods such as grains; and sucrose, commonly known as table sugar,
a blend of fructose and glucose. When you eat sugary or starchy foods, your
liver can take the fructose and glucose and turn it into energy, store it as
glycogen, turn it into fat, or send it to other parts of the body. While the
liver send glucose to other parts of the body once it has enough, it holds on
to fructose — loading it into the liver, whether it needs it or not.
“Nearly all the
fructose we eat ends up in the liver,” explains Kimber Stanhope, PhD, RD, a
researcher at the University of California, Davis. Problems start if you're
taking in a lot of fructose from, say, many fructose-sweetened drinks. Your
liver gets overloaded and starts sending out excess triglycerides, which contribute to heart disease risk.
In addition, Stanhope says, some of the triglycerides can stay in your liver,
decreasing insulin sensitivity and contributing to diabetes risk.
Davy notes that it's
important to be cautious with these studies. “Studies linking fructose to
health problems often use levels of fructose that are very high," she
says. "It is not clear if fructose consumed in lower amounts more common
to our diet is a problem compared with other dietary sugars.” But she says she
still prefers to err on the side of caution, and "as a dietitian, a
recommendation to limit overall sugar intake, particularly sugar-sweetened
beverages, seems prudent.”
Her advice is
supported by a small study recently published in the journal Diabetes
Care. Researchers demonstrated that young men who drank the equivalent
of two 12-ounce sodas each day for three weeks had greater insulin resistance,
higher LDL cholesterol, and higher total cholesterol levels than those
consuming an equivalent amount of glucose, pointing again toward the unhealthy
impact of fructose.
The Benefits of Fruit
Davy, Dr. Bray, and
others stress that there are benefits to eating whole fruit as part of your
general diet and even a weight-loss diet. Whole fruit has multiple health
benefits, including:
·
Better weight control. Fiber and fruit intake
could protect against increasing waist circumference over time, a review of 50
nutrition studies published in Food Nutrition Research showed.
This could be in part because whole fruit is filling,
keeping you from overeating.
·
Better appetite control. “Fruit and fruit
juices are associated with slower stomach emptying, and this means that the
rise in blood sugar and insulin is less dramatic,” points out food biochemist
Jennie Brand-Miller, PhD, who's with the Boden Institute of Obesity, Nutrition,
Exercise & Eating Disorders at the University of Sydney in Australia. “I
think it's hard to overeat fruit because it takes a long time to chew an apple,
and this makes you feel full.” The fiber and water content of fruit is also
filling, making fruit a great weight-loss snack.
·
Protection against cancer. If Americans ate just
one additional serving of fruit (or vegetables) a day, it could prevent 20,000
cases of cancer every year, according to a review of literature in Food
and Chemical Toxicology. The U.S. Department of Agriculture and the
U.S. Department of Health and Human Services stress that the cancer-preventing
potential of fruit is one reason to try to meet the guidelines for healthy fruit
consumption.
·
Better health in general. According to research
published in The American Journal of Clinical Nutrition, the
higher your fiber intake, the lower your risk for early death from all causes.
The daily goal is 25 grams of fiber, and fruit can play a role in meeting it.
·
Better heart health. “Dietary plans like
the DASH diet have been found to reduce blood pressure and improve blood
lipids, thus lowering heart disease risk, and DASH recommends a high intake of
fruits,” notes Davy.
Fruit Cautions
Keep these cautions in
mind to avoid possible drawbacks to including fruit in your diet:
·
Weight gain. Any food or beverage can lead to weight
gain if you eat too much of it. Make fruit fit into your calorie allotment.
·
Digestive discomfort. Because fruit is a
good source of fiber, if you increase your intake rapidly, you risk gut
discomfort, gas, and bloating. Add fruit (and any fiber-rich food) slowly.
·
Cost. Fresh fruit can be expensive, especially
out of season. But if you’re a savvy shopper, you can fit fruit into your
budget. Buy in season.
The Bottom Line
“I never restrict my
fruit intake,” Stanhope says, who agrees that two servings is a healthy daily
goal. And if there’s more fruit available and you want to eat it, don’t fret
about the fructose.In fact, fruit may be a good way to help manage your diet. For
example, if you like a sweet treat after dinner, replacing ice cream with a
bowl of berries is a calorie bargain.
So enjoy the bounty —
just cut down on the fructose you might be getting from other sources, such as
sweetened beverages. As Bray says, “I have yet to run into anyone who I thought
was eating too much fruit.”