Grapefruit Lowers Weight, Fights Cancer
A grapefruit or two a day, along with
a healthy diet, could help shrink widening waistlines. It might
also cut smokers' risk for cancer as it inhibits a carcinogen
in tobacco smoke.
Those findings come from two of
several studies on the benefits of citrus fruits presented Wednesday
at the annual meeting of the American Chemical Society in Philadelphia.
The so-called grapefruit diet --
which advocates mostly eating grapefruit with some protein --
has been popular on and off for weight loss for years, said Dr.
Ken Fujioka, director of nutrition and metabolism research at
the Scripps Clinic in San Diego and lead author of a study evaluating
grapefruit for weight loss. Most nutrition experts have deemed
the grapefruit-and-protein regimen unhealthy, and Fujioka is not
advocating any return to such a strict diet.
However, his findings do suggest
that a grapefruit or two each day, added to a balanced diet, might
help the weight-conscious stay svelte.
In the study, Fujioka and his colleagues
assigned 100 men and women who were obese to one of four groups.
One group received grapefruit extract, another drank grapefruit
juice with each meal, another ate half a grapefruit with each
meal, while the fourth group received a placebo. "They weren't
trying to diet," he said. "To make everyone even [on activity],
all were asked to walk 30 minutes three times a week."
At the end of 12 weeks the placebo
group lost on average just under half a pound, the extract group
2.4 pounds, the grapefruit juice group 3.3 pounds, and the fresh
grapefruit group 3.5 pounds.
"In this study they had one and
a half grapefruits a day," he noted. "That's not easy to do."
And participants ate the fruit more like an orange: "They cut
it in half, then into four sections, then separated the fruit
from the skin." Eating grapefruit this way is thought to yield
more beneficial compounds, he explained.
Exactly how grapefruit might spur
weight loss isn't known, Fujioka said, but "it appears to help
insulin resistance," which develops as people become obese.
The weight loss associated with
eating grapefruit isn't surprising to another expert familiar
with the study. "Eat fruit before any meal and you will lose weight,"
said Julie Upton, an American Dietetic Association spokeswoman.
"The fiber fills you up, and fruit has fewer calories than other
One half of a grapefruit has 60
calories, no fat, and six grams of fiber.
The fruit may have other health
benefits. In a second study, grapefruit juice helped decrease
the activity of an enzyme that makes cigarette smoke more carcinogenic.
Kristine Cuthrell, a research nutritionist
at the University of Hawaii's Cancer Research Center, gave 49
smokers grapefruit juice or another test food, onions. Then they
evaluated their urine to evaluate the activity of a liver enzyme
called CYPIA2, thought to activate the cancer-causing chemicals
found in tobacco smoke. Those who drank three six-ounce glasses
of grapefruit juice a day reduced the activity of the enzyme,
Other studies have also found that
foods rich in flavonoids, like grapefruit, can inhibit the activation
of a carcinogen, Cuthrell said.
The finding that grapefruit juice
reduced the activity of the enzyme linked with making smoke more
carcinogenic is also not surprising, Upton said, since a multitude
of studies link eating a diet rich in fruits and vegetables with
lowering cancer risk.
But she advised picking whole fruit
over fruit juice whenever possible, because the whole fruit is
Cuthrell said, "My initial advice,
of course, is to stop smoking. If you are not able to do that,
it would not be a bad idea to drink a reasonable amount of grapefruit
juice -- six to 12 ounces a day -- in addition to eating other
fruits and vegetables." In the study, the grapefruit juice tested
Reference Source 101
Aug 25, 2004