Whole fruits protect against diabetes, but juice is risk factor, say researchers
Eating blueberries, grapes, apples
and pears cuts the risk of type 2
diabetes but drinking fruit juice
can increase it, a large study has
found.
Researchers including a team from
Harvard School of Public Health in
the US examined whether certain
fruits impact on type 2 diabetes,
which affects more than 3 million
Britons.
People who ate three standard
servings a week of blueberries had
a 26% lower chance of developing
the disease, they found. Those
eating grapes and raisins had a
12% reduced risk and apples and
pears cut the chances by 7%.
Prunes also had a protective effect,
giving an 11% drop in the risk of
developing type 2 diabetes.
Other fruits such as bananas,
plums, peaches and apricots had a
negligible impact but drinking fruit
juice increased the risk by 8%,
according to the study.
People who replaced all fruit juice
with eating whole fruits could
expect a 7% drop in their risk of
developing type 2 diabetes.
For individual fruits, replacing
three servings a week of fruit juice
with blueberries cut the risk by
33% while replacing juice with
grapes and raisins cut the risk by
19%. The risk was also 14% lower
if juice was replaced with apples
and pears, 13% lower if replaced
with bananas and 12% lower if
replaced with grapefruit.
The research, published in the
British Medical Journal, includes
data on 187,382 people taken from
three separate studies, of whom
12,198 developed type 2 diabetes.
Food questionnaires were used
every four years to assess diet and
asked how often, on average,
people consumed each food in a
standard portion size.
The relatively high glycaemic load
of fruit juice along with "reduced
levels of beneficial nutrients
through juicing processes" may
explain why juice increases the risk
of type 2 diabetes, the authors
suggest. "Fluids pass through the
stomach to the intestine more
rapidly than solids even if
nutritional content is similar. For
example, fruit juices lead to more
rapid and larger changes in serum
levels of glucose and insulin than
whole fruits," they said.
More research was needed, they
added, but concluded: "Greater
consumption of specific whole
fruits, particularly blueberries,
grapes and apples, is significantly
associated with a lower risk of type
2 diabetes, whereas greater
consumption of fruit juice is
associated with a higher risk."
About 2.7 million people in the UK
are diagnosed with type 2 diabetes
and a further 850,000 are thought
to have it but not know. Another 7
million people are estimated to be
at high risk of developing the
disease, which is linked to obesity
and inactive lifestyle.
Complications of type 2 diabetes
include limb amputation,
blindness, kidney failure, heart
disease and stroke.
Dr Matthew Hobbs, head of
research for Diabetes UK, said: "The
best way to reduce your risk of
developing type 2 diabetes is to eat
a balanced, healthy diet that
includes a variety of fruits and
vegetables and to be as physically
active as possible.
"This research provides further
evidence that eating plenty of
whole fruit is a key part of the
balanced diet that will help you to
achieve a healthy weight and so
minimise your risk of developing
type 2 diabetes.
"However, the associations between
type 2 diabetes and specific types
or fruit or fruit drinks must be
treated with much more caution.
Some of the findings are based on
a number of assumptions and
models which may have distorted
the results significantly.
"For example, the researchers used
surveys to ask participants how
often they ate certain foods. This
type of survey can often be
unreliable as people are more
likely to remember certain types of
food."
