People who eat more raw fruits or drink juice do not
necessarily have lower blood pressure, according to a new study that goes
against previous evidence.
Larger, more rigorous studies have found that eating more
fruits and vegetables does lower blood pressure over time, but the specific
role of fruit remained unknown, lead author Dr Linda Oude-Griep said.
Based on the new results, it is unclear if eating more fruit
will influence blood pressure, said Oude-Griep, of the Imperial College London
School of Public Health. Oude-Griep and her coauthors analysed data from a
study of 4 680 middle aged men and women randomly selected from Japan, China,
US and UK.
Participants recalled what they had eaten the previous day
two days in a row, having blood pressure measurements taken as well, then
repeated the process three weeks later. Their blood pressures averaged at or
just below 120/80, the safe cutoff point according to the Centers for Disease
Control, but people with higher measurements were included.
Participants’ fruit consumption
The researchers calculated each person's fruit and fruit
juice consumption as grams per 4200 kilojoules of food eaten. People in the US
ate the least raw fruit, averaging 52 grams, equivalent to half an apple, per 4 200
kilojoules, compared to 68 grams in China, the country with highest
consumption. Fruit juice was not commonly consumed in the Asian countries; in
the US, the average was 46 grams, or less than a cup. For the group as a whole,
there was no association between fruit and blood pressure.
When the researchers considered Japan and China alone, blood
pressure actually increased with more fruit, but the change was almost imperceptible.
But the study was small and only looked at one group of people at one point in
time, so the results have limitations and the door is open for more research,
Oude-Griep said."The main limitation of this study is that dietary intake
was assessed on only a single day, and that is not a good representation of a
person's usual diet," Dr Walter Willett told Reuters Health by email.
results included decrease in blood pressure
Previous studies which found a decrease in blood pressure
followed individual eating patterns over longer periods of time and were
probably more reliable, said Willett, chair of the nutrition department at
Harvard School of Public Health in Boston.
Other differences may have also played a role. In the new
study, high fruit consumers were more often women, older, more educated, less
likely to smoke or drink alcohol, and tended to have healthier diets overall.
People who ate more fruit got more vitamin C, fiber, potassium and magnesium,
according to the study.
Fruit juices contain lots of rapidly absorbed sugars that
might offset some of the benefits of fruit itself, Willett said."My main
concern is that this article should not dissuade people from eating fruit,
which has increasingly been found to be part of a healthy diet (along with
vegetables)," said Dr Martha Grogan, a cardiologist at the Mayo Clinic in
Most doctors don't expect eating more fruit to lower
blood pressure by itself, but achieving a healthy weight does lower blood
pressure, and eating more fruit and vegetables is a part of that process, Grogan said.