In terms of U.S. fruit consumption, blueberries
rank only second to strawberries in popularity of berries. Blueberries are not
only popular, but also repeatedly ranked in the U.S. diet as having one of the
highest antioxidant capacities among all fruits, vegetables, spices and
seasonings.
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Antioxidants are essential to optimizing health by helping to
combat the free radicals that can damage cellular structures as well as DNA.
Young and middle-aged women who eat blueberries and
strawberries regularly may help lower their risk of a heart
attack later.
In a new study, researchers wanted to focus on whether
substances known as anthocyanins are good for the heart.
Anthocyanins are antioxidants,
substances found in plants that protect and repair cells from damage.
Anthocyanins provide the red, blue, and purple colors found in strawberries,
blueberries, and other fruits and vegetables.
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The study followed more than 93,000 women for 18 years. The
women, ages 25 to 42 when they joined the study, reported on their diet every four years.
A trend toward lower risk of heart attack was found in women
who ate more than three servings of blueberries and strawberries weekly,
compared to those who ate fewer servings. A serving is roughly half a cup.
"Substances naturally present in red/blue colored
fruits and vegetables can reduce the risk of a heart attack 32% in young and
middle-aged women," says Aedin Cassidy, PhD, a researcher at the
University of East Anglia in the U.K.
What's
New and Beneficial About Blueberries
- After many years of research on blueberry
antioxidants and their potential benefits for the nervous system and for
brain health, there is exciting new evidence that blueberries can improve
memory. In a study involving older adults (with an average age of 76
years), 12 weeks of daily blueberry consumption was enough to improve
scores on two different tests of cognitive function including memory.
While participants in the study consumed blueberries in the form of juice,
three-quarters of a pound of blueberries were used to make each cup of
juice. As participants consumed between 2 to 2-1/2 cups each day, the
participants actually received a very plentiful amount of berries. The
authors of this study were encouraged by the results and suggested that
blueberries might turn out to be beneficial not only for improvement of
memory, but for slowing down or postponing the onset of other cognitive
problems frequently associated with aging.
- New studies make it clear that we can freeze
blueberries without doing damage to their delicate anthocyanin
antioxidants. There's no question about the delicate nature of many
antioxidant nutrients found in blueberries. These antioxidants include
many different types of anthocyanins, the colorful pigments that give many
foods their wonderful shades of blue, purple, and red. After freezing
blueberries at temperatures of 0°F (-17°C) or lower for periods of time
between 3-6 months, researchers have discovered no significant lowering of
overall antioxidant capacity or anthocyanin concentrations. Anthocyanins
studied have included malvidins, delphinidins, pelargonidins, cyanidins,
and peonidins. These findings are great news for anyone who grows, buys,
or picks fresh berries in season and wants to enjoy them year round. They
are also great news for anyone who has restricted access to fresh
blueberries but can find them in the freezer section of the market.
- Berries in general are considered low in terms
of their glycemic index (GI). GI is a common way of identifying the
potential impact of a food on our blood sugar level once we've consumed
and digested that food. In general, foods with a GI of 50 or below are
considered "low" in terms of their glycemic index value. When
compared to other berries, blueberries are not particularly low in terms
of their GI. Studies show the GI for blueberries as falling somewhere in
the range of 40-53, with berries like blackberries, raspberries, and
strawberries repeatedly scoring closer to 30 than to 40. However, a recent
study that included blueberries as a low-GI fruit has found that
blueberries, along with other berries, clearly have a favorable impact on
blood sugar regulation in persons already diagnosed with type 2 diabetes.
Participants in the study who consumed at last 3 servings of low-GI fruits
per day (including blueberries) saw significant improvement in their
regulation of blood sugar over a three-month period of time. (Their blood
levels of glycosylated hemoglobin, or HgA1C were used as the standard of
measurement in this study.) It's great to see blueberries providing these
clear health benefits for blood sugar regulation!
- If you want to maximize your antioxidant
benefits from blueberries, go organic! A recent study has directly
compared the total antioxidant capacity of organically grown versus
non-organically grown highbush blueberries (Vaccinium corymbosum L.,
var. Bluecrop) and found some very impressive results for the organically
grown berries. Organically grown blueberries turned out to have
significantly higher concentrations of total phenol antioxidants and total
anthocyanin antioxidants than conventionally grown blueberries, as well as
significantly higher total antioxidant capacity. Numerous specific
antioxidant anthocyanins were measured in the study, including
delphinidins, malvidins, and petunidins. The antioxidant flavonoid
quercetin was also measured.
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Blueberry nutritional values, raw
Nutritional value per 100 g (3.5 oz)
Energy 60 kcal 240 kJ
Nutritional value per 100 g (3.5 oz)
Energy 60 kcal 240 kJ
14.5 g
|
|
0.3 g
|
|
0.7 g
|
|
3%
|
|
3%
|
|
3%
|
|
2%
|
|
8%
|
|
17%
|
|
4%
|
|
1%
|
|
2%
|
|
2%
|
|
2%
|
|
2%
|
|
2%
|
|
20%
|
|
24%
|
Percentages are
relative to US recommendations for adults.
Researchers
chose blueberries and strawberries because they are among the most commonly
eaten berries.
They divided the women into five groups based on how much of
the fruits they ate. Women who ate the most berries had the greatest impact on
their heart attack risk.
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Cassidy and her team also looked at other factors that are
known to raise heart attack risk. These included age, high
blood pressure, a family history of heart attack, being overweight or obese, exercise habits, smoking, and
drinking caffeineand
alcohol.
Women who ate more of the fruits also reported other
heart-healthy habits, such as being less likely to smoke and more likely to
exercise.
The new
findings echo those of other studies showing that a diet rich in fruits and
vegetables is linked with lower heart disease,
says C. Noel Bairey Merz, MD, director of the Barbra Streisand Women's Heart
Center at Cedars-Sinai Heart Institute in Los Angeles.
Merz says the study is observational, meaning it does not
prove that berries help with heart health. Women who eat
berries may also have other healthy habits that could prevent heart attacks,
she says.
Cassidy
says the study focused on younger women because there is not much research on
preventing heart attacks in that age group.
Although the actual drop in the number of heart attacks was
small, Cassidy believes that eating anthocyanin-rich fruits and vegetables
early on could pay off later, when heart attack risks rise with age.
The substances may work by improving HDL "good" cholesterol,
the researchers say. They may also lessen inflammation, which is linked
with heart attack risk.
Although the study focused on blueberries and strawberries,
many other fruits and vegetables are rich in the anthocyanins, Cassidy says.
Among them: eggplant, raspberries, black currants, plums, and cherries.
Eating more of these fruits and vegetables ''could have a
have a significant effect on prevention efforts," says Cassidy.
The study is published in the journal Circulation.
Source:
Cassidy, A. Circulation, January 2013.
Aedin Cassidy, PhD, researcher, Norwich
Medical School of the University of East Anglia, Norwich, U.K.
Mitchell Seymour, PhD, research
investigator, University of Michigan School of Medicine, Department of Cardiac
Surgery, Ann Arbor.
C. Noel Bairey Merz, MD, director,
Barbra Streisand Women's Heart Center, Cedars-Sinai Heart Institute, Los
Angeles.