Blueberries are the fruits of
a shrub that belong to the heath (Ericaceae) family whose other
members include the cranberry and bilberry as well as the azalea,
mountain laurel and rhododendron. Blueberries grow in clusters and
range in size from that of a small pea to a marble. They are deep in
color, ranging from blue to maroon to purple-black, and feature a
white-gray waxy "bloom" that covers the berry's surface and serves
as a protective coat. The skin surrounds a semi-transparent flesh
that encases tiny seeds. Cultivated blueberries are typically mildly
sweet, while those that grow wild have a more tart and tangy flavor.
are native to North America where they grow throughout the woods and
mountainous regions in the United States and Canada. This fruit is
rarely found growing in Europe and has only been recently introduced
There are approximately 30 different species of
blueberries with different ones growing throughout various regions.
For example, the Highbush variety can be found throughout the
Eastern seaboard from Maine to Florida, the Lowbush variety
throughout the Northeast and Eastern Canada, and the Evergreen
variety throughout states in the Pacific Northwest.
While blueberries played an important role in North
American Indian food culture, being an ingredient in pemmican, a
traditional dish composed of the fruit and dried meat, they were not
consumed in great amounts by the colonists until the mid-19th
century. This seems to be related to the fact that people did not
appreciate their tart flavor, and only when sugar became more widely
available as a sweetener at this time, did they become more popular.
Blueberries were not cultivated until the beginning
of the 20th century, becoming commercially available in 1916.
Cultivation of blueberries was spearheaded by a botanist at the
United States Department of Agriculture who pioneered research into
blueberry production. His work was forwarded by Elizabeth White,
whose family established the first commercial blueberry fields.
Blueberries are literally bursting with nutrients
and flavor, yet very low in calories. Recently, researchers at Tufts
University analyzed 60 fruits and vegetables for their antioxidant
capability. Blueberries came out on top, rating highest in their
capacity to destroy free radicals.
Packed with antioxidant phytonutrients called
anthocyanidins, blueberries neutralize free radical damage to the
collagen matrix of cells and tissues that can lead to cataracts,
glaucoma, varicose veins, hemorrhoids, peptic ulcers, heart disease
and cancer. Anthocyanins, the blue-red pigments found in
blueberries, improve the integrity of support structures in the
veins and entire vascular system. Anthocyanins have been shown to
enhance the effects of vitamin C, improve capillary integrity, and
stabilize the collagen matrix (the ground substance of all body
tissues). They work their protective magic by preventing
free-radical damage, inhibiting enzymes from cleaving the collagen
matrix, and directly cross-linking with collagen fibers to form a
more stable collagen matrix.
While wine, particularly red wine, is touted as
cardioprotective since it is a good source of antioxidant
anthocyanins, a recent study found that blueberries deliver 38% more
of these free radical fighters. In this study, published in the
Journal of Agriculture and Food Chemistry, researchers found that a
moderate drink (about 4 ounces) of white wine contained .47 mmol of
free radical absorbing antioxidants, red wine provided 2.04 mmol,
and a wine made from highbush blueberries delivered 2.42 mmol of
these protective plant compounds.
Extracts of bilberry (a cousin of blueberry) have
been shown in numerous studies to improve nighttime visual acuity
and promote quicker adjustment to darkness and faster restoration of
visual acuity after exposure to glare. This research was conducted
to evaluate claims of bilberry's beneficial effects on night vision
made by British Air Force pilots during World War II who regularly
consumed bilberry preserves before their night missions.
Your mother may have told you carrots would
keep your eyes bright as a child, but as an adult, it looks like
fruit is even more important for keeping your sight. Data reported
in a study published in the Archives of Ophthalmology indicates that
eating 3 or more servings of fruit per day may lower your risk of
age-related macular degeneration (ARMD), the primary cause of vision
loss in older adults, by 36%, compared to persons who consume less
than 1.5 servings of fruit daily.
In this study, which involved over 110,000 women and
men, researchers evaluated the effect of study participants'
consumption of fruits; vegetables; the antioxidant vitamins A, C,
and E; and carotenoids on the development of early ARMD or
neovascular ARMD, a more severe form of the illness associated with
vision loss. Food intake information was collected periodically for
up to 18 years for women and 12 years for men.
While, surprisingly, intakes of vegetables,
antioxidant vitamins and carotenoids were not strongly related to
incidence of either form of ARMD, fruit intake was definitely
protective against the severe form of this vision-destroying
disease. Three servings of fruit may sound like a lot to eat each
day, but by simply topping off a cup of yogurt or green salad with a
half cup of blueberries, tossing a banana into your morning smoothie
or slicing it over your cereal, and snacking on an apple, plum,
nectarine or pear, you've reached this goal.
In laboratory animal studies, researchers have
found that blueberries help protect the brain from oxidative stress
and may reduce the effects of age-related conditions such as
Alzheimer's disease or dementia. Researchers found that diets rich
in blueberries significantly improved both the learning capacity and
motor skills of aging animals, making them mentally equivalent to
much younger ones.
In addition to their powerful anthocyanins,
blueberries contain another antioxidant compound called ellagic
acid, which blocks metabolic pathways that can lead to cancer. In a
study of over 1,200 elderly people, those who ate the most
strawberries (another berry that contains ellagic acid) were three
times less likely to develop cancer than those who ate few or no
strawberries. In addition to containing ellagic acid, blueberries
are high in the soluble fiber pectin, which has been shown to lower
cholesterol and to prevent bile acid from being transformed into a
potentially cancer-causing form.
Laboratory studies published in the Journal of
Agricultural and Food Chemistry show that phenolic compounds in
blueberries can inhibit colon cancer cell proliferation and induce
apoptosis (programmed cell death).
Extracts were made of the blueberry phenols, which
were freeze-dried and further separated into phenolic acids,
tannins, flavonols, and anthocyanins. Then the dried extracts and
fractions were added to cell cultures containing two colon cancer
cell lines, HT-29 and Caco-2.
In concentrations normally found in laboratory
animal plasma after eating blueberries, anthyocyanin fractions
increased DNA fragmentation (a sign that apoptosis or cell death had
been triggered) by 2-7 times. Flavonol and tannin fractions cut cell
proliferation in half at concentrations of 70-100 and 50-100
microg/mL, while the phenolic fraction was also effective, but less
potent, reducing proliferation by half at concentrations of 1000
microg/mL. Bottom line: eating blueberries may reduce colon cancer
Blueberries can help relieve both diarrhea and
constipation. In addition to soluble and insoluble fiber,
blueberries also contain tannins, which act as astringents in the
digestive system to reduce inflammation. Blueberries also promote
urinary tract health. Blueberries contain the same compounds found
in cranberries that help prevent or eliminate urinary tract
infections. In order for bacteria to infect, they must first adhere
to the mucosal lining of the urethra and bladder. Components found
in cranberry and blueberry juice reduce the ability of E. coli, the
bacteria that is the most common cause of urinary tract infections,
Choose blueberries that are firm and have a lively,
uniform hue colored with a whitish bloom. Shake the container,
noticing whether the berries have the tendency to move freely; if
they do not, this may indicate that they are soft and damaged or
moldy. Avoid berries that appear dull in color or are soft and
watery in texture. They should be free from moisture since the
presence of water will cause the berries to decay. When purchasing
frozen berries, shake the bag gently to ensure that the berries move
freely and are not clumped together, which may suggest that they
have been thawed and refrozen. Blueberries that are cultivated in
the United States are available from May through October while
imported berries may be found at other times of the year.
Ripe blueberries should be stored in a covered
container in the refrigerator where they will keep for about a week,
although they will be freshest if consumed within a few days. Always
check berries before storing and remove any damaged berries to
prevent the spread of mold. But don't wash berries until right
before eating as washing will remove the bloom that protects the
berries' skins from degradation. If kept out at room temperature for
more than a day, the berries may spoil.
Ripe berries can also be frozen, although this will
slightly change their texture and flavor. Before freezing, wash,
drain and remove any damaged berries. To better ensure uniform
texture upon thawing, spread the berries out on a cookie sheet or
baking pan, place in the freezer until frozen, then put the berries
in a plastic bag for storage in the freezer. Berries should last up
to a year in the freezer.
Baby foods containing berries are bereft of
anthocyanins, the water-soluble plant pigments responsible not only
for the blue, purple, and red color of berries, but also for many of
their health benefits.
Anthocyanins are found in fresh and frozen berries,
but not in processed foods.
A study published in the Journal of Agricultural and
Food Chemistry found anthocyanins were almost undetectable in canned
foods, bread, cereals, and baby foods containing berries, even in
baby foods prepared from fruits high in anthocyanins, such as
This may be due to anthocyanins' unique chemical
structure, which renders them unstable even at a neutral pH and
therefore much more susceptible to destruction during processing
than other phytonutrients, such as proanthocyanidins. To give your
children the full health benefits of berries, purchase fresh or
frozen berries and purée them.
Fresh berries are very fragile and should be
washed briefly and carefully and then gently patted dry if they are
not organic. Wash berries just prior to use to not prematurely
remove the protective bloom that resides on the skin's surface. If
you know the source of either wild or organic berries try not to
wash them at all.
When using frozen berries in recipes that do not
require cooking, thaw well and drain prior to using. For cooked
recipes, use unthawed berries since this will ensure maximum flavor.
Extend the cooking time a few minutes to accommodate for the frozen
berries. You may notice that berries used in baked products may take
on a green color. This is a natural reaction of their anthocyanidin
pigments and does not make the food item unsafe to eat.
Add frozen blueberries to your breakfast shake. If
the blender container is plastic, allow berries a few minutes to
soften, so they will not damage the blender.
Fresh or dried
blueberries add a colorful punch to cold breakfast cereals.
deliciously elegant dessert, layer yogurt and blueberries in wine
glasses and top with crystallized ginger. Blueberry pie, cobbler and
muffins are classic favorites that can be enjoyed throughout the
Blueberries are among
a small number of foods that contain measurable amounts of oxalates,
naturally-occurring substances found in plants, animals, and human
beings. When oxalates become too concentrated in body fluids, they
can crystallize and cause health problems. For this reason,
individuals with already existing and untreated kidney or
gallbladder problems may want to avoid eating blueberries.
Laboratory studies have shown that oxalates may also interfere with
absorption of calcium from the body. Yet, in every peer-reviewed
research study we've seen, the ability of oxalates to lower calcium
absorption is relatively small and definitely does not outweigh the
ability of oxalate-containing foods to contribute calcium to the
meal plan. If your digestive tract is healthy, and you do a good job
of chewing and relaxing while you enjoy your meals, you will get
significant benefits including absorption of calcium—from
calcium-rich foods plant foods that also contain oxalic acid.
Ordinarily, a healthcare practitioner would not discourage a person
focused on ensuring that they are meeting their calcium requirements
from eating these nutrient-rich foods because of their oxalate