In this age of marketing of new fruits of every stripe—“super,” “exotic,” “rainforest,” etc. — it is easy to overlook the fact the best of the fruits for many purposes
may be those long known. Bilberry is a good example.
Black currant is another. Also called the cassis berry (Ribes
nigrum), black currant offers many benefits similar to those
found with bilberry and blueberry. Indeed, the list of benefits is
quite impressive and includes brain, digestive and eye health
along with positive influences in the areas of asthma and overall
lung function, colds and flu, and women’s health.
The black currant is a small shrub standing up to six feet
tall. It grows in Europe, European Asia, North America and, as
a cultivated crop, is especially well represented in New Zealand.
The berry comes in vivid shades of deep red, purple and
black. It is quite small, being similar is size to the bilberry, and
is similarly nutrient dense. It is particularly high in anthocyanins,
which are the purple-black pigments that color the skin of
the black currant, giving it its name. Anthocyanins are powerful
plant or phyto-antioxidants. In addition to the anthocyanins
found primarily in the skin, black currant by way of its seeds is
a rich source of both the omega-3 fatty acid alpha-linolenic acid
(ALA) and the omega-6 fatty acid gamma-linolenic acid (GLA).
The origin of the fruit can have a strong bearing on its nutrient
content. New Zealand’s pristine conditions and mineral-rich
environment combined with its elevated exposure to ultraviolet
light results in black currants that exceed the fruit grown in
other areas in terms of anthocyanin content. The protective
delphinidin-3-rutinoside constitutes 40 percent of the total anthocyanin
content of the New Zealand fruit. Black currant also
is a source of proanthocyanidins, compounds more commonly
associated with grape seed and pine bark extracts.
Brain Health
Today, approximately a third of Americans are over the age of
50 and individuals over the age of eighty-five may make up the
fastest growing segment of the population. The “Baby Boom”
generation can expect to liver longer than its parents, but with
this comes certain challenges. At least nine million Americans
currently exhibit sub-clinical cognitive impairment and approximately
14–15 percent of all individuals over the age of sixty-five
suffer from some form of age-related dementia.
Epidemiology studies, including both regional incidence
and the analysis of specific risk factors for Alzheimer’s disease,
indicate that substantial prevention of the disease in the 50 –70
percent range is a practical possibility for the United States.
Brain aging, including conditions such as Alzheimer’s disease,
should not be viewed as if it takes place separately from the
deterioration of other bodily systems. It long has been established
that elevated blood sugar levels, which is to say, diabetes
and pre-diabetes, are linked to the rate of various forms of
dementia. Glycation, a deleterious form of modification of protein
and lipid macromolecules in which a sugar inappropriately
binds to the molecules, has been linked to diseases such as
diabetes, Alzheimer’s, and Parkinson’s as well as physiological
aging more generally. Therefore, controlling weight and preventing
blood sugar spikes are candidate courses of action for
anyone seriously interested in preventing dementias.
Although we have grown accustomed to blaming cholesterol
for almost any condition, cholesterol is linked to Alzheimer’s
disease only when certain contributors to oxidative
stress are present. Such findings corroborate the hardly novel
observation that only twenty percent of Americans eat the recommended
five-a-day fruits and vegetables: it is phytonutrients
from the diet that typically control free radical-inducing
conditions.
This is where black currant enters the picture. Certain
areas of the brain, such as the areas that involves the neurotransmitter
dopamine, are particularly vulnerable to oxidative
damage, in part as a result of the neurotransmitter itself.
This damage is significant in the manifestation of Alzheimer’s
disease and is associated with reduced dopamine levels. Perhaps
surprisingly, dopamine inhibits the formation of amyloidbeta
peptide fibrils. Researchers have found anthocyanins are
powerful protectors against oxidative stressors, with whole
fruit extracts more powerful than single fractions. James
Joseph of Tufts has been quoted to the effect that black currant
is effective in increasing dopamine levels, which are low
in Alzheimer’s patients. Dilip Gosh of HortResearch, New Zealand,
has performed related research that suggests the ability
of brain cells to control calcium concentrations is central to
their ability to recover from dopamine cytotoxicity. Animal experiments
suggest that anthocyanins taken orally can deliver their benefits centrally, which is to say, to the brain, to protect memory and motor coordination. The polyphenolics in fruits
and vegetables, especially those of berries, have been shown
to retard and even reverse age-related decrements in motor
and cognitive performance.
Eye Health
For eye health, the black currant may be even more protective
than the bilberry. The bilberry has many historical or traditional
uses based upon both the dried berries and the leaves. Used
as a medicinal herb since the 16th century, modern interest in
the bilberry is partly based on the fruit’s use by British pilots
during the Second World War. These pilots noticed that their
night vision improved when they ate bilberry jam prior to night
bombing raids. In the intervening years, scientists discovered
that anthocyanosides, the bioflavonoid complex in bilberries,
black currant and a number of other berries, are potent antioxidants.
Anthocyanosides, i.e., anthocyanins (the name changes
based on whether a sugar molecule is attached), provide
three primary benefits to the eyes. First, these highly colored
plant pigments nourish the retina. Night vision depends on
the retina’s ability to constantly regenerate visual purple (rhodopsin),
and anthocyanins serve as “building blocks” for this
important substance. Tests have confirmed these benefits.
When subjects with normal vision supplemented with either
black currant or bilberry extract, it was found the acuity of
their nighttime vision improved, as did the speed at which
they adjusted to darkness and the rate at which they recovered
from blinding glare. However, it is important to bear in
mind that positive results in trials required the ingestion of 50
mg or more per day of anthocyanins. A prudent level of intake
would be on the order of 90 or 100 mg of the anthocyanins
per day.
Another area of benefit involves the inducement of short
distance vision and/or its aggravation or exacerbation if already
present. Continual close range visual tasking, such as
extended viewing of computer screens, leads to the development
of tension of the ciliary smooth muscle, which impairs
the eye’s refractory adjustment function. One result is axial
length elongation, an aspect of myopia or “nearsightedness.”
Bilberry extracts may help counter axial length elongation
and at least one in vivo test provides evidence black currant
is superior to bilberry in this regard. Related to ciliary smooth
muscle tension is visual fatigue. As most computer users
know well, the fatigue of the eyes can extend to the neck, head,
arms, shoulders and lower back. Anthocyanin ingestion may
be helpful.
Several types of deterioration that are typical of aging eyes,
such as cataracts and macular degeneration, appear to be
influenced by the rate of generation of free radicals. In laboratory
trials, changing the diets from commercial laboratory
chow to “well-defined” diets rich in flavonoids has shown to
be beneficial. Interesting results have been found with human
trials in which anthocyanins were supplemented, either
alone or in combination with vitamin E.
Digestive Health
One of the more unexpected benefits of black currant extract
is in the area of digestive health. When researchers at Massey
University of New Zealand used an animal model to examine
the impact of supplementation of the diet with inulin, 30 percent
anthocyanin extract concentrate (BCE) or cassis infused
dried fruit (IDF), they found significant results. Desirable bacteria,
in this test meaning Bifidobacteria and Lactobacilli, were
increased and unwanted gut inhabitants, meaning Bacteriodes
and Clostridia, were reduced. Other research has shown black
currant may support gastrointestinal health by reducing the activity
of â-glucuronidase and increasing that of â-glucosidase.
Lung Function
As mentioned already, black currant contains proanthocyanidins
as well as anthocyanins and other polyphenolic compounds.
Work performed at The Plant and Food Research Institute
of New Zealand examined the impact of black currant
extract on immune function and aspects of normal inflammatory
response when the lungs are challenged. The findings
were that black currant supports normal inflammatory and
immune responses under challenge conditions. Researchers
have suggested black currant extracts may be supportive in
conditions such as asthma.
Colds and Flu
Elderberry has been used in folk medicine for centuries to treat
influenza, colds and sinusitis, and has been reported to have
antiviral activity against influenza and herpes simplex. Many people are familiar with these uses. However, relatively few individuals are aware of the fact many anthocyanins are active
against viruses. Researchers at the Department of Microbiology,
Asahikawa Medical College in Japan looked at the effects
of black currant against influenza virus types A and B in vitro.
According to the study results, both IVA and IVB were inactivated
up to 99.9 percent by 10 ìg/ml of the black currant
extract at pH 2.8, and 95 to 98 percent by this concentration at
pH 7.2. The growth of IVA in cells treated with 10 and 100 ìg/
ml of the extract after infection was completely suppressed in
six hours. The results indicated that the extract was effective
under test conditions in inhibiting the release of the virus from
infected cells.
Women’s Health
Every part of the black currant berry can be used, not just the
anthocyanidins and proanthocyanidins found chiefly in the
skin. The seed oil is a source of both the omega-3 fatty acid
alpha-linolenic acid (ALA) and the omega-6 fatty acid gammalinolenic
acid (GLA). GLA is recognized as one of the “good”
essential fatty acids used to enhance cell membrane fluidity
and function. Although the body can manufacture GLA from
dietary linoleic acid, it can be more efficiently utilized for body
functions when supplied directly by dietary sources. GLA supports
a balanced inflammatory response and has been shown
to be important for lung, joint, and eye health. According to
authorities such as Andrew Weil, MD, the combination of essential
fatty acids found in black currant seeds may influence
the production of prostaglandins and assist hormone production
to support women during menopause.
Conclusions
Black currant has earned its place in the ranks of the “super”
fruits. Its range of benefits is similar to that found with bilberry
and far better documented than those often asserted rather
than demonstrated for acai and other recently promoted fruits.
For the health of the brain and eyes, black currant is a winner. It
supports normal immune and inflammatory functions. Starting
at an intake as low as 50 mg per day of the concentrated
anthocyanins, it is compact health insurance against a world of
health challenges.
