Blackcurrant: The Forgotten Superfruit

Article by Arnie Gitomer

The Forgotten Superfruit: Blackcurrant

by Brad J. Douglass, PhD

The rap sheet on blackcurrant reads like that of an international spy: banned in the United States for almost a century, sponsored by the government in the U.K. during World War II, impersonated by a Greek imposter, residing in four continents and yet unknown to many.  Blackcurrant also has a long list of aliases to match, including the “forgotten superfruit,” the “forbidden fruit,” the “king of berries,” and the “#1 Superfruit.” Next up: double-O…currant?!
But blackcurrant is not just hyperbole: it exudes substance.  It is packed with nutrients and taste.  And medical scientists are currently researching its benefits toward inflammation, eye, brain and cardiovascular health.  So let’s unmask this wondrous berry and find out why it’s extolled by so many.

Blackcurrants: Tangy & Friendly!

Fresh blackcurrants tend to have a tart and sweet taste and a pleasing aroma to match.  The volatile components that lead to the distinct blackcurrant taste, and aroma notes, allow it to accentuate paired flavors—like a fine wine. Some Guinness connoisseurs like to add blackcurrant juice to bring out the flavors of Guinness.   
The astringency of blackcurrants is valued in many recipes, often leading to popular pairings with sweet and creamy counterpoints: blackcurrant yogurt, blackcurrant mousse, blackcurrant meringue or simply blackcurrants topped with whipped cream.  Popular in Great Britain, blackcurrant jams and cordials were also popular American recipe favorites before blackcurrant cultivation was banned in the U.S.  Popular drinks like Kir, or Kir Royale, feature the blackcurrant flavor with white wine, or champagne.    

From the Earth

Blackcurrants are the edible berries of a shrub that grows to about 3-6 feet in height.  The species (Ribes nigrum) was originally native to North and Central Europe and Northern Asia, but has undergone significant botanical selection since the Middle Ages.  The shrub grows best in temperate climates usually at latitudes greater than 35 degrees.  Various cultivars of the blackcurrant species have found a thriving home around the globe, especially in Eastern Europe, New Zealand, New York and Great Britain.
Over 50% of blackcurrants cultivated commercially around the globe start with the name ‘Ben,’ having been named after mountains in Scotland.  These cultivars trace their lineage from the Scottish Crop Research Institute (SCRI).  ‘Ben Hope’ is the most widely grown variety in the U.K. and Europe.  The ‘Ben Ard’ is an offshoot cultivar that is popular in New Zealand and is touted to have anthocyanin contents in excess of 700 mg/100g fruit.  A variety named ‘Titania’ is patented in the U.S. and possesses good resistance to White Pine Blister Rust—an important player in blackcurrant’s U.S. heritage.   

Currants are Berries—Not Raisins    

Blackcurrants suffer from an image problem.  Not only was their cultivation forbidden in the U.S., but while they were banned an imposter stole their good name.  This imposter was a mini raisin from Greece.  The story goes that these raisins i.e., dried grapes not berries, began being imported about a decade after blackcurrant cultivation was banned in the U.S.  The shipping container was labeled with the Greek characters “????????,” the Greek spelling for Corinth, a city in Greece. This was purportedly mistaken for “currant.”  This name likely stuck thereafter because it filled a niche left vacated by real blackcurrants when they were outlawed.  And since the origin of these mini raisins is the Greek Island of Zakýnthos, also called Zante, we are left with the name “Zante Currants” for something that is not a currant at all.  Worse, many in this country now hear “currant” and mistakenly associate it with the taste of a raisin.
Unfortunately for blackcurrants everywhere, that is not the only confusion resulting from naming and labeling.  The blackcurrant flavor is often labeled in the U.S. under its French pseudonym “cassis.”  But like the chickpea and the garbanzo bean, blackcurrant and cassis are one and the same.  
Then there is the issue of the spelling: “blackcurrant” or “black currant.”  Historically, black currant was used to simply describe the dark currants in a currant environment replete with various colored currants.  Now, even though these other colored currants still exist, the dark ones greatly overshadow their brethren.  Consciously or unconsciously, the space in “black currant” was likely elided because of this distinction.  Currently “blackcurrants,” “black currants” or simply “currants” are typically accepted terminology.  But if you hear someone refer to “Zante Currants” as just “currants”—throw a raisin at them.

Historical Health Use

Blackcurrants have been used to impact human health since at least the Middle Ages in Europe and have a long history in Russia and North America, as well.  Native American tribes used various parts of the blackcurrant plant to treat swellings as well as kidney, uterine and stomach ailments.  There is record of German apothecaries administering cordials for lung conditions and recommending wild blackcurrants for use in treating bladder stones and liver disorders.  Interestingly, there is at least one scientific study that suggests substantiation for this use.
In the nineteenth and beginning of the twentieth century, European physicians intuitively recognized the benefits of blackcurrants high vitamin C content in preventing scurvy and as a useful tonic.  During this period blackcurrant was also indicated for various infections, including urinary tract infections, inflammations and intestinal ailments.  Research surrounding the high anthocyanin content and specific polysaccharide composition of blackcurrant is now turning up evidence that may support some of these traditional uses.

U.S. Public Enemy: blackcurrants??

Prior to the 20th century, blackcurrants were a very popular fruit in the United States.  Their sweet and tangy taste, wholesome nutrient profile and versatility provided much to love.  However in the first few years of the 1900s, the Northeastern U.S. was stricken by an outbreak of white pine blister rust that threatened many species of pine.  It was determined that the blackcurrant plant was an integral host in the life cycle of this fungus. The powerful lumber industry pointed to the unassuming blackcurrant as the cause and lobbied for a federal planting ban.  It was enacted.  And since perishables, like fresh produce, could not be transported around the world at the time the blackcurrant fell off the American radar and was forgotten.
Later botanists and plant pathologists would determine that blackcurrant was not the cause of the rust at all—just an unwilling accomplice.  It seems the rust appeared in Germany and infected white pines there that had been originally imported from the U.S.  U.S. interests later acquired seedlings of these trees from Germany, without knowledge of the blight.   These seedlings, when planted in the U.S, were then able to spread the fungus to other white pines and to blackcurrants plants.  But not all plants.  Some varieties are extremely resistant and do not pose a real threat.  All blackcurrants were not the enemy to white pines that they were made out to be.
The Federal ban of the wrongly accused blackcurrant was shifted to States’ jurisdictions in the 1960s. The development of fungicides and resistant varieties that help prevent blights, like the white pine blister rust, led to blackcurrant lobbying efforts.  Greg Quinn, a horticulturist and farmer in New York’s Hudson Valley successfully spearheaded the effort to overturn the ban in New York in 2003. Since then most other states have followed the lead.  Quinn adds 'by starting one of the first currant farms in the U.S., encouraging other farmers to grow currants, educating the public about this little known nutrient packed berry and producing the first domestic, nationally available black currant product of any kind, we have done a lot to revive the blackcurrant industry in the U.S.'  Greg Quinn is president of The Currant Company, which produces CurrantC™ All Natural Black Currant Nectar (www.CurrantC.com).

U.K. Public Savior

During World War II with global shipping and supply lines in disarray, the United Kingdom could not import oranges.  Without oranges U.K. public officials grew concerned about vitamin C deficiencies in the populace.  The government guidebook probably suggested limes, the juice of which British sea captains had added to their ships’ water supply centuries before (hence: “limeys”) to prevent scurvy caused by vitamin C deficiency.  Unfortunately, limes are grown tropically so they faced the same problem as oranges.
The UK then smartly hit upon blackcurrants.  They were grown domestically and they had many times the vitamin C of oranges or limes.  The government encouraged growing efforts resulting in a greatly increased crop.  In 1942, the public health necessity seemed of such importance that the entire blackcurrant crop was processed into jams and cordials and given away to the people free of charge.

Nutrient Info

The vitamin and mineral content of blackcurrants has garnered much acclaim.  Some have proclaimed it the “#1 Superfruit.”  Others have declared blackcurrant the new “king of berries,” dethroning the previously proclaimed king of berries, the blueberry.  Let’s take a look at how blackcurrant measures up.
Blackcurrants typically possess a vitamin C content 3-4 times that of an equal weight of oranges and an equivalent amount of potassium as bananas.   Due to their color, it may be obvious that blackcurrants surpass blueberries in anthocyanin content.  In fact, many blackcurrant varieties consistently produce crops that have upwards of four times the anthocyanin content and twice the antioxidant power of blueberries. “The pristine mountain water, fresh air and harsh growing conditions in New Zealand create wonderful blackcurrants," says Eddie Shiojima, PhD, Director of Product Development for Just The Berries Ltd (www.justtheberries.com/). “It is believed that the high amount of UV radiation in New Zealand leads to increased levels of anthocyanins.”  Blackcurrants are also particularly rich in the essential minerals calcium, iron, magnesium and zinc.  And Ribes spp. often weigh-in with a calcium:magnesium content ratio of 2:1, which some believe is important for bone health. In addition, blackcurrants contain significant amounts of vitamins B2, B6, E and K. Finally, fresh blackcurrants are a good source of fiber with 100 g providing about 30% of one’s RDA.

What are Anthocyanins?

Anthocyanins are a class of compounds that are naturally found in colored berries.  Usually, the darker the berry, the higher the anthocyanin content.  The class is composed of more than 300 different anthocynanins that have been discovered to date.  It is believed that fruits producing these compounds benefit from the resulting coloration in pollination, seed dispersal and protection from the sun’s UV radiation.  Technically anthocyanins are water soluble pigments that are composed of an anthocyanidin component and a sugar component.  The structure of the anthocyanidin component is similar to that of flavonoids, or bioflavonoids—another important class of phytonutrients.
Anthocyanins are responsible for the dark hue of blackcurrants.  Growers will sometimes use the darkness of the berries as a qualitative evaluation of their worth.  And the reason for this worth?  Anthocyanins possess strong antioxidant activity and are believed to be responsible for other beneficial health effects in humans.
Much health research has been devoted to anthocyanins.  Some of the indications they have been studied for include: inflammation, diabetes, aging and neurological diseases, bacterial infections and cancer.  Looking at this research it is tempting to think of anthocyanins as a panacea—and some proclaim them so.   As a whole, their importance as a dietary-source of antioxidants is well accepted and there is a good amount of evidence to support their anti-inflammatory activity.  However anthocyanins are a large class of molecules, so it can be more useful to focus on the properties of specific anthocyanins, from specific fruits, rather than as a whole.

Blackcurrant Health Science

Eyes

Two anthocyanins, delphinidin-3-rutinoside and cyanidin-3-rutinoside, which account for more than 80% of blackcurrant anthocyanins, have shown beneficial effects specific for eye health.  Delphinidin-3-rutinoside appears to relax the ciliary smooth muscle of the eye.  In myopia, or near-sightedness, the ciliary smooth muscle cannot relax enough to allow focusing on distant objects.1  Whereas cyanidin-3-rutinoside was found to assist in the regeneration of rhodopsin in frogs.2 Rhodopsin is the primary photopigment of rod cells enabling night vision in humans.  There have also been two studies conducted in Japan that have suggested increased blood flow to the optic papilla and reduced susceptibility to eye fatigue and eye strain due to consumption of blackcurrant.3

Cardiovascular

Vasorelaxation is important for healthy circulation and blood pressure.  Multiple studies have now found that blackcurrant anthocyanins have a positive impact on vasorelaxation.  One study found that two of the four most abundant anthocyanins in blackcurrant, delphinidin-3-rutinoside and delphinidin-3-glucoside, decrease vascular resistance and encourage blood flow.4  This may be the result of blackcurrant anthocyanins affecting nitric oxide production.5  These beneficial blood flow results may explain a study that found improved shoulder stiffness and decreased muscle fatigue when blackcurrant anthocyanins were given to those doing typing work. 6  Vasorelaxation may also be an important mechanism in explaining some of the positive effects of blackcurrants on eye health.

Inflammation

In a recently published study, consumption of a mixture of blackcurrant and orange juices caused significant decreases of the important inflammation biomarkers C-reactive protein (CRP) and fibrinogen.9  High CRP levels are a risk factor for cardiovascular disease.  In 2007, a preliminary study found that a mixture of blackcurrant and bilberry anthocyanins reduced plasma levels of pro-inflammatory agents in the blood of humans.7  And since pro-inflammatory agents promote inflammation this could turn out to be good news for sufferers of chronic inflammatory diseases like arthritis.

Brain  

New Zealand researchers have found that an anthocyanin containing extract of blackcurrants has protective effects for brain cells against oxidative stress.6  This seems to be the first demonstration of neuroprotection from a berry extract.  Another blackcurrant researcher from Tufts University, James Joseph, believes results from this line of research may suggest promise in protecting against Alzheimer's disease by possibly influencing gene expression involved in learning and memory.

Immune

A Japanese research group has investigated the immune stimulating properties of a mixture of polysaccharides extracted from blackcurrants—dubbed cassis polysaccharide (CAPS).  The researchers report that CAPS stimulates macrophage and interleukin 1 activity, two important players in the body’s immune response.10
“We were cognizant of many of these health studies when we created our blackcurrant + pomegranate juice concentrate,” says Kevin Connolly PhD, Director of Research & Development at Jarrow Formulas (www.jarrow.com) “but we also wanted to create a beverage that tasted good.  The pairing of blackcurrant with pomegranate has turned out to be a popular flavor combination.”

Forgotten No Longer

Blackcurrant is back.  And it is easy to see why.  Sporting 3-4 times the vitamin C as oranges, providing a rich source of beneficial anthocyanins and containing twice the antioxidant power of blueberries, this berry already looks good.  Factor in it being a great source of potassium, iron, magnesium, zinc, B2, B6 and fiber with a sweet and tangy flavor profile and it’s starting to look great.  Then when one takes into account burgeoning medical research surrounding its health benefits, blackcurrant looks downright super.  So try a fresh berry, blackcurrant juice, or blackcurrant juice concentrate, today.  You know you want to—and after all, do you really need another raisin…I mean, reason.

Brad Douglass, Ph.D is a Jarrow Formulas consultant. He obtained his Ph.D from USC in Organic Chemistry where his research efforts concentrated on drug discovery.  He was also a postdoctoral fellow at USC where he investigated novel blood-brain barrier transport methods for use in drug delivery to the brain.

1.    Matsumoto H, et al. (2005) Delphinidin-3-rutinoside relaxes the bovine ciliary  smooth muscle through activation of ETB receptor and NO/cGMP pathway.  J. Exp. Eye Research, 80: p. 313-22.
2.    Matsumoto H, et al. (2003)  Stimulatory Effect of Cyanidin 3-Glycosides on the     Regeneration of Rhodopsin. J. of Agricultural and Food Chemistry, 51(12):     p. 3560-3563.
3.    Nakaishi H, et al. (2000) Effects of Black Currant Anthocyanoside Intake on Dark     Adaptation and VDT Work-induced Transient Refractive Alteration in Healthy     Humans.  Alt. Med Review, 5(6): p. 553-562.
4.    Iwasaki-Kurashige K, et al. (2006) Possible mediators involved in decreasing peripheral vascular resistance with blackcurrant concentrate (BC) in hind-limb perfusion model of the rat. Vascul Pharmacol. 2006 Apr;44(4):215-23.
5.    Nakamura Y, et al. (2002) Endothelium-dependent vasorelaxation induced by black currant concentrate in rat thoracic aorta.  Jpn J Pharmacol, 89(1):29-35.
6.    Matsumoto H, et al. (2005) Effects of blackcurrant anthocyanin intake on peripheral muscle circulation during typing work in humans.  Eur J Appl Physiol, 94(1-2):36-45.
7.    Karlsen A, et al.  (2007) Anthocyanins Inhibit Nuclear Factor- B Activation in Monocytes and Reduce Plasma Concentrations of Pro-Inflammatory Mediators in Healthy Adults.  J. Nutr. 137:1951-1954, August.
8.    Dalgård C, et al. (2008) Supplementation with orange and blackcurrant juice, but not vitamin E, improves inflammatory markers in patients with peripheral arterial disease. Brit J Nutr, May 28:1-7.
9.    D. Ghosh, et al. (2006) Effects of anthocyanins and other phenolics of boysenberry and blackcurrant as inhibitors of oxidative stress and damage to cellular DNA in SH-SY5Y and HL-60 cells. J Sci Food and Agr. 86(5): 678-686(9).
10.    Takata R, et al. (2005) Immunostimulatory effects of a polysaccharide-rich substance with antitumor activity isolated from black currant (Ribes nigrum L.) Biosci Biotechnol Biochem, 69(11): 2042-50.
Reprinted with permission from Whole Foods Magazine January 2009