Bilberry and Black Currants

Vision-Supporting Nutrients Enhance Heart Health, Build Immunity and Protect Against Damage from Computer Use

By Chris D. Meletis, ND

Some of the most powerful antioxidants in the plant kingdom are pigments known as anthocyanosides. These pigments are found in a variety of fruits—especially bilberry and black currants—and are even partly responsible for the intense red and orange hues seen in fall foliage. Anthocyanosides are not a household name, but anyone who wants to improve his or her health should take note of this plant-derived compound. Although anthocyanosides are best known for their eye-protective properties, studies indicate this compound’s uses go far beyond those involved in maintaining vision. Animal studies have found that anthocyanosides strengthen blood vessels and improve blood flow and that these plant pigments also help maintain healthy blood sugar levels. In addition, anthocyanosides are extremely powerful antioxidants and anti-inflammatories that can protect against DNA damage and LDL oxidation, the process by which cholesterol turns rancid and increases the risk for heart disease. They also mount a defense against the yeast/fungus candida albicans and against the ulcer-causing bacterium Helicobacter pylori.

Bilberries and black currants are a particularly rich source of anthocyanosides. Bilberries, which are related to blueberries, have a high antioxidant content. Black currants, a popular fruit in Europe, is a powerful source of antioxidants—even more so than blueberries—and has four times the amount of vitamin C than oranges and more potassium than bananas. Black currants also have an extremely high anthocyanosides’ content. This article will address potential uses for bilberry and black currants.

Ocular Advantages

The anthocyanosides found in bilberries are drawn to the retina’s visual purple area. This area of the eye controls vision and adjustments to various lighting conditions. It is thought that anthocyanosides, by their presence in the retina, provide ocular nourishment.

During World War II, French researchers noted Bilberry extract’s ability to strengthen eye health when it was given to Royal Air Force pilots. When given bilberry extract, these subjects experienced improved night vision, faster adjustment to darkness, and faster restoration of visual acuity after they were exposed to glare.1 Many subsequent studies achieved similar results.2-3

Researchers have proposed that bilberry extract’s effects might be more pronounced in individuals with impaired visual acuity since studies of bilberry extract on subjects with retinitis pigmentosa3 and hemeralopia (inability to see directly in bright light)4 resulted in a significant improvement in visual performance.

Because bilberry enhances collagen structures through the inhibition of free radicals, it also has proved supportive in human studies of glaucoma patients. Researchers believe that the integrity of the aging eye is weakened and that it undergoes a reduction in tensile strength, causing an increase in intraocular pressure and the peripheral vision loss that occurs in glaucoma. Because bilberry stops collagen breakdown, researchers have investigated its effects in glaucoma. In one study, eight glaucoma patients given a single oral dose of 200 mg bilberry anthocyanosides experienced noteworthy improvement.5

Studies have shown that bilberry may play an equally supportive role in stopping cataract development. In 50 patients with senile cortical cataracts, 180 mg, twice per day of bilberry extract combined with vitamin E resulted in arrested cataract formation in 48 of the 50 subjects.6

Another form of ocular disorder in which bilberry has been investigated is diabetic retinopathy. Several clinical studies support its use in diabetics with this condition. One month-long, double-blind study of participants with diabetic and/or hypertensive retinopathy investigated the effects of bilberry extract compared to a placebo. Researchers observed significant improvement in the interior of the eye in 11 of the 14 subjects receiving bilberry. Furthermore, 12 patients experienced an improvement in the function of blood vessels of the eye.7

Researchers believe that the reason why bilberry-derived anthocyanosides have shown such results in studies of diabetic retinopathy is because of their ability to affect the synthesis of connective tissue. In diabetic retinopathy, connective tissue synthesis is abnormally increased to help the eye repair leaking capillaries and form new capillaries. Human studies have shown that anthocyanosides decrease biosynthesis-activity of connective tissue, helping to prevent injuries in diabetic eyes.8

Scientists also have begun studying black currant for its visual effects. In a double-blind, placebo-controlled, crossover study of healthy human subjects, researchers investigated black currant’s effects on several factors: 1) the ability of eyes to adjust to the dark 2) the negative effects on vision that occurs after using a video display terminal and 3) subjective symptoms of weakness or tiring of the eyes accompanied by pain, headache and dimness of vision (asthenopia). In the study of dark adaptation, researchers gave 12 subjects a 12.5 mg, 20 mg or 50 mg dose of black currant. In each of these groups, the ability of eyes to adapt to the dark improved, although the 50 mg dose had the largest effect. In the study with the video display terminal, 21 subjects who received 50 mg of black currant anthocyanosides experienced no decline in visual health after using the computer, whereas the placebo group’s visual health declined. When the researchers assessed the subjective symptoms of asthenopia by administering a questionnaire, they noted significant symptom improvement in the subjects.9

Cardiovascular Support

The anthocyanosides in bilberries and black currants have a number of interesting effects on the heart. Both bilberries and black currants can play an important role in improving the health of the body’s microcirculation. Although it is usually macrocirculation—the network of arteries and larger blood vessels—that receives a great deal of attention, microcirculation—the smaller blood vessels and capillary system—is equally important. Because atherosclerosis is a systemic disease, patients who experience it have both damaged macrocirculation (large blood vessels) and microcirculation (small vessels and capillaries).

A rodent study showed that black currants can improve the function of smooth muscle in the aorta. In the animals given black currant concentrate, there occurred a relaxation of the aorta, indicating black currant improved blood flow.10

Improving the body’s microcirculation can be especially helpful for people with venous insufficiency and varicose veins. Animal studies of bilberry show that it helps decrease vascular permeability and improve vascular tone and blood flow.11

In humans, clinical trials have reached similar conclusions. One such study involved 15 patients with polyneuritis due to peripheral vascular insufficiency. Researchers gave the subjects 480 mg per day of bilberry extract and noted significant improvement in microcirculation in the subjects.12 The same dose of bilberry extract in 47 patients who suffered from venous diseases resulted in an elimination of the microstagnation that occurs in the vessels in these patients and increased blood flow in the foot.11 A review of uncontrolled trials on bilberry that involved 568 patients with venous insufficiency of the lower limbs added further support for bilberry’s vein-enhancing actions. The review found that bilberry extract rapidly decreased symptoms and improved both venous microcirculation and lymph drainage.13 Other studies have confirmed that anthocyanosides can reduce capillary fragility.14

Another way in which bilberry extract supports circulatory system health is by virtue of its ability to stop blood platelets from sticking together. It has demonstrated this effect in humans when given at doses of 480 mg per day for 30 to 60 days.15

Furthermore, bilberry extract protects LDL cholesterol from oxidation. In the body, when lipids oxidize, it initiates the atherosclerosis process. Even small amounts of bilberry extract have strongly inhibited LDL oxidation, leading researchers to suggest that bilberry may be even  more powerful than ascorbic acid in stopping the initiation of this destructive process.16

Immune Enhancement

Beyond their heart-protective and vision-enhancing abilities, anthocyanosides appear to have an equally strong effect on the immune system. In particular, researchers have studied black currant for its antiviral, antifungal, antibacterial and antimutagenic actions and its ability to stimulate immune cells.

Black currant may stop H. pylori, the bacterium thought to cause ulcers and gastric cancer, from adhering to the gastric mucosa in humans.17

Another in vitro study investigating black currant’s antiviral actions found that it completely stopped the herpes simplex virus from attaching to the cell membrane.18 Black currant has been equally effective during in vitro studies at inhibiting influenza A and B viruses. Black currant inhibited the virus release from infected cells and inhibited virus adsorption to cells.19-20

Help for Hyperglycemia

Bilberry has a long history of traditional use to help support healthy blood sugar levels. In studies of dogs, oral administration of bilberry reduces hyperglycemia even when the dogs are given bilberry together with glucose injections. The blood-sugar-lowering component of bilberry is thought to be the anthocyanoside known as myrtillin. Bilberry extracts also are thought to protect against some of the neurological complications of diabetes by virtue of their ability to improve collagen integrity, stabilize capillary permeability and inhibit sorbitol accumulation.21

Multi-Functional Nutrients

Researchers have investigated a number of other interesting properties of bilberry and black currant. New science shows that black currant may be especially useful in today’s society where many people spend much of the day in front of a computer. In a double-blind, placebo-controlled study in humans performing typing tasks, black currant anthocyanosides improved shoulder stiffness in the subjects by increasing peripheral blood flow and reducing muscle fatigue.22 Black currants have demonstrated powerful anti-inflammatory effects23 and have inhibited the growth of tumor cells in mice.24 Black currants also may reduce risk factors associated with kidney stone formation, due to their alkalizing effect.25

Bilberries are equally powerful anti-inflammatory agents that have reduced symptoms of experimental rheumatoid arthritis in rodents.26 In women with painful periods (dysmenorrhea), bilberry extract given three days before and during menstruation resulted in significant improvement in pelvic pain, breast tension, nausea, and lower-limb heaviness.27 In animals, bilberry decreased the incidence and severity of experimentally induced ulcers.28

Eye-Supporting Nutrients

Bilberry and black currants work synergistically with other eye-supporting nutrients such as carnosine, taurine, N-acetyl cysteine, ginkgo biloba, lutein, R-lipoic acid and quercetin. Bilberry is particularly effective when teamed up with lutein and zeaxanthin as each of these nutrients have been shown to be important to the health of the macula of the eye. Age-related macular degeneration (AMD) is thought to be the result of a lifetime of oxidative insult that results in photoreceptor death within the macula. Because lutein and zeaxanthin are important antioxidants, increased risk of AMD may result from low levels of these nutrients in the diet, serum or retina combined with excessive exposure to sun light.

Although consumption of lutein and zeaxanthin is best known for the reduced risk of AMD, studies also are now linking their consumption to a reduced risk of cataracts. One group of researchers studied 899 subjects and determined that the highest levels of plasma zeaxanthin was significantly associated with reduced risk of AMD, nuclear cataract and any cataract. The highest combined plasma lutein and zeaxanthin levels were significantly associated with a reduced risk of AMD.29 Therefore, combining bilberry with these and other eye-supporting nutrients can prove useful in maintaining ocular health.

Increasing Anthocyanosides Intake

Because the active components in bilberry and black currant are the anthocyanosides, choosing a supplement that contains a high concentration of these plant pigments is important. A new formulation provides both 80 mg of bilberry extract delivering 25 percent anthocyanosides per capsule together with 40 mg of a high-ORAC black currant. ORAC is a measure of a substance’s antioxidant capacity, indicating the black currant found in the supplement is particularly effective at fighting free radicals.

References

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