Index
- Description of the plant: habitat and hints of botany
- Introduction to phytotherapeutic use
- Leaves
- Oil
- Fruits
- Gems
- Conclusion
Questions and answers
Description of the plant: habitat and hints of botany
The Ribes nigrum L. plant, better known as black currant , is a shrub belonging to the Grossulariaceae family, which includes shrubs, sometimes thorny, whose fruits consist of capsules or berries .
Undoubtedly the genus Ribes is the most representative of this family, populated by different species and widely diffused in the temperate regions of the northern hemisphere .
Black currant is a shrub about 1.5 meters high, it grows spontaneously in Europe (with the exception of the Mediterranean region), but it is also cultivated for its fruits, often used by the food industry for the preparation, among other uses, of syrups ,jellies and liqueurs . This plant, during the late summer ( August-September ) produces its fleshy fruits, dark spherical berries, appreciated by many for their flavor and aroma, and rich in seeds.
The small hanging flowers are made up of five white or green petals, sprouting in the spring season, while the leaves, consisting of three or five lobes, have a toothed margin and have an underside full of secretory glands that give off a very aromatic odor .
Introduction to phytotherapeutic use
In addition to its food use, this plant is known and studied for its various beneficial effects on humans. In this article we will describe the main traditional uses and the recent clinical evidence supporting the different properties.
Ribes nigrum L. is one of the rare plant cases whose phytotherapeutic use includes the use of different parts of the plant. The main scientific evidence will be described below, divided on the basis of the three main parts studied: leaves, seed oil and fruits.
Leaves
Constituents
The Ribes nigrum L. drug consists of dried leaves , as described in the ESCOP monograph (2017), and must have a minimum content of flavonoids of 1% (corresponding to dry weight), expressed as isoquercitroside.
There are several molecular constituents that may be present in it, among these there are mono and diglycosides of campferol, isoramnetina and quercetin (including the aforementioned isoquercitroside); monomeric flavanols (gallocatechin and epigallocatechin); proanthocyanidins (especially di- and trimeric prodelphinidins); hydroxycinnamic acid derivatives (including chlorogenic, caffeic and p-coumaric acid); phenolic acids and traces of an essential oil.
Properties and indications
Black currant leaves are indicated as adjuvants for the treatment of rheumatic conditions , but it should be noted that there are no direct human studies to support these properties. The efficacy is considered plausible on the basis of human experience accumulated during the long tradition of use, the indications are however supported by some studies conducted on animal cells or models.
Four studies published between 1989 and 2005 demonstrated the anti – inflammatory activity of a currant leaf extract against carrageenan-induced edema in the rat paw, with activity comparable to the anti-inflammatory drug indomethacin. The effect occurred following both oral and injection administrationintraperitoneal (in the latter case the effect is facilitated by the direct crossing of the gastrointestinal barrier).
Regarding the tradition of using the leaves as a reliever of cough and bronchial asthma , there are two more recent studies on rats, published in 2004 and 2005, which have shown anti-inflammatory effects on the pleural level. Although these data cannot be directly connected to humans, it is plausible to assume that some active ingredients contained in the leaves can reach the respiratory system , but further confirmation is necessary.
In vitro studies have shown that purified flavonoids from black currant leaves reduce synthesis andrelease of inflammatory prostaglandins . Similarly, the prodelfinidins, purified from the leaves, inhibited the action of cyclooxygenase-2 (COX-2), a human enzyme responsible for the production of inflammatory prostaglandins and target of various anti-inflammatory drugs such as NSAIDs (non-steroidal anti-inflammatory drugs) .
Other indications deriving from popular tradition suggest the use of black currant leaves to stimulate diuresis , a study conducted in rats confirmed this property following oral administration, but supporting data are still scarce.
For information purposes there are two old studies on leaf extracts (70-80 years), conducted on two different animal models, which showed areduction of blood pressure , effects which, however, are not found in humans. As described in the following section, however, some extracts of the black currant fruit confirm the vasorelaxant activity in humans.
Preparations and doses
For the treatment of rheumatic conditions in adults, the oral intake of an infusion of leaves ( 20-50g / liter , for 15 minutes ), in about 250-500 ml per day, is indicated. Alternatively it is possible to take a fluid extract (1: 1), 5 ml twice a day , before meals.
Side effects
There are no reported cases of overdose or contraindications, it is however recommended not to take black currant products during pregnancy or breastfeeding .
Oil
Constituents
The seeds of Ribes nigrum L. contain a significant amount of polyunsaturated fatty acids , molecules characterized by the presence of double bonds on the lipid chain. Among the most abundant we find the γ-linolenic acid of the omega-6 (ω-6) series, on average between 18 and 23% of the total fatty acids, in addition to α-linolenic acid (ω-3) , linoleic (ω-6) and oleic (ω-9).
Properties and indications
L ‘ oil of black currant is one of the few plant sources of γ-linolenic acid (ω-6), which also include the oil of evening primrose and borage . This compound is the precursor of prostaglandins , a series of molecules present in our body involved in the regulation of various biological processes including: inflammation, blood pressure and the synthesis of cholesterol .
A deficiency of γ-linolenic acid is characteristic of some disorders and diseases, such as schizophrenia , alcoholism and manic depressive syndromes .
Various clinical studies have shown that the intake of γ-linolenic acid with thediet can be helpful in cases of arthritis, obesity and heart ailments , but much research has been conducted with natural sources other than black currants. Some exceptions are the studies described below.
In a randomized clinical trial, performed on 24 patients with rheumatoid arthritis , black currant oil , administered at a daily dose of 10.5 g (corresponding to 2.5 g of γ-linolenic acid) for six months, reduced the symptoms of the disease compared to placebo. No side effects have been reported, however some patients have been reported to have difficulty in taking large quantities of capsules daily (15 capsules per day in the case of this study).
The fatty acids of the series ω-3 , such as α-linolenic acid and its derivatives, have shown activity antiplatelet and hypolipidemic and, although present in an amount not higher oil of black currant, could contribute to vascular protective activity of prepared. A clinical study conducted with blackcurrant oil in healthy and heart attack patients demonstrated an inhibition of platelet aggregation and a greater anticoagulant effect, while a second study improved the fatty acid composition of red blood cells in stroke patients .
A clinical study conducted in 15 healthy women showed how the oral consumption of black currant oil is able to reduce LDL cholesterol values , while an observational study, on more than two thousand dyslipidemic patients, associated the intake of capsules of currant oil to lower triglyceride values in hyperlipidemic patients with low BMI.
Finally, it has been repeatedly hypothesized that γ-linolenic acid may manifest an anti-inflammatory effect on the cells that mediate the inflammatory process in chronic skin diseases, such asdermatitis and psoriasis . Although several clinical studies have been conducted, mixed data has emerged. At present the systematic reviews relating to the integration of the diet with γ-linolenic acid (evening primrose oil or borage) for inflammatory skin diseases have highlighted the lack of scientific evidence to support this treatment.
Preparations and doses
There is no recommended dosage for black currant seed oil. For comparison, evening primrose oil is administered in capsules for oral use titrated in the content of γ-linolenic acid (higher than in black currant oil). The EMA suggests the use of 4-6 g / day of γ-linolenic acid for the treatment of eczema in adults and 2-4 g / day in children (1 to 12 years), for a period of at least three months (evening primrose oil).
Side effects
There are no reported cases of undesirable effects for currant oil unlike the consumption of evening primrose oil for which clinical cases have been reported suggesting the epileptogenic potential of evening primrose oil, however the causality remains uncertain and not confirmed.
Other adverse effects, the frequency of which is not known, include nausea, soft stools, headache and, in some rare cases, skin rashes .
Fruits
Constituents
Blackcurrant fruits contain several constituents including: flavonoids , polyunsaturated fatty acids (characteristic of seeds, included in the preparations obtained from the fruit), carbohydrates , non-volatile organic acids , tannins (both condensed and hydrolysable) and stilbenoids .
Among the most abundant flavonoids we find anthocyanins, present on average in quantities about four times higher than other fruits, up to 300 mg per 100 g of fruit. The most representative compounds of this group are the glycosides of delphinidin and cyanidin. The fruit also contains flavonols such as quercetin , myricetin andcampferol (and their glycosylated forms). Other analyzes found a high content of minerals, such as potassium, calcium, magnesium and iron.
Properties and indications
In recent times, studies evaluating the properties of black currant fruits have increased and some clinical studies have been conducted that have highlighted some beneficial properties of the fruit or some of its components. A concentrate of anthocyanins deriving from the black currant fruit improves circulation , decreases fatigue and muscle stiffness , in subjects subjected to sedentary work.
As for the possible cardiovascular effects , the consumption of 500 mLfruit juice of Ribes nigrum L. reduced the presence of some inflammatory plasma markers, including c-reactive protein, in patients with peripheral arterial circulation problems. However, further investigation conducted on healthy subjects, with another juice containing blackcurrant anthocyanins, did not show beneficial effects on inflammatory markers or on vascular reactivity measured by laser doppler.
Two clinical studies have evaluated the potential of fruit anthocyanins for ocular disorders. Many studies have shown that cyanidin, one of the major anthocyanins present in black currant fruit, is able to improve the regeneration of rhodopsin, one of the proteins responsible for vision, also improving the adaptation to the dark. A powdered blackcurrant anthocyanin concentrate, administered orally to 12 healthy volunteers via capsules, caused vasodilation of the eye vessels, increasing blood flow to the eye and decreasing fatigue . Furthermore, in 28 Japanese patients suffering from cedar pollen allergy , the intake of the same preparation in capsules brought benefits to the nose-ocular system, in terms of allergic symptoms.
Finally, a study evaluated the effect of blackcurrant fruit juice on kidney stone formation . The consumption of juice alkalized the urine of 12 healthy subjects, increasing the excretion of citric and oxalic acids, lowering the risk of stone formation.
Preparations and doses
There are no dosage indications for blackcurrant fruit preparations.
Side effects
No cases of undesirable effects were reported in the studies evaluated.
Gems
Constituents
Through the maceration in glycerol and alcohol of fresh buds of Ribes nigrum L. you are obtained called prepared gemmoderivati , which in the case of black currant have a content of higher polyphenols compared to the fruits of the same plant, as well as various essential oils (such as sabinene , δ-3-carene and terpinolene).
The composition of these preparations is greatly influenced by the stage of development of the bud and by the genotype of the plant itself, therefore it is difficult to establish a unique reference composition. Flavan-3-oils, such as epigallocatechin and epicatechin, and several flavonols (quercetin glycosides) decrease with increasing bud development, unlike phenolic acids, among which chlorogenic acid stands out. The total content of phenols is also higher in the early stages of bud development.
Properties and indications
Ribes nigrum L. gemmoderivatives are widely used in gemmotherapy , due to their anti-inflammatory activity, in order to stimulate the release of cortisol from the adrenal cortex , often in combination with other bud derivatives. However, the studies describing these properties are very dated, generally carried out in the 70s and 80s and do not benefit from any support from official medicine.
It is right to underline that there is no recent research to demonstrate this activity, not even in animal models, the only studies in the literature show antibacterial properties , especially for the essential oil component of the gems, carried out strictly in vitro.
Conclusion
Ribes nigrum L. has proved to be a plant rich in health potential , in several of its components, such as leaves, seeds and fruits.
The leaves , as an infusion, have traditionally been used as a diuretic or antirheumatic , but it is above all the symptomatic treatment of joint pain that has found greater scientific confirmation. The fruits are now indicated for the treatment of symptoms related to capillary venous fragility , but there are several clinical studies that identify new benefits, even in the ocular field . Finally, the oilderived from seeds, it is one of the few plant sources of γ-linolenic acid (ω-6), a fatty acid which, in addition to being essential, therefore necessary in our diet, has evident benefits at the cardiovascular and skin level . The use of gems, as fascinating as it may be, has no scientific evidence at present that demonstrates its therapeutic efficacy.
BIBLIOGRAPHICAL REFERENCES
- Monograph: Ribes nigri folium – Black Currant Leaf
Site: https://escop.com
Publisher: ESCOP – European Scientific Cooperative On Phytotherapy
Year: 2017 - Book: Pharmacognosy and phytotherapy: pharmacological bases and application aspects.
Authors: Mazzanti G, Dell’Agli M, Izzo A.
Publisher: Piccin
Year: 2020 - Book: Pharmaceutical Botany, IX Edition.
Authors: Maugini E, Maleci Bini L, Mariotti Lippi M.
Publisher: Piccin
Year: 2014 - Book: Phytotherapy: rational use of plant drugs
Authors: Capasso F, Grandolini G, Izzo A.
Publisher: Springer
Year: 2006
Questions and answers
CAN RIBES NIGRUM L. LEAVES BE USEFUL FOR THE TREATMENT OF RHEUMATIC PAINS?
Black currant leaves can help reduce inflammation, thanks to the action of various molecules capable of inducing positive effects, even after oral consumption. In this context many experiments have been conducted on animal models and in vitro, however, despite the lack of clear evidence on humans, the long tradition of use cannot be ignored, which is sufficient to identify the treatment of rheumatic pain as the main indication use of black currant leaves.
ARE THERE ANY CONTRAINDICATIONS FOR THE USE OF BLACK CURRANT?
To date, no cases of serious side effects have been reported due to the intake of Ribes nigrum L. preparations, but despite this, as a precaution, it is not recommended to administer it to children and pregnant or breastfeeding women. Given the lack of interaction data, the association of blackcurrant preparations with other products of natural origin must be weighed according to the situation, as well as the association of blackcurrant with other pharmacological therapies, to be evaluated in advance with your doctor.
WHAT ARE THE POSITIVE EFFECTS ASSOCIATED WITH CONSUMING RIBES NIGRUM L. SEED OIL?
The positive effects associated with the consumption of black currant oil are mainly due to the presence of γ-linolenic acid. Evidence on humans has shown a reduction in inflammatory parameters at the cardiovascular level, both as an antiplatelet and lipid-lowering agent. The anti-inflammatory effects in other areas, such as the skin, seem to require higher concentrations.
CAN THE CONSUMPTION OF BLACK CURRANT FRUIT HAVE BENEFICIAL EFFECTS ON HUMANS?
The data collected so far attribute to the anthocyanins present in the juice of Ribes nigrum L. vasorelaxing effects. Although a clear dosage is not indicated, due to the variability of the anthocyanin content also due to the preparation method, the juice seems to bring benefits especially at the ocular level.
