Based on evidence obtained from pre-clinical and clinical studies, blackcurrants demonstrated significant therapeutic potential in a range of disease states.
In a study a total of 145 plant samples were analysed for their polyphenol content and blackcurrants were indicated to be one of the best sources of these compounds.
The contents of polyphenols in fruits and berries are known to be mainly affected by genetic differences.
However, they can also be influenced by cultivation techniques, harvesting time, growth locations and environmental factors. By using this knowledge, it is possible to produce berries which are as health-promoting as possible.
Anthocyanin content
The study, performed by scientists at the Finnish Natural Resources Institute, was designed to investigate the variation of flavonoid contents and composition in Northern currant varieties grown in Finland.
The methodology looked into 32 botanical varieties of blackcurrant, 12 varieties of redcurrant, two varieties green currant and one variety of white currant.
The researchers found that in every blackcurrant variety, the anthocyanin profile consisted of four major anthocyanins. These were dephinidin-3-glucoside, delphinidin-3-rutinoside, cyanidin-3-glucoside, and cyanidin-3-rutinoside.
In blackcurrants, total anthocyanin content varied between 1260–2878 mg/100 g dry weight and total flavonol content between 43.6–89.9 mg/100 g dry weight.
In redcurrants, the content of anthocyanins and flavonols varied 138–462 mg/100 g dry weight and from not detectable to 17.7 mg/100 g dry weight, respectively.
The green currants contained flavonols 26.1 and 15.4 mg/100 g dry weight, while in the white variety no flavonols were detected.
The findings correspond to previous studies that showed a twofold flavanol variation on blackcurrant cultivars, 83–199 mg/100 g FW and 129–411 mg/100 g FW, respectively.
Flavonol content
There was a strong link observed between the total flavonol content and anthocyanins in the varieties studied. This observation has been found earlier in grapes. The production of flavonols is closely related to that of anthocyanins which may explain this relationship.
“The results showed that although blackcurrants are a good source of anthocyanins and flavonols, there is remarkable variation in their contents between varieties,” the authors noted.
“The differences within the particular northern collection were more than double between the poorest and the richest variety. In redcurrants, the differences were even bigger – as much as three to fourfold. This shows the importance of screening the varieties if nutritional quality is important in terms of the utilisation of plants, such as in breeding.”
Despite the high contents of anthocyanins, particularly in black and red currants, it is not known which polyphenol groups (flavonols, proanthocyanidins and phenolic acids) are most beneficial for human nutrition.
Recent studies have placed flavonols and anthocyanins as particularly health-promoting as the use of HPLC–MS (high performance liquid chromatography-mass spectrometry) for the analysis of flavonoids and related compounds in foods and biological samples has significantly enhanced understanding of polyphenol bioavailability.
It has led to findings on the bioavailability and biological activity of polyphenols on urinary tract infections (UTIs), cognitive function and age-related cognitive decline, cancer and cardiovascular disease.
Source: Food Chemistry
Published online ahead of print, doi:10.1016/j.foodchem.2016.02.056
“High variability in flavonoid contents and composition between different North-European currant (Ribes spp.) varieties”
Authors: Pirjo H. Mattila, Jarkko Hellström, Saila Karhu, Juha-Matti Pihlava, Merja Veteläinen