Anthocyanins' anti-inflammatory properties probed

Increased intake of anthocyanins - compounds behind the red and blue colour of berries and other fruit - from dietary or supplemental sources may protect against inflammation, says a new study from Norway.

Writing in the Journal of Nutrition, the researchers from the University of Oslo and Ullevaal University Hospital report that a mixture of anthocyanins from bilberries and blackcurrants reduced levels of transcription factor NF-kB - responsible for orchestrating a wide range of inflammatory responses.

"Dampening NF-kB activation and limiting inflammatory responses by anthocyanin supplements should therefore be tested further as a strategy for prevention and treatment of chronic inflammatory diseases," wrote lead author Anette Karlsen.

Chronic inflammation, brought about by an over-expression or lack of control of the normal protective mechanism, has been linked to range of conditions linked to heart disease, osteoporosis, cognitive decline and Alzheimer's, and type-2 diabetes.

Corresponding author of the study Rune Blomhoff told NutraIngredients.com: "This study is part of a large program where we first identify antioxidant and phytochemical rich foods or food components, and then study whether these foods, extracts or components can dampen oxidative stress or inflammation in cell cultures, transgenic mice, clinical trials and epidemiological studies."

The researchers tested the anthocyanins isolated from bilberries and black currants (Medox) on NF-kB response both in vitro using cultured monocytes, and in a parallel-designed, placebo-controlled clinical trial (300 mg/d for 3 weeks).

The in vitro study showed that administration of the anthocyanin mix reduced NF-kB activation by 27.6 per cent, compared to control, when the cells were exposed to LPS, a compound that elicits an inflammatory response.

The clinical trial, involving 120 men and women (average age 61, average BMI 24.5 kg per sq. m, 61 women) assigned them to receive the anthocyanin supplements or placebo (maltodextrin and blue colouring).

The researchers observed differences in NF-kB related inflammatory mediators after anthocyanin supplementation, with interleukin-8 (IL-8), IFN and normal T cell expression decreasing by 25, 25 and 15 per cent, respectively, compared to placebo.

Changes were also observed for IL-4 and IL-13, two mediators of pro-inflammatory responses and inducers of NF-kB, with anthocyanin supplementation associated with 60 and 38 per cent decreases from baseline, respectively, compared to four and six per cent decreases, respectively, in the placebo group.

"The mechanisms whereby anthocyanins inhibit NF-kB activation are not fully understood," wrote the researchers.

"One possible mechanism is that anthocyanins, their breakdown products, or metabolites serve as redox buffers capable of suppressing oxidative stress and thereby dampen the inflammatory response by direct ROS scavenging. These events may eventually be followed by decreased secretion of pro-inflammatory signaling molecules and mediators, as observed in this study"

The bilberry industry recently called for better testing of imported extracts, after reports surfaced of extracts mixed with mulberry or black bean skins or azo-dyes

Concerns were raised last year when Australian scientists discovered that azo dyes were used to mimic the colour of bilberries in a commercial product (J. Agric. Food Chem. 2006, Vol. 54, Issue 19, pp. 7378 -7382). This has since expanded to reports of mulberry or black bean skins being used to increase the anthocyanin content of the extracts.

The anthocyanins content is used as the standard for bilberry, and UV spectrometry is needed to verify the 25 per cent anthocyanins. However, according to unconfirmed reports, this has led to extracts masquerading as bilberry but actually containing mulberry (22-24 per cent), or black bean skin (20 per cent).

A simple test using high performance liquid chromatography (HPLC) is recommended to verify the anthocyanin profile as well as the concentration of these polyphenols.

These claims have not been substantiated or approved by the FDA.

Source: Journal of Nutrition
August 2007, Volume 137, Pages 1951-1954
"Anthocyanins Inhibit Nuclear Factor-B Activation in Monocytes and Reduce Plasma Concentrations of Pro-Inflammatory Mediators in Healthy Adults"
Authors: Anette Karlsen, L. Retterstol, P. Laake, I. Paur, S. Kjolsrud-Bohn, L. Sandvik and R. Blomhoff