This study compared the antioxidant activity of blueberries, cranberries, cowberries and chokeberries. It established that aronia has a much higher antioxidant effect than the other berries. This can be explained by the fact that its total phenol and anthocyanin content is also higher than in the other berries.

The phenolic acids contained in aronia are mainly caffeic acid and its derivatives, which have a very high antioxidant activity (caffeic acid: 20.6%; derivatives: 17.6%). It also contains cyanidin-3-arabinosides (18.4%) and cyanidin-3-galactosides (28.5%), which also have a very high antioxidant activity compared to the overall antioxidant activity of the aronia berry. Quercetin and cyanidin phenols also have a high rate of radical formation and can be found in all four berry types.

This study analyses variations in the antioxidant capacity of individual fruit components. It establishes the differences in the antioxidant capacity of a berry’s juice, press residue (pomace) and the whole berry in terms of its dry matter. The pomace of the aronia berry was found to have a much higher phenol content than its juice and dry matter. As the aronia berry is very soluble in water, however, the concentration of phenolic acids is higher in its fruit juice than its pomace.

The most common forms are the group of polyphenols and proanthocyanidins (PAs), which are predominantly composed of (-)-epicatechin. These make up 66% of all polyphenols in the aronia. The antioxidant and anti-carcinogenic effect of the aronia is similar to that of the plants used in traditional Chinese medicine. This effect is created by o-diphenol compounds like quinic acid, (-)-epicatechin, cyanidin and quercetin derivatives.

Oxidative stress leads to the proliferation of free radicals in our body. This can be counteracted by taking in antioxidants through our diet. The ACs contained in the aronia are natural antioxidants that can prevent the onset of cardiovascular diseases. The capacity of anthocyanins to reduce oxidative stress was established through an in vivo experiment on rats (Kowalczyk, Kopff).

In order to determine the effect of aronia juice on oxidative stress in the human body in another in vivo experiment,, the test subjects were put through physical strain on a rowing machine (Pilaczynska-Szczesniak). The changes in biomarkers (measurable indicators in an organism) were measured in the blood before training, directly afterwards and 24 hours later. This showed that the concentration of TBARS (thiobarbituric acid reactive substances) in the blood could be reduced by consuming 150 ml of aronia juice (23 mg ACs / 100 ml juice) over a one-month period. TBARS are a way of measuring lipid peroxidation and oxidative stress.

It was also demonstrated that the oxidative damage caused to the red blood cells through physical strain could be reduced and prevented by taking in more aronia anthocyanins. However, this study was only conducted on a small test group, so further studies will be necessary to confirm these results.

The protective effect of aronia preparations on cardiovascular diseases and their risk factors (e.g. high blood pressure) was already suspected by practitioners of popular medicine. The studies described below dealt with the aronia berry’s influence on these risk factors.

These studies include:

• Protection against platelet aggregation
• Protection against reactive oxygen species (ROS)
• Protection against high blood lipid levels (plasma cholesterol, LDL cholesterol and triglycerides)
• Positive influence on type 2 diabetes
• Protection against platelet aggregation (Ryszawa et al. 2006)

Blood platelet aggregation is a very common cause of cardiovascular diseases, and the risk factors include high blood pressure, hypercholesterolemia, diabetes mellitus and smoking. This study describes the positive influence of aronia extracts on platelet aggregation in people with cardiovascular risk factors. Depending on their concentration, the aronia extracts caused a reduction in superoxide production in humans with these risk factors.

No changes were noted in the risk-free control group, suggesting that the aronia extracts had brought the risk group and control group closer together in terms of their superoxide production and, depending on their concentration, prevented platelet aggregation. However, this effect only occurs with a phenol concentration of 1 µg / ml blood. No significant effect on platelet aggregation was noted at lower concentration levels (0.001 – 1 µg).

This study was carried out on isolated pig arteries to investigate the effect of aronia anthocyanin extracts on coronary arteries. Reactive oxygen species (ROS) play a major role in the development of cardiovascular diseases and are involved in the production of oxidative stress. As anthocyanins (ACs) are good radical scavengers, AC-rich extracts of chokeberries, bilberries and elderberries were examined in this experiment to determine their coronary vasoactive and vasoprotective properties.

In order to aid understanding, “coronary” refers to the coronary arteries, “vasoactive” means it affects the blood vessels, and “vasoprotective” means it protects the blood vessels.

The results indicate endothelium-dependent vasorelaxation in the coronary arteries following the absorption of berry extracts. The endothelium is the innermost coating of a vessel wall; it acts as a barrier, regulates the exchange of substances between tissue and blood (e.g. blood-brain barrier), and has other important functions. All vessels in the cardiovascular system have a single layer of endothelial cells. Aronia extracts have a particularly strong effect on the coronary arteries, and even a small concentration can protect them against reactive oxygen species.

Nowadays, arteriosclerosis is a widespread problem. High blood lipid levels (hyperlipidaemia) have been identified as the cause of atherosclerotic changes in blood vessels. Aronia juice was shown to lower blood lipid levels on a high-cholesterol diet. The liver and aorta values of rats were measured before and after feeding them with aronia juice. The amount of plasma lipids in the normally fed rats didn’t change when they received 5, 10 and 20 ml of aronia juice per kg of body weight over a period of 30 days.

An increase in plasma cholesterol, LDL cholesterol and triglycerides was prevented in the rats that received a diet containing 4% cholesterol.  No changes to the aorta, liver or HDL cholesterol levels were noted in the study. The results indicate that the consumption of aronia juice can help to maintain and even improve blood lipid levels.

Diabetes mellitus is another risk factor behind the development of cardiovascular diseases. This study shows that the consumption of aronia juice has a positive effect on the blood sugar levels of patients with type 2 diabetes. The blood sugar, glycated haemoglobin and plasma lipid levels of patients with type 2 diabetes were measured 60 minutes following their last consumption of the juice.

After drinking 400 ml of aronia juice over a three-month period, their blood sugar levels had sunk from an average of 13.3 to 9.1 mmol / l. The glycated haemoglobin value, which indicates long-term blood sugar levels, had also fallen from 9.4 to 7.5%, cholesterol levels from 6.5 to 5.1 mmol / l, and plasma blood lipid levels from 2.9 to 1.7 mmol / l. Aronia juice was also found to lower blood pressure in patients suffering from hypertension.

Mutagens are chemical or natural agents that change the genetic material. Radiation (e.g. UV and radioactive radiation) can also have a mutagenic effect. Chemical mutagens include the various compounds found in cigarette smoke. Strong heating and the reaction of separate ingredients during food preparation can also cause the formation of mutagens like nitrosamines, as well as polycyclic aromatic hydrocarbons like benzo[a]pyrene. The Ames test is often used to determine the mutagenicity of a compound.

This is carried out by taking bacteria that can no longer synthesise individual essential amino acids due to a certain mutation and then cultivating these bacteria in a culture medium that lacks that very amino acid. If the tested compound is mutagenic, it’s statistically likely to undergo a reverse mutation to its bacteria wild type, which can then synthesise the amino acids again and form colonies.

Another method is the sister chromatid exchange (SCE) test, which is used to examine the DNA of two sister chromatids in a duplicated chromosome. A chromatid is part of a chromosome. When a cell divides, it has to duplicate its genetic material, forming two identical chromatids. The cell then divides, and each daughter cell contains a nucleus with a chromosome.

This study reveals that aronia anthocyanins stem the mutagenic activity of the polycyclic aromatic hydrocarbons benzo[a]pyrene and 2-aminofluorene. Benzo[a]pyrene is one of the carcinogenic substances that has been known about and tested the longest. This in vitro experiment with human blood lymphocytes revealed a significant reduction in the mutagenic activity of benzo[a]pyrene when aronia anthocyanins were absorbed at the same time. Only a limited positive effect was noted during a treatment carried out at the same time with the drug mitomycin C.

The antimutagenic effect of ACs is believed to be due to their property as radical scavengers, as aronia ACs were found to prevent the formation and transfer of superoxide radicals to the granulocytes (part of the white blood cells). ACs are also believed to inhibit endogenous enzymes that cause the activation of promutagenic compounds in the mutagens themselves, which can then react with DNA.

Nevertheless, the antimutagenic effect of the natural ACs contained in vitro in aronia is much lower (6 – 9 times weaker) compared to synthetic compounds like the drug fluphenazine (Gasiorowski and Brokos 2001).

Nitrosamines are carcinogens that are often associated with the development of gastric cancer (Watzl and Leitzmann 1999). In this study, aronia juice was shown to stem the formation of nitrosamines in the stomachs of rats kept in experimental conditions. Analysis was carried out to determine whether the production of nitrosamines in the stomach – and therefore the risk of developing gastric cancer – could be reduced by consuming aronia nectar. The results indicate that aronia nectar can change the pH value of the digestive tract, and that its high tannin content prevents the formation of nitrosamines in the stomach.

A carcinogen is a substance in the body that causes cancer or aids its growth. Studies on the anti-carcinogenic effect of the aronia have only been published in relation to cancer cells in the small and large intestine. Intestinal cancer is one of the most common types of cancer in Western industrialised countries

and the second most common in Germany. All four studies presented below document this effect on intestinal cancer cells:

This study investigates the effect of anthocyanin-rich extracts (AREs) on healthy and cancerous cells in the large intestine. AREs from the chokeberry, bilberry and grape were investigated for their potential chemopreventive activity against colon cancer. Colon-cancer-derived HT-29 and non-tumorigenic colon cells were exposed to 10 – 75 μg of monomeric anthocyanin / ml, and their growth was monitored for 72 hours. All extracts inhibited the growth of HT-29 cells, with chokeberry AREs being the most potent inhibitors. Cell growth was inhibited by around 50% after 48 hours of exposure to 25 μg / ml of chokeberry AREs. In contrast to the non-tumorigenic colon cells, the growth of healthy cells was only slightly inhibited at lower ARE concentration levels over a 72-hour period. Of all the berries tested, the aronia had the highest phenol content (737 mg / g of extract) and demonstrated the greatest inhibitory effect on the growth of cancer cells.

• The aronia preparations:
• blocked the cell cycle in the intestinal cancer cells;
• suppressed COX-2, an enzyme that accelerates tumour formation;
• boosted CEACAM1, an enzyme that suppresses tumour formation;
• caused changes to gene expression, cell growth and cell proliferation; and
• positively affected ACF, a biomarker for cancer

This study revealed the inhibitory effect of aronia AREs on the growth of cancer cells in the large intestine. Purified aronia AREs were measured on cell lines from cancerous and healthy cells in the large intestine. A concentration of 50 µg of monomeric ACs / ml of aronia extract stemmed the growth of HT-29 cancer cells in the large intestine by around 60% within a 24-hour treatment period.

Prolonged treatment with the extract doesn’t cause any further changes in the cell. The growth of healthy cells in the large intestine was inhibited by around 10% over a 48-hour treatment period with the highest concentration (50 µg of monumeric ACs / ml of aronia extract). The growth of HT-29 cancer cells was reduced by 90% during the same period. The treated cells produced a blockade between the G1/G10 and G2/M phase of the cell cycle. The cell cycle stopped due to the increasing amount of regulators that play a key role in the process.

One important biomarker for colon cancer is the enzyme cyclooxygenase-2 (COX-2), and this dropped by 35% during a 24-hour treatment of HT-29 cancer cells. COX-2 is a sub-form of cyclooxygenase (COX), which is an intercellular enzyme formed through prostaglandin synthesis. Prostaglandin is a tissue hormone that plays a crucial role in carcinogenesis. 10 µg / ml of aronia AREs is the smallest quantity that has a reducing effect on COX-2.

This in vitro study confirmed this mechanism’s blocking effect on the cell cycle. It was demonstrated that the tumour marker CEACAM1 (carcinoembryonic antigen-related cell adhesion molecule 1) can be up-regulated by repeatedly exposing Caco-2 intestinal cancer cells to subtoxic amounts of phenol-rich aronia juice. CEACAM1 suppresses tumour growth and is of great interest in the early stages of carcinogenesis due to the significant role it plays in the regulation of cell proliferation. It may also be a potential target for chemoprevention using food components, such as those present in polyphenol-rich fruits. The daily consumption of polyphenol-rich food like aronia juice can strongly inhibit the in vitro formation of the Caco-2 intestinal cancer cell line.

Following exposure to aronia juice, the effects on the cell cycle and the longevity and growth of the cells were examined alongside the changes in gene expression (genetic information about the cell). Changes were found in a group of genes that affect cell growth, cell proliferation and the regulation of the cell cycle.

The study group investigated various biomarkers for colon cancer to confirm the positive effects of phenol-rich fruits on cancerous cells in the large intestine. Various biomarkers for colon cancer were analysed in rats following the administration of AREs from grapes, bilberries and chokeberries.

The biomarkers involved in the study were aberrant crypt foci (ACFs, thought to be precursors to colon cancer), colonic cell proliferation (growth), urinary levels of oxidative DNA damage, and COX-2. To assess the bioavailability, AC levels were measured in serum, urine, and faeces.

ACF levels were lower in all three rat groups that had been fed with the extracts compared to the control group. The size of ACFs has a greater influence on tumour formation than the number of ACFs. The lower the number of large ACFs, the lower the probability of developing cancer. The rats that had been fed with bilberry and aronia AREs had fewer large ACFs than the control group. The bilberry AREs had a greater effect (70%) than aronia AREs (59%) on the reduction of large ACFs. Grape AREs had the smallest effect.

A reduction in colonic cell proliferation was observed in the rats that received the blueberry and aronia AREs. High quantities of ACs were found in their faeces, which points towards lower bioavailability. The absorption of AREs also led to a reduction in the production of faecal bile acids.

No changes in uric acid levels were observed. Furthermore, aronia AREs had no effect on COX-2 in this experiment. The structure of the ACs, particularly the degree of glycosylation, had an influence on the amount of ACs that were absorbed. This study confirms that the daily consumption of AREs has a positive and chemopreventive effect on colon cancer.

Amount of aberrant crypt foci (ACFs) following the consumption of AREs

In 2004, a study was carried out on rats with acute liver damage to evaluate the protective effect of aronia juice on the liver. The liver damage was induced using carbon tetrachloride (CCI₄) (0.2 ml / kg of body weight for 2 days). Carbon tetrachloride is a chlorinated hydrocarbon that is both toxic and carcinogenic. In the past, CCI₄ was used as a degreasing agent, detergent, solvent and thinner. Nowadays, its use is only permitted for experimental purposes.

The aim of this study was to observe changes to the liver damaged with CCI₄ following the absorption of aronia juice. The exposure to CCI₄ triggered cell damage caused by lipid peroxidation. The amount of malondialdehyde (MDA) in the rats’ plasma and liver was measured as a biomarker for lipid peroxidation.

Furthermore, glutathione levels were depleted in their reduced form in the liver. Aronia juice was administered over a period of 4 days in various doses (5, 10 and 20 ml / kg of body weight). Depending on the dosage, the juice reduced necrosis (pathological decay of individual cells) in the liver and prevented an increase in plasma aspartate transaminase (AST) and alanine transaminase (ALT), which cause lipid peroxidation and cell damage. This confirms that aronia juice can protect a rat’s liver against damage caused by CCI₄ and prevent an increase in MDA levels, while glutathione levels normalise (Valcheva-Kuzmanova, Borisova et al. 2004).

Damage to the stomach lining can be caused by painkillers, anti-inflammatory drugs, or oxidative stress following a bacterial infection. Valcheva-Kuzmanova conducted a study in 2005 to investigate the effects of aronia juice on stomach lining damage. Damage was caused to the stomach lining of rats using indomethacin (painkiller), and this could be partially prevented through the prior consumption of aronia juice.

One hour before the ingestion of indomethacin (830 mg / kg of body weight), various amounts of aronia juice (5, 10 and 20 ml / kg of body weight) were orally administered to the rats. Around 4 hours after ingesting the painkiller, the rats presented a higher amount of risk factors for the formation of a stomach ulcer. The amount of malondialdehyde (MDA), reduced glutathione (GSH) and oxidised glutathione levels in the stomach lining were used as biomarkers for oxidative stress.

The prior ingestion of aronia juice reduced the number and size of the injuries induced by the painkiller. The aronia juice increased the production of gastric mucus, thereby reducing the profundity and severity of the injuries. The amount of gastric and plasmatic MDA remained largely constant. The consumption of aronia juice had no effect on glutathione levels. The study used MDA as a biomarker to demonstrate that stomach lining damage induced by indomethacin is accompanied by oxidative stress. The prior ingestion of aronia juice reduces the number of injuries to the stomach lining, and this is probably due to the increased production of gastric mucus (Valcheva-Kuzmanova, Marazova et al. 2005).

A study published by Matsumoto et al. in 2004 confirms the strong correlation between oxidative stress and stomach lining damage. As part of this study, the antioxidant activity of aronia ACs and aronia extracts was measured in rats with ethanol-induced gastric damage. Around 30 mg of aronia ACs per kg of body weight was enough to reduce stomach lining damage by about 50%, and this reduction was attributed to the antioxidant capacity of the ACs. Approximately 2 g of aronia extract per kg of body weight offers virtually the same level of protection against stomach lining damage as 100 mg of quercetin per kg of body weight, and it has a similar ulcer-suppressing effect to 300 mg of ACs from the fruit. Aronia ACs have no influence on gastric acid production (Matsumoto, Hara et al. 2004)

The anti-inflammatory effect of aronia anthocyanins was described in a study published by Borissova in 1994. This experiment was conducted to investigate the effect of ACs from quercetin glycoside. Two experimental models were used on a rat’s hind paw. In the first case, inflammation was triggered with a 0.5% histamine solution.

In the second case, inflammation was induced with a 0.1% serotonin solution. The swelling of the rat’s paw was measured using a plethysmograph. A plethysmograph is an instrument used to measure changes in volume within all or part of the body. Aronia anthocyanins had a clear effect in both cases (approx. 90% reduction in swelling after 4 hours of using 30 ml / kg of ACs) in comparison to the moderate effect shown by rutin.

The rutin-magnesium complex did not exhibit any anti-inflammatory activity against histamine-induced inflammation, although its effects against serotonin-induced inflammation were comparable to those of rutin. This study confirms that aronia anthocyanins reduce the swelling of histamine- and serotonin-induced inflammation, and that their effect is much greater than that of rutin (Borissova, Valcheva et al. 1994).

Aronia was even found to have an anti-inflammatory effect on uveitis, a viral and bacterial inflammation of the uvea. Ohgami carried out a study in which rats were infected with uveitis. The animals were given various amounts of raw aronia extracts. In order to compare the results, the uveitis was also treated with a drug (prednisolone). 100 mg of raw aronia extract were as effective as 10 mg of prednisolone. Raw aronia extracts have a greater anti-inflammatory effect than quercetin and anthocyanin. This anti-inflammatory effect is associated with the blocking of COX-2 enzymes (Ohgami, Ilieva et al. 2005).