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The Many Health Benefits of Berries
Berries are excellent sources of several antioxidant compounds such as flavonoids, phenolic acids, and vitamins C and E. The hypothesized health benefits related to berry consumption include their role in the prevention of inflammation, oxidative stress, cardiovascular disease (CVD), cancers, type 2 diabetes, obesity, and neurodegeneration.
Antioxidant Activity of Various Berry Compounds
Berries vary in their natural antioxidant capacity, and they owe their antioxidant capability mainly to the various phenolic compounds including tannins, phenolic acids, stilbenes, and flavonoids. The antioxidant compounds in berries exert their action through various mechanisms. Phenolic acids may inhibit the oxidation of vitamin C, carotenoids, and unsaturated fatty acids. Flavonoids can chelate metal, scavenge oxygen radical, and also inhibit lipid oxidation. Anthocyanins could also scavenge free radicals and inhibit the oxidation of human low density lipoproteins (LDL). Carotenoids are also scavengers of active oxygen species preventing the oxidation of LDL. Blueberries and cranberries are ranked among the fruits with high antioxidant capacity owing to the presence of substantial amounts of several phytochemicals such as phenolic compounds. The antioxidant capacity ranges from 13.9 to 45.9 μmol of Trolox equivalents per gram of fresh berry.
Evidence from in vitro and animal studies suggests that berry bioactive components can influence parameters or factors associated with CVD risks. There is evidence that the addition of berries to the diet could positively affect risk factors for CVD by inhibiting inflammation and improving the plasma lipid profile and free radical scavenging. In a study conducted in middle-aged unmedicated subjects, long-term consumption of moderate amounts of mixed berries resulted in increased high-density lipoprotein cholesterol, decreased blood pressure (BP), and also induced favorable changes in platelet function, indicating that certain constituents of berries alone or in combination play a role in decreasing the CVD risk. Berry and grape consumption has also resulted in increased high density lipoprotein-C (HDL-C) levels and decreased LDL-C levels in healthy, at-risk, and diseased individuals. Some recent study also suggests that berry consumption may also improve insulin sensitivity. Berries have also been associated with the prevention of obesity through interference with lipid digestion and/or through the modulation of lipid metabolism. In dyslipidemic subjects, anthocyanin intake resulted in an increase in plasma HDL cholesterol and a decrease in LDL cholesterol concentrations.
Studies have shown that chokeberry improves blood circulation and can boost the body’s immune system. Chokeberry fruit and its products have a protective effect against atherosclerosis, hypertension, and gastrointestinal tract infection. Improvement in vascular function has been reported following intake of pure anthocyanins and cranberry juice (4 weeks) in human subjects. Improvement in endothelium-dependent vasodilation and serum lipid profiles following berry anthocyanin intake was reported in individuals with elevated cholesterol. A decrease in BP has been reported after consumption (6–8 weeks) of mixed berries, anthocyanin-rich tea, and chokeberry and blueberry extracts by individuals with hypertension, myocardial infarction, and markers of metabolic syndrome. Lack of efficacy was noticed in healthy individuals, chronic smokers, dyslipidemic, and obese subjects who consumed blueberry and cranberry juice. Reduction in oxidative stress markers was noticed in overweight and obese children following a short-term blueberry consumption for 8 weeks. Elevated plasma antioxidant capacity was noticed in elderly women and middle-aged men after consumption of strawberry fruit and blueberry extracts. Oxidative DNA damage was significantly decreased in blood cells isolated from human subjects after the consumption of Aronia, blueberry, and boysenberry juice for 5 weeks. Bilberry extracts improved circulation in volunteers with a variety of circulatory problems.
Neuroprotective/Neurodegenerative Diseases and Aging
A combination of epidemiological and preclinical studies suggests that the consumption of berries and berry products may be effective in reversing neurodegenerative symptoms and age-related declines. But a direct association between berry consumption and improvement in neurological health cannot be made at present. A number of observational and human interventional studies have indicated that regular intake of flavonoid-rich plant food and extracts induced improvements in cognitive functions. Evidence from in vitro studies also supported the possibility that polyphenolics in berries can beneficially remodel beta-amyloid aggregation in vitro. Blueberry consumption and strawberry consumption have been shown to improve memory in older adults.
Polyphenol-rich berry extracts showed α-amylase and α-glucosidase inhibition in vitro. Consumption of a berry puree (blueberry, strawberry, black currant, and cranberry) altered the glycemic responses in volunteers. SBT berry induced changes in postprandial glycemic and insulin responses after glucose intake in a human intervention study. Consumption of black currant juice with crowberry powder altered the glycemic and insulin responses of healthy subjects after sucrose-sweetened juice intake. These effects may originate from the inhibition of α-amylase and α-glucosidase activities.
The antiproliferative and anti-inflammatory activities of strawberry, raspberry, blueberry, blackberry, and cranberry juices were evaluated against the human stomach, prostate, intestine, and breast cancer cell lines, and the strongest inhibition of cell growth was observed for the raspberry, lowbush blueberry, and cranberry juices. Reduction in the proliferation of the breast cancer (MCF-7) and colon cell lines (HT-29) was noticed on treatment with extracts from fruits and berries including blueberries, black chokeberries, black currant, and raspberries. The raspberry extracts also conferred significant effective protection to DNA damage induced by hydrogen peroxide in the colon cells. A recent study has shown that freeze-dried black raspberry extracts suppressed cell proliferation of human oral carcinoma cells without affecting their viability and also induced apoptosis. The chemoprotective effects of blackberry extracts were demonstrated in studies conducted in a human lung cancer line, A549 with blackberry extracts that inhibited tumor promoter-induced carcinogenesis and associated cell signaling. Cranberry extracts and cranberry press cake showed strong inhibition of the growth of human breast, prostate, skin, and brain cancer cells, which was attributed to its ability to initiate apoptosis and induce G1 phase arrest in the cell cycle. Bilberry extracts induced programmed cell death in human leukemia cells. In vitro digested raspberry extracts significantly decreased the population of HT-29 cells in the G1 phase of the cell cycle and showed that raspberry extracts can inhibit key stages in colorectal cancer development, namely, initiation, promotion, and invasiveness.
Different proanthocyanidin fractions from wild and cultivated blueberries also suppressed the proliferation of the androgen-sensitive (LNCaP) and androgen-insensitive prostate cancer cell lines (DU-145). Cranberry flavonoid fractions inhibited the proliferation of various cancer cell lines (androgen-dependent prostate, breast, skin, colon, lung, and brain cell lines) at varying levels. Esters of ursolic acid also inhibited the growth of several types of tumor cells in vitro including MCF-7 breast, HT-29 colon, DU-145 prostate, H460 lung, ME180 cervical, and K562 leukemia cell lines. Ursolic acid isolated from cranberry fruit also showed the inhibition of proliferation of HepG2 human liver cancer cells.
Another important anticancer therapeutic property of berries and berry components derives from their ability to inhibit angiogenesis. Studies conducted using extracts from strawberry, bilberry, wild berry, cranberry, elderberry, and raspberry seeds inhibited angiogenesis inhibiting TNF-α-induced vascular endothelial growth factor expression in human keratinocytes. Berries also impaired angiogenesis in human dermal microvascular endothelial cells. Seed flours from berries including black raspberry, red raspberry, blueberry, and cranberry also showed anticancer properties suggesting that berry seed flours have the potential for the development of products for cancer prevention and overall health.
Medicinal Properties of Berry Bioactives
Research has found that bilberry and its products improve the elasticity and permeability of the capillary vessels of the eyeball improving circulation. Cranberry juice has been effectively used for the prevention and treatment of urinary tract infection (UTI). The antibacterial activity of cranberry juice has been known for a long time. It was reported that proanthocyanidins isolated from cranberry fruit exhibited strong bacterial antiadhesion activity offering protection against UTI. Research has found that proanthocyanidins from cranberry are unique and compositionally different from proanthocyanidins from other fruits such as apple and grape. Cranberry juice and cranberry compounds were capable of exerting bacterial antiadhesion activities against Helicobacter pylori and oral bacteria including Streptococcus mutans. Blueberry compound also exhibited weak antiadhesion activity to S. mutans. Ellagitannin fractions from cloudberry and raspberry also demonstrated potent antibacterial activity against S. aureus. Recent studies have shown that pure phenolic acids such as hydroxycinnamic acid have bactericidal and bacteriostatic activity against several strains of Listeria monocytogenes. In vitro studies demonstrated that bilberry and lingonberry extracts containing high amounts of polyphenols exert protective effects against blue LED light-induced retinal photoreceptor cell damage mainly through inhibition of ROS production and activation of proapoptotic proteins.
Read the full article Berries and Related Fruits here. The article is included in the Encyclopedia of Food and Health which looks at the availability, digestion, absorption, and metabolism of key food constituents and explores how they can prevent disease and improve global health. The Encyclopedia is included in the recently published Reference Module in Food Science, a one-stop authoritative resource that is continuously reviewed and updated to advance as science advances, learn more here or click here to access 10 free articles from the Reference Module.
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