Vaccinium fruits (blueberries, cranberries and bilberries) are rich in antioxidants. Their purported health benefits include maintenance of cardiovascular health, prevention of diabetes, slow down aging, maintenance of vision, and prevention of urinary diseases. Although many species are edible, only a few are grown commercially. In many cultures, vaccinium fruits have an important place. Higher agricultural production has led to better supplies and as the result, many health organizations have started or sponsored researches on the preventive or curative effects of these berries.
In China, lesser bilberry, south china blueberry and asiatic bilberry are included in the Chinese Materia Medica. The bilberry (vaccinium myrtillus) is a native plant to Northern Europe, but it has also been grown in Asia and North America. The fruits have pigmented flesh and intense dark blue color; and it has found application in dietary and pharmaceutical supplement markets.
Blueberries are commonly found as either the highbush or lowbush variety. In both varieties, the dark blue pigments are confined only to the skin. Cranberry is found in parts of the worlds for commercial applications.
Anthocyanin pigments are the most apparent phytochemicals in vaccinium fruits. Anthicyanins activity can be reduced by polyphenoloxidase, light, ascorbic acid, oxygen and heat. Other flavanoids and phenolics are present in varying amounts. Chlorogenic acid is the dominant phenolic compound in blueberries, while benzoic acid is the predominant phenolic in cranberry. The phytochemical contents of blueberries are significantly affected by cultivar variations and geographics, however, it is less significant for cranberries.
Due to changes in modern habits, cardiovascular diseases are expected to grow in developed countries. Some researchers have summarized possible benefits of flavanoids in the prevention of cardiovascular diseases. Atherosclerosis and plaque formation can result in poor blood flow. A test on rats shows that aorta that is exposed to anthocyanin from blueberry experiences relaxation.
Some experts believe that anthicyanins stabilize phospholipids membrane and increase the mucopollysaccharides acid production, which contribute to healthier blood vessels.
Capillary strength is another essential component in cardiovascular health. Porous or easily damaged capillaries increase the chance for electrolyte imbalances, edema and dysfunctions. Anthocyanins such as difrarel (V. Myrtillus preparation) is well-tolerated by patients with chronic blood vessel diseases, although the effect on each individual may vary. However, the oral version of V. Myrtillus may be slightly less effective in improving capillary resistance to permeability. Accidental or therapeutic radiation exposure can also weaken capillaries and it is known that V. myrtillus have some protective effects. Excessive platelet aggregation can cause blood vessel blockage. A test shows that people who consume cranberry and bilberry extract each day, experienced reduced platelet aggregation.
Diabetes is one of the leading causes of death and in developed countries, the incidence of type 2 diabetes is growing. The fruit and leaves of V. myrtillus are commonly used in Europe to treat diabetes symptoms and complications. A consistently high level of serum glucose causes many adverse physiological symptoms. Common complications of diabetes are hyperlipidemia, vulnerability to infections, neuropathy, blindness due to retinopathy, cataracts and microaniopathy. The accumulation of glycoprotein and collagen cause thickened capillary walls in diabetes patients. As the result, atherosclerosis and blockages are more likely to happen on people with thickened capillaries. A test on rat aorta shows that bilberry can maintain normal capillary structure and in some cases it can reduce collagen contents better than insulin. However, improvement in microaneurysm and capillaries were not found in all patients.
As we age, memory retrieval, short-term-memory, coordination and balance are hindered. Oxidative stress that happens throughout our life may inflict damages to proteins and lipids, which lead to cellular damages. Both acute and chronic dementia happens due to impaired vascular supply, while the amyloid plaques formation is associated with Alzheimer’s disease. A recent study should that dietary antioxidants may protect us from oxygen-induced damages in the brain. Rats that are given dried blueberry show slower nerve damages on the basal forebrain after given pure oxygen for two days to simulate oxidative damages found in aged rat.
Triidothyronine (T3) and thyroxine (T4) are thyroid hormones that regulate metabolism and temperature. Rat that is given billbery anthocyanins injections (200mg/kg/day) for 5 days, show an increased level of T3 on the brain than rats given the placebo. T3 enters brain through specific capillaries and because anthocyanins can improve capillaries functions, it indirectly mediates T3 transport.
Regular consumption of vaccinium fruits is associated with the lower risks of cancer. However, because the relative value of each fruit component isn’t clear, it is difficult to determine a recommended consumption level.
Digestive and Urinary Tract Health
Cranberries, bilberries and blueberries are used on some countries to treat digestive and urinary tract infections. For example, aflatoxin production by aspergillus flavus can be inhibited by anthocyanidins.
Annually, urinary tract infections result in more than 10 million doctor visits in United States alone. This condition can be excruciatingly painful and affects other organs, such as the kidneys. Each year, 500,000 Americans have interstitial cystitis, while half of women in long-term care facilities for elderly may have UTI. This condition may recur, however there is no firm data about the recurrence data. To improve quality of life and reduce medical expenses, it is advisable to prevent this condition from happening on high-risk groups.
UTIs occur when bacteria, fungi or yeast develop inside the urinary tract, which is normally devoid of microorganisms. Catheters, poor hygiene and sexual intercourse increase the risk of urinary tract infection. When the bacteria multiply, patients may experience fever, burning sensations and painful urination. Repeated treatment of UTI with antibiotic may cause the appearance of drug-resistant bacteria, however without antibiotic treatment the microbes may proliferate easily and more likely to spread to nearby organs. Due to risks posed by antibiotics, many people have turned to alternative solutions such as cranberry juice to treat urinary tract infection. For centuries, Native Americans have used cranberries (V. macrocarpon) to treat this illness. However, currently, there is still no conclusive confirmation from the medical community about the benefits of cranberry in treating UTI.
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