Health

Some of the properties demonstrated by blueberries are of vital importance for the prevention of "civilisation diseases", i.e. cancer and cardiovascular diseases. Among 40 kinds of fruit and vegetables, blueberries came first in terms of the content of antioxidants, i.e. substances that neutralise free radicals. The second spot was taken by grape juice, whose capacity was 2/3 that of antioxidant potential found for blueberries. They were followed by strawberries, kale, and spinach. Furthermore, it was demonstrated that the equal amount of blueberries contains five times the antioxidants of pea, carrots, apples, marrow, or broccoli.

What makes those substances so important? For an explanation we need to take a closer look at the way free radicals originate and act. These unstable oxygen atoms are by-products of human metabolism. They are produced in those of our cells that take part in energy processing. Free radicals are absorbed and neutralised by the vitamin E, which becomes a free radical itself in the process. That in turn is absorbed by vitamin C, removed from the cell and transferred to other substances. However, a certain amount of free radicals penetrates outside of the cell. In its search for chemical balance, a free radical reacts easily with the substances it encounters, thus restoring its balance while upsetting the balance of the system. Free radicals that end up in the skin damage collagen fibres, accelerating the aging of the skin and causing wrinkles. In the eyes, they speed up the progress of cataract, and by oxidising cholesterol in blood vessels they accelerate sclerosis. If they end up in cell nuclei and damage DNA, they may cause cancer.

The production of free radicals is stimulated by cigarette smoke, UV radiation and environmental pollution. The substances that neutralise free radicals are antioxidants. Those are: vitamins A, C, and E, as well as anthocyanins, which are natural dyes that give blueberries their navy-blue colour (and the red colour to strawberries for that matter), flavonoids, and other unidentified substances whose antioxidant properties are yet to be fully understood. In order to function properly, antioxidants require the presence of minerals such as selenium, zinc, copper, and manganese, which are also found in blueberries.

Another group of substances that make blueberries a valuable addition to our diet are phytyoestrogens (i.e. plant hormones). Among the plants of the heather family, cranberries are the richest in phytochemical content (five times more than blueberries and bilberries), followed by cowberries (three times). However, both cranberries and cowberries can hardly be eaten fresh, and any processing (such as cooking) deactivates the substances of interest. Even drying results in the destruction of 20% of phytoestrogens, so that the only form of preservation to be recommended that does not result in the reduction of phytochemical content is freezing. By entering our metabolism, phytoestrogens inhibit the enzymes that cause the development of hormone-related tumours in males and females. Research has also demonstrated that phytoestrogens protect us from arteriosclerosis and heart disease by decreasing the levels of "bad" cholesterol (LDL) and increasing the levels of the "good" one (HDL).

In addition, blueberries contain ellagic and folic acids, whose effects on humans are currently being researched. In all probability they are inhibitors (barriers) of carcinogenic substances. Studies on mice demonstrated that ellagic acid prevents the development of liver, lung, and oesophagus cancer, while the folic acid enhances protection from uterus cancer and has positive influence on the development of the foetus.

Another substance important for our health is dietary fibre. One hundred grams of blueberries contain some 4.54 g of dietary fibre, the recommended daily intake being 25 g. As is the case with other substances, the role of dietary fibre is not yet fully understood. It is assumed that by facilitating the movement of food, fibre decreases the time it spends in our digestive track. Some scientists believe that certain intestinal bacteria convert bile acids into carcinogenic substances. Dietary fibre is capable of fixing bile acids and some other toxins, contributing to their dilution and removal from the body. Interesting results were obtained by neurologists at the Boston University from their research study on rats. The animals were divided into two groups, one of which was fed blueberries. After a couple of weeks the rats on the blueberry diet were more vigorous and mentally fitter as compared to the control group. They demonstrated better memory skills and physical activity - running faster, showing better coordination and reflexes than their peers. Another study showed that animals who feed on blueberries have a much faster rate of neural transmission, which in turn results in shorter times required to perform various tasks. The exact nature of that "rejuvenation" is yet to be fully explained, as is the case with the regenerating effect of blueberries on human sight, a property discovered a few decades ago.

Blueberries are a popular alternative treatment in Japan, where people who spend long periods of time working in front of a computer screen drink blueberry juice to prevent eye fatigue. Blueberry vitamin pills are sold in health food stores in Japan. Blueberries prevent bacterial infections, especially those of the urinary tract caused by E. Coli. Substances contained in blueberry juice prevent bacteria from sticking to bladder walls and causing infections.