Anthocyanins—More Than Nature's Colours

Research over the past decade has produced incontrovertible evidence for a vast array of health benefits arising from the consumption of fruits and vegetables. In an endeavor to identify the active health-promoting ingredients , many researchers have focused on the properties of the flavonoids, a large class of phenolic compounds that is abundant in such foods. Most prominent among the flavonoids are the anthocyanins—universal plant col-orants responsible for the red, purple, and blue hues evident in many fruits, vegetables, cereal grains, and flowers. Represented by over 600 molecular structures as identified to date, anthocyanins are of particular interest to the food colorant industry due to their ability to impart vibrant colours to the product. Now it seems highly likely that they also enhance the health-promoting qualities of foods. Anthocyanins were incorporated into the human diet many centuries ago. They were components of the traditional herbal medicines used by North American Indians, the Europeans, and the Chinese, and were habitually derived from dried leaves, fruits (berries), storage roots, or seeds. Anthocyanin-rich mixtures and extracts (though not purified compounds) have been used historically to treat conditions as diverse as hypertension, pyrexia, liver disorders, dysentery and diarrhoea, urinary problems including kidney stones and urinary tract infections, and the common cold. They have even been purported to yield improvements to vision and blood circulation. Recent studies using purified anthocyanins or antho-cyanin-rich extracts on in vitro experimental systems have confirmed the potential potency of these pigments. Demonstrable benefits include protection against liver injuries; significant reduction of blood pressure; improvement of eyesight; strong anti-inflammatory and antimicrobial activities; inhibition of mutations caused by mutagens from cooked food; and suppression of proliferation of human cancer cells. Along with other phenolic compounds, they are potent scavengers of free radicals, although they can also behave as pro-oxidants. Because of their diverse physiological activities, the consumption of anthocyanins may play a significant role in preventing lifestyle-related diseases such as cancer, diabetes, and car-diovascular and neurological diseases. Many questions remain. We do not know, for example , whether these apparent health benefits stem from anthocyanins alone, or from their synergistic interactions with other phenolic compounds. Are the health-promoting qualities of anthocyanin-phenolic mixtures preserved across the various food systems? What is the fate of anthocyanin molecules after consumption? Reports on bioavailability of anthocyanins indicate that less than 1% of consumed anthocyanins is detectable in human plasma and urine. Are the health-protective qualities observed …