Functional foods are whole, fortified, enriched or enhanced foods that provide health benefits beyond the provision of essential nutrients, such as vitamins and minerals, when they are consumed in sufficient amounts on a regular basis. Successful examples of functional foods recognised around the world include fortified margarines, psyllium, soy, whole oat products and fish oil. Such functional foods contain various bioactive components including polysaccharides as prebiotics, omega-3 fatty acids, plant sterols, probiotics and polyphenols.
Polyphenols are widely distributed in nature. Anthocyanins are polyphenols that impart their characteristic colours to various fruits and vegetables, ranging from pink to red and violet to dark blue and often purple. Anthocyanins are highly coloured because they contain the anthocyanidin ring that is connected to different sugar molecules to produce a wide range of anthocyanins. The most common anthocyanidins are cyanidin, pelargonidin, delphinidin, peonidin, petunidin and malvidin. Foods containing anthocyanins include fruits such as berries, cherries, grapes and plums as well as vegetables such as eggplant, red onions, red cabbage and purple potatoes, and pigmented grains such as purple maize, red sorghum and black rice.
Cyanidin 3-glucoside is an anthocyanin that provides purple colour to various fruits and vegetables such as blueberry, raspberry, strawberry, chokeberry, plums, black olives and red lettuce. Grains such as blue maize, black beans as well as drinks such as red wine, pomegranate juice and blood orange juice are other sources of dietary cyanidin 3-glucoside.
In animal models of metabolic syndrome, supplementation of pure anthocyanin or foods containing anthocyanins improved pathophysiological parameters. Supplementation of cyanidin 3-glucoside reduced body weight, systolic blood pressure, blood lipids and improved heart and liver structure and function. In human participants with metabolic syndrome, ingestion of various berries improved signs and symptoms of metabolic syndrome. In these participants, elevated systolic and diastolic blood pressure, plasma concentrations of total cholesterol, LDL-cholesterol and pro-inflammatory markers were decreased. The participants also showed improved endothelial function and attenuation of cardio-metabolic risk by reducing low-grade inflammation associated with metabolic syndrome and cardiovascular disease. Anthocyanins thus possess many health promoting properties including cardioprotective, anti-inflammatory, anti-obesity and anti-diabetes effects.
In summary, purple coloured fruits and vegetables, as well as supplements derived from them, represent a natural and safe approach to prevention from degenerative diseases. The term “colour” has always been associated with good nutrition, but more specifically the power of purple is only now being fully recognized as a means of optimizing health and wellness.
References
- Bhaswant, M., et al. Pharmacological Research, 2015; 102: 208-217.
- Bhaswant, M. Nutrition, 2017; 41: 24-31.
- Brown, L., et al. Obesity Reviews, 2015; 16: 914-941.
