Berries have been part of our diet since time immemorial, as there are historical accounts of indigenous ancestral “hunter-gatherers” using wild berries as a source of food. Scientists are discovering the many health benefits of consuming those berries. In the United States, blueberries have been in the forefront of this research, and recently, raspberries and blackberries are receiving attention.
Berries contain many bioactive compounds, including carbohydrates, vitamins, minerals, fiber and are rich sources of hydroxycinnamic acids, ellagitannins, flavonol glycosides, anthocyanins, flavan-3-ols, and proanthocyanidins. These compounds contribute to the very high antioxidant activity of berries and berry extracts. Currently, the compounds responsible for the beautiful range of red, purple and blue colors of berries, the anthocyanins, are considered to be the most bioactive compounds. Health effects that have been studied include prevention and decreased incidences of cancer, age-related cognitive function, vision, heart disease, and obesity.
Animal models have demonstrated that feeding dried berries, berry extracts, or anthocyanin-rich extracts will prevent the development of cancers of the gastrointestinal tract, including oral cancer, esophageal cancer, and colorectal cancers. Cancerous cell line growth is also inhibited by the addition of berry extracts or anthocyanin-rich extracts, and several clinical studies are underway in individuals with a high risk of gastrointestinal cancer.
The potent antioxidant activity of anthocyanins is well known and led to the hypothesis that these compounds may be protective against health conditions thought to be due to accumulation of oxidant damage, including age-associated loss of memory and cognitive function, and heart disease. Anthocyanins from berries including blueberries have very recently been shown to enhance memory and slow or reduce age-associated loss of cognitive function in rats.
Another health benefit of berries that has been investigated is the potential for berry extracts and/or anthocyanins to improve vision pathologies or reduce the loss of vision with age; however, the clinical studies to date have shown no significant improvement with supplementation.
Similarly, although the high antioxidant capacity of berries, including blueberries, has led to the speculation that these foods would offer protection against heart disease, but the evidence for this association is not well documented. One explanation may be the current level of consumption of these fruits is too low in the diet of populations studied to be identified as an important dietary factor. Clinical studies with anthocyanin-rich pomegranate juice have provided convincing and impressive results showing dramatic improvement in cardiac disease patients. However, further work needs to be done to determine whether anthocyanins and other phenolics in berries would yield similar results.
Prevention of obesity by anthocyanins has been demonstrated in several mice studies. Mice had lower liver lipid accumulation, and lower serum levels of glucose, insulin and leptin.
In summary, current research is showing that our berry-gathering ancestors were adding more than just tasty, attractive treats to their diets. Furthering our understanding of the components responsible for these beneficial effects will be useful in developing value-added foods and in developing plant varieties rich in the health-promoting phytochemicals.