The Color Purple

I ‘m not referring to the amazing novel by Alice Walker, which won the 1983 Pulitzer Prize and the National Book Award for fiction.  I’m not writing about the movie with Whoopi Goldberg, Danny Glover and Oprah Winfrey, directed by Steven Spielberg, although I am planning to see it again.  I’m writing about (you guessed it) the benefits of purple foods, such as, purple cabbage, the skin of eggplant, purple corn, black rice, raspberries, cherries, blueberries, blackberries, cranberries, blood oranges, dark grapes and red wines. The dark red and purple color in these foods contain a pigment known as anthocyanin, which may appear red, purple or blue depending on the pH. 

Anthocyanins occur in the leaves, stems, flowers, fruits and roots of many plants.  Their colors attracts pollinators and other animals, enhances the scattering of seeds, and also protect plants from sun damage. 

Researchers at Ohio State University have done studies on human colon cancer cells and in rats, to determine what gives anthocyanins cancer –protective properties.  Extracts derived from purple corn were the most potent, with chokeberry and bilberry extracts also effective in reducing colon cancer cell growth in laboratory dishes. The researchers said that only small amounts of anthocyanin is absorbed by the blood stream in animals, but a large portion travels through the gastro-intestinal tract, where tissues absorb the compound. Anthocyanins may also help with esophageal cancers.   The researchers also noted that plant pigments such as anthocyanins could be used instead of synthetic dyes to color foods and enhance their health-promoting properties.

A comprehensive review of anthocyanin consumption and human health was published by an Italian research center in 2013.  They cited papers showing that anthocyanins  can protect against heart disease, obesity and diabetes, and gave rodent pancreatic cells increased insulin secretion.  Anticancer activity was found in leukemia cells, colon cancer cells, oral cancer cells, and other forms of cancer.  Laboratory studies have shown that anthocyanins can inhibit malignant cell growth, and stimulate apoptosis (tumor cell death).  The authors cited studies showing potent anti-oxidant activity of anthocyanins, which is enhanced by the other phytonutrients and vitamins in fruits.  Studies have shown neuroprotective  activity in animals with brain injuries, memory problems and visual decline with aging.  Recent studies also indicate that anthocyanins can inhibit the growth of some pathogenic bacteria, and may enhance the growth of healthy bacteria in the intestinal tract. 

What inspired me to write this column were the purple yams now on sale at the Bolinas People’s Store.  They are deep in color and amazingly good.  I also recall that Dr. Donald Abrams, an integrative oncologist at UCSF’s Osher Center, has said that he eats a yam every day of the year.   My advice:  Try those yams and also purple potatoes.  Once you plant the little Peruvian potatoes in your yard (gopher proof area) they will keep on giving, I have some ready to plant – call me if you want a few.  They are hardy in the winter. Include berries in your diet as often as possible, including frozen berries during the winter months.  Stock up on the cranberries now in season, and freeze some for later.  Eat prunes – they are purple plums and are high in anthocyanins.  Get purple popcorn and black rice at a natural food store.  Just think of the color purple; it’s powerful. 

Sadja Greenwood, MD, MPH – back issues on this blog