The pigments, called anthocyanins, provide fruit and vegetables with beneficial blue, purple and red coloring, and are a group of healthful compounds that fall within the flavonoid class of plant nutrients.
ARS scientists have identified 36 anthocyanins in red cabbage, including eight that have never before been detected in the cabbage.
The study was conducted at the ARS Beltsville Human Nutrition Research Center (BHNRC) in Beltsville, Md., where scientists have pioneered methods for identifying and measuring various phytonutrients in fruits and vegetables.
Physiologist Janet Novotny, nutritionist Beverly Clevidence, plant physiologist Steven Britz and research associate Craig Charron, all with the BHNRC's Food Components and Health Laboratory, published the findings in the Journal of Agricultural and Food Chemistry .
According to the scientists, emerging evidence suggests that anthocyanins may provide cancer protection, improve brain function and promote heart health.
An earlier ARS study showed that some anthocyanins yield twice the antioxidant power of the same amount of vitamin C in test tubes, although the amount absorbed by the human body was not explored.
Twelve volunteers consumed three different amounts of cooked red cabbage along with a full diet of carefully controlled foods.
Each volunteer completed three two-day meal regimens, which included 2/3 cup, 1-1/3 cups, or 2 cups of red cabbage.
The volunteers were capable of absorbing the most anthocyanins when given the largest serving of cooked cabbage.
One intriguing result of the research was the evidence that showed that all anthocyanins are not the same, with some absorbed more quickly and easily into the human blood stream.
Nearly 80 percent of cabbage anthocyanins tested were acylated, meaning attached to acyl groups, which made them more stable and less absorbable.
The non-acylated anthocyanins present were at least four times more bioavailable, or absorbed, than the acylated anthocyanins, the study showed.
Anthocyanins have also been shown to have potential as 'fat-fighters' according to a Japanese study published earlier this month.
Experiments showed that the antioxidants influenced the function of fat cells, and could help tackle problems such as metabolic syndrome (MetS), a condition characterised by central obesity, hypertension, and disturbed glucose and insulin metabolism.
The syndrome has been linked to increased risks of both type 2 diabetes and CVD.
The antioxidant power of anthocyanins has given rise to a whole new market segment: superfruits.
These are fruits that have a particularly high antioxidant content or other beneficial nutrients, such as cranberries or blueberries.
But while fruit such as this also appeals to modern consumers' on-the-go lifestyles - they can easily be added to a lunch box or eaten on the hoof, the same cannot yet be said of less easily palatable products such as red cabbage.
But if, as the researchers suggest, their study helps plant breeders in developing varieties that are bursting with easily bioavailable anthocyanin, then perhaps red cabbage, too, will become a staple of the healthy lunch.
Source: Journal of Agricultural and Food Chemistry Volume 55, Number 13, Pages 5354-5362.
doi: 10.1021/jf0710736 "Effect of Dose Size on Bioavailability of Acylated and Nonacylated Anthocyanins from Red Cabbage (Brassica oleracea L. Var.
capitata)"
Authors: C.S. Charron, B.A. Clevidence, S.J. Britz, J.A. Novotny