Honey – The Darker The Better – Has Potential As Dietary Antioxidant

Like a UI study in 1999, researchers found in both studies that dark-colored honey, especially buckwheat, provided more protective punch than lighter-colored honeys. “It still is too early to say definitively, but honey seems to have the potential to serve as a dietary antioxidant,” said principal researcher Nicki Engeseth, a professor of food chemistry in the UI College of Agricultural, Consumer and Environmental Sciences.

The newest study – published online April 6 in the Journal of Agricultural & Food Chemistry – is the first to look at honey’s effect on human blood. The study also found, using a much more precise method than the one used in 1999, that honey’s antioxidants are equal to those in many fruits and vegetables in their ability to counter the degenerating activity of highly reactive molecules known as free radicals.

In January, Engeseth and Jason McKibben, a researcher with Anheuser Busch in Santa Monica, Calif., reported in the same journal that honey was more effective than traditional preservatives (butylated hydroxytoluene and tocopherol) in slowing oxidation in cooked, refrigerated ground turkey.

While the meat browned during cooking more extensively than traditionally preserved products, taste was not negatively affected. For the just-published study, Engeseth and Nele Gheldof, a doctoral student in the department of food science and human nutrition, measured the antioxidant and phenolic contents in honeys taken from seven floral sources.

The study covered acacia, buckwheat, clover, fireweed, Hawaiian Christmas berry, soybean and tupelo honeys. Researchers used the oxygen radical absorbance capacity (ORAC) assay, a tool that for the past decade has been widely used to analyze the same components in fruits, vegetables and wines. Darker honeys had the highest values.

“We got ORAC values ranging from 3 to 17,” Engeseth said. “Commonly consumed fruits and vegetables generally range from 0.5 to 16, based on a per gram basis. This finding is significant, because it clearly shows that there are antioxidants in the honey. If you ate as much honey as you did of melon, for example, you would be getting a similar dose of antioxidants in your diet.”

Is such a scenario likely? No, but the idea that honey packs healthy quantities of antioxidants does strengthen the idea of using honey as sugar substitute, Engeseth said.

Engeseth and Gheldof obtained blood samples from healthy human volunteers coming off a 12-hour fast. To the blood, they added the various honey varieties in an experiment to watch honey’s impact on LDL, the so-called bad cholesterol. In test samples, they also added copper to stimulate lipoprotein oxidation. Using a spectrometer, they found that honey – the darker the better – dramatically slowed the rate of formation of conjugated dienes, products of oxidation related to LDL in blood.

“The one thing about this study is that even though it involved human blood in a test-tube assay, it does show that if honey is present it can act positively,” Engeseth said.

Follow-up studies, either in progress or undergoing data analyses, will shed more light on the exact phenolic compounds in honey and on how effectively honey that is consumed prevents oxidation in the blood of human subjects.

Phenolic compounds are phytochemicals, which are non-nutritious compounds in foods that may carry specific disease-fighting abilities. UI researchers also have also found a significant correlation of phenolic content and antioxidant capacity of honey.

Both recent studies were partially funded by the National Honey Board.