Eating 'Green' Could be Beneficial

July 24, 2000

COLUMBUS, Ohio -- Chlorophyll has long been touted as a holistic healing aid, with claims that it does everything from healing wounds to curing bad breath. But when people consume foods that contain chlorophyll, is it -- or its digestive products -- absorbed like beta carotene or other plant pigments with health-promoting effects? Researchers at Ohio State University decided to find out.

"This would be significant, because it's easy to consume a lot of chlorophyll," said Mario Ferruzzi, doctoral researcher who studied the issue with Mark Failla, professor and chair of the Department of Human Nutrition and Food Management, and Steven Schwartz, food science professor and holder of the Carl E. Haas Food Industries Endowed Chair. Chlorophyll, the compound that makes plants green, is by far the most abundant plant pigment in nature, Ferruzzi said. Plant-based foods contain three to four times more chlorophyll than beta-carotene and other carotenoids. If the body does absorb chlorophyll or its derivatives, it would be very easy for people to consume enough of it to have a beneficial effect, he said. However, there's been very limited study of the digestion and absorption of chlorophyll and its metabolites, and their effects on the body. "The general consensus among researchers was that chlorophyll molecules were too large to be absorbed by the body," Failla said. "And if they were absorbed, they said, we would turn green." But in the researchers' recent studies, chlorophyll's potential as a health promoter has taken a leap forward. One of the studies was recently published in the Journal of Agricultural and Food Chemistry. In the studies, the researchers used an artificial digestion system that makes it possible to study the human digestive process without using human subjects. The types of chlorophyll derivatives that appear to have the most potential for absorption are called pheophytins, the researchers said. Pheophytins are very similar in structure to natural chlorophyll. However, molecules of natural chlorophyll contain magnesium in their center; as chlorophyll is digested and transformed into pheophytins, hydrogen replaces the magnesium. Pheophytins are much more stable than naturally occurring chlorophyll. "Natural chlorophyll is so unstable during processing and during digestion that we've never been sure what to look for in the bloodstream," Schwartz said. Food processors have known about the instability of chlorophyll for a long time, he said. This instability leads to the olive-green color most green vegetables assume after undergoing canning. "Some processors put zinc chloride in the brine, which causes zinc pheophytins to form in the vegetable," Schwartz said. Zinc pheophytins are similar to the other derivatives, but the magnesium in the center of the molecule is replaced not with hydrogen but with zinc. "This stabilizes the pigment, and you end up with canned vegetables that look as green as fresh-picked." From the Ohio State studies, the researchers concluded that chlorophyll undergoes the same types of changes during digestion as when it's canned. "The acidic conditions in the stomach cause the magnesium to be lost, and the chlorophyll becomes a pheophytin, the same as you'd get if you canned some green vegetables," Failla said. The artificial digestion system, known as the Coupled In Vitro Digestion and Caco-2 Human Cell Model, showed that absorptive cells lining the small intestine actually do uptake pheophytins formed during digestion of spinach puree. The next step, the researchers said, is to find out if they make it past that step and are actually absorbed into the bloodstream. "These results are very preliminary, but they do give us some idea of what to look for next," Schwartz said. Ferruzzi added, "This study certainly points the direction of how we should be thinking, and what we should be looking for, when we study what happens to chlorophyll in the body." Editor's Note: This story, originally posted on 7/24/2001, was updated on 2/26/07. The previous version called chlorophyll an antioxidant. While chlorophyll may have beneficial effects, it should not be classified as an antioxidant.

Author(s): 
Martha Filipic
Source(s): 
Mark Failla, Steven Schwartz, Mario Ferruzzi