Immune function enhanced by red grapes and blueberries

Compounds in blueberries and red grapes came out ahead of more than 400 other compounds in a study conducted at the Linus Pauling Institute at Oregon State University (OSU). The resveratrol in red grapes and pterostilbene in blueberries were found to boost humans’ immune systems, the researchers found.

In the laboratory, both of these compounds, which are called stilbenoids, worked in synergy with vitamin D and had a significant impact in raising the expression of the human cathelicidin antimicrobial peptide, or CAMP gene, that is involved in immune function.

“Out of a study of hundreds of compounds, just these two popped right out,” said Adrian Gombart, an LPI principal investigator and Associate Professor in the OSU College of Science.

“Their synergy with vitamin D to increase CAMP gene expression was significant and intriguing. It’s a pretty interesting interaction.”

While resveratrol has been linked with improved cardiovascular health and reduced inflammation, this research is the first to show a clear synergy with vitamin D that increased CAMP expression by several times, the scientists said.

A strong link has been established between adequate vitamin D levels and the function of the CAMP gene, and the new research suggests that certain other compounds may play a role as well.

Stilbenoids are compounds produced by plants to fight infections and in human biology appear to affect some of the signalling pathways that allow vitamin D to do its job, researchers said. It appears that combining these compounds with vitamin D has considerably more biological impact than any of them would separately.

Continued research could lead to a better understanding of how diet and nutrition affect immune function and possibly lead to the development of therapeutically useful natural compounds that could boost the innate immune response, the researchers said in their report.

Despite the interest in compounds such as resveratrol and pterostilbene, their bioavailability remains a question, the researchers said. Some applications that may evolve could be with topical use to improve barrier defence in wounds or infections, they said.

The researchers warn that the findings were made in laboratory cell cultures and, as such, do not prove that dietary intake would give similar results.

The research was published in the journal Molecular Nutrition and Food Research.