In a study reported in the Journal of the Academy of Nutrition and Dietetics, intake of blueberries delayed progression of prehypertension and improved arterial stiffness.Mr. T in DC/Flickr

Red grapes and blueberries can help improve the innate immune system and help the body provide an immediate resistance against infections, revealed a new study.

Scientists from Oregon State University selected 446 chemical compounds and thoroughly examined their role in strengthening the innate immune system in humans. The innate immune system is the first line of defence that identifies and responds to foreign bodies, including pathogens.

At the end of the experiment, researchers found that two chemical compounds - resveratrol in red grapes and pterostilbene in blueberries, were highly effective in boosting the immune system. The compounds joined hands with vitamin D and elevated the expression of the human cathelicidin antimicrobial peptide (CAMP) that is involved with various immune functions - destroying bacteria persistently and immunomodulatory effects (controlling or amending one or more immune functions).

"Out of a study of hundreds of compounds, just these two popped right out," Adrian Gombart, an LPI principal investigator and associate professor in the OSU College of Science, said in a university press release. "Their synergy with vitamin D to increase CAMP gene expression was significant and intriguing. It's a pretty interesting interaction."

The findings support previous studies which found that resveratrol helped decrease inflammation, prevented cancer and thus improved cardiovascular health. There also exists solid evidence to prove that sufficient levels of vitamin D help raise the expression of CAMP gene. 

While explaining their study scientists said that stilbenoids when combined with vitamin D in human body help plants fight some diseases more effectively, than when acted separately.

Researchers said that the experiments were only conducted in laboratory cell cultures. Hence, they have to collect more evidence to prove that the immunity development can be achieved via dietary intake.

The study has been published in the journal Molecular Nutrition and Food Research.