Vitamin D, Blueberries, and Grapes: Partners in the Immune System?

Blueberries - can they work with vitamin D?

Part of a healthy immune system involves responding to bacterial invasion. The body has many mechanisms to combat bacteria, including the white blood cells or leukocytes.

Several types of white blood cells produce small strings of amino acids (that are typically referred to as ‘peptides’) that can target invading bacteria. Through a variety of mechanisms, these peptides can associate with a bacterial cell membrane, breaking the cell open and driving it toward death. Collectively, these are known as “antimicrobial peptides”.

Here’s where vitamin D gets involved:

One of these antimicrobial peptides is known as cathelicidin. What makes cathelicidin unique among these peptides is that the gene associated with it (known as CAMP for Cathelicidin Antimicrobial Peptide) is regulated by vitamin D. Providing vitamin D to leukocytes promotes the expression of CAMP and to increase their bacteria-killing activities.

Regulation of the CAMP gene, especially in context of vitamin D, has been a central question driving the research of Adrian Gombart, PhD, at the Linus Pauling Institute for many years. Recently, he spearheaded an effort at LPI to look for additional small molecules that may work alongside vitamin D to regulate cathelicidin production.Fritz in lab

Their two-step approach involved some genetic manipulation in cells. First, they fused the promoter (a region of DNA that regulates expression of a gene) from the human CAMP gene to another gene that makes a protein called a ‘transcriptional activator.’ The transcriptional activator, if produced, then turned on the production of an enzyme called firefly luciferase. The end result is simple: if any compound added to cells activated CAMP, the cells would glow like a firefly.

Dr. Gombart and his research team then screened 446 different molecules that are currently being tested in clinical trials by the NIH. At the end of the process they found two molecules that not only promoted CAMP gene expression but also worked in combination with vitamin D! Even more interesting, these compounds were normal dietary components: resveratrol (found in red grapes and red wine) and pterostilbene (found in blueberries).

Neutrophil and Bacteria“Out of a study of hundreds of compounds, just these two popped right out,” said Dr. Gombart, who is an LPI principal investigator and an associate professor in the Biochemistry and Biophysics department at Oregon State University. “Their synergy with vitamin D to increase CAMP gene expression was significant and intriguing. It’s a pretty interesting interaction.”

Does this mean drinking red wine and eating blueberries, along with taking vitamin D, will increase your innate defense against invading bacteria? Unfortunately, we don’t know yet. Dr. Gombart’s lab is working hard on determining how these compounds work in the immune system and whether they can boost cathelicidin levels in leukocytes.

There are plenty of other reasons to enjoy a glass of red wine, eat a handful of blueberries, and get your vitamin D. As for improving your immune response, that would just be a bonus!

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Alexander Michels, PhD

Alexander Michels is a Research Associate and Communications Officer for the Linus Pauling Institute. He has an extensive background in the research on vitamin C, with a specialty in understanding vitamin C transport through the body. His expertise also extends to research on other aspects of antioxidant vitamin metabolism and the action of phytochemicals.