Vitamine D en ontstekingen*
Uit een Amerikaanse studie blijkt dat bloedwaarden vitamine D gerelateerd zijn aan waarden Tumornecrosefactor-alfa (TNFa), een van de twee bekende tumornecrosefactoren en een daarmee een cytokine, een proteïne die een rol speelt in de immuunafweer. TNFa speelt een belangrijke rol bij ontstekingsprocessen waardonder hartziekte, multiple sclerose en reumatische artritis (RA). Lage bloedwaarden vitamine D
geven hogere waarden TNFa, omgekeerd geven hogere bloedwaarden vitamine D lagere waarden TNFa. Omdat uit recente studies blijkt dat wel 75% van alle Amerikanen te lage bloedwaarden vitamine D hebben is voldoende
vitamine D wel heel belangrijk in de aanpak en voorkomen van ontstekingsziektes. Doch zijn volgens de onderzoekers de geadviseerde dagelijkse hoeveelheden daarvoor wel veel te laag en zouden de meeste mensen minimaal 25 mcg per dag geadviseerd moeten worden.
Relationship Between Vitamin D Deficiency And Increased Inflammation In Healthy Women
According to a recent study in the Archives of Internal Medicine, 75 percent of Americans do not get enough Vitamin D. Researchers have found that the deficiency may negatively impact immune function and cardiovascular health and increase cancer risk. Now, a University of Missouri nutritional sciences researcher has found that vitamin D deficiency is associated with inflammation, a negative response of the immune system, in healthy women.
Increased concentrations of serum TNF-a, an inflammatory marker, were found in women who had insufficient vitamin D levels. This study is the first to find an inverse relationship between vitamin D levels and concentrations of TNF-a in a healthy, non-diseased population. This may explain the vitamin's role in the prevention and treatment of inflammatory diseases, including heart disease, multiple sclerosis and rheumatoid
arthritis.
"The findings reveal that low vitamin D levels negatively impact inflammation and immune response, even in healthy women," said Catherine Peterson, assistant professor in the MU College of Human Environmental Sciences. "Increased inflammation normally is found in people with obesity or chronic diseases; a small decrease in vitamin D levels may aggravate symptoms in people who are
sick."
The results support the need to re-examine the biological basis for determining the dietary reference intake (DRI) of vitamin D, Peterson said. The Institute of Medicine's DRI for vitamin D is 200 IU for people age 50 and younger and 400 IU for people 50 to 70 years old. The guidelines, created in 1997, are being revised to reflect new research, and Peterson is confident the DRI will be
increased.
"Adequate vitamin D levels identified in this study are consistent with recent research that suggests the DRI should be increased," Peterson said. "To improve vitamin D status and achieve its related health benefits, most people should get at least 1000 IU of vitamin D per day. Sunlight is a readily-available, free source of vitamin D. Exposing 25 percent of the skin's surface area to 10 minutes of sunlight three days per week will maintain adequate levels in the majority of people; however, people with darkly-pigmented skin need more. Only a few foods contain vitamin D naturally, such as fatty fish; other sources are dietary supplements and vitamin-D-fortified foods, including milk and orange juice."
In future studies, Peterson will determine the effectiveness of Vitamin D in reducing disease symptoms and reducing blood glucose levels in
diabetics. (Mei
2009)
