Increased intakes of compounds called flavonoids from citrus may be associated with lower levels of markers of inflammation, according to a new study from researchers at Harvard, Sweden and Singapore.
Data from between 1,200 and 1,600 women showed that women with the highest intakes of total flavonoids, which includes various subclasses such as flavones, flavonols, flavanones, flavan-3-ols, anthocyanidins, and polymeric flavonoids, were associated with an 8 percent lower level of the pro-inflammatory compound interleukin-18 (IL-18), compared with women with the lowest intake.
“Higher intakes of selected flavonoid subclasses were associated with modestly lower concentrations of inflammatory biomarkers,” wrote the researchers in the Journal of Nutrition.
“In particular, flavonoids typically found in citrus fruits were modestly associated with lower plasma IL-18 concentrations,” they added.
If the study can be repeated in further studies and intervention trials, it may offers promise for reducing the risk of chronic inflammation, brought about by an over-expression or lack of control of the normal protective mechanism. Chronic inflammation has been linked to range of conditions linked to heart disease, osteoporosis, cognitive decline and Alzheimer's, type-2 diabetes, and arthritis.
The flavonoids family
A vast body of epidemiological studies has linked increased dietary intake of antioxidants from fruits, vegetables wine, chocolate, coffee, tea, and other foods to reduced risks of a range of diseases including cancer, cardiovascular disease and diabetes.
Flavonoids can be split into a number of sub-classes, including anthocyanins found in berries, flavonols from a variety of fruit and vegetables, flavones from parsley and thyme, for example, flavanones from citrus, isoflavones from soy, mono- and poly-meric flavonols like the catechins in tea, and proanthocyanidins from berries, wine and chocolate.
Led by Rikard Landberg from the Swedish University of Agricultural Sciences in Uppsala, the researchers used data from participants of the Nurses’ Health Study cohort.
Using a food frequency questionnaire, the researchers evaluated intake for the six flavonoid subclasses of flavones, flavonols, flavanones, flavan-3-ols, anthocyanidins, and polymeric flavonoids. Blood samples were taken to correlate with levels of markers of inflammation, including IL-6, IL-18, C-reactive protein (CRP), and soluble vascular adhesion molecule-1 (sVCAM-1), amongst others.
Results showed that the highest intakes of flavones and flavanones were associated with 9 and 11 percent lower levels of IL-18, compared with women with the lowest average intakes.
In addition women with the highest average intakes of flavonol has 4 percent lower levels of sVCAM-1, compared with women with the lowest average intakes.
When the researchers looked at foods, they noted that grapefruit consumption was associated with lower levels of CRP.
Source: Journal of Nutrition
Published online ahead of print, , doi: 10.3945/jn.110.133843
“Selected Dietary Flavonoids Are Associated with Markers of Inflammation and Endothelial Dysfunction in U.S. Women”
Authors: R. Landberg, Q. Sun, E.B. Rimm, A. Cassidy, A. Scalbert, C.S. Mantzoros, F.B. Hu, R.M. van Dam