Elsevier

Clinical Nutrition

Volume 30, Issue 4, August 2011, Pages 506-512
Clinical Nutrition

Original Article
Quercetin reduces markers of oxidative stress and inflammation in sarcoidosis

https://doi.org/10.1016/j.clnu.2011.01.010Get rights and content
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Summary

Background & aims

Oxidative stress and low antioxidant levels are implicated in the aetiology of sarcoidosis, an inflammatory disease. Quercetin is a potent dietary antioxidant that also displays anti-inflammatory activities. Consequently, the aim is to examine the effect of quercetin supplementation on markers of oxidative stress and inflammation in sarcoidosis.

Methods

A double-blind intervention study has been conducted with two groups of non-smoking, un-treated sarcoidosis patients, matched for age and gender. One group was given 4x500 mg quercetin (n = 12) orally within 24 h, the other one placebo (n = 6). Plasma malondialdehyde levels were used as marker of oxidative damage, plasma ratios of TNFα/IL-10 and IL-8/IL-10 as pro-inflammatory markers.

Results

Quercetin supplementation improved the antioxidant defence, indicated by the increased total plasma antioxidant capacity. Moreover, quercetin supplementation also reduced markers of oxidative stress and inflammation in the blood of sarcoidosis patients. The effects of quercetin supplementation appeared to be more pronounced when the levels of the oxidative stress and inflammation markers were higher at baseline.

Conclusions

Sarcoidosis patients might benefit from the use of antioxidants, such as quercetin, to reduce the occurring oxidative stress as well as inflammation. The effects of long-term use of antioxidant supplementation in sarcoidosis, using e.g. quercetin, on improvement of lung function remain to be investigated. (www.clinicaltrials.gov; NCT-00402623).

Keywords

Antioxidant supplementation
Interstitial lung disease
Cytokines
Oxidative damage

Abbreviations used

BALF
bronchoalveolar lavage fluid
DLCO
diffusing capacity for carbon monoxide
FEV1
forced expiratory volume in 1 s
FVC
forced vital capacity
GSH
glutathione
GSSG
glutathione disulphide
IL
interleukin
LPS
lipopolysaccharide
MDA
malondialdehyde
NF-κB
nuclear factor kappa-B
RNS
reactive nitrogen species
ROS
reactive oxygen species
SSA
sulfosalicyclic acid
TCA
trichloric acid
TEAC
trolox equivalent antioxidant capacity
TNFα
tumor necrosis factor alpha
UA
uric acid

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