"Our study confirms that one particular carotenoid, lutein, can suppress long-term inflammation in patients with coronary artery disease. We have also shown that lutein is absorbed and stored by the cells of the immune system in the blood," commented Rosanna Chung, lead author of the study team from Linköping University.
The study also identified an inverse association between lutein and the blood level of the inflammatory molecule interleukin-6 (IL-6) in CAD patients.
The findings present a potentially important new tool in the battle against inflammation.
“Taken together, these results show that lutein has the potential to play a role in resolution of chronic inflammation in CAD patients,” wrote the researchers.
Carotenoids are fat soluble compounds found in fruit, vegetables and plants which are sometimes use as colouring agents. Previous research has indicated that carotenoids may be inversely related to inflammatory markers.
The research team initially confirmed this inverse relationship for lutein, although a similar relationship was not seen for other carotenoids.
The correlation suggested the possibility of lutein’s direct influence of the inflammatory process. The researchers therefore administered lutein to immune cells in the bloodstream known as peripheral blood mononuclear cells (PBMCs) which secrete inflammatory molecules including IL-6.
Chronic low-grade inflammation is widely recognised in CAD patients, despite drug treatment, lifestyle changes or arterial by-pass surgery.
"The patients were receiving the best possible treatment for their disease according to clinical guidelines, but even so, many of them had a persistent inflammation. At the same time, the patients had lower levels of lutein," commented Professor Lena Jonasson, study team leader.
The team found that PBMCs absorbed and stored lutein, and subsequently significantly reduced production of IL-6 and other inflammatory molecules known as cytokines.
PBMCs were treated with colloidal solutions containing lutein with concentrations of up to 25micromolar. Lutein was absorbed both dose and time dependently. The treatment response time was quick. More than 50% uptake was achieved within six hours, with further increases during throughout the 48-hour test period.
The anti-inflammatory effects were seen in patients with stable angina (SA), but not in acute coronary syndrome (ACS) subjects. Previous research indicates long-term low-level chronic inflammation is predominant in the former condition, whereas acute inflammation is a characteristic of ACS.
The researchers intend to investigate whether increasing consumption of lutein-rich foods has a beneficial effect on the immune system of CAD patients. The long-term aim would be to determine whether lutein could make a material reduction in chronic inflammation in CAD patients.
“Future dietary intervention studies are warranted to confirm whether increasing the consumption of lutein has beneficial effects on clinical outcomes in patients with CAD,” they concluded.
Published online ahead of print. DOI: 10.1016/j.atherosclerosis.2017.05.008
“Lutein exerts anti-inflammatory effects in patients with coronary artery disease”
Authors: Rosanna WS Chung, Per Leanderson, Anna K Lundberg, Lena Jonasson