Study sheds light on lutein's anti-inflammatory effect
retina from damage by inhibiting inflammation, according to a new
study from Korea.
The new research, supported by Kemin Food Asia, looked at the effects of lutein on retinal ischemia (reduced blood flow to the retina), reported to be a good model for retinal neuronal cell death that occurs for several eye conditions including diabetic retinopathy and age-related macular degeneration (AMD).
AMD is a progressive eye disease that affects the central macula of the eye, leaving sufferers with only peripheral vision. It is the most common cause of blindness in the over-50s in the Western world, according to AMD Alliance International, and is estimated to affect 25 to 30m people.
"These results suggest that a lutein supplement may protect against ischemia-mediated cell death in the retina," concluded lead author Jun-Sub Choi from the Catholic University of Korea.
The new study, published on-line in the journal Nutrition (doi: 10.1016/j.nut.2005.08.011), used high intraocular pressure (HIOP) to induce retinal ischemia in eight week old Sprague-Dawley rats.
The rats then received an intravitreal injection of lutein (Kemin's FloraGLO, 20 per cent in corn oil). This was given half an hour before retinal ischemia, and expression of the proteins COX-2 (a pro-inflammatory protein) and nNOS (neuronal Nitric Oxide Synthsase) was measured. The latter generates nitric oxide (NO), a reactive oxygen species (ROS) that can kill cells by oxidative stress when generated in excessive amounts.
The control rats (no lutein administration) experienced an increase in the expression of these two proteins. However, lutein appeared to inhibit their expression in a dose-dependent manner.
The researchers report that lutein increased the survival of retinal neurons by 86 per cent in the eyes of the rats, compared to control.
"We have confirmed that nNOS and COX-2 expressions are inhibited by lutein. These results suggest two mechanisms of lutein: 1) an antioxidant effect and 2) direct inhibition of nNOS and COX-2 expressions," wrote Choi.
The researchers called for more study to further investigate the effects of lutein in ischemia.
Zoraida DeFreitas, Kemin's vice president of research and development, told NutraIngredients.com that the research adds support to the antioxidant benefits of lutein.
"Furthermore, the study suggests a role for lutein in reducing the damage induced by retinal ischemia and diabetic retinopathy. The former diseases have been associated with oxidative stress caused by high intraocular pressure and high glucose blood levels, respectively," said DeFreitas.
"Another important finding from this study is the reduction of inflammatory markers induced by ischemic injury in the presence of lutein, which provides further understanding on lutein's mechanism of action in the eye," she said.
Interestingly, DeFreitas added: "This study shows the potential neuroprotectant benefit of lutein in the neuronal degeneration, expanding our knowledge beyond eye health."
A recent survey, from Frost and Sullivan and commissioned by Kemin, found that awareness of the antioxidant carotenoid has never been so high in Europe. Five hundred consumers aged between 20 and 65 years were questioned across Italy, Germany, Spain, Portugal, France and the UK (500 in each country).
In Italy and France awareness has doubled compared to last year, to 25.8 per cent and 16 per cent respectively. Germans showed the greatest awareness, of 33.3 per cent. The UK was the only country where it seemed to have slipped slightly, to 20 per cent (compared to 25.8 in 2005).
