Next to being found in many green leafy plants and colorful fruits and vegetables, lutein is found in high concentrations in the macula of the human eye, giving the macula its yellowish color. In fact, the macula also is called the "macula lutea" (from the Latin macula, meaning "spot," and lutea, meaning "yellow").
Cooked spinach is one of the best natural food sources of lutein.
Cataracts are responsible for about 30 to 50 million cases of blindness throughout the world. Cataract increases with age, reducing visual acuity and constituting a major cause of disability in the elderly, according to the researchers.
The team investigated the effect of long-term antioxidant supplementation, testing both lutein and alpha-tocopherol (or vitamin E), on serum levels and visual performance in seventeen patients with cataracts. They found that the patients' eyesight improved with both nutrients, although most significantly with lutein supplements.
The patients were randomised in a double-blind study. They took either 15mg of lutein, 100mg of alpha-tocopherol, or a placebo, three times a week for up to two years. Serum carotenoid and tocopherol concentrations were measured, and visual performance (visual acuity and glare sensitivity) was monitored every 3 months throughout the study.
The authors noted: "Serum concentrations of lutein and alphatocopherol increased with supplementation, although statistical significance was reached only in the lutein group." Visual performance (visual acuity and glare sensitivity) improved in the lutein group, but with vitamin E it remained at the same level and it decreased in those taking placebos. They reported no significant side effects in any of the subjects during the study.
The researchers say the results suggest that a higher intake of lutein, through lutein-rich fruit and vegetables or supplements, may have improve the visual performance of people with age-related cataracts.
A study by researchers from the Department of Optometry and Neurosciences at the University of Manchester in England has raised hopes that patients already experiencing early stages of AMD may be able to delay or even prevent its progress through dietary intervention.
Evidence has been growing in recent years that a tiny part of the retina, the macular pigment, may give the eye in-built protection from Age-related Macular Degeneration (AMD), the disease that is the principal cause of irreversible blindness in the elderly. The macular pigment is entirely made up of lutein and zeaxanthin, plant pigments found in many fruits and vegetables.
Research findings strongly indicate that people are at greater risk of developing AMD if the density of their macular pigment is low. Researchers around the world have been investigating the effects of increasing macular pigment density, by simply adding extra sources of the carotenoids lutein and zeaxanthin to the diets of those at risk, to find out if this can reduce the risk of the disease.
While this theory has not yet been proven, Dr Ian Murray, who presented his group's latest findings to the annual meeting of the Association for Research in Vision and Ophthalmology in Florida, said: "I have seen many patients who are suffering from the disabling effects of AMD. Of course we are excited by the prospect that a simple addition to the diet may impede the progress of the disease and prevent others who are at risk from experiencing such problems. Right now, dietary intervention is the only hope for most of them."
In one study, Dr Murray's group selected eight patients at an early stage of development of the disease. Aged between 60 and 81, these patients so far have normal visual acuity. They were compared with 'normal' subjects, matched for sex, eye-colour and age. The researchers observed, as in earlier studies, that eyes at risk of developing early-stage AMD have lower macular pigment density than eyes without such risk, adding credibility to the theory that the macular pigment has an AMD-protective role.
In the second ongoing study, the researchers gave a daily supplement of Cognis' Xangold 15 per cent Natural Lutein Esters to eight patients (six from the first group) and to eight normal subjects, over a period of 18 weeks and measured the effects. Interim data after 12 weeks of supplementation indicate that the density of macular pigment in both patients and normal subjects increased at the same rate. Further, the researchers found that, where patients already had AMD in one eye, both eyes responded equally well to supplementation.
These results suggest that, at least in the early stages of AMD, the disease does not stop lutein from being deposited in the retina. The significant implication of this finding is that in patients at an early stage of AMD, dietary intervention, in this case with Xangold 15 per cent, may help promote eye health by maintaining the density of the macular pigment.