Is your vision not what it used to be? Having a hard time seeing at night? Not ready to give up driving after dark? Perhaps lutein holds the solution for you.
Lutein is an orange-red carotenoid pigment that you’ll find in colorful fruits and vegetables. One of the best sources of lutein is kale which provides more than 20 mg per cup. Cooked spinach, collard greens and turnip greens also pack a similar punch. This compares to romaine lettuce and raw spinach (interestingly, a nutrient that increases during the cooking process) which have less than 4 mg of lutein available for use.
In the body, lutein is one of the predominant pigments concentrated in a specialized area of the eye called the macula that is responsible for central vision. In addition, it is also found in the skin. It is thought that lutein’s functional role in these vulnerable tissues is to protect against sunlight-induced free radical production.
Ever since the highly discussed Blue Mountain Eye Study reported that higher dietary lutein and zeaxanthin intake reduced the risk for incident of age-related macular degeneration (AMD) over 5 and 10 years, significant interest has been placed on these particular carotenoids.
In an interesting study, middle-aged adults who drove for a living (i.e. taxi drivers) were given 20 mg of lutein or a placebo for one year. Researchers measured a variety of outcomes including something called macular pigment optical density (MPOD) MPOD has been associated with improvements in visual function in those with age-related macular degeneration.
This study showed that supplemental lutein, at this dose, increases serum levels of lutein. However, of key importance is the length of the study and the measurement of vision performance. Under low light conditions, the group receiving treatment of lutein performed better at testing of contrast sensitivity and glare sensitivity. MPOD was also increased.
Encouragingly, no significant side effects were reported in this study. Carotenodermia, an orange pigmentation of the skin, is one concern of large doses of carotenoids and while transient and relatively harmless, it was not seen in this study.
Previous studies have considered doses of 6 and 12 mg and showed peak serum lutein levels after 3-6 months. However, in this research, peak levels were seen after just 30 days. This was attributed to the higher dose and good compliance among participants.
Getting lutein from the blood to the macula takes considerably longer, however. Uptake of lutein by the macula can take several months after achieving peak serum levels. Indeed, this effect was seen in this study as well. Despite seeing a six-fold increase in serum levels after only one month, visual performance did not improve until three months after initiation of lutein administration.
While 6 mg did not improve macular pigment optical density (MPOD) in previous studies, this study confirmed increases in this valuable biomarker using the 20mg dose.4 Several hypotheses remain about how macular pigment plays a role in the health of the eye but a leading theory is that antioxidants in the pigment reduce oxidized products produced by the interaction of light and tissues.
One of the challenges of the study was that serum levels of lutein in the participants prior to the study were found to be lower than expected. It is thought that profession or economic status could play a role in this. Unfortunately, it creates another question. If a person already has adequate lutein levels in serum, will they not benefit from supplementation? This remains to be determined.
Another question that may arise concerns other carotenoids. The family of carotenoids (including beta carotene, alpha carotene, astaxanthin, zeaxanthin and others) may compete for absorption and excess dosing of a single carotenoid may hypothetically lead to insufficient levels among the other phytonutrients. Unfortunately, serum levels of these other carotenoids were not measured prior to or throughout the study.
Interestingly, after a year of the study, visual acuity was not significantly different among those receiving supplementation and the placebo group. Essentially, participants could not read a Snellen chart, the chart with the large E at the top that optometrists and physicians use, any better than the placebo group. However, seeing movement in the periphery under low light conditions was improved.
This is interesting because visual performance is more of a real-life analysis. Especially in this demographic studied, those whose job requires long hours of driving, even minor improvements in vision can result in improved driving performance and safer roads. Up to 23% of car accidents have been associated with reduced visual performance.
The challenge of the results of this study is the age-group that was studied. Young to midlife adults are not often the ones commonly complaining of decreased night vision. More often than not, the aging person no longer trusts their ability to navigate in low light conditions and this may result in decreased activity and a lower perceived quality of life. As people age, reduced participation in activity is a concern for incidence of depression. Those who continue to drive despite declining vision are putting themselves and others at risk.
It would be curious to see if similar results could be replicated in an older population. Until that result is published, people may find this relatively inexpensive and safe intervention worth a one year trial for themselves.
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photo credit: helgabj