Lutein as a dietary supplement
Lutein is a carotenoid, a type of antioxidant found primarily in green vegetables such as spinach, kale, and collard greens. It is recognized for its potential benefits in eye health, particularly in protecting against age-related conditions like macular degeneration and cataracts. Lutein may function as a natural filter against harmful light and neutralizes free radicals, which can cause cellular damage. While it is not considered an essential nutrient, many people seek it out for its possible health advantages. Therapeutic dosages for lutein supplements typically range from five to thirty milligrams daily, but the exact amount needed for optimal effects remains unclear.
Studies indicate that individuals who consume foods rich in lutein may experience a reduced risk of developing significant vision issues. However, the scientific community is divided on its effectiveness, as some larger studies have found limited benefits from supplementation. Safety evaluations suggest that lutein is generally safe when taken in moderate amounts, although long-term use may carry potential risks, especially in specific populations. As research continues, lutein remains a popular choice among those interested in dietary supplements for eye health and overall well-being.
Lutein as a dietary supplement
Definition: Natural substance promoted as a dietary supplement for specific health benefits.
Principal proposed uses: None
Other proposed uses: Atherosclerosis, cataracts, macular degeneration, retinitis pigmentosa
Overview
Lutein, a chemical found in green vegetables, is a member of a family of substances known as carotenoids. Beta-carotene is the best-known nutrient in this class. Like beta-carotene, lutein is an antioxidant that protects cells against damage caused by dangerous, naturally occurring chemicals known as free radicals.
Evidence has shown that lutein may play an important role in protecting eyes and eyesight. It may work in two ways: by acting directly as a kind of natural sunblock and also by neutralizing free radicals that can damage the eye.
Sources
Lutein is not an essential nutrient. However, it may be useful for optimal health. Green vegetables are the best source of lutein, especially spinach, kale, collard greens, romaine lettuce, leeks, and peas. Unlike beta-carotene, lutein is not found in high concentrations in yellow and orange vegetables such as carrots.
Therapeutic Dosages
It is not known how much lutein is necessary for a therapeutic effect, but estimates range from five to thirty milligrams (mg) daily.
Therapeutic Uses
According to theoretical findings and two preliminary double-blind studies, it appears that the use of lutein supplements might help prevent or slow the development of age-related macular degeneration and possibly cataracts, the two most common causes of vision loss in the elderly. Lutein has also shown some promise for the treatment of retinitis pigmentosa, an inherited form of eye disease that causes progressive vision loss. Weak evidence hints that lutein might help prevent atherosclerosis.
Scientific Evidence
Most observational studies suggest that people who eat foods containing lutein are less likely to develop cataracts and perhaps macular degeneration, the two most common causes of vision loss in adults. Furthermore, there are good theoretical reasons to believe that lutein may play an important role in protecting the eyes.
Lutein is the main pigment (coloring chemical) in the center of the retina, the region of maximum visual sensitivity known as the macula. Macular degeneration consists of injury to the macula and leads to a severe loss of vision. One of the main causes of macular degeneration appears to be sun damage to the sensitive tissue. Lutein appears to act as a natural eyeshade, protecting the retina against too much light. It is also an antioxidant, meaning that it fights free radicals. Free radicals may play a role in macular degeneration.
Based on this information, researchers conducted a double-blind, placebo-controlled trial of lutein. The study enrolled ninety people with dry-type macular degeneration and followed them for twelve months. The participants received either lutein (ten mg), lutein plus other antioxidants and a multivitamin-multimineral supplement, or a placebo. At the end of the study period, participants who had taken lutein alone or lutein plus the other nutrients showed improvements in vision, while no change in vision was seen in the placebo group.
A subsequent study failed to find benefit with lutein, but it used a lower dose (six mg daily) and involved fewer people. Ultimately, further study is needed to establish whether lutein is helpful for macular degeneration.
Besides protecting the macula, lutein might also shield the lens of the eye from light damage, slowing the development of cataracts. One small, two-year, double-blind, placebo-controlled trial found some evidence that lutein may improve vision in people who already have cataracts. A trial involving 225 adults with retinitis pigmentosa found that four years of daily supplementation with lutein and vitamin A slowed the rate of visual loss in the mid-peripheral field.
Though lutein has shown the potential to protect against vision-related conditions and illnesses, emerging studies in the 2010s cast doubt on its effectiveness. A very large 2013 study, the Age-Related Eye Disease Study, found no benefit from supplementation with lutein, while a systematic review of literature published in 2017 found similar evidence of lutein’s limited effectiveness in preventing and alleviating vision issues.
Lutein has also been studied for benefits beyond protecting the eyes and eyesight. The same antioxidant properties that protect eye health also aid in heart health as well. Lutein was also found to lower cholesterol and triglycerides through its anti-inflammatory properties. Several small studies pointed to the potential of lutein to be an anti-cancer tool. Finally, small studies have also shown lutein’s potential to protect against neurodegenerative diseases and raise cognitive function.
Safety Issues
Although lutein is a normal part of the diet, there has not been much evaluation of lutein’s safety when taken as a concentrated supplement. One study found evidence that lutein is safe in doses up to the highest tested dose of ten mg daily. A review of other evidence concluded that long-term use of lutein should be safe when taken at a dose of up to twenty mg per day. A 2009 study following 77,126 adults (older than age fifty years), however, suggests that there may be some harm in long-term supplementation with lutein. This study found that long-term use of beta-carotene, lutein, or retinol supplements may increase lung cancer risk. Long-term supplement use was determined by participants’ memory of the previous ten years, so the results of this large study should be interpreted with some caution. Finally, maximum safe dosages for young children, pregnant or nursing women, and those with severe liver or kidney disease have not been established.
Bibliography
Berson, E. L., et al. “Clinical Trial of Lutein in Patients with Retinitis Pigmentosa Receiving Vitamin A.” Archives of Ophthalmology 128 (2010): 403-411.
Lefton, Jennifer. “Lutein: Uses, Side Effects, Dosage, & More.” Verywell Health, 28 May 2023, www.verywellhealth.com/can-lutein-supplements-protect-your-eyes-89060. Accessed 28 Aug. 2023.
Olmedilla, B., et al. “Lutein, but Not Alpha-Tocopherol, Supplementation Improves Visual Function in Patients with Age-Related Cataracts.” Nutrition 19 (2003): 21-24.
Satia, J. A., et al. “Long-Term Use of Beta-Carotene, Retinol, Lycopene, and Lutein Supplements and Lung Cancer Risk.” American Journal of Epidemiology 169 (2009): 815-828.
Shao, A., and J. N. Hathcock. “Risk Assessment for the Carotenoids Lutein and Lycopene.” Regulatory Toxicology and Pharmacology 45 (2006): 289-298.
Rosenthal, J. M., et al. “Dose-Ranging Study of Lutein Supplementation in Persons Aged Sixty Years or Older.” Investigative Ophthalmology and Visual Science 47 (2006): 5227-5233.
Warwick, Kathy W., and Debra Rose Wilson. “Health Benefits of Lutein and Top Food Sources.” Healthline, 26 Aug. 2021, www.healthline.com/nutrition/lutein. Accessed 28 Aug. 2023.