Wednesday, January 9, 2013

Can nutrition fight glare, increase contrast, help you see farther, and help you process visual information faster? Yes.

A field of kale.  Kale is very high in  lutein and zeaxanthin.
Much attention has been devoted lately to macular pigment (MP), which is composed of the  carotenoids lutein and zeaxanthin.  Macular pigment is found in a part of your eye called the retina.  In fact, it is found in high concentrations in a part of the retina called the macula.   People who have lots of lutein and zeaxanthin in their system have a much lower risk of developing eye diseases like cataracts and macular degeneration.  Those diseases can cause permanent vision loss and blindness.

The interesting thing is that, in addition to protecting you from very bad eye diseases, recent science has discovered that lutein and zeaxanthin have the following every-day vision benefits:
  • reduce glare discomfort and disability, 
  • shorten photostress recovery times, 
  • enhance chromatic contrast,
  • increase visual range (how far one can see in the distance),
  • lutein and zeaxanthin within the brain might also increase temporal processing speeds. 

The new research on lutein and zeaxanthin has clear implication for all those who desire optimal visual performance.  And who doesn't desire optimal visual performance?  However, the benefits of lutein and zeaxanthin will be greatest for those who place high demands on their visual system, such as athletes.  But ordinary people can benefit too.  For example increased contrast helps with night driving, reduced glare discomfort and disability helps when driving and whenever you are outdoors, increased visual rage is a benefit to golfers, drivers and people engaged in recreational activities such as hiking, sightseeing, etc.  

One recent study published in November 2012 in the American Journal of Clinical Nutrition examined the recent research into lutein and zeaxanthin and the way lutein and zeaxanthin supplementation could affect baseball players.   Here is a passage form the study (for the entire study see Billy R Hammond, Jr and Laura M Fletcher Influence of the dietary carotenoids lutein and zeaxanthin on visual performance: application to basebal lAm J Clin Nutr 2012 96: 1207S-1213S; First published online October 10, 2012.):
:   

In fact, recent data have shown that a number of visual abilities that would be relevant to athletic performance may be amenable to large improvements simply by focused changes in diet or through supplementation. For example, glare discomfort, glare disability, photostress recovery, chromatic contrast, visible range, and temporal processing speed are all likely to be important to baseball players. Some, if not all, of these visual capabilities can be enhanced by increased intake of the dietary carotenoids lutein and zeaxanthin. These dietary pigments are found throughout the tissues of the eye and brain and are strongly concentrated in the central macular portion of the retina [referred to as macular pigment (MP);]. It is possible that many baseball players have very low concentrations of these pigments because of their relatively poor diets, which typically do not include enough carotenoid-rich fruit and vegetables. A poor diet for baseball players would be consistent with the overall poor quality of the American diet in general (∼1–2 mg lutein and zeaxanthin/d; in comparison, a cup of spinach contains ∼10–12 mg lutein and zeaxanthin;). Hence, it is possible that some athletes might garner large improvements in performance by the relatively simple (and in fact healthy) expedient of increasing their intake of carotenoid-rich foods and/or supplementing purified forms of these antioxidant pigments.
Lutein and zeaxanthin are still thought of as nutrients for old people.  That is clearly not the best way to think about them.   Lutein and zeaxanthin have benefits for everyone, even (and perhaps the with greatest benefit) for athletes and others who depend on their vision to be at its best.

Citations:

Billy R Hammond, Jr and Laura M Fletcher
Influence of the dietary carotenoids lutein and zeaxanthin on visual performance: application to basebal lAm J Clin Nutr 2012 96: 1207S-1213S; First published online October 10, 2012.

Wooten BR, Hammond BR. Macular pigment: influences on visual acuity and visibility. Prog Retin Eye Res 2002;21:225–40.

Stringham JM, Fuld K, Wenzel AJ. Action spectrum for photophobia. J Opt Soc Am A Opt Image Sci Vis 2003;20:1852–8.
Stringham JM, Hammond BR. The glare hypothesis for macular pigment function. Optom Vis Sci 2007;84:859–64.

Stringham JM, Hammond BR. Macular pigment and visual performance under glare conditions. Optom Vis Sci 2008;85:82–8. 

Stringham JM, Garcia PV, Smith PA, McLin LN,
Foutch BK. Macular pigment and visual performance in glare: benefits for photostress recovery, disability glare, and visual discomfort. Invest Ophthalmol Vis Sci 2011;52:7406–15.

Renzi LM, Hammond BR. The effect of macular pigment on heterochromatic luminance contrast. Exp Eye Res 2010A;91:896–900.

Renzi LM, Hammond BR. The relation between the macular carotenoids, lutein and zeaxanthin, and temporal vision. Ophthalmic Physiol Opt 2010b;30:351–7. 


Image courtesy of worradmu / FreeDigitalPhotos.net