By Nicole Crane, B.S., NTP
Every season, a new superfood takes hold over the minds and plates of foodies everywhere, and the last several years, there has certainly been a craze over kale. This powerhouse leafy green is one of the most nutrient dense veggies you can eat, with 20 different nutrients and good amounts of 45 different antioxidant flavinols. (i) Yet the average American only eats about 2-3 cups of kale over the course of the entire year. This may indicate that a few people are eating a lot but most are eating none. Spinach consumption is far better, and in 2014, this leafy green was the 11th most popular vegetable of 50 and the average consumption of fresh spinach was 1.7 lbs, or about 17 cups for the year. (ii) These leafy greens are powerhouse of nutrition, rich in Omega-3 fats, beta carotene, potassium, magnesium, iron, most of the B vitamins, vitamin C and K1. What is unique to vegetables like kale and spinach are two very special carotenoids (antioxidants) called lutein and zeaxanthin. Cooking these veggies increases the bioavailability of lutein and zeaxanthin by a remarkable five times! There are few nutrients that are more beneficial for the eyes, but the people who need these carotenoids most (older adults) are the same population who consume them the least. Luckily, a simple supplement means you can reap the benefits of lutein and zeaxanthin without transforming your diet.
Of the 600 or so carotenoids researchers have discovered so far, only twenty can even make it into the eye, but only two get deposited into a very important area of the eye called the retina. Those two carotenoids that are most essential to eye health are lutein and zeaxanthin. There are about 10 million Americans living with macular degenerationiii, another 22 million with cataracts (iv) and 4 million people who have a visual impairment. (v) Despite so many people at risk for blindness, lutein and zeaxanthin have yet to get the mainstream attention that they deserve. Lutein and zeaxanthin (pronounced “loo-teen” and zee-uh-zan-thin) are both carotenoids, in the same family as beta-carotene, but far more powerful. Their most important job is to act as build in sunglasses for the eye, if you have enough. These special eye carotenoids filter out harmful high energy blue wavelengths of light and generally protect the cells of the eye from damage. Cell phones, television and computer screens all emit blue light, so it is more important now that ever to protect the retina. The retina is the innermost of three layers in the eye and covers the back of the eyeball. The retina is highly light sensitive and when light passes into the cornea and lens of the eye and hits the retina, nerve impulses to the brain are triggered. This produces an image in the brain of the local environment, what you see and perceive. Within the center of the retina is a specialized, very sensitive area called the macula that is responsible for our central vision, what we look at directly. In the center of the macula is a small depression called the fovea which is responsible for our sharp central vision. It is this area that is essential to activities where visual details are important, like reading or driving. As a fetus is developing, the retina and the optic nerve actually start out as part of the brain and central nervous system. (vi) Our eyes are simply the most visible part of our brain, and need to be nourished well for optimal function.
As medical technology continues to advance, there are certain biomarkers that can be used to predict the risk of certain diseases and evaluate body system functionality. One of the best ways to assess eye health is measuring MPOD ( macular pigment optical density). MPOD measures the quantity of lutein and zeaxanthin in the macular region of the retina. MPOD is an effective biomarker for not only predicting eye disease but also for assessing visual acuity. This means that when we have optimal levels of pigments from carotenoids like lutein and zeaxanthin in the retina, we have healthy eyes and healthy sight. By supporting the health of the retina and the macula, lutein and zeaxanthin play a significant role in warding off diseases like age-related macular degeneration and even cataracts. (vii) The human body cannot make the lutein and zeaxanthin it needs, which is the reason why colorful vegetables are essential to good nutrition, especially for the eyes and brain. If you aren’t getting enough leafy greens and other colorful veggies, it is ideal to supplement with these essential nutrients. The average American is getting just 10% of the amount of lutein and zeaxanthin (about 2 mg combined) that is required by the eye to stay healthy for a lifetime.viii The research shows how effective and essential these under consumed nutrients are for supporting vision and eye health. An early study showed that just 6 mg of lutein per day has been shown to reduce the risk of age related macular degeneration by 43%. (ix) Macular degeneration is the leading cause for blindness among the elderly (in the western world) and there are few nutrients more protective than lutein and zeaxanthin. A recent review of the research, published in 2009, showed that not only do lutein and zeaxanthin successfully increase macular pigment optical density, but these carotenoids reduce the development and can even halt the progression of age related macular degenration.x Research using natural forms of lutein and zeaxanthin that examines the role they play in healthy vision have had very positive outcomes.
Good nutrition is essential for both preventing and addressing the buildup of cataracts. Cataracts are the slow clouding of the lens of the eye, and are the cause of half the cases of blindness worldwide. While there are many factors that contribute to cataracts, a high intake of sugar and a low intake of carotenoids and antioxidants from fruits and vegetables tend to be major causes that are often overlooked. As high levels of sugar in the blood cause advanced glycation end products (AGEs) to build up, and especially without the protection of antioxidants, the proteins in the lens of the eye and the ion transporters (that bring energy and electrolytes and other materials into the cells) become damaged.xi These proteins cross link and cause the lens to become cloudy, even in those who are not diabetic. It seems that lutein as an antioxidant, can even aid in improving vision in those with age related cataracts. In a two year long study of 17 participants who received either 15 mg of lutein, 100 mg of tocopherol (vitamin E) or a placebo, only the lutein group had a significant improvement in vision, including a reduction in glare and an improved visual acuity, the sharpness of vision, assessed by the lettered eye chart. The tocopherol group maintained their current vision, while the placebo group had a decrease in visual performance.xii Lutein is a powerful antioxidant, like Vitamin E, but the ability of lutein to cross the blood retinal barrier into the eye is what makes lutein an irreplaceable nutrient for the eyes.
Our eyes are very fragile, but they are also resilient. Given the right nutrients, especially those who can cross into the eye, like lutein and zeaxanthin, the eyes can be supported in the way that nature intended.
The next time you look someone right in the eye, remember that you are actually looking at their brain. Having a healthy amount of golden colored lutein and zeaxanthin protect the eyes and help them function optimally well into your golden years. Do not let your diet keep you from getting these essential eye carotenoids and consider a simple supplement of lutein and zeaxanthin that gives your eyes exactly what they need today. You can work on increasing your intake of kale another day.
vii Mozaffarieh, Maneli, Stefan Sacu, and Andreas Wedrich. "The role of the carotenoids, lutein and zeaxanthin, in protecting against age-related macular degeneration: a review based on controversial evidence." Nutr J 2.1 (2003): 20.
viii Abdel-Aal, El-Sayed M., et al. "Dietary sources of lutein and zeaxanthin carotenoids and their role in eye health." Nutrients 5.4 (2013): 1169-1185.
ix Johanna M. Seddon et al, 1994, Journal of American Medical Association 272:1413-20.
x Carpentier, Shannon, Maria Knaus, and Miyoung Suh. "Associations between lutein, zeaxanthin, and age-related macular degeneration: an overview." Critical reviews in food science and nutrition 49.4 (2009): 313-326.
xi Gul, Anjuman, et al. "Advanced glycation end products in senile diabetic and nondiabetic patients with cataract." Journal of diabetes and its complications 23.5 (2009): 343-348.
xii Olmedilla, B., et al. "Lutein, but not α-tocopherol, supplementation improves visual function in patients with age-related cataracts: a 2-y double-blind, placebo-controlled pilot study." Nutrition 19.1 (2003): 21-24.
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