Tuesday, November 13, 2012

Lutein and Zeaxanthin - nutrients for eye health




Cataracts and age-related macular degeneration (AMD) are the leading causes of visual impairment and acquired blindness in North America and they negatively impact the quality of life for millions of people. In fact, people with AMD are among the leading users of the low vision clinic at Vision Source Vancouver Optometrists.

Approximately 1 million Canadians suffer from early signs of AMD and tens of thousands have significant and permanent vision loss from late-stage AMD.

Cataract surgery is the most  common surgical procedure performed in Canada.  That costs taxpayers tens of millions of dollars and poses a health risk for patients as well.  While most cataract surgeries go smoothly, there are risks and patients can be negatively impacted by cataract surgery (justly like any other surgery). It has been estimated that if the progression of cataracts could be delayed by 10 years, the number of cataract extraction surgeries per year would be reduced by 45 percent.

The severity and irreversibility of cataracts and AMD have motivated scientists to find ways to postpone or delay the progression of these diseases. Nutrition is one promising way of protecting the eyes from these diseases.  As an eye doctor with a degree in human, Dr. M.K. Randhawa is in a unique position to advise patients on how nutrition, supplements and diet can improve their chances of fighting diseases like AMD and cataracts. 



Nutrition that prevents disease


Research has shown that lutein (pronounced loo-teen) and zeaxanthin (pronounced zee-uhzan-thin) may protect against cataracts and AMD.   Lutein and zeaxanthin are antioxidents that are part of a class of nutrients known as carotenoids.  They are the only carotenoids located in the eye.


Research on Lutein and Zeaxanthin and AMD


One of the first large studies on carotenoids is the Eye Disease Case Control Study, in which diet was compared to the risk for developing AMD. Results found a significantly lower risk for developing the disease in people with high amounts of lutein+zeaxanthin in their blood. Also, those people eating a diet with the most lutein+zeaxanthin (as much as 5.8 milligrams (mg) per day) had a significantly lower risk for AMD than those whose diet contained the least amount (as low as 1.2 mg per day). Dietary studies confirmed the association between frequent consumption of spinach or collard greens, particularly good sources of lutein and zeaxanthin, and lower AMD risk.

Similar results were found in a recent analysis of a national dietary study called the Third National Health and Nutrition Examination Survey or NHANES III. This analysis also showed that consuming 6 mg per day of lutein+zeaxanthin was associated with reduced risk for developing AMD.


Research on Lutein and Zeaxanthin and Cataracts


Lutein and zeaxanthin intake and its relationship to risk of cataracts has been examined in four recent studies:

  1. The Nurses' Health Study found that consuming high amounts of lutein+zeaxanthin reduced the need for cataract surgery. Intake among this group was approximately 6 mg per day.
  2. The Health Professional's Follow-Up Study also found that high amounts of lutein+zeaxanthin (6.9 mg per day) lowered the need for cataract surgery.
  3. The five-year follow-up to the Beaver Dam Eye Study showed that people who got the most lutein+zeaxanthin had a much lower risk for developing new cataracts than people had the least amounts.
  4. A study of 372 men and women aged 66-75 in England found that the risk for specific type of cataracts was the lowest in people with the highest amount of lutein in their blood. 

What does it all mean?


Given that the scientific research suggests that increased lutein+zeaxanthin in the diet lowers the risk of cataracts and AMD, it is a good idea for most people to try to get higher amounts of these nutrients from their dient, through supplementation or a combination of both.

Eating five servings of fruits and vegetables each day can provide about 5 to 6 mg of carotenoids, including lutein and zeaxanthin if you give some thought to your food choices and choose fruits and vegetables that are high in these nutrients.

The problem is that most people in North America do not eat five servings of fruits and vegetables each day.  While the studies recommend that you consume 6 milligrams or more of lutein and zeaxanthin, the average intake of lutein and zeaxanthin is approximately 2 mg per day. For people who have trouble eating the recommend  amount of lutein and zeaxanthin, vitamin supplements are available.  Ask your eye doctor to recommend a trustworth, clinically proven formulation.


Food Sources of Lutein and zeaxanthin 


Dark green leafy vegetables are the primary source of lutein and zeaxanthin, but they are also present in lesser amounts in other colorful fruits and vegetables, such as broccoli, orange peppers, corn, peas, persimmons and tangerines.

Good Food Sources of Lutein and Zeaxanthin (mg/serving)


Food/Serving
(1 cup)
Lutein and
Zeaxanthin
LuteinZeaxanthin
Kale
20.5 - 26.5*-1.1 - 2.2*
Collard greens
15.3-5.1
Spinach
3.6 - 12.6*1.7 - 13.3*0.5 - 5.9*
Turnip greens
12.1-0.4
Broccoli
2.1 - 3.5*1.4 - 1.6*-
Corn, yellow
1.4 - 3.00.60.9
Peas, green
2.32.2-
Orange pepper
--1.7
Persimmons
1.4-0.8
Tangerine
0.5-0.2
*depending on variety and preparation