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Protecting vision


QUITE a number of conditions can lead to deteriorating vision, including near-sightedness, far-sightedness, presbyopia, astigmatism, glaucoma, aged-related macular degeneration and cataracts. As we age, we become increasingly susceptible to many of these problems.

However, contrary to popular belief, some of these conditions can be prevented.

Did you know that cataracts and aged-related macular degeneration (AMD) are the leading causes of visual impairment and acquired blindness in the world?

According to the World Health Organization (WHO), cataract is responsible for 51% of world blindness, which represents about 20 million people.

Closer to home, did you know cataracts contribute to 39% of blindness in Malaysia?

AMD is another eye condition that can cause blindness. Studies have found that approximately 10 million Americans suffer from early signs of AMD and almost half a million people have significant visual loss from late-stage AMD.

The twin threats of cataracts and AMD have created interest in ways to either prevent or delay their progression.

Nutrition is one promising means of protecting the eyes from such problems.

Of the more than 600 plant pigments called carotenoids found in nature, only two carotenoids - Zeaxanthin and Lutein - selectively accumulate in the retina, macula and lens.

Zeaxanthin is the dominant component in the centre of the macula, which is the most critical area for central vision, while Lutein dominates at the outer edges.

Results from the Eye Disease Case Control Study as well as a dietary study conducted by the Third National Examination Survey (NHANES III) have suggested a minimum of 6-10mg per day of Lutein and Zeaxanthin to reduce the risk of AMD.

In addition, a five-year follow-up to the Beaver Dam Eye Study funded by the US National Eye Institute showed that people who got the most Lutein and Zeaxanthin had a much lower risk for developing new cataracts than people who had the least amounts.

In a similar study, Brown and collaborators studied the association between carotenoids (alpha-carotene, beta-carotene, Lutein, lycopene, beta-cryptoxanthin and lycopene) and vitamin A intake on cataracts extraction in 36,344 male health professionals from 45 to 75 years old. Researchers found that men with the highest consumption of Lutein and Zeaxanthin had a 19% lower risk of cataract extraction compared to men with the lowest consumption.

Furthermore, foods high in Lutein and Zeaxanthin, such as green leafy vegetables like broccoli and colourful vegetables like red peppers and sweet corn, had the strongest association with a lower risk of cataracts.

Given the positive connection between Lutein and Zeaxanthin and age-related eye diseases, it seems prudent for people to obtain higher amounts of these nutrients from the diet or via nutritional supplements.

Lutein and Zeaxanthin are found together in many food sources. Dark green leafy vegetables such as spinach are the primary source of Lutein and Zeaxanthin, but you'd have to eat over two bowls of raw spinach every day to get the recommended daily dose of 6mg Lutein.

Various studies have found that a typical intake of Zeaxanthin is less than 0.5mg a day. The adequate amount, however, for the body to reap the benefits of Zeaxanthin is between 2mg and 4mg. The easier way to ensure you get enough Zeaxanthin is to top it up with nutritional supplements.

If Zeaxanthin is so essential for eye health, why do most eye supplements have such measly amounts - in the micrograms (mcg)? The reason is simple. Zeaxanthin is very expensive due to its scarcity in nature. It is 20 times less abundant than Lutein in our diet.

If you look at most eye supplement label facts, you would find that most eye formulas contain only about 6mg of Lutein and 320mcg of Zeaxanthin, which is extracted simultaneously with the Lutein. These minute amounts of Zeaxanthin, according to studies, will not allow you to reap its potential eye health benefits.

For convenience of dosing, it would make sense to look for a two-in-one formula with concentrated Lutein and Zeaxanthin to protect the eyes from AMD and cataracts, as well as promote sharper vision and healthier eyes.

Try looking for an eye supplement with standardised marigold flower (Tagates erecta) containing a minimum of 15% Lutein esters and 40% Zeaxanthin to ensure every capsule contains the exact amount of active ingredients as stated on the label.

Alternatively, select an eye supplement that contains at least 6mg (preferably 10mg) of standardised Lutein and at least 4-5mg of Zeaxanthin per dose for expected benefits.

You can always ask your pharmacist to choose the right eye supplement for you.

References:
  1. American Optometric Association (AOA).
  2. National Eye Survey 1996, Malaysia.
  3. US National Eye Institute (NEI).
  4. World Health Organisation (WHO).



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