The
eyes are not just a window to the soul; they may be a surprisingly reliable
guide to how healthily you eat. While there is no correlation between refusing
to eat your carrots and actual night vision, nutrition and optical health are
closely linked, with scientists currently looking at the role played by
vitamins and minerals in the prevention of eye diseases, such as age-related
macular degeneration (AMD) and cataracts.
That a
link exists has long been understood: the eye condition xerophthalmia, a common
cause of blindness in developing countries, is known to be caused by a lack of
vitamin A, which is found in sources such as meat and fresh vegetables.
In
fact, vitamins and minerals are crucial to eye health, as they are constantly
required to help ward off damage caused by UV light rays. A healthy blood
supply is necessary to supply nutrients and oxygen to the eye. So, conditions
such as high cholesterol, which clog arteries elsewhere in the body, are also
important in the eye region.
Professor
Ian Grierson, head of ophthalmology at the University of Liverpool, is one of
the pioneers in nutritional research. He says: “It is quite difficult to show
real benefit to an individual, that by changing their diet it will benefit
their sight – the studies needed would be too big and expensive.” However,
Prof Grierson approaches the idea from a different angle: “My interest is in
AMD. For a lot of sufferers of this condition, there are no treatments at all,
so it occurred to me to look at the risk factors for the disease instead, with
a view to prevention.
“These
risk factors don’t just make you more prone to developing AMD, but to it
becoming more severe if you do have it.” He explains: “AMD is on the march
as we are all living longer [according to the Macular Disease Society, AMD
affects 30 million people worldwide, half a million of them in the UK], and it
is undoubtedly lifestyle related.
“The
main risk factors are gender (females are more susceptible), your age (the
older you are, the more likely you are to develop it), whether you smoke or
have done, your weight, and your diet.”
Problems
occur because the macula (the centre of the retina) works so hard to give us
colour and fine vision, it also produces by-products called free radicals that
damage the cells.
Prof
Grierson explains: “It is like a factory in there. The antioxidants which we
get from food protect our cells from these toxins by neutralising them, but if
the diet is deficient in the right ones there is no safety net, and the macula
suffers permanent damage. “We really need to increase levels of the right
antioxidants in patients and the general population.”
So,
which are the nutrients that we need to top up our diets with? According to
Prof Grierson, while research suggests that vitamins A, C, E and zinc can help
keep the eye healthy, it is carotenoids, the pigments that occur naturally in
plants and algae, which offer the most precise way of targeting the damage that
causes sight loss.
In
particular, the carotenoids lutein and zeaxanthin seem to act directly to
absorb damaging blue and near-ultraviolet light, in order to protect the
macula. “I call them the macula’s sunglasses,” says Prof Grierson. “Any plant
or vegetable which is yellow or orange in colour contains them.” They are also
found in abundance in green vegetables such as kale and spinach.
We
should be eating 6mg of lutein a day, but the average consumption is 2mg.
“That’s way too low,” says the professor. “In the Second World War, our average
intake was 4-5mg and we weren’t even trying.”
But you
can’t just eat vegetables alone: the lutein needs fat to be absorbed, so you
are allowed a little butter on your garden peas. In fact, a 2005 study at the
Ohio State University, Columbus, found that carotenoids absorption was enhanced
by the consumption of avocado oil and fruit.
So,
should you take one of the many supplements on the market to help maintain
healthy eyes? Prof Grierson says: “I’d prefer that you thought about diet and
then take a supplement rather than jump straight to the tablet. But when I go
to the US on lecture tours, I know I won’t eat as healthily as at home, so I
take a supplement with me to make sure.
Even if
you have a good diet, there will be times when you can’t eat perfectly or won’t
have control over your diet.”
And, if
you choose a supplement, “Use your common sense,” he advises. “Creating a
vitamin supplement is an expensive business, so don’t look for or expect a
bargain. Find one that gives you 6mg of lutein a day.”
Other
nutrients have been found to be potentially beneficial, such as the red pigment
lycopene (found in fresh tomatoes, tomato sauces and water melons), which has
shown promise in studies on the prevention of prostate cancer.
Nutritionist
Ian Marber adds: “Night vision may be improved with vitamin A found in fresh
fruits and vegetables as they contain a variety of carotenoids, but supplements
may not be necessary. There is some evidence that suggests that vitamin A
supplementation can increase the risk of some forms of cancer, and so getting
it from food is advisable.”
If you
do want to get more vegetables into your diet, greengrocer and author Gregg
Wallace, co-presenter of BBC1’s Masterchef, suggests you always buy as fresh as
possible, and try to keep nutrients and taste intact. Remember this is or was a
living thing; don’t stick it in the fridge, keep it in the sunshine.”
When
you’re cooking, “Don’t over-peel veg,” he advises. “In root vegetables, such as
carrots, the nutrients are just under the skin, so just give them a gentle
scrape.”
Potatoes
should be cooked in their skins to preserve nutrients, “otherwise all the
vitamins just leach into the cooking water which you throw away. Peel them
afterwards using a tea towel to hold them.” He points out that frozen veg
is not disastrous, either, as it is often frozen so fast after picking. But he
says that we should try to eat seasonally (bar fruit and veg which won’t grow
here, such as bananas) if possible. “At the moment I’m eating lots of pears (I
love the honeyed juice) and brassicas, such as cabbage and kale. I can feel
them doing me good.”
Don’t Forget Your Eye Test
Everyone
should take an eye test at least every two years, says London-based
ophthalmologist David Allamby, and not just to watch for changes in their
prescription. “We need to check for glaucoma, an eye disease in which the
optic nerve suffers damage, caused by increased pressure of the fluid in the
eye. it is often called a ‘silent’ disease, as it can cause permanent damage to
your sight before you realise anything is wrong.
“With
other blinding conditions, such as macular disease (when the cells in the
retina degenerate causing loss of vision) or cataracts (clouding of the lens),
you will probably notice a difference yourself, but the sooner you come in, the
better.
“With
cataracts, we can operate to remove them; and even with macular degeneration,
we may be able to prevent spread (in some cases), and give you advice on how to
cope.
“If you
are concerned about changes to your vision, we can advise on surgery or lenses.
short sight tends to develop in the teens or 20s; and long sight in middle age
— 40s-60s — when you’ll need reading glasses. “New laser techniques, such
as Z-Lasik, can help even that group, and offer ‘blended’ vision, which may
leave you seeing better than ever before.”
http://www.telegraph.co.uk/health/wellbeing/8390367/Can-you-eat-your-way-to-better-sight.html Total Health Fitness
http://www.telegraph.co.uk/health/wellbeing/8390367/Can-you-eat-your-way-to-better-sight.html Total Health Fitness