- NEW YORK (Reuters
Health) - A strict vegan diet -- defined as avoiding the consumption of
all animal products -- may lead to deficiency of important vitamins that
are critical to eyesight, warn researchers. They advise vegans to take
- The warning comes from the case of a French patient who
lost most of his eyesight as the result of following a strict vegan diet,
without taking vitamins, leading to B12 deficiency. This vitamin is important
in maintaining the health of nerves, including the optic nerve that transmits
signals from the eye to the brain.
- In a letter published in the March 23rd issue of The
New England Journal of Medicine, researchers from the Groupe Hospitalier
Pitie-Salpetriere in Paris, France, describe a case involving a 33-year-old
patient who had been a vegan since the age of 20. His diet contained no
eggs, dairy products, fish or animal protein. He had no history of alcohol
abuse and did not smoke cigarettes, and he was not taking any vitamin supplements.
- At the time of examination, the patient was diagnosed
with severe optic neuropathy in both eyes, with poor vision of 20/400 each
eye. With no evidence of an infectious cause for this severe loss of vision,
the researchers took blood samples to check for vitamin deficiencies. They
found that his levels of B1, B12, A, C, D, E, zinc, and selenium were all
measurably below normal.
- The researchers treated the patient by giving him intramuscular
and oral multivitamins until his blood levels normalized, but his eyesight
did not recover. They concluded that the nutritional deficiencies in the
patient's vegan diet -- particularly the insufficient amount of vitamin
B12 he had been absorbing -- may be the cause for the deterioration in
the optic nerves and the resulting blindness. They note that such damage
to the optic nerves may prove to be irreversible.
- ``Vitamin supplementation is essential in persons who
adhere to a strict vegetarian diet, especially because vitamin deficiencies
may cause severe, irreversible optic (nerve damage),'' the team concludes.
- In an interview with Reuters Health, Chris Rosenbloom
-- a nutritionist and spokesperson for the American Dietetic Association
(ADA) -- was careful to point out the distinction between a vegetarian
and a vegan. ``This study might scare people off from a vegetarian lifestyle,
and being a vegetarian is very different from being a vegan.''
- She noted that a vegan diet can be very restrictive in
that the total lack of animal products in the diet goes well beyond the
choices some vegetarians make to simply avoid red meat or whole milk. ``It's
important that someone who's going to undertake a vegan diet get sound
nutritional advice before they undertake such a regimen,'' she said. ``Consulting
a registered dietitian is one option. Also the ADA has a book on the subject
called 'Being Vegetarian', which is helpful. Finding these kinds of resources
is very important.''
- She cautioned, however, that anyone concerned about monitoring
their eating habits must understand that not all the available books and
magazines discussing diet options are credible. ``Sometimes when people
undertake something that radical they might not have all the resources
at their disposal,'' she noted. ``And there are a lot of people that give
advice that might not be experts on the subject.''
- For those who do choose to begin a vegan regimen, Rosenbloom
emphasized that such a diet does not necessarily lead to nutritional deficiencies.
``There's no reason one has to be a vegan, but a lot of people do choose
that path for environmental or ecological reasons and it can be very helpful.
But you've got to do it the right way. Just giving up animal products isn't
going to lead to good health -- you have to learn what you need to.''
- ``I'm sure this is probably an extreme case,'' she added,
''but a case study does point out to people that these things can happen,
so you have to be vigilant when you take on this program and make sure
you're well informed.'' SOURCE: The New England Journal Of Medicine 2000;342:897-898.
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