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Mar⁄ Apr 2011
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Wellness
Enough or too much?
When it comes to vitamins and minerals, moderation is key. By Thava Rani
vitamin A can lead to serious health risks,
including damage to the liver.
This is because the body absorbs some
vitamins – such as A and E – and minerals
only slowly. Taking more than the daily
recommended levels can lead to a steady
buildup of these substances in the liver
and fatty tissues which increase the risk
of amounts reaching toxic levels.
Water-soluble vitamin C is flushed out
of the body when too much is consumed.
“Even so,” said Mr Johnathan Diong,
Pharmacist, Department of Pharmacy,
Singapore General Hospital, “they can be
harmful in a normal healthy individual
when taken at very high doses over a
long period.”
Vitamins and minerals play different
roles in the proper growth and functioning of the body.
Vitamin C, present in fruits and vegetables, is a basic ingredient for beauty and
is an agent for promoting wound healing,
Mr Diong said. Someone who doesn’t get
enough vitamin C may suffer from bleeding gums and frequent bruising.
Vitamins C and E – found in nuts
and oils, green leafy and root vegetables
– boost the body’s natural antioxidants to
help mop up excess free radicals which
can hasten ageing and cause cancer. Calcium and phosphate are crucial for bone
formation, while iron is essential for the
production of red blood cells.
Vitamins and minerals are present
naturally in the foods we eat. Thus, eating
a balanced meal with a
wide variety of fresh
meat, grains and vegetables ought to supply
the body with all the
vitamins and minerals
it needs. But long hours
at work and the convenience of takeout meals
mean more people
are not get-
Iron
Essential for boosting the
body’s immune system and an
important component of
many enzymes. Also functions
as an antioxidant
US RDA:
8mg (men), 18mg (women)
Food sources:
Red meat such as beef, oysters,
shrimp, tuna, lentils, kidney
beans and cashew nuts
Excessive intake:
Slight excess causes
constipation. Higher excesses
may result in gastric mucosal
ulceration, and increase
the likelihood of
multi-organ damage
Overdose symptoms:
Vomiting and diarrhoea
Zinc
Essential for boosting
the body’s immune
system and an
important component
of many enzymes.
Also functions as an
antioxidant
US RDA:
11mg (men), 8mg (women)
Food sources:
Red meat such as beef,
oysters, milk, baked beans
and chickpeas
Excessive intake:
May result in
copper deficiency
Overdose symptoms:
Nausea and vomiting
Vitamin A
Essential for healthy
skin, retinas and
mucous membranes
US RDA:
700mcg (men),
900mcg (women)
Food sources:
Yellow and orange
vegetables like carrots and
pumpkins, spinach, sweet
potatoes and cod liver oil
Excessive intake:
May be harmful to skin and
bones, causing weakness
and brittleness
Overdose symptoms:
Tiredness, decreased
appetite, vomiting, joint
soreness, drying and
cracking of lips and skin,
hair loss and yellowing
of the skin
Mr Johnathan
Diong, Pharmacist,
Department
of Pharmacy,
Singapore General
Hospital, advocates
a balanced meal to
meet daily vitamin
requirements.
Calcium
Crucial for maintaining
a normal heartbeat
and for normal
functioning of nerves
and muscles. Acts as
a building block for bones
US RDA:
1,000mg
Food sources:
Dairy products such as
milk, cheese and yoghurt,
vegetables like broccoli and
Chinese cabbage
Excessive intake:
May impair kidney function
and decrease absorption
of other minerals
Overdose symptoms:
Nausea, vomiting,
loss of appetite and
increased urination
PHOTO: Photolibrary
Vitamins A, C and E are known
as antioxidants that can help
prevent cancer. But taking
excessive amounts of vitamin C
can cause diarrhoea, or worse,
kidney stones. Similarly, too much
ting their full recommended daily dose of
vitamins and minerals.
“With our busy work
schedules, I wonder how
many of us are able to
meet Health Sciences
Authority’s recommendation to consume two
portions each of fresh
fruits and vegetables a
day,” said Mr Diong.
In such cases, taking
a daily multivitamin can help ensure
nutritional requirements are met. The
multivitamin tablet contains sufficient
vitamins to prevent and correct nutrient deficiency, but does not provide the
full daily requirement. For instance,
it does not contain sufficient calcium
to meet the US recommended daily
allowance of 1,000mg of elemental cal-
Vitamin C
Helps form strong collagen
fibres which are essential
for the strength and
integrity of connective
tissue beneath the skin in
the blood vessels, bones,
tendons and ligaments. Also
acts as an antioxidant
US RDA:
90mg (men), 75mg (women)
Food sources:
Fruits such as oranges,
grapefruits and strawberries,
vegetables like broccoli
and tomatoes
Excessive intake:
Increases the likelihood
of calcium oxalate kidney
stones and can deplete the
body of copper, another
essential nutrient
Overdose symptoms:
Diarrhoea, stomach cramps
and nausea
cium for an average adult.
But it has become popular for many people to
take a variety of vitamins
and minerals in the belief
that large amounts of supplements can help delay
ageing, prevent disease as
well as enhance mental or
physical abilities.
Although what is consumed may fall below the
upper limit of tolerance
for that particular mineral
or vitamin, problems arise
when vitamins and minerals are taken in excess over
a long period.
As with all good things,
moderation is the key to
maintaining a strong and
healthy body.