Recent studies have found that a diet rich in vitamin A can cause a loss in bone mineral density
and increase one’s risk for hip fracture. According to a group of Scandinavian
scientists led by Karl Michaelsson, even the amount of Vitamin A in a multivitamin supplement can significantly increase one’s
risk (Melhus et al, 1998). “What does this matter to me?” you ask. “I’m just a college student, I don’t take multivitamins. I’m lucky if I can find a piece of cold pizza and a Dr. Pepper for breakfast.” Well, you may not have an abnormal amount of vitamin A in your diet, but your beloved Duke basketball team
probably does. To support their conditioning regimens and long practice sessions,
our star basketball players need diets high in protein and vitamins. Little do
they know, they could be putting themselves at risk for future injury.
In addition to those who take vitamin supplements, people with diets consisting of large amounts
of meat, eggs or fish consume large amounts of vitamin A. The Food and Drug Administration’s
Recommended Daily Allowance of vitamin A is 1 mg and the U.S. Institute of Medicine recommends no more than 3.3 mg per day
(Seppa 2003). Studies have shown that the 1.6 mg contained in many multivitamins
alone can put men at a higher risk for bone fracture than men with average amounts of vitamin A in their diet (Seppa, 2003). This increased risk of injury due to a supplement designed to be a health benefit
should concern anyone who takes multivitamins.
Swedish orthopedic surgeon Karl Michaëlsson and his colleagues conducted two separate scientific
studies that have suggested an association between vitamin A intake and bone fracture.
The first study used 175 women aged 28 to 75 as subjects. These subjects’
vitamin A intakes were found through four weeklong diet surveys. Bone mineral
density comparisons were made between women of similar age with considerations made for height and weight. This study concluded that high intake of vitamin A led to a higher rate of bone mineral density decrease
and bone fracture (Melhus et al, 1998).
A more recent study by this same group involved a much larger subject group. 2322 men with an approximate age of 50 years were divided into five groups, based on the amount of vitamin
A in their blood. In the 30 years following the initial testing, 266 men had
some type of bone fracture. Michaëlsson and his colleagues found that men in
the group with the highest blood concentration of Vitamin A were almost twice as likely as the men in the middle group to
have broken a bone, especially the hip. The middle group represented individuals
with an average amount of vitamin A in their diets. Compared with the middle
group, members in the highest group showed a 1.66 times greater chance of breaking any bone.
Their risk for breaking the hip was 2.47 times greater than that of the middle group (Lipps, 2003). This evidence is striking, showing that a full fifth of the population in this study had enough vitamin
A in their diet to double their risk of breaking a bone.
Michaëlsson claims the safe daily upper limit of 3.3 mg given by the U.S. Institute of Medicine should
be lowered (Seppa, 2003). Though a normal amount of vitamin A in one’s
diet (average for Americans is just under 1 mg daily) is important for vision and healthy skin (Lipps, 2003), his results
suggest that men who consume 1.6 mg daily show a significant increase in risk of bone fracture (Seppa, 2003).
So next time you see Dahntay standing outside Cameron polishing off a cool glass of Vitamin A &
D fortified 1% milk after practice or Casey eating a quick roast beef sandwich to push him through one of his four day a week
weightlifting sessions, consider grabbing that food right out of their hands. It’s
for their own good, after all.
References
Lipps, Paul. “Hypervitaminosis A and Fractures” New England Journal of Medicine.
Jan. 23, 2003. Vol. 348; No. 4. pp347-349. Accessed at http://gateway2.ovid.com/ovidweb.cgi
Melhus, Hakan, MD; Michaëlsson,
Karl, MD; Kindmark, Andreas, MD;
Bergström, Reinhold, PhD;
Holmberg Lars, MD; Mallmin, Hans, MD; Wolk, Alicja, PhD; and Ljunghall, Sverker, MD.
“Excessive Dietary Intake of Vitamin A Is Associated with Reduced “Bone
Mineral Density and Increased Risk for Hip Fracture” Annals of Internal Medicine. 1998.
Nov. 15, 1998. Vol. 129:770-778. http://www.acponline.org/journals/annals/15nov98/vitamina.htm (stable link)
Seppa, Nathan. “Too Much of
a Good Thing: Excess vitamin A may hike bone-fracture
rate” Science News Online. Week of Jan. 25, 2003. Vol 163; No. 4.
http://www.sciencenews.org/20030125/fob4.asp (stable link)
