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by Jonathan Kirchner

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 MichaŽlsson 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.  MichaŽlsson 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.

MichaŽlsson 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; MichaŽlsson, Karl, MD; Kindmark, Andreas, MD;

BergstrŲm, 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)

 



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