Government urged to raise levels for vital vitamin D HealthReport also warns about detrimental amounts of vitamin A
BY DAVID ZIZZO
Published: November 25, 2008
Decades ago, American children faced a dreaded daily routine to prevent rickets and promote overall health: swallowing cod liver oil.
"Before the 1930s, when milk began to be fortified with vitamin D in this country, it was very, very common that children would have been given cod liver oil as a source of vitamin D,” said Allen Knehans, professor of nutritional sciences at the University of Oklahoma Health Sciences Center.
A new study says those doses of cod liver oil can contain detrimental levels of vitamin A. ILLUSTRATION BY LIQUIDLIBRARY.COM
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However, a report issued this month by 16 experts said cod liver oil is not a good source of vital vitamin D because the oil also includes toxic levels of vitamin A.
"Americans continue to consume multivitamins and/or cod liver oil containing disproportionately small amounts of vitamin D but detrimental quantities of vitamin A,” the experts said in the report in the Annals of Otology, Rhinology & Laryngology. The high level of vitamin A in cod liver oil "will mask the benefit of adequate vitamin D nutrition,” it said.
Knehans, who was not involved in creating the report, said vitamin A is "clearly toxic” and that high doses over a long period could result in blurred vision, stupor, even coma. "It can be pretty serious.”
The report lauded many apparent benefits of vitamin D, from reduction of influenza and respiratory infections to increased immunity and even prevention of cancer, diabetes and chronic diseases. It also warned of dangers of vitamin D deficiency, including autism, asthma and autoimmune diabetes.
Diet alone cannot solve the problem, the scientists said.
They also said many multivitamins contain far too much vitamin A and far too little vitamin D. They called on federal officials to boost the recommended levels of vitamin D, saying "current official guidelines and limitations for vitamin D intakes are scientifically indefensible.”
Federal guidelines urge people to have a daily vitamin D intake of 200 IU for infants to 600 IU for those 71 and older.
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Vitamin D is produced naturally when skin is exposed to sunlight, although people with dark skin cannot produce as much this way. Because of worries over skin cancer, many people have reduced their exposure. A new report by 16 nutrition experts said "... vitamin D deficiency in childhood is now epidemic in Western populations, probably because of the advent of sun exposure protection in the 1980s.”
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