Over 500 million people in the world have dementia, including eight in every 100 people over the age of 65 in Taiwan. The National Health Research Institutes says it has discovered that taking Vitamin D3 does not lower the risk of dementia like everyone thinks and seniors that take Vitamin D3 for more than 146 days out of the year are at higher risk of developing dementia.
After the National Health Research Institutes' Institute of Molecular and Genomic Medicine analyzed data from tests involving mice with Alzheimer's disease and the National Health Insurance Research Database, it concluded that seniors that take Vitamin D3 more than 146 days out of the year are 1.8 times more likely to develop dementia and 2.17 times more likely to die than seniors that don't.
Chuang Chih-li, Division Head, National Health Research Institutes: “We observed a very interesting phenomenon. The more Vitamin D you take, the higher your risk of dementia. This goes against what everyone believes. Supplementing with Vitamin D has no virtually no effect on people with diseases, but most people still take Vitamin D.”
According to the research team, people that take high-dose Vitamin D three or more times a week may end up worse off. At the same time, the team says this isn't absolute and Vitamin D can help with development and bone density in younger age groups.
Chuang Chih-li, Division Head, National Health Research Institutes: “You only get a good result with it if you take it at the right time. If you take large amounts of it when you're already ill, it could have the opposite effect because it is not the cause of your illness.”
NHRI researchers say there is no clear link between Alzheimer's and Vitamin D3 deficiency and seniors should get more sun instead of supplementing with Vitamin D3 unless directed to do so by a doctor.
維生素D3在過去研究中顯示有助於促進腦部健康，不過國家衛生研究院分子與基因醫學研究所團隊，利用阿茲海默症小鼠的動物實驗和台灣健保資料庫的分析發現，年長者一年服用維生素D3超過146天，發生失智症的風險是沒有服用者的1.8倍；失智症患者長期服用維生素D3，死亡風險則增加2.17倍。
國家衛生研究院副所長莊志立表示：「我們看到一個很有趣的現象，就是維生素D吃越多的失智風險就越高，這個完全不是大家所想像的。補充維他命D似乎是對這個疾病本身幫助不大，可是多數人還在服用這個維生素D。」
如果以每周超過三天、且符合高劑量條件的方式補充維生素D3，反而可能有害健康。這項研究也顛覆了過往傳統觀念，不過研究團隊也強調並非全盤推翻，對小孩和年輕人而言，維生素D3仍然可以幫助發育及骨質。
國家衛生研究院副所長莊志立表示：「適當的時機用它，才會得到一個好的結果。當進入一個疾病的狀態的時候用它，因為它不是造成這個疾病的原因，所以大量用它的話恐怕造成反效果。」
失智症成為了高齡化社會最嚴重的危機之一，但仍沒有確切有效治療的藥物。學者指出，發生阿茲海默症的風險和缺乏維生素D3這兩者因果關係還不清楚，因此除非是醫生叮囑，否則建議可讓年長者用曬太陽的方式來補充維生素D。