Hole In The Wall


Vitamin Dと骨の健康。


It’s long been known that bike riders are more susceptible to having weaker bones than people who do higher-impact sports like running or basketball. In one study, University of Oklahoma researchers performed bone scans on 32 male road cyclists between the ages of 18 and 45 who trained and raced competitively. They found that almost all the riders had lower bone density compared with a control group; some even had osteopenia, a precursor to osteoporosis, a disease in which bones become brittle and prone to breaking.

Build Bone Strength for Cycling Injury Prevention | Bicycling Magazine

この記事にもあるけれど、いままでVitamin Dはカルシウムの吸収を助け、骨の育成に役立つ成分という理解だった。それを覆すような研究結果が。

The supplement has been widely promoted to prevent osteoporosis and fight a host of other ills. But recent studies haven’t found much benefit, for bones or for general health.
This latest review looks at 23 randomized controlled trials involving more than 4,000 people to study vitamin D’s effect on bones. Vitamin D, which is converted into a hormone by the body, makes it easier for us absorb calcium in the intestines. So it’s easy to presume that more “D” would lead to stronger bones.
But this review found that for middle-aged people, taking vitamin D supplements for two years didn’t affect bone mineral density in the spine, hip, arm bone and skeleton overall. They did find increased bone density in the neck of the femur bone, where it often breaks in the elderly. The review also found no relation between bone density and taking calcium supplements, people’s overall vitamin D levels, length of treatment or age.

Vitamin D Not So Great for Building Bones in Middle Aged Adults After All | State of Health Blog from KQED News

研究によると、ビタミンDをサプリとして2年摂取した中年の被験者では背骨・腰・腕及び骨格全体の骨密度に変化がなかったらしい。ただ高齢者の大腿骨の付け根部分(高齢者ではよく折れるらしい)の骨密度は向上したとのこと。自分は自転車で何度も骨折していて、骨が弱いんじゃないかという印象はうすうす持っていた。なのでVitamin Dを取っているのだけれど、それがあまり効果が無いのかも。ただVitamin Dが骨粗鬆症には効くけれど、健常者の骨密度向上には貢献しないという仮説も成り立ちそう。まあまだ結論を出すには弱すぎるレポートだけれど、これは今後注目に値する。