Infographic: Suspected Effects of Vitamin D
View full size JPG | PDF Harry Campbell
Time and time again, everyone jumped on the bandwagon and then the randomized trials did not have favorable results, and in fact, the risks outweighed the benefits.Scientists critical of the VITAL study question whether the daily dose of 2,000 IU is enough to distinguish the treatment group from the controls. If this were a drug trial, the placebo group would go without the drug completely. But it’s unethical to ask anyone to go without vitamin D. Doctors inform all participants that they can take up to 800 IU of vitamin D daily (the national recommendation for people over 70 years old) in addition to the pills they receive in the mail. If they do, the control group will sustain more than adequate levels. But some participants might decide to break the rules and head to the nearest corner store for high-dose supplements after being told that vitamin D may help prevent cancer and other diseases. And of course, many participants won’t follow through with taking the pills they’ve been sent in the mail. “You hope drop-ins and drop-outs will be equal on both sides, but they may not be,” warns biostatistician Gary Cutter at the University of Alabama at Birmingham.
—JoAnn Manson, Harvard Medical School
NAME OF TRIAL | PRIMARY OUTCOME | START DATE | DURATION OF TREATMENT | STATUS | NO. PARTICIPANTS/ EXPECTED ENROLLMENT | DOSE OF VITAMIN D3 |
NCT01169259 | All cancers, heart disease, and stroke | July 2010 | 5 years | Recruiting participants | 20,000 healthy men over 50 and women over 55 | 2,000 IU daily |
To be announced (lingering ethical approvals have delayed the official listing of this trial) | nfections, cognitive decline, blood pressure increase, decline in muscle strength, risk of non-vertebral fractures | June 2012 | 3 years | Approved | 2,000 men and women over 70 who have had a fracture or a fall | 2,000 IU daily |
NCT01052051 | All cancers | Jan. 2009 | 4 years | Ongoing | 2,332 healthy postmenopausal women over 55 | 2,000 IU (and 1,500 mg calcium) daily |
NCT01463813 | All cancers and cardiovascular disease | Jan. 2012 | 4 years | Approved | 18,000 healthy men over 60 and women over 65 | 3,200 IU or 1,600 IU daily |
NCT00920621 | Asthma or recurrent wheeze at 3 years old | Sept. 2009 | 1 year | Ongoing | 871 pregnant women whose babies have a family history of asthma, eczema, or allergic rhinitis | 4,000 IU daily |
NCT00685594 | Type 2 diabetes | March 2008 | 5 years | Ongoing | 517 adults with impaired glucose tolerance | 20,000 IU per week |
NCT00876928 | Type 2 diabetes | March 2009 | 1 year | Ongoing | 186 Latino and African American adults over age 40 with risk factors for diabetes | Dose determined by BMI; average dose is 89,684 IU per week |
NCT01069874 | Influenza and other respiratory infections | March 2010 | 1 year | Recruiting participants | Approx. 290 permanent residents or staff at 116 independent living units | 120,000 IU once every 2 months |
欢迎光临 肝胆相照论坛 (http://hbvhbv.info/forum/) | Powered by Discuz! X1.5 |