天博体育

Vitamin D has been talked about as the vitamin 鈥� the one聽that might help fend off聽everything from cancer to heart disease to autoimmune disorders, if only we were to get enough of it.

鈥淲hoa!鈥� is the message from聽a committee of experts assembled by the Institute of Medicine (IOM) to update聽recommendations聽for vitamin D (and for calcium).

, released聽this morning, says evidence for聽many of 聽the health claims for聽vitamin D聽is 鈥渋nconsistent and/or conflicting or did not demonstrate causality.鈥� The exception is the vitamin鈥檚 well-documented聽(and noncontroversial) benefits on聽bone growth and maintenance.

The IOM panel鈥檚 report also聽says most North Americans (Canadians as well as Americans)聽have more than enough vitamin D in their blood to achieve the desired effect on bone. The聽committee said聽a blood level of 20 nanograms per milliliter (ng/mL) is sufficient for most people.

The聽panel聽set 600 International Units (IU) as聽the recommended daily聽intake聽for children and聽for adults ages 19 to 70. People ages 71 and older are supposed to聽get an additional聽200 IU,聽or 800 IU a day.

That鈥檚聽a fairly sizable聽increase over the聽previous recommendations of聽200 IU per day through age 50,聽 400 IU for people ages 51 to 70, and聽600 IU for people ages 71 and older.

The safe upper limit on daily intake had been 2,000 IU for most age groups. Today鈥檚 committee report聽increased that to 4,000 IU.

Here is the conclusion of a聽four-page summary of the聽full book-length report:

Scientific evidence indicates that calcium and vitamin D play key roles in bone health. The current evidence, however, does not support other benefits for vitamin D or calcium intake. More targeted research should continue. However, the committee emphasizes that, with few exceptions, all North Americans are receiving enough calcium and vitamin D. Higher levels have not been shown to confer greater benefits, and in fact, they have been linked to other health problems, challenging the concept that that 鈥渕ore is better.鈥�

The new vitamin D recommendations are聽bound to kick up some聽controversy聽because many researchers,聽led by ,聽have argued that聽Americans should be consuming a lot more vitamin D than they are now,聽with聽800 to 1,000 IU a day聽being the聽bare minimum and聽over 2,000 IU a day聽as聽being聽closer to the聽optimum.

Vitamin D proponents have also said the goal for聽blood levels should be聽30 ng/mL. The聽IOM panel says聽levels that high are not associated with any health benefit and adds that levels above 50 ng/mL 鈥渕ay be reason for concern.鈥�

The committee鈥檚 calcium聽recommendations are not likely to be nearly as controversial as聽its advice on vitamin D.

The summary of the panels鈥� report聽says聽national surveys show that most people in the United States and Canada get enough calcium, the notable exception being聽girls ages 9 to 18.聽The panel warns that postmenopausal women who take calcium supplements may be increasing their risk for kidney stones by getting too much of the mineral.