Get a load of the range of headlines after last week’s vitamin D studies:
New York Times: “Low vitamin D levels linked to disease in two big studies”
Philly.com: “Jury still out on benefits of vitamin D”
Discover magazine: “D-bunked: vitamin D’s benefits are overhyped, study says”
Yahoo News: “Higher levels of vitamin D might save your life”
ABC7Chicago.com: “Vitamin D may cut risk of cancer, heart disease”
What’s the story here?
The first study looked at 73 observational studies with almost 850,000 participants, as well as 22 randomized controlled trials with more than 30,000 participants using vitamin D alone versus placebo or no treatment. The researchers found that, in the observational studies, that the risk of death from cardiovascular disease, cancer and other causes was significantly higher for those who did not take vitamin D supplements.
Specifically, the researchers found that adults who had lower levels of vitamin D in their bodies had a 35 percent increased risk of death from heart disease, 14 percent greater likelihood of death from cancer, and overall a higher risk of death from all causes.
They also found that those who supplemented with vitamin D2 had no benefit, whereas those taking vitamin D3 had an 11 percent reduction in mortality from all causes compared to adults who did not supplement. Vitamin D2 is often used by vegetarians because D3 comes from lanolin derived from sheep wool. I must say, I’m pretty sure we’re doing the sheep a favor to shave off all that wool in the middle of summertime, so why the vegetarian angst?
Regardless, this is great news for D3. The researchers wrote, “Supplementation with vitamin D3 significantly reduces overall mortality among older adults. However, before any widespread supplementation, further investigations will be required to establish the optimal dose and duration.”
As for duration, think about where we get most vitamin D if not from supplements: the sun. So, if you’re a person who works inside, or if you’re anybody in the season when the sun is too low to give much benefit, supplement every day. “In wintertime, everybody has to supplement,” said Brant Cebulla, Development Director at the Vitamin D Council. “In New York City or Boston you won’t raise your vitamin D levels in wintertime.”
As for dose, the Vitamin D Council has a paleo take on things. “When researchers measured the vitamin D levels of hunter-gatherers, they are at 40-50 ng/dl, and that correlates to 5,000IU/day, so the Vitamin D Council recommends 5,000 IU/day.”
Before I go on, a word about meta-analysis: I have issues with meta-analysis because of the potential for bias – they combine results of studies that might be similar but are rarely the same, so they have within them an “essential conundrum,” as Aldo Bernasconi, director of information and research at GOED, the Global Organization for EPA and EHA Omega-3s, put it. “On the one hand, a meta-analysis has a greater chance of resolving a question because more subjects are included. On the other hand it has a smaller chance because the studies are never absolutely similar.”
Okay, thanks for letting me get that out of the way. What’s up with the second study?
The second meta-analysis looked at vitamin D’s role in death from cardiovascular disease, cancer or other conditions, and found that those who had low vitamin D levels in their blood tended to have increased risk of death from cardio disease, cancer and other causes. If the people in the 14 trials assessed here were taking vitamin D supplements, their risk of death was cut by 11 percent.