Vitamin D and may be less deficient than you think.

Are you getting enough vitamin D in your diet? Um...yes, you probably are. Maybe too much. A recent report from the Institute of Medicine of the National Academies found that the amount of calcium and vitamin D needed by most Americans and Canadians was less than previous studies had supposed. Scientists found that most of us only need about 600 IU of vitamin D and 1000 mg of calcium per day. In fact, the authors of the study found that the majority of people in the US and Canada were already getting enough vitamin D and calcium, and they worried that overuse of supplements could lead to other health problems. Too much calcium could lead to kidney stones or heart disease, and excess vitamin D is linked to kidney and heart damage. The IOM's new report, which was performed at the request of the US and Canadian governments and analyzed almost 1000 previous studies, calls into question the growing amounts of calcium and vitamin D added into food and taken as health supplements. While it's probably only a matter of time before the IOM study is itself challenged by further research, I think this is a good time for us all to take a breath and consider our fascination with pigging out on pills to make ourselves healthier.

Over the past few years, the benefits of vitamin D (and calcium) have been trumpeted often. It has been linked to reduced instances of cancer and heart disease. When paired with calcium, it's also been associated with increased bone health. Sounds like something you'd want to be taking lots of. And we have. According to the New York Times, the sales of vitamin D supplements in the US rose 82% from 2008 to 2009, up to $430 million. Scientists, doctors, and nutritionists have urged patients to increase their intake of vitamin D to stave off potential health disasters down the road.

What happens, though, when you look at all the studies that link vitamin D to extraordinary health benefits as a whole? You get disappointed. Here's what the press release about the recent IOM study had to say:

"The committee that wrote the report also reviewed hundreds of studies and reports on other possible health effects of vitamin D, such as protection against cancer, heart disease, autoimmune diseases, and diabetes. While these studies point to possibilities that warrant further investigation, they have yielded conflicting and mixed results and do not offer the evidence needed to confirm that vitamin D has these effects."
---IOM National Academies Press Release

In other words, there's no conclusive evidence that we need to be taking so much vitamin D and calcium. Sure, we've had plenty of interesting studies suggest some links between these substances and better health, but when you look at these experiments in aggregate you don't see a need for increased doses. We simply haven't proven that taking large amounts of these supplements causes better health.

What about the so-called widespread vitamin D deficiency that is plaguing the US? It's mostly a matter of opinion. According to the IOM, researchers and nutritionists have used an inappropriately high requirement for vitamin D in their calculations. The IOM believes that your blood should contain 20-30 nanograms of vitamin D per milliliter to be healthy. Many studies have supposed that you need at least 30 (sometimes 50 or more) nanograms per milliliter. At that level, the IOM points out, 80% of the US population would be considered deficient. When the media (Singularity Hub included) warned you about the growing vitamin D deficiency epidemic, it may have been based on an unreasonable assumption about how much vitamin D you need.

How much do we really need? Well, the IOM has established intake recommendations based on their 20-30 blood levels. You can see them, broken down according to various age and gender, in the chart below. The IOM points out that the upper intake levels are not something to aspire to. You don't need to go for the high score. Those upper levels are where you start to run the risk of complications due to excessive amounts of vitamin D and calcium.

IOM recommendations

Every medical report like this one only has a certain shelf life. I can almost guarantee you that in another year or two we'll have further reports that contradict the Institute of Medicine study in part or full. In fact, VITAL, the super-sized trial that will look at vitamin D and fish oil, is due to finish by 2015 and will probably rewrite the book on those supplements. Every bit of new medical information complicates the picture of our health. It's not easy to know what to take and what not to take.

Why though, are we taking anything at all? I admit that I am as susceptible as the next person (if not more so) to the scientific promises of health supplements. When I heard that magnesium might be able to increase your intelligence I started gobbling pills of the stuff like they were breath mints. (No, not really, but it seemed that way.) The problem is that the scientific process is often insanely slow when it comes to deciding on what's good for your health, and there are many bumps and reversals along the way. We've already seen how fish oil, a long championed supplement, is having trouble showing that it helps with heart disease or Alzheimer's. It could be several years (I'm guessing after VITAL is completed) that we'll have a better idea about how much, if any, fish oil we should take.

Which leads me to wonder if I shouldn't be very conservative about what vitamins pills I ingest. As we've seen with centenarians the world over, living a long and healthy life may be actually pretty simple. First, be born with the right genes. If you can't do that, don't worry, you can still make it to an old age. You mostly need to eat right (more plants, less processed foods), exercise regularly, and counteract stress by forming social relationships. Even when we were worried about vitamin D deficiency, Singularity Hub was pushing that formula for health. Trying to follow the latest trends in supplement science can get confusing, but good living seems fairly straightforward.

For now.

One day, we will know more about health supplements and other chemicals, and we may be able to pinpoint how to use them to extend our lives and fortify our bodies. Expecting pills to magically make you young and strong is ridiculous today, but eventually we could create therapies that do just that. The Institute of Medicine's report on calcium and vitamin D may have us rethinking our current understanding about supplements, but the struggle to augment our health goes on.

[image credits: Ian Blackwell via CookingLight, Institute of Medicine]
[sources: IOM National Academies, NY Times]