Nutrition experts have been grumbling for years that the government got our vitamin D recommendations wrong. When the Institute of Medicine (IOM) guidelines of 600 IU a day were released in 2010, respected Harvard professor Walter Willett, MD, primary researcher behind the Mediterranean Diet, stated publicly that this wasn’t enough—especially for people living in northern, sun-deprived climates. Now, new findings have confirmed everyone’s fears: The IOM recommendations are literally flawed. We may need at least 10 times as much of this vital nutrient.
The error first came to light in October 2014, when two public health scientists at the University of Alberta published as a study in the journal Nutrients. They went back through the IOMs studies and discovered a statistical mistake: The institute had based its vitamin D recommendations upon an average that was far too low to achieve healthy levels of D in the blood. After rerunning the numbers, they discovered that adults might need more than 8,000 IU to reach safe levels, though the researchers hesitated to recommend such high doses since none of the volunteers in the studies had taken more than 2400 IU daily.
In March, 2015, researchers at the University of San Diego and Creighton University went a step further in a letter to the same journal. They analyzed several new studies in which people were taking much higher levels of vitamin D, and they were able to confirm the Canadian research. The new findings suggested that the daily recommendations for vitamin D should be around 7,000 IU.
Although up to 10,000 IU a day is deemed safe, James E. Dowd, MD, associate clinical professor of medicine at Michigan State University and author of The Vitamin D Cure, believes it’s still not clear what the daily dose should be. “But it’s clear that there does appear to be a statistical misinterpretation by the IOM.”
The error is especially worrisome since vitamin D deficiency is one of the most common health problems in the world. An estimated 30 to 50% of children and adults are deficient. Low D has been linked to bone fractures, heart disease, cancer, diabetes, and dementia.
What should you do? The best way to make sure you’re getting enough is to ask for a vitamin D blood test, says Dowd. Your levels should be between 45 to 50 µg/mL. If you’re deficient, work with your doctor to find the supplement dose that’s right for you rather than taking a stab at what dose you think you might need. “In my practice, most patients’ vitamin D levels are between 30 to 60 µg/mL, and then I can adjust their dose of vitamin D up or down to achieve the bull’s eye,” he says.
You can get vitamin D from fatty fish, cheese, liver, eggs, fortified foods like cereal and milk, and sun exposure. Another thing to keep in mind, says Dowd, is that the more you weigh, the more D you might need. Plus, as we age, our D-making machinery slows down. The bottom line may be that a universal RDAs for vitamin D isn’t practical, he says. It pays to get tested and to work with your MD to find the supplement dose that’s right for you.