Vitamin D: Setting the Record Straight
On Wednesday, November 30, 2010, the Institute of Medicine’s Food and Nutrition Board issued a report saying, in essence, that taking more than 800 IU of supplemental vitamin D was unnecessary and could even be harmful (more on this in a minute).
Should you ignore this report? Simply put, yes. It lacks any basis in the latest scientific research, ignores the “real world” findings of medical practitioners who routinely prescribe higher doses of vitamin D and see dramatic results in their patients, and it fails the common sense “sniff” test. Let me explain.
The Smart Nutrient…
The committee only looked at the amount of vitamin D known to be needed for strong bones. That’s like evaluating an iPhone based solely on the ability of its built-in calculator to add and subtract. The calculator is one tiny feature of the iPhone, but it’s hardly a complete picture of what a good smartphone can do.
Similarly, vitamin D is important for strengthening bones, but that’s only one of the many important things this miraculous “smart” nutrient does.
Vitamin D expert William Grant, PhD, puts it this way:
“The health benefits of vitamin D extend to at least 100 types of disease, with the strongest evidence for many types of cancer (breast, colon, ovarian, pancreatic, prostate, and rectal), cardiovascular disease, diabetes types 1 and 2, respiratory infections such as type A influenza and pneumonia, other infections such as sepsis, and autoimmune diseases such as multiple sclerosis1.”
The Many Faces of Vitamin D…
There is a massive amount of research showing that low levels of vitamin D increase the risk for with every disease mentioned by Dr. Grant (above). What’s more, when people are low in vitamin D, it affects their mood, ability to lose weight, physical performance, immune system function and even their chances of dying.
A 2008 study found that low levels of vitamin D increased the risk for death from any cause — called the mortality risk — by a whopping 26 percent compared to those who had “optimal” levels in their blood2.
Which brings us to the question of “optimal” levels, and the related question of toxicity.
Vitamin D Research…
Dietitians and doctors are mired in a culture that looks at vitamin needs solely in terms of what’s needed to prevent deficiency diseases. The “recommended daily allowance” for vitamin C is the amount you need to prevent scurvy. The recommended daily allowance for vitamin B1 (thiamine) is the amount you need to prevent beriberi. I call this “minimum wage nutrition” and consider it utterly irrelevant to those interested in optimal health and well-being.
If you’ve got enough vitamin D in your system, taking more won’t necessarily make you faster or stronger, or give you the energy to run a marathon. Problem is, many people are very far from having “enough” of it. And when you don’t have enough of it, it can cost you dearly in terms of energy, health and physical performance.
We first began to notice the connection between vitamin D and physical performance when a pair of studies—one published in the Journal of Clinical Endocrinology and Metabolism3 and another by the Gerontological Society of Amercia4 both reported on the relationship between vitamin D, physical performance and disability in older people.
In a third study, Netherlands researchers at the American Society of Mineral and Bone Research’s annual meeting in 2005 also found that low levels of vitamin D are associated with low physical performance. In their study5, 1238 older men and women with low serum levels of vitamin D performed significantly worse than controls on basic tests of balance and strength such as a basic walking test, having to get up from a seated position on a chair, or having to stand balanced with one foot in front of the other.
Scores for all three tests showed significant improvement with increased levels of vitamin D. “Persons with low serum vitamin D had a higher risk for low physical performance,” Ilse Wicherts, PhD told Medscape Medical News at the time. “The strongest effects were found in persons with a major deficiency.”
But that deficiency might be more common than anyone thought. A couple of years later, in 2007, researchers at the Wake Forest University of Medicine found that, in a sample of 976 adults 65 years of age or older, a whopping 75 percent of women and 51 percent of men had insufficient vitamin D levels6. And, in testing the participants physical performance using such measures as handgrip strength, the researchers once again confirmed that those with lower levels of vitamin D performed much worse than those who weren’t deficient.
The literature on vitamin D is enormous, and the above studies are only the tip of the iceberg. Three more examples concern the immune system, cognitive decline, and weight loss.
According to Oregon State University researchers7, vitamin D induces the expression of a gene that’s actually antimicrobal. The gene is called cathelicidin, and the researchers believe that it may be responsible for vitamin D’s capacity to function as one’s primary immune response. They nicknamed cathelicidin “nature’s antibiotic,” and they believe that in the future the cathelicidin gene may form the basis for new immune-based therapies. Vitamin D “turns on” this gene.
Since an estimated 70 percent of Americans have far less than optimal levels of vitamin D, and nearly a billion people worldwide are vitamin D deficient, the Oregon State researchers warn of an impending public health problem, in both developed and developing nations.
The second example has to do with cognitive decline. Recently, a study in the prestigious Archives of Internal Medicine found that adults with the lowest levels of vitamin D were most likely to have higher levels of cognitive decline as they age8. Does this mean vitamin D supplementation will protect you from memory loss? We don’t know for sure, but we do know that not having enough D in your system increases the risk for just such problems.
The third example connects optimal vitamin D levels with greater success on a weight-loss program. Researchers measured circulating blood levels of vitamin D in overweight women and men both before and after they followed an 11-week diet plan consisting of extreme calorie reduction (750 calories a day!). You would expect just about everyone to lose on such a restrictive number of calories, and most did. But the researchers found that “pre-diet” levels of vitamin D predicted weight loss success. For every increase of 1 ng/mL (a tiny amount) in blood levels of vitamin D, folks ended up losing almost a half-pound more on their calorie-restricted diet9.
In addition, higher baseline values of vitamin D in the blood predicted greater loss of abdominal fat!
Finding the Right Dose…
So what is the optimal level of vitamin D anyway? Well — not surprisingly — there’s some dispute about this. Dr. Grant says it should be “at least 40-60 ng/mL.”
According to Dr. Grant’s research10, raising serum vitamin 25(OH)D levels to 40 ng/mL could reduce mortality rates by 15 percent in the United States, corresponding to a two-year increase in life expectancy.
The vitamin D council thinks 50 ng/ml is the minimum acceptable level, and that optimal levels are between 50 ng/ml and 70 ng/ml.* (This is in line with what most experts I know believe to be ideal. Many of them use 70 ng/ml or 80 ng/ ml as the optimal goal.)
It’s impossible to get anywhere near that number without supplements. And there’s virtually no chance of achieving it with the paltry 600 IUs a day recommended by the Food and Nutrition Board (FNB).
According to vitamin D expert Zoltan Roma, MD, MSc, author of “Vitamin D: The Sunshine Vitamin”: Research now indicates that the correct figure for the minimum daily requirement is 4,000 IUs,” adding that “it will probably take another decade before the government nutritional authorities acknowledge this fact and recommend higher vitamin D intakes for the population.
The Question of Toxicity…
This brings us to the issue of toxicity.
The FNB also reported that vitamin D toxicity might occur at an intake of 10,000 IU/day (250 micrograms/day), although they could produce no reproducible evidence that 10,000 IU/day has ever caused toxicity in humans. Also, only one poorly conducted study indicated 20,000 IU/day may cause mild elevations in serum calcium, but not clinical toxicity.
In an excellent review of all the literature on vitamin D, Reinhold Vieth, PhD, professor in the Departments of Nutritional Sciences, Laboratory Medicine and Pahtobiology of the University of Toronto, had this to say:
“Throughout my preparation of this review, I was amazed at the lack of evidence supporting statements about the toxicity of moderate doses of vitamin D.” He added: “If there is published evidence of toxicity in adults from an intake of 250 ug (10,000 IU) per day, and that is verified by the 25(OH)D concentration, I have yet to find it11.”
Vieth reports human toxicity probably begins to occur after chronic daily consumption of approximately 40,000 IUs a day (about 100 of the typical 400 IU capsules). Dr. Rona says, “Real toxicity begins at 40,000 IUs a day after only many weeks of use.”
Let’s remember that the body itself will easily make 10,000 IUs a day in a few hours in the sun. As one cynic commenting on the new report put it, “I guess they think God doesn’t know what she’s doing.”
It’s very disheartening that this report, which has been horribly reported by the mainstream media with headlines like “vitamin D can be dangerous,” will probably scare off many people who would benefit enormously from supplementing with this important nutrient.
I consider vitamin D right up there with fish oil as one of the most important supplements to take on a daily basis. I strongly suggest you pay no attention to this report, especially if you’re reading about it second hand from the mainstream media who have demonstrated a shocking indifference to its limitations (if indeed, they even understand what those limitations are to begin with).
This is yet one more sad example of the “conventional wisdom” being anything but wise.
*Remember that there are two ways to measure vitamin D in the blood; don’t confuse the measurements. In the U.S., we usually use ng/ml, but the international measure is nmol/ mL. So if someone tells you their level is “50,” be sure to ask which measurement they’re using. (A measurement of 50 ng/ml is equal to 124.8 nmol/L.)
10Grant, WB. In defense of the sun: An estimate of changes in mortality rates in the United States if mean serum 25-hydroxyvitamin D levels were raised to 45 ng/mL by solar ultraviolet-B radiance. Dermato-Endocrinology. 2009;1(4):207-14
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