CONSUMER REPORTS: The real deal with vitamin D
Lots of articles and even some medical professionals have touted vitamin D as the answer to all kinds of health problems and deemed most of us deficient, notes Shop Smart, the shopping magazine from the publisher of Consumer Reports. So taking supplements seems like a no-brainer.
Problem is, many of those claims are overblown — and some calcium-vitamin D supplements exceed a California lead limit. A November 2010 report by the Institute of Medicine (IOM), which examined more than 1,000 studies and other reports, concluded that although vitamin D is essential to bone health, evidence of other benefits was inconclusive.
And what about the “deficiency epidemic”? One explanation is that it blossomed almost overnight when many testing laboratories in this country upped the threshold for what’s considered a normal blood level of vitamin D. Currently, nearly 80 percent of people are labeled deficient.
So when it comes to supplements, what makes sense for you?
With the help of its medical experts, ShopSmart waded through the hype to answer four top questions about vitamin D.
Do I need more D?
It depends. It’s a good idea if you don’t get at least some midday sun exposure during the warmer months (the body makes D from exposure to sunlight) or regularly consume vitamin D-rich foods such as fatty fish, eggs and fortified milk or soy products. In those cases, a vitamin D supplement might help.
Supplements are also recommended for people with osteoporosis (weak bones) or who have a condition, such as celiac disease or Crohn’s disease, that impairs their ability to absorb fat-soluble vitamins.
Being middle-aged or older, dark-skinned or overweight can slightly increase your risk of deficiency and might tip the balance in favor of taking supplements, particularly if your diet or lifestyle is likely to be “D-ficient.”
If you take this supplement, there’s no reason to exceed the recommended intake of 600 International Unit (IU) daily for adults up to age 70; 800 IU for those who are older. But try to avoid exceeding 4,000 IU daily unless your doctor has prescribed a higher dose to make up for a deficiency. At very high levels, too much D can cause kidney damage. The symptoms of toxicity include nausea, vomiting, poor appetite, constipation, weakness, weight loss and confusion.
Should I get tested?
Not unless you are at risk for deficiency. If you do get tested, ShopSmart says to keep in mind that vitamin D levels fluctuate with your exposure to sunlight and diet and that results can differ from one laboratory to another. If results are abnormal or unexpected, you should be retested. Results are more likely to be accurate if you use labs that perform high volumes of testing — say, more than 50 vitamin D tests a day.
Although in some labs healthy blood levels of vitamin D are considered to be at least 30 nanograms per milliliter (ng/ml), the IOM says that levels of at least 20 ng/ml are fine to ensure healthy bones.
If your levels are well below 20, your doctor will probably recommend a high dose of D for several months followed by a regular supplement thereafter.
Does it matter what supplement I take?
No, not really. The D3 form (cholecalciferol) has a reputation for being more potent than D2 (ergocalciferol), but research suggests that’s the case only at high doses. At recommended doses, they work equally well, experts say.
Do I need to take calcium with it?
Yes, unless you meet your recommended calcium intake through your diet. That’s 1,200 milligrams daily for women older than 50 and men older than 70 and 1,000 milligrams for other adults. In most of the clinical trials linking vitamin D supplementation to denser bones or fewer fractures, the nutrient was combined with calcium.
The few studies that examined vitamin D alone did not find the same benefits.