Medicine
Vitamin D seems to be all the rage in medicine these days. A family physician colleague commented to me last week that the laboratory test for vitamin D deficiency is becoming the most frequently ordered test in his practice. This clinical bandwagon is likely a response to data from multiple recent studies that found low vitamin D levels in the majority of children and adults of all ages. While vitamin D has always been thought to play an important role in keeping bones strong, researchers are suggesting that low levels may increase one’s risk for a variety of diseases, including cancer and cardiovascular disease.
Before you go out to your local drugstore to buy mega-doses of vitamin D supplements, though, there are at least two good reasons to proceed with caution. First, association does not always translate into causation. In other words, just because people with a low (or high) level of a nutrient are more likely to suffer from a particular illness doesn’t mean that the abnormal level caused the illness, nor does it mean that restoring a normal level will cure it. For example, studies have showed that high homocysteine levels are associated with an increased heart attack risk. When I was in residency training, cardiologists routinely prescribed folate supplements to patients who had had heart attacks in order to lower their homocysteine levels and reduce their risk of having another heart attack. However, subsequent studies determined that lowering homocysteine levels does absolutely nothing for these patients.
The second reason to be wary of the vitamin D hype is that we’ve been down this road before, with vitamins A, B, C, and E. An editorial published recently in the American Journal of Epidemiology provides a sobering summary of initial high hopes placed in each “anticancer vitamin du jour” that were subsequently dashed by randomized controlled trials. In the case of vitamin E, high doses actually appear to be harmful.
There’s a lot we don’t know about vitamin D, as an exhaustive review of the evidence for the U.S. Institute of Medicine concluded last year. Although most studies suggest that vitamin D supplements reduce the risk of fractures and falls in older adults, it’s not at all clear what the best dose should be; in a recent study, older women taking a single large dose of vitamin D each year suffered more fractures and falls than women who didn’t. In the meantime, there are many other things that you can do to keep your bones healthy, including regular weight-bearing exercise, not smoking, and eating a balanced diet that includes two to three servings of dairy products each day.
**
This post was first published on my CommonSense MD blog at Family Health Guide.
- Calcium, Heart Attack And Osteoporosis
. A recent meta-analysis published in the British Medical Journal by Bolland, et. al., finds that there is a 30% increase in the risk of myocardial infarction (MI) in women taking calcium supplements for osteoporosis (“Effect of calcium supplements...
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- Vitamin D Screening: Few Pros, Many Cons
The U.S. Preventive Services Task Force recently announced its intent to review the evidence and issue recommendations about screening for vitamin D deficiency, after finding insufficient evidence to recommend routine supplementation for the prevention...
- Concerns About Calcium Supplements
Until recently, the idea that calcium-containing supplements, which more than half of older adults in the U.S. consume regularly, could be harmful would have seemed absurd. Primary care clinicians have long recommended calcium supplements to reduce the...
Medicine
Is Vitamin D vastly overrated?
Vitamin D seems to be all the rage in medicine these days. A family physician colleague commented to me last week that the laboratory test for vitamin D deficiency is becoming the most frequently ordered test in his practice. This clinical bandwagon is likely a response to data from multiple recent studies that found low vitamin D levels in the majority of children and adults of all ages. While vitamin D has always been thought to play an important role in keeping bones strong, researchers are suggesting that low levels may increase one’s risk for a variety of diseases, including cancer and cardiovascular disease.
Before you go out to your local drugstore to buy mega-doses of vitamin D supplements, though, there are at least two good reasons to proceed with caution. First, association does not always translate into causation. In other words, just because people with a low (or high) level of a nutrient are more likely to suffer from a particular illness doesn’t mean that the abnormal level caused the illness, nor does it mean that restoring a normal level will cure it. For example, studies have showed that high homocysteine levels are associated with an increased heart attack risk. When I was in residency training, cardiologists routinely prescribed folate supplements to patients who had had heart attacks in order to lower their homocysteine levels and reduce their risk of having another heart attack. However, subsequent studies determined that lowering homocysteine levels does absolutely nothing for these patients.
The second reason to be wary of the vitamin D hype is that we’ve been down this road before, with vitamins A, B, C, and E. An editorial published recently in the American Journal of Epidemiology provides a sobering summary of initial high hopes placed in each “anticancer vitamin du jour” that were subsequently dashed by randomized controlled trials. In the case of vitamin E, high doses actually appear to be harmful.
There’s a lot we don’t know about vitamin D, as an exhaustive review of the evidence for the U.S. Institute of Medicine concluded last year. Although most studies suggest that vitamin D supplements reduce the risk of fractures and falls in older adults, it’s not at all clear what the best dose should be; in a recent study, older women taking a single large dose of vitamin D each year suffered more fractures and falls than women who didn’t. In the meantime, there are many other things that you can do to keep your bones healthy, including regular weight-bearing exercise, not smoking, and eating a balanced diet that includes two to three servings of dairy products each day.
**
This post was first published on my CommonSense MD blog at Family Health Guide.
- Calcium, Heart Attack And Osteoporosis
. A recent meta-analysis published in the British Medical Journal by Bolland, et. al., finds that there is a 30% increase in the risk of myocardial infarction (MI) in women taking calcium supplements for osteoporosis (“Effect of calcium supplements...
- Book Review: "ending Medical Reversal" Is Revolutionary
The take-home message of the first lecture of my first clinical clerkship (Obstetrics and Gynecology) was that we should prescribe supplemental estrogen to all postmenopausal women to prevent cardiovascular disease. That lecture happened in 1999. Less...
- Debating Testosterone Screening And Therapy In Older Men
A good number of new patients to my practice are older men whose previous physicians have retired. More and more often, I've noticed while reviewing records from previous physicals that they have had their testosterone levels checked - usually without...
- Vitamin D Screening: Few Pros, Many Cons
The U.S. Preventive Services Task Force recently announced its intent to review the evidence and issue recommendations about screening for vitamin D deficiency, after finding insufficient evidence to recommend routine supplementation for the prevention...
- Concerns About Calcium Supplements
Until recently, the idea that calcium-containing supplements, which more than half of older adults in the U.S. consume regularly, could be harmful would have seemed absurd. Primary care clinicians have long recommended calcium supplements to reduce the...