Cooper Clinic Experts Interpret New Research on Vitamin D
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As research on vitamin D and its effect on health grows, so does the debate over what the optimal level of vitamin D is and how we get it. Two articles recently published in the British Medical Journal (BMJ) reviewed and analyzed some of the existing research available.
Vitamin D and Multiple Health Outcomes, BMJ, April 2014
In an umbrella review of 268 studies*, 137 outcomes were explored and covered everything from metabolic disorders to cancer and autoimmune diseases. The authors concluded there is “suggestive evidence” that people with higher levels of vitamin D were resistant to stroke, diabetes, high blood pressure and other ailments, but stopped short of recommending vitamin D supplements.
Despite the clear relationship between vitamin D plasma levels and the overall risk of illness and death, the authors reported no clear evidence that vitamin D supplements are beneficial. We believe the reason for this anomaly is largely due to the fact that in most of the randomized clinical control trials reviewed the amount of vitamin D studied was only 400-1,000 IU per day.
Through testing vitamin D levels of patients since 2007, Cooper Clinic physicians realized early on these levels are less than adequate. For this reason, our baseline vitamin D recommendation is 2,000 IU per day, which is the amount of vitamin D included in all adult Cooper Complete multivitamin formulations. Following blood testing, many patients find they need far more than 2,000 IU per day in order to maintain the optimal level of vitamin D between 30-100 ng/mL per day. For these individuals, a standalone Cooper Complete Vitamin D supplement containing 1,000 IU is available to take in addition to a multivitamin.
Vitamin D and Risk of Cause Specific Death, BMJ, April 2014
In the second article**, the authors reviewed 73 cohort studies totaling 849,412 participants and 22 randomized controlled trials of 30,716 participants where vitamin D was given alone versus placebo or no treatment.
The studies showed that people with low levels of vitamin D (less than 30 ng/mL) in their blood streams were at greater mortality risk overall than the individuals with higher levels of vitamin D. Specifically people with low levels of vitamin D were 35 percent more likely to die of heart disease and 14 percent more likely to die of cancer. The researchers calculated that roughly 13 percent of all deaths in the U.S. could be attributed to low vitamin D levels.
One set of study investigators suggests, that vitamin D be obtained completely through sunlight and a healthy diet concentrating on fish, fortified dairy and vegetables. Cooper Clinic has always recommended food as the primary and preferred source of nutrition, but it’s difficult for many people to get adequate vitamin D levels from food alone. The National Institute of Health (NIH) reports the following amounts of vitamin D.
Sockeye salmon (3 oz.)—447 IU
Canned tuna fish, water-packed (3 oz.)—154 IU
Fortified milk—120 IU
Yogurt (3/4 cup)—80 IU
The levels are even lower in vegetables. While it’s possible to get mushrooms with higher levels of vitamin D (through exposure to ultraviolet light), a cup of “normal” grocery store Portobello mushrooms contains only 9 IU vitamin D. With these low numbers, an individual trying to consume all of his/her vitamin D through foods is going to drown in salmon and dairy.
The potential for getting enough vitamin D from sunlight is equally problematic. Scientists have determined that 10 minutes of midday sun in shorts and a tank top without sunscreen generates about 10,000 IU vitamin D. However, in many parts of the country the weather for at least half the year makes the idea of standing outside in shorts and a tank top ridiculous—it’s just too cold! Furthermore, most adults, regardless of where they live, don’t have lives that accommodate a midday clothing change.
It’s positive to see the continued research and validation of the importance of vitamin D for good health. Cooper Clinic recommends 2,000 IU of vitamin D per day and an annual preventive exam with blood analysis that includes vitamin D testing. For optimal nutrition, we should consume fish, fortified dairy and vegetables. And when possible we should accept the opportunities that allow us to expose (even parts of) our skin to sunlight. However, for optimal health, we continue to believe that vitamin D-3 supplements are a realistic option for the majority of adults who don’t have optimal vitamin D levels by diet and lifestyle alone.
*107 are systematic literature reviews, 74 are meta-analyses of observational studies of vitamin D concentrations in blood and 87 are meta-analyses of randomized controlled trials of vitamin D supplementation.
**Systematic review and meta-analysis of observation cohort and randomized intervention studies. The studies and trials were meta-analyzed using random effect models and were grouped by study and population characteristics.
Vitamin D Fact Sheet for Health Professionals, NIH
Vitamin D and Multiple Health Outcomes, BMJ Group
Vitamin D and Risk of Cause Specific Death, BMJ Group