Optimizing Your Vitamin D Status
According to Dr. Cannell: “Healthy humans should be supplemented with enough vitamin D or exposed to enough ultraviolet B radiation to achieve natural activated vitamin D levels of 40-70 ng/mL.”11 Dr. Campbell aims for even higher levels of 50-80 ng/mL.8 Testing for vitamin D status is of course the first and crucial step.
“I tested everyone in my practice a few years ago,” says Dr. Campbell, “and found that in summer 55% were deficient, rising to 76% in winter.” Campbell, like other experts, defines deficiency as levels below 30 ng/mL, and insufficiency as levels between 30 and 50. Cannell elaborates: “Even without physical signs or symptoms, the physician should screen those at risk” at least twice yearly.11
These experts also caution that many physicians and labs perform the wrong test. Most labs measure only levels of the kidney-modified 1,25 dihydroxy-vitamin D, which do not correlate to actual vitamin D deficiency.11 The correct test to obtain, and on which to base supplementation, is for 25-hydroxyvitamin D (often abbreviated “25(OH)D” on laboratory order forms). Be sure you get tested at least once in late winter and once in late summer, and be certain that your doctor orders the correct 25-hydroxyvitamin D test. You do not have to wait for test results before starting on at least a reasonable maintenance dose of vitamin D. The supplement is safe and it’s important to get started on adequate coverage right away.
Many different forms of vitamin D are available, and in many doses. Our experts unanimously recommend using vitamin D3. Like them, you and your doctor may at first be shocked at the amount you’ll require to bring your blood level up to the 40-50 ng/mL range. Cannell and others calculate that to raise serum vitamin D levels by 10 ng/mL requires daily supplementation of a minimum of 1,000 IU over three to four months.11 That means that if your initial level was 10 ng/mL, you’d need to take 2,000 IU over that period just to reach 30. Cannell and Campbell caution that the response rate is not linear. That is, it may be easy to raise initially low levels into the existing normal range, but you may require larger amounts to achieve the 40-50 ng/mL minimum that they recommend.7,8 Furthermore, dark-skinned, older, and large or obese people often require higher doses than do fair-skinned, small, thin, or young ones.39,47
Both Drs. Campbell and Cannell recommend an initial loading dose for people found to have low levels. As one option, Cannell and others recommend oral loading doses of 50,000 IU (1.25 mg) of vitamin D3 per day for a week (two weeks at most), before beginning maintenance therapy.11,48 Given the incredibly high rate of vitamin D-deficient patients in her practice, Dr. Campbell has developed an aggressive initial approach. “I give an intramuscular injection of 400,000 IU of vitamin D3 to my patients whose levels are less than 32 on a first test, or less than 35 if they actually show symptoms such as fatigue, fibromyalgia, or bone pain,” Campbell reports. That apparently huge dose is well-supported by international authorities; injections of up to 600,000 IU have been given with excellent result—and no side effects.1 Please note that these high doses were administered under a doctor’s supervision. If considering such mega-dosing, we suggest that you do so in concert with your health practitioner.
Regarding maintenance therapy, Cannell notes that daily 2,000 IU supplements for one year failed to achieve a 32 ng/mL concentration in 40% of women in one study.11,49 And 4,000 IU/day for more than six months achieved an acceptable levels of 44 ng/mL with no side effects other than improved mood.11,50 “Current evidence suggests that healthy adult men utilize up to 5,000 IU of vitamin D per day, if it is available,” observes Cannell.11,51
Dr. Campbell bases her maintenance therapy on patients’ size, age, skin color, and the results of repeat testing after the loading dose. “My patients typically require 2,000 to 7,000 IU per day, averaging 5,000,” she says. “I re-test my patients at three- to six-month intervals, and adjust the dosing as needed to maintain their levels in the 50-80 ng/mL range,” Campbell concludes. Do people ever exceed the upper limit? “It has happened rarely,” says Dr. Campbell. “I just have them skip doses on weekends for a few months, and test again at the regular interval.” That approach has returned everyone to the healthy range, she reports.
The Food and Nutrition Board identifies the Tolerable Upper Limit of Vitamin D intake as 2,000 IU per day. Nevertheless, they acknowledge that many nutrition scientists have challenged these limits, as far back as 1997. A 2007 risk assessment conducted by the Council for Responsible Nutrition and published in the American Journal of Clinical Nutrition found that, in healthy adults, the data support a tolerable upper limit as high as 10,000 IU/day.52
Meanwhile, Dr. Cannell and others also recommend periodic urine testing for calcium in patients taking high-dose vitamin D.11 This helps detect the relatively rare cases of excessive calcium uptake that can occur with higher levels of vitamin D supplementation. Virtually no other side effects have been detected in studies to date.
Perhaps the best evidence of how vitamin D helps individuals ward off the flu lies in Dr. Campbell’s records. “Three years ago I was ordering 200 doses of flu vaccine. I ordered a hundred last year, and this year I’ve needed none. Maybe they are getting vaccinated somewhere else, but my guess is that they are simply realizing the benefit of adequate vitamin D protection.”
These doctors suggest that you should not skip immunizations for either seasonal flu or H1N1 “swine” flu—they remain an important part of overall public health protection. However, when properly taken and monitored with a simple blood test, vitamin D affords powerful, clinically supported immune protection.
Vitamin D wards off the flu by ramping up the body’s innate immune system. Influenza (both seasonal and H1N1 “swine flu”) and other respiratory infections kill thousands of Americans each year, and hospitalize hundreds of thousands more.52,53 Despite increasing availability of flu vaccines, mortality rates among the elderly may not be dropping.54 At the same time, vitamin D deficiency is epidemic, owing to inadequate sun exposure and incredibly low levels of dietary intake.55 Compelling evidence supports vitamin D supplementation at much higher levels than are currently recommended by the medical establishment.
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