Q: I heard about a research study that reported that excess vitamin D can cause heart problems. Should I be concerned?
A: The study you’re referring to was presented at the American Heart Association conference: “Vitamin D Excess Is Significantly Associated With Risk of Atrial Fibrillation.”
Atrial fibrillation is an irregular heartbeat, which is more common as people age. It occurs when the electrical impulse from the heart does not travel in an orderly fashion through the atria. Rather, many impulses begin at the same time and cause a disorganized heartbeat. Regular atrial fibrillation can be influenced by a number of health issues, including heart problems, hypertension and lung disease. It’s unclear if the increased association of atrial fibrillation with excess vitamin D in this study was due to the vitamin D or to other health concerns.
Take note that participants whose vitamin D levels were between 81 and 100 ng/ml had a 36 percent lower risk of hypertension than those classified as deficient, meaning below 20 ng/ml. Additionally, participants whose levels were between 61 and 80 ng/ml had a 52 percent reduction in diabetes compared with those who were deficient in vitamin D. The vast majority of participants had vitamin D levels that were below “excessive,” which was pegged at 100 ng/ml, while a small number (291 people, or 0.22 percent of the population) had a higher-than-excessive vitamin D measurement. The group whose vitamin D levels were above 100 ng/ml had a risk of atrial fibrillation that was 2.5 times greater than the below-100 ng/ml group.
So one takeaway here is that although the upper limit for vitamin D is still being established, there is evidence that you don’t want your own D3 levels to exceed 100 ng/ml for any length of time. Another takeaway: Get your vitamin D tested on a regular basis.
Rather than just following some arbitrary protocol such as “take 5,000 IU three times a week,” you should base your vitamin D supplementation on test results. Vitamin D can be affected by environment and lifestyle—for example, if you live in Las Vegas and frequently swim outside, your levels will probably be pretty good. So start by getting your blood vitamin D measured—independent tests range in price from $12 to $40 in most cities.
Ideally, I suggest having your vitamin D level tested once a month to give you a baseline measurement that will dictate how much you should take. For example, if you are deficient, you’ll need to use a dosing system to raise vitamin D levels. Then, I suggest a maintenance dose that is smaller. Also, remember that blood vitamin D often varies seasonally due to differences in the amount of sun you are exposed to.
Editor’s note: Charles Poliquin is recognized as one of the world’s most suc-cessful strength coaches, having coached Olympic med-alists in 12 different sports, including the U.S. women’s track-and-field team for the 2000 Olympics. He’s spent years researching European journals (he’s fluent in English, French and German) and speaking with other coaches and scientists in his quest to optimize training methods. For more on his books, seminars and methods, visit www.CharlesPoliquin.com. Also, see his ad on page 159. IM