EDITOR's NOTE: Welcome Dr. Michelle Cardel, PhD, RD to the Gainesville Lunch Out Blog Staff as our resident expert on all important food information that is healthy, smart, and good for your body, mind, stomach and waistline. Dr. MC will share smart food advice with us on a regular basis and looks forward to answering, discussing any food questions you might have.
As Americans, we tend to believe, "If something is good, then more is better." However, this is not the case with the wildly popular supplement vitamin D. Vitamin D is a fat-soluble vitamin, which means it is stored in your body for long periods of time and, when consumed excessively, poses a greater risk of toxicity than water-soluble vitamins. Vitamin D is consumed by diet, but also from synthesis in the skin through sunlight exposure. It is nearly impossible to get too much vitamin D from sunlight or foods â€“ unless you eat way too much cod liver oil-but who wants to do that? Rather, almost all excess vitamin D consumption comes from supplements.
How much vitamin D should I take?
The Institute of Medicine (IOM) recommends 600-800 International Units (IUs) of vitamin D daily for healthy adults, with no more than 4,000 IUs per day.1 It's important, too, that very high levels (above 10,000 IUs per day) can cause kidney and tissue damage, so you should strive to stay within the recommended amount as directed by the IOM, which challenges the concept that "more is better."
How do I know if I am deficient in vitamin D and need to take a vitamin D supplement?
Vitamin D deficiency is fairly common in the United States, the Center for Disease Control (CDC) reporting that 1 out of every 3 people are vitamin D deficient.2 It is likely that these numbers underestimate deficiencies in the United States, because the estimate did not account for the vitamin D level that is needed for optimal bone health. Don't assume that, just because you live in Florida and get plenty of sunlight, you aren't deficient in vitamin D. Women, older adults, pregnant/lactating women, people who always wear sun protection, and persons with darker skin are at increased risk for vitamin D deficiency.
If you want to know if you are vitamin D deficient, then ask your doctor. Your level can be checked with a simple blood test. The IOM defines vitamin D deficiency as a levels under 20 ng/mL. If your blood level is under 20 ng/mL, your doctor will likely recommend that you take a vitamin D supplement. You can safely take a supplement of 2,000 IUs a day, but be sure not to take over the recommended 4,000 IUs a day, unless specifically instructed by your doctor. Always consult with your doctor before starting any supplement.
An issue with supplements is that they are not regulated by the Food and Drug Administration (FDA). That means that sometimes supplements can have more or less of the nutrients listed on their labels or they can be contaminated with unwanted chemicals. Thus, when purchasing a supplement, you want to look for the United States Pharmacopeia (USP) seal of approval. The USP is a scientific, non-profit organization that sets standards and analyzes pills and supplements to ensure that what is inside is accurately labeled on the vitamin bottle label.
If a product contains the USP seal, you can be assured that it:
Contains the ingredients listed on the label in the declared potency and amounts.
Does not contain harmful levels of contaminants.
Breaks down and releases its ingredient within a specified amount of time.
Has been made according to FDA current Good Manufacturing Practices, which specifies sanitary and well-controlled procedures.
If you want to learn more about the USP, check out the USP website: http://www.usp.org/. Something the USP also does is check to make sure that your vitamin meets dissolution standards, meaning the supplement actually dissolves. This is because some supplements don't dissolve quickly in the stomach and you end up excreting the majority of the vitamins and your body loses out on the important nutrients. If you already have a supplement you use at home, you can do this quick test to make sure your vitamin is actually dissolving in your stomach:
Put one of your vitamins in a half a cup of white or apple cider vinegar for 30 minutes or so, and stir it every 5 minutes. Within 30 minutes or 45 if the pill has a gelatin or hard coat on it, you want to see that the pill has dissolved. At the very least you want the pill to have separated into little particles.
NOTE: Dr. Michelle Cardel does not have any conflict of interest to report. She does not work for USP in any way, nor has she received money from them in any capacity.