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Vitamin D and Why You Need to Know More Than Your ABCs

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Vitamins A, B, and C have all had their turns in the spotlight. Now it’s time for the elusive and misunderstood D to have its turn at stardom.

For years, vitamin D was simply calcium’s escort, helping it move from the stomach through the blood stream and then into the bones. But now, we are starting to understand its true colors - and what a rainbow of tasks it performs.

Turns out, vitamin D is involved in nearly every single vital function of our body – from cell renewal, insulin production, and immune system function. Deficiencies of the vitamin have been linked to autism, cancer, depression, osteoporosis, heart disease, hypertension, autoimmune disorders, and chronic fatigue.

The scariest part of all is that most of us are not getting enough of it. According to a report in the Archives of Internal Medicine, up to 77 percent of Americans are vitamin D deficient.

So where does vitamin D come from and how can you up your dose? It’s actually not so straightforward. Sunlight converts a substance found in our skin to vitamin D naturally. However, to get enough of it, you would take in 15 minutes of midday sun on most of your body. But to do that would mean exposing your body to cancer-causing UV rays, something none of us should risk.

To make matters even more complicated, it’s not in many of the foods we eat. Some fish and fortified dairy products may have it, but the best way to get your recommended 1,000-plus IU a day is to take a supplement. That's right - after all the talk of that it’s better to get your nutrients from a balanced diet, there’s an exception to the rule. But luckily, vitamin D supplements are an easy, inexpensive way to make sure you are getting the minimum daily dose.

So pop your pills – all those D’s add up to grade-A health.

Add a Comment8 Comments

EmpowHER Guest

I just read in my daily newspaper that a women had leg and back pain, she was told to take 25,000? of vitiam D and with 1 pill she felt so much younger. This would be such a dream come true for me. Every day I have leg and back pain but I refuse to go to the DRS. because whenever I take meds. I seem to gain weight and I really cant afford to do that. I am 53 and weigh 200lbs I hate it!!!! I have tried everything I have changed all my habits. I am wondering if vitiam D would help me with my pains.

July 23, 2009 - 11:46am

Where did you find your information on the 1,000 IU a day as a recommended requirement for Vitamin D?

Here's what the Mayo Clinic says:

"The National Academy of Sciences currently recommends 200 international units (IU) of vitamin D a day for children and adults up to age 50. This is about the amount of vitamin D in 3 ounces of tuna or 16 ounces of fortified milk. For adults older than age 50, the recommendation increases to 400 to 600 IU a day. If you're not getting enough vitamin D, your doctor may recommend vitamin D supplements. Still, moderation is important."

The clinic notes that we're unlikely to ever get too much Vitamin D from the FOODS we eat. But in regards to supplements: "Over time, however, megadoses of vitamin D supplements can cause nausea, vomiting, poor appetite, constipation, weakness and weight loss. More seriously, excessive doses of vitamin D can raise the level of calcium in your blood — which can cause confusion and changes in heart rhythm. Generally, the upper limit for vitamin D is 2,000 IU a day."

Here's the Mayo Clinic source:

And here's the National Institutes of Health Dietary Supplement Fact Sheet, which recommends 200 IU from birth to age 50, 400 IU from ages 51 to 70, and 600 IU from ages 70 up:


That page also lists a lot of foods and the IU equivalent of how much Vitamin D they contain.

Can you reconcile these recommended IUs with the sources for the 1,000 a day number you have? I'd appreciate it, as I'm very interested in this topic.

June 22, 2009 - 9:50am
(reply to Diane Porter)

Hi Diane, thank you for all these great sources! This really is a hot topic - I am so happy that I covered it this past week and thank you for being so engaged and interested.

The Institute of Medicine recommends an intake of 200 IU up to age 50 and then 400 IU between the ages of 51 and 70. After age 70, your intake should be higher at roughly 600 IU. However, it says that optimum intakes are much higher - 1,000 to 2,000 IU over the age of two.

I recommended taking a supplement because it seems to be very difficult to get those levels just from the foods that we eat each day. The Institute sites that taking up to 2,000 IU per day as a supplement is safe. It also sites that some people, particularly those with darker skin, live in the northern US, or spend little time in the sun, may need 3,000 to 4,000 IU a day.

If anything, this piece and the discussion that followed definitely sent me to the store to buy a vitamin D supplement! I hope this helps answer your question and thank you again for those great sources. This is a really interesting topic and I hope that there will be more studies that help narrow down how much we need - and from what sources - in the near future.

If you're still interested in vitamin D and nutrition in general - the information that I site above is from this resource: http://www.hsph.harvard.edu/nutritionsource/what-should-you-eat/vitamin-d/index.html.

Hope this helps!

June 22, 2009 - 4:31pm
EmpowHER Guest

Carlson, a well known and quality brand, has vitamin D available in gelcaps at 1,000, 2,000 and 4,000 IU. WalMart now has a 2,000 IU in gelcap. One should not promote any "standard" dose. Dr. Davis(cardiologist)-Heart Scan blog- has noted that in his practice the dose range to maintain the desired blood level can be anywhere from 1,000 to 16,000 IU per day. Obviously that top number must be a very unusual case and only done under the supervision of a doctor who is current in vitamin D research. Age and weight have a significant effect. Because we are dealing with a hormone it is essential that the proper dose be determined by testing the 25(OH)D level. After 30 months at 2,500 IU/day my level was 34 ng/ml. I then went up to 4,400 IU/day for two years and reached 48 ng/ml when tested in February. I live in a northern climate. My goal is to maintain 50-60 ng/ml year around.

June 20, 2009 - 10:40am
EmpowHER Guest

My blood level was only 10ng/ml (severely deficient even with the 400 IU in a multivitamin) - After taking 2500 IU for 2 years, it only got up to 35ng/ml which is barely in the non-deficient range.

I just upped my dosage to 5000 IU, which will get it to around 50-60, which is considered by optimal.

1000 units just isn't enough for most people. Generally, it's 30 IU per pound of body weight that's needed.

June 20, 2009 - 9:11am
(reply to Anonymous)

Thank you for your sharing this insight. In doing the research, the clearest thing that came across is that there doesn't seem to be a ceiling. Do you have a supplement that you prefer? And do you take multiple 1,000 IU dosages or is there a higher dosage brand?

June 20, 2009 - 9:21am
EmpowHER Guest

I take a basic one-a-day multivitamin for women...does this contain a sufficient amount of vitamin D? Or should I consider an additional vitamin D supplement?

June 19, 2009 - 9:10pm
(reply to Anonymous)

Check the nutritional information on the bottle. You need a minimum of 1,000 IU a day of vitamin D. One a Day Women's, for example, only has 800 IU, so you would still need an additional supplement or a few glasses of D-fortified milk to meet your daily quota. There is no evidence that you can get too much vitamin D, so it's best to take a supplement if your multi has less that 1,000 IU a day.

June 19, 2009 - 9:26pm
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We value and respect our HERWriters' experiences, but everyone is different. Many of our writers are speaking from personal experience, and what's worked for them may not work for you. Their articles are not a substitute for medical advice, although we hope you can gain knowledge from their insight.