Skip to main content
ASK AN EXPERT
Got a question about a health story in the news or a health topic? Here's your chance to get an answer. Send us your questions about general health topics, diet and fitness and mental health. If your question is chosen, it could be featured on CNN.com's health page with an answer from one of our health experts, or by a participant in the CNNhealth community.




* CNN encourages you to contribute a question. By submitting a question, you agree to the following terms found below.
You may not post any unlawful, threatening, libelous, defamatory, obscene, pornographic or other material that would violate the law. By submitting your question, you hereby give CNN the right, but not the obligation, to post, air, edit, exhibit, telecast, cablecast, webcast, re-use, publish, reproduce, use, license, print, distribute or otherwise use your questions(s) and accompanying personal identifying and other information you provide via all forms of media now known or hereafter devised, worldwide, in perpetuity. CNN Privacy Statment.
Thank you for your question!

It will be reviewed and considered for posting on CNNHealth.com. Questions and comments are moderated by CNN and will not appear until after they have been reviewed and approved. Unfortunately, because of the voume of questions we receive, not all can be posted.

Submit another question or Go back to CNNHealth.com

Read answers from our experts: Living Well | Diet & Fitness | Mental Health | Conditions

Expert Q&A

How much vitamin D do I need?

Asked by Terry, Dodge City, Kansas

Open quote
Close quote

I have some 2,000 IU vitamin D capsules that I am about to take. I'm a 60-year-old male, in pretty good health and not overweight or underweight. I'm also active. I've read that 2,000 is the upper limit for daily dosage, and I don't think I need to take that much anyway. The capsules I have cannot be split, so could I use them every other day and be OK? Thank you very much, and have a great week. I appreciate your site and the info.

Expert Bio Picture

Diet and Fitness Expert Dr. Melina Jampolis Physician Nutrition Specialist

Expert answer

Hi Terry. I wrote about vitamin D awhile back but since the RDA (recommended daily allowance) has changed since then, I thought it would be worthwhile to update my response.

Vitamin D is a fat soluble vitamin that is mainly produced by exposure of the skin to ultraviolet light.

Your ability to produce vitamin D in the skin decreases with age, and since it is present in very few foods naturally, consuming fortified foods or taking a vitamin D supplement is necessary for many people, particularly people with osteoporosis and those at higher risk of deficiency due to limited sun exposure, breast fed infants, overweight/obese individuals, older adults, dark-skinned people, and people with fat malabsorption.

Vitamin D is essential for bone and muscle health in both adults and children. In addition, vitamin D has numerous other roles in the body, and a growing body of research is finding that deficiencies may be associated with an increased risk of certain types of cancer (especially colon cancer), type 2 diabetes, heart disease and autoimmune diseases like multiple sclerosis.

Because these studies are mainly observational, extensive research is under way to determine the causal relationship between vitamin D levels and disease as well as the role of increasing vitamin D intake.

Vitamin D levels can be checked by a simple blood test called 25OHD, which is considered the best indication of vitamin D status. While optimal levels have not been firmly established, levels above 50 nmol/L (20 ng/ml) are considered adequate by the Institute of Medicine.

A report published in 2007 suggested that greater than or equal to 75 nmol/L (30 ng/ml) may be a better target, and last April, the International Osteoporosis Foundation issued a position paper in which most of the experts felt that the higher target blood levels (75 nmol/L or 30 ng/ml) were more appropriate for older adults to decrease their risk of fractures and falls.

As with most things in nutrition, more is not always better. Research suggests that levels above 150 nmol/L (60 ng/ml) may have adverse health effects.

The latest RDAs of vitamin D increased to 600 IU for adults up to the age of 70 and 800 IU for adults older than 70, and the tolerable upper limit increased from 2,000 to 4,000 IU per day for adults. The IOF estimated that doses of 800 to 1,000 IU (20-25 mcg) or higher may be required in older adults to prevent fractures and falls but stated that more research is necessary.

In your case, you do not appear to have any risk factors for vitamin D deficiency, but if you are concerned, I recommend having a blood test done.

If your blood level is low, you will need a higher dose to raise and keep levels in the normal range. This is best done under the supervision of your doctor, as responses to vitamin D supplements are variable and there are dosage guidelines that your doctor can utilize.

If your levels are normal, taking 2,000 IU every other day or every third day would be fine, according to Dr. Bess Dawson-Hughes, senior scientist and director of the Bone Metabolism Laboratory at the Jean Mayer USDA HNRCA at Tufts University.

In fact, similar blood level responses are seen when equivalent doses of vitamin D are taken daily, weekly, or monthly.

Follow Dr. Jampolis on Twitter

More Q&A

  • CNN's Medical UnitCNN's medical unit brings you the best experts available to answer your questions about current events and health issues that matter most to you.
Will jogging hurt an obese person's joints?asked by: Asked by John Simmet; St. Paul, Minnesota
Is creatine a safe supplement?asked by: Asked by Ralph; New York
What foods cause flatulence?asked by: Asked by Peter; United States

CNN Comment Policy: CNN encourages you to add a comment to this discussion. You may not post any unlawful, threatening, defamatory, obscene, pornographic or other material that would violate the law. All comments should be relevant to the topic and remain respectful of other authors and commenters. You are solely responsible for your own comments, the consequences of posting those comments, and the consequences of any reliance by you on the comments of others. By submitting your comment, you hereby give CNN the right, but not the obligation, to post, air, edit, exhibit, telecast, cablecast, webcast, re-use, publish, reproduce, use, license, print, distribute or otherwise use your comment(s) and accompanying personal identifying and other information you provide via all forms of media now known or hereafter devised, worldwide, in perpetuity. CNN Privacy Statement.

The information contained on this page does not and is not intended to convey medical advice. CNN is not responsible for any actions or inaction on your part based on the information that is presented here. Please consult a physician or medical professional for personal medical advice or treatment.