health guides

The latest “D”ecisions

The Institute of Medicine (IOM) panel increased vitamin D recommendations across the board:

• Recommended daily vitamin D intake tripled from 200 IU to 600 IU for all people between 1 and 70.
• For those 71 and up, the recommended intake has increased to 800 IU per day from 600 IU.
• The IOM panel agrees with the American Academy of Paediatrics 2008 recommendation that daily vitamin D for infants under one year increase from 200 IU to 400 IU.

The safe upper limits for vitamin D intake have been raised as well:

• 1,500 IU per day for infants six months to 1 year
• 2,500 IU per day for children 1 to 3 years
• 3,000 IU per day for children aged 4 to 8 years
• 4,000 IU per day for all people 9 years and older

Sorting through the “D”ebate

Tripling the recommended vitamin D intake for most people may seem like a lot, but many advocates feel it isn’t enough. Yet while vitamin D has been well studied in recent years and widely shown to protect against a host of diseases, the science is complicated and results can be interpreted in many ways. Due to issues ranging from uneven study type and quality to challenges in firmly establishing optimal blood levels of vitamin D for good health, the IOM panel chose to stick to only what has been shown conclusively, leading to conservative recommendations.

The panel was also conservative with raising the safe upper limits, though for these decisions they did not rely on conclusive research but counted potential harm suggested by the limited available research. While doctors frequently prescribe short-term high-dose vitamin D supplementation to correct deficiencies common to certain groups (see below), studies suggesting it’s safe to supplement with up to 10,000 IU per day of vitamin D are of a few month’s duration, which do not tell us whether those levels might offer long-term risks. (Note: It is possible that the body may form 10,000 IU of vitamin D from a single day of sun exposure. However, vitamin D formed through a natural process affects the body differently than high doses taken by mouth.)

What you can “D”o right now

How to interpret the information? Alan Gaby, MD, chief science editor at Aisle7, has this perspective: “The increases in recommended intakes for vitamin D are encouraging. While even higher intake levels may turn out to be optimal for some people, it is wise to proceed with caution, since excessive doses of vitamin D can be toxic.” So, while the scientific debate settles, you can feel confident using the following tips to guide your vitamin D decisions:

• Consider your age and ethnicity. As we age, our bodies become less efficient at making vitamin D when exposed to sunlight, and we tend to spend less overall time in the sun. Also, people with darker skin are more prone to deficiency as skin pigment slows down the vitamin D production that normally occurs with sunlight exposure.
• Test first. Before supplementing more than the upper limit for your age, get your blood levels tested. If you are low in vitamin D, work with your doctor or dietitian to figure out how much you should supplement to get the number into the appropriate range.
• Supplement seasonally. If you live north of Atlanta, Georgia, the sun is not strong enough in the winter to spur the body to make adequate vitamin D. To prevent levels from dipping, consider supplementing from October through May.
• Count sources. If you want to take extra vitamin D, stick to the guidelines and pay attention to whether you are also getting some from fortified foods such as milk, orange juice, and cereal. Healthy adults who spend time in the midday sun without sunscreen during summer months make plenty of vitamin D as well.
• Aim appropriately. Working with your doctor, aim to get your blood levels to around 30 ng/mL, the higher end of the IOM panel normal range, since it can take some time and diligence to recover from deficiency.
• Sun yourself, carefully! Many health experts feel that the benefits of a small amount of sun exposure outweigh the risks. During the summer, 10 to 15 minutes of midday sun exposure will increase vitamin D levels (a little longer for those with darker skin). After that, put on the sunscreen.

(The Institute of Medicine of the National Academies. Dietary Reference Intakes for Calcium and Vitamin D. Available at: www.iom.edu/Reports/2010/Dietary-Reference-Intakes-for-Calcium-and-Vitamin-D.aspx. Accessed November 30, 2010.)