Dr. Michael Holick on Vitamin D and its Health-Promoting Properties

Dr. Michael Holick is one of the world's foremost experts on vitamin D and its role in preventing disease and promoting optimal health.

Many thanks to the University of California Television network for making Dr. Holick's one-hour lecture on vitamin D available here:

Summary of Key Points from Dr. Holick's Lecture on Vitamin D

• Vitamin D is essential to building and maintaining healthy bones, teeth, and muscles.

• There is a strong association between vitamin D deficiency and increased risk of requiring a C-section.

• In addition to taking a multivitamin (typically containing 400 IU of vitamin D) and getting some vitamin D from meals, pregnant women should be taking a minimum of 1000 IU of vitamin D per day.

• If you give lactating women between 4000 and 6000 IUs of vitamin D per day, through breastfeeding alone, their babies can get all of the vitamin D that they need.

• Infants need vitamin D at birth.

• There aren't too many foods that are naturally rich in vitamin D. Oily fish like wild salmon contain about 500 to 1000 IUs per serving (3.5 ounces), so you would have to eat salmon almost every day to barely get enough vitamin D to meet all of your needs.

• Wild salmon get their vitamin D from the food chain, where it's abundant. Food pellets that are fed to farmed salmon don't contain vitamin D, so farmed salmon typically provide 100 to 250 IU of vitamin D per serving, which is only 10 to 25% of the vitamin D found in wild salmon.

• In the summer, UV-B rays from the sun can create all of the vitamin D that we need if we get some exposure on our skin.

• In the winter, the further away we get from the equator, the less chance we have of being exposed to UV-B rays to make vitamin D in our skin. For example, in Boston, you can make all the vitamin D that you need in the spring, summer, and fall months, but from about November to February, you can't make any at all from sunlight exposure.

• Above 35 degrees north latitude and below 35 degrees south, you can't make any vitamin D from sunlight exposure from November to February.

• Excessive exposure to sunlight increases risk of non-melanoma skin cancer, which is relatively easy to detect and treat if detected early enough.

• Using a sunscreen with an SPF of 15 will decrease your ability to make vitamin D via sunlight exposure by 99%.

• The key to responsible use of sunlight to ensure optimal vitamin D status is to make sure that you don't get sunburned.

• Getting enough sunlight (1 MED) to create a light pinkness in skin tone creates around 20,000 IU of vitamin D in your system.

• Aging decreases our ability to produce vitamin D via sunlight. A 70-year old has a 70% reduced ability to produce vitamin D via sunlight compared to a 20-year old. So the older we get, the more likely it is that we will need to get some of our vitamin D from supplementation.

• Obesity increases the need for vitamin D intake and/or creation via sunlight because storage of vitamin D in fat cells reduces the amount of vitamin D that's available to the rest of the body.

• For most people and locations, during the summer, a good amount of sunlight exposure is 5 to 15 minutes on the arms and legs, two to three times a week. After this amount of time, sunscreen can be used to help prevent premature aging and increased risk of non-melanoma skin cancer.

• People with darker skin tone need significantly more sunlight than Caucasians to produce optimal vitamin D levels.

• The best blood test to assess vitamin D status is 25 hydroxy D.

• Dr. Holick believes that most people (adults and kids) should be supplementing with a minimum of 1000 IU of vitamin D per day in addition to the vitamin D found in a multivitamin and a couple servings of foods that contain vitamin D.

• Vitamin D deficiency is extremely common among all races, even in the summer.

• Many people that exhibit symptoms of chronic fatigue syndrome and fibromyalgia may actually have osteomalacia, which is caused by vitamin D deficiency.

• Higher levels of vitamin D (within the normal range) are associated with optimal lower extremity function (healthy bones and muscles in your legs).

• Optimal vitamin D status reduces risk of fracture as you age.

• You want your 25 hydroxy D level to be above 30 ng/ml. The optimal range is likely between 50 and 60 ng/ml.

• For every 100 IU of vitamin D that you ingest, you raise your blood level by 1 ng/ml.

• Optimal vitamin D status is associated with a decreased risk of breast, colon and prostate cancers.

For more information on Dr. Michael Holick and his research on vitamin D, view:

VitaminDHealth.org

To review these and other essential guidelines on ensuring adequate vitamin D status, view:

How to Make Sure that You Are Getting Enough Vitamin D for Your Best Health