Michael Holick is one of the world's foremost experts on vitamin
D and its role in preventing disease and promoting optimal health.
thanks to the University of California Television network for making
Dr. Holick's one-hour lecture on vitamin D available here:
of Key Points from Dr. Holick's Lecture on Vitamin D
D is essential to building and maintaining healthy bones, teeth,
is a strong association between vitamin D deficiency and increased
risk of requiring a C-section.
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.
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.
need vitamin D at birth.
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.
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.
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.
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
35 degrees north latitude and below 35 degrees south, you can't
make any vitamin D from sunlight exposure from November to February.
exposure to sunlight increases risk of non-melanoma skin cancer,
which is relatively easy to detect and treat if detected early
a sunscreen with an SPF of 15 will decrease your ability to make
vitamin D via sunlight exposure by 99%.
key to responsible use of sunlight to ensure optimal vitamin D
status is to make sure that you don't get sunburned.
enough sunlight (1 MED) to create a light pinkness in skin tone
creates around 20,000 IU of vitamin D in your system.
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.
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.
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.
with darker skin tone need significantly more sunlight than Caucasians
to produce optimal vitamin D levels.
best blood test to assess vitamin D status is 25 hydroxy D.
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.
D deficiency is extremely common among all races, even in the
people that exhibit symptoms of chronic fatigue syndrome and fibromyalgia
may actually have osteomalacia, which is caused by vitamin D deficiency.
levels of vitamin D (within the normal range) are associated with
optimal lower extremity function (healthy bones and muscles in
vitamin D status reduces risk of fracture as you age.
want your 25 hydroxy D level to be above 30 ng/ml. The optimal
range is likely between 50 and 60 ng/ml.
every 100 IU of vitamin D that you ingest, you raise your blood
level by 1 ng/ml.
vitamin D status is associated with a decreased risk of breast,
colon and prostate cancers.
more information on Dr. Michael Holick and his research on vitamin
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