Counting on the sun alone for vitamin D will leave most people deprived of adequate amounts of this nutrient, especially during the winter in the northern parts of the US.
This is true even for people who work outside during the summer and get plenty of sun in the warmer months but not in the winter.
Vitamin D is formed in the skin, but it requires ultraviolet rays of the sun to activate it to a form the body can use. Vitamin D, which assists the intestines in absorbing calcium and phosphorus, is also contained in some fortified foods.
Dr. Robert Heaney from Creighton University calculated the daily skin dose of vitamin D that 26 men who worked outdoors during the summer would have received.
They brought the men back about 6 months later to assess how much vitamin D they may have lost over the winter. The team estimated that the amount of vitamin D that the group had received from the sun during the summer was equivalent to approximately 2800 international units (IU) of vitamin D a day.
Current RDAs of vitamin D are 200 IU per day for adults aged 19 to 50, 400 IU for those aged 51 to 70, and 600 IU for those over 70.
When the men were reassessed during February and March of the following year For the purposes of this study, vitamin D insufficiency was defined as a serum 25 OH D concentration of <15 n/ml. Over one-third had serum 25 OH vitamin D concentrations of less than 15 ng/ml, while the mean total 25 OH D concentration was 19.4 ng/ml.
The researchers concluded that vitamin D deficiency is more common than previously thought and it is not restricted to high-risk groups such as the homebound elderly.
24th Annual Meeting of the American Society for Bone and Mineral Research San Antonio, Texas September 24, 2002
Now is the time for most of us to start back on the cod liver oil. The only exceptions in the US are those who have regular access to sunshine in the warmer southern states.
As the above studies show most of us become quite deficient in vitamin D. I have been measuring levels in nearly all my patients since February. Towards the end of the winter well over 95% of patients had suboptimal levels of vitamin D.
I have a lecture to about 350 high-powered nutritionists in August and was quite surprised to find that only one person was regularly measuring vitamin D levels.
Folks vitamin D is one of the most important vitamins you can optimize, largely because it is not a vitamin. It is the "only" vitamin that even traditional experts advise breast fed babies to be on in the winter. That is because it is not transferred in breast milk at all. The grand design was to get it from sun exposure to the skin, but that just doesn’t happen for most of us in the winter.
The dose of cod liver oil for infants is the same as adults, one teaspoon for every 50 pounds of body weight. So a 10-pound newborn would take 1/5 of a teaspoon. This is about 25 drops if you use a dropper.
The liquid is far easier to take then capsules as a 150 pound adult would need to take one tablespoon and this would be the equivalent of about 15 standard fish oil capsules. Additionally my experience is that most of the liquids are higher quality than the capsules and also less expensive.
Paying attention to quality is an issue as fish oil can easily go rancid and you absolutely don’t want bad fish oil. I have been very pleased with Carlson brand and it is the only one that we stock in our office.
Many of you have not been able to obtain this locally so we finally decided to carry it in our store.
If you have any further questions about vitamin D please read the articles I wrote earlier this year.
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Breakthrough Updates You Need to Know on Vitamin D
Vitamin D Is Not A Vitamin But A Steroid Hormone Precursor
Test Values and Treatment for Vitamin D Deficiency