Click to View Response to Dr. Martiquet, Vancouver Coastal Health Overdoing the sunshine vitamin
Nov 27, 2015

Dear Dr. Martiquet,

I was very disappointed to read your recent article in the Coast Reporter on vitamin D:

Overdoing the sunshine vitamin

The main focus of your article seems to be to ensure that people do not exceed the vitamin D doses recommended by Health Canada and the IOM for fear of toxicity. This will frighten many people away from vitamin D supplementation who are vitamin D deficient and require supplementation.

November is Vitamin D Awareness Month. A time when we encourage all Canadians to check and ensure that their vitamin D intake provides them with optimal levels of vitamin D for best health. The problem that the Canadian public face, contrary to your focus, is that the great majority do not receive enough vitamin D. Statistics Canada report that 35% of Canadians fall below the Health Canada and IOM guideline for vitamin D of a 25(OH)D blood level of 50 nmol/L. That represents 12 million people. This rises in winter to over 40%. This puts this large group of Canadians at a much higher risk for many serious diseases such as CVD, cancer, MS, diabetes, osteoporosis, dementia, Alzheimers disease and more.

Why not use this editorial space to help reduce the epidemic of vitamin D deficiency in Canada and prevent disease? We need to set priorities. What is the risk of possible vitamin D toxicity vs the risk of vitamin D deficiency? Instead you alert people to a very minute problem of possible vitamin D toxicity while ignoring the elephant in the room, the enormous problem of vitamin D deficiency in Canada.

Instead of believing the IOM and Health Canada, why not do your own independent review of toxicity and vitamin D. The Endocrine Society have set the upper limit for adults (age >18) at 10,000 IU/d. I have attached a couple of papers for you to consider. Vitamin D toxicity may occur at 25(OH)D blood levels over 500 nmol/L or at a consistent daily intake of greater than 30,000 IU/day (Hathcock). A Canadian study looking at pharmacological dosing on MS patients found that doses of up to 40,000 IU/d and serum concentrations of 25(OH)D in the range of 400 nmol/L can be attained without causing hypercalcemia or hypercalcuria, and they do not cause adverse clinical or paraclinical effects (Kimball). How many people in Canada have 25(OH)D levels in this range? 500 nmol/L? .1%?

When looking at vitamin D you can't objectively look at dosing because everyone is different and the same dose will provide a great variation in individual 25(OH)D blood levels. One of the largest factors in this variation is body weight. Heavier people need a higher intake of vitamin D to reach a certain 25(OH)D level. The IOM and Health Canada obviously do not understand this concept. For example the Health Canada recommended dose for an infant baby is 400 IU. That is 40 IU per pound for a 10 pound infant. Health Canada also recommend 600 IU for adults. So a 200 pound man would get 600 IU or 3 IU per pound?? Does that seem correct to you? As a doctor, I'm sure you would not prescribe a drug to a baby in the same dose amount as you would to an adult.

Studies have been completed that show that a 400 IU/d dose to a baby infant would provide them with a vitamin D 25(OH)D level of over 100 nmol/L (Wagner). Clearly this cannot be a health risk as Health Canada and the IOM are both recommending this intake and would never put the health of Canadian or American infants in jeopardy. So the logical/safe dose for an adult would be 40 IU per pound. This would work out to 8,000 IU for a 200 pound man. For a very obese person who weighs 350 - 400 pounds that may in fact be 15,000 IU. The only way to find out would be to measure their 25(OH)D.

The key to vitamin D is 25(OH)D blood level. The Vitamin D Society use a recommendation endorsed by 48 vitamin D doctors, scientists and researchers who through GrassrootsHealth published a Scientists Call to D*action which recommends everyone, all ages, all skin types, all weights, achieve an optimal vitamin D level of between 100-150 nmol/L.

I would be happy to send you any additional papers you might require on vitamin D toxicity. I can also arrange to have one of our scientific advisors call you regarding vitamin D toxicity. Please let me know what you require.

For now I would suggest you complete another editorial for the Coast Reporter and set the record straight on vitamin D toxicity. Thank you.


Perry Holman

Executive Director

Vitamin D Society