I’ve often struggled in trying to explain to my dear patients that it was ok if they chose to combine a weeks dose of Vitamin D and take it once every week. Turned out, that choice, made things slightly complicated! “Really? XX,000 Units of Vitamin D at once? There must be some damage!?” (If you like taking your vitamins every morning and have no problem remembering them, then continue with what works for you! If you however, have a hard time with compliance then read on!)
Every vitamin is unique in the way it funcions in the body with regards to it’s absorption, storage and excretion. Vitamin D is a fat-soluble vitamin which ends up being stored in your liver and not excreted (as opposed to water-soluble vitamins that end up being excreted when taken in excess). As a result, there’s legitimate fear regarding vitamin D’s toxicity in high dosages. Vitamin D however is known to have double the therapeutic index as that of water. As in, if you were to drink 40 glasses of water a day (therapeutic index of 5 (40/8)), you could seriously hurt yourself. Research indicates that healthy humans utilize about 4,000 units of vitamin D a day (Heaney et. al). However, 40,000 units a day, over several years, will hurt them. Therefore, vitamin D has a therapeutic index of 10 (40,000/4,000).
If you live in the northern hemisphere, are not frequenting a tanning salon (with UVB), are not drinking gallons of Vitamin D fortified milk, and have not vacationed to a sunny location recently, then you are most likely Vitamin D deficient. Although it’s always best to assess your level of deficiency by checking your serum levels, due to recent changes to regulations, medical doctors will no longer be doing ‘routine’ testing for Vitamin D levels (Health Canada Vitamin D fact Sheet).
To adequately assess your Vitamin D needs, seek the advice of a professional. Then, based on that advice know that if you do end up forgetting today’s or last week’s, or even last month’s dosage of vitamin D, that it’s O.K. to take it all at once! For further evidence you can always peruse the many articles that have outlined the safety of for example, yearly or twice yearly intramuscular injections of 100, 000 – 300,000 Units of Vitamin D (Diamond T.H. et al.) among others (van Groningen et. al)…
NOTE: please remember that this article refers specifically to Vitamin D and that such supplementation practises are not O.K. with other Vitamins (be they water or fat-soluble) due to each vitamin’s unique actions.