MISCELLANEOUS INSTRUCTIONS ON VITAMIN D3 DOSE—this is a steroid hormone mistakenly named a “vitamin” in ~1922.

[Take heed:  Avoid vitamin D2, which is available by prescription only,  as 50,000 I.U. gel capsules, to be taken once a week. D2 is from plants, is less potent and has a shorter ½ life. It was grandfathered in as a prescription since it was the only good source of vitamin D 80+ years ago. Virtually all the vitamin D one buys with]ithout a prescription is D3—the identical vitamin D we use.]
The basic dose of D3 is 1000 I.U. per day for every 25 lbs—in children and adults. A Chassidic Rabbi—Herschel Meisels– told me this years ago.  My reading of the literature since then confirms it.  So a 100 lb person needs about 4000 I.U./day,  10 lb baby needs about 1/10 that = 400 I.U./day , and a 200 lb person needs about 8000 I.U./day.  A 250 lbs person needs 10,000 I.U. /day.   I weigh 210 lbs, take 6 pills of 50,000 I.U. once a month = 300,000 I.U. in one dose = an average of 10,000 I.U. /day and my level is 66 ng/ml —the level should be between 50 and 100 ng/ml.  My internist thinks about 70 is perfect.

  • We make this hormone in about 5 steps. We need the UVB light to strike the skin for one of the steps—when the sun is high in the sky.   Light skinned people can make 15,000 I.U. of D3 in 45 minutes if sunbathing in the middle of the day—with a lot of skin exposed.  People over 65 make ¼ to ½ as much as someone 30 y.o.
  • For adults, the usual dose of the HORMONE called “vitamin” D3  is 4 pills once a month, using  50,000 I.U. pills.  It is probably a little better to take one per week, so that the level is steadier.  But it is easier to remember once a month.  One can take it monthly [or even take 12 pills every 3 months] because #1: the half-life is about 6 weeks, and #2: the next step is the storage form –vitamin D 25-OH (calcidiol), which is stored in large amounts in the blood, attached to vitamin D binding protein. If you cannot remember if you took 4 pills, take 4 again.  Toxicity is only if you take ≥ 30 pills of 50,000 I.U. each per month for a few months.
  • This is lifelong hormone replacement. The 3rd of 5 steps in the manufacture of this steroid hormone involves UVB striking the skin and converting 7-dehydrocholesterol into D3 (cholecalciferol).   No one in the developed world is in the sun enough to produce enough D3.



  • Someone weighing 100 to 150 lbs can take just 3 pills once a month. With 10 years of experience I have found that people are much more likely to stay on this if it is only a once a month dose.   Also, if one has several children, it is much easier to give them each their dose once a month.
  • Someone > 150 lbs can take 4 pills per month.
  • For a person weighing 50 to 100 lbs, the dose is 2 pills once a month.
  • SOMEONE over 70 y.o. may be metabolizing it slowly so may only need 1000 to 3000 I.U. /daye., 1- 2 pills per month of 50,000 I.U. pills.  Check your level.    If you change the dose, check the level 3 to 6 months later.
  • Because the half life of vitamin D is about 6 weeks, it builds up slowly. If you start at 5000 I.U. /day [or 3 pills of 50,000 once a month], each dose will be adding to previous doses.  You may not reach a steady state for 5 x 6 weeks = 30 weeks, about 6 months.  A steady state is consistent, steady level that will stay where it is as long as you continue on the same regular dose.   If your level is very low, this makes it advisable to take a loading dose—e.g., double the dose for the first month.   [There was one study where young adults had an average level of about 15 ng/ml.  They gave them a single dose of 600,000 I.U.  [12 pills of 50K I.U.]—i.e., a 3 month supply all in one dose.  A few days later their vitamin D level was about 70 ng/ml.]


  • Children can take Zahler’s liquid D where there is 4000 I.U. in each tiny drop of olive oil. The dose is completely weight related.  Adults and children need about 1000 I.U./day for every 25 lbs.   [A recent paper indicates that infants in their first year may be better off on more, but for now I am staying at a conservative 1000 I.U. per 25 lbs = 400 I.U. for every 10 lbs.]
  • A 100 lb person needs 30 drops once a month. A 50 lb  child therefor needs 15 drops once a month.  You don’t have to be exact.  Since ½ dropper full is about 15 drops, then you can give a 50 lb child ½ dropper full once a month.
  • Remember, each tiny drop of olive oil [not a dropper full!] contains 4000 I.U. of vitamin D3, and the dose is 1000 I.U./day for every 25 lbs.  One drop per day is the idea dose for a 100 lb person and 2 drops /day is the ideal dose for a 200 lb person.

A 10 lbs baby needs 3 drops once a month;

15 lbs: needs 4 drops/ once a month

20 lbs: 6 drops/ mo

25 lbs: 8 drops/ mo

50 lbs:15 drops/ mo

75 lbs:  23 drops/ mo

100 lbs:30 drops/mo



SOURCES OF 50K I.U. PILLS:  David’s Choice http://www.applehealthfoods.net  has  #180 of 50K I.U. pills for ~$25—i.e.,  a 2½ year supply—i.e., $8/year.

Zahler’s Vitamins [kosher]  50K I.U. pills—120 pills for ~$25.

Zahler’s has liquid D with 4000 I.U. in each drop.

50,000 I.U. pills of D3:

The dose for people over 125 lbs is 1 pill per week, or 4 once a month.

            For someone over 225 lbs, I think 6 per month is more appropriate.

For 100 to 125 lbs, the dose is 3 pills once a month.

For 50 to 100 lbs, the dose is 2 pills once a month. 

The half life is about 6 weeks).    If in doubt, get a blood level of vitamin D 25-OH.  Most physicians do not yet know that the appropriate dose is about 1000 I.U. /day for every 25 lbs for adults as well as children.   With such a dose the level usually gradually comes between 50 and 100 ng/ml, when “normal” is between 32 and 100.   Levels to 200ng/ml are quite safe, according to NIH and many experts, though the lab report says above 100 is excessive or even “toxic”.  The labs say 100 ng/ml is maximum because people cannot naturally obtain a level above 100 ng/ml no matter how much sun they are in.

For children I use Zahler’s Liquid that has 4000 I.U. in each drop of olive oil.  It is easy to induce children to take it, as it tastes like olive oil and you can put it on the food.  I put this on the bottle:

Each tiny drop of olive oil [not a dropper full!] contains 4000 I.U. of vitamin D3, and the dose is 1000 I.U./day  for every 25 lbs.  For every 50 lbs, dose is 15 drops/mo – or 4 drops/week  10 lbs: needs 3 drops/mo  15 lbs: needs 4 drops/ mo  20 lbs: 6 drops/ mo  25 lbs: 8 drops/ mo 50 lbs:15 drops/ mo 75 lbs:  23 drops/ mo  100 lbs:30 drops/ mo