For fall prevention, 100-15,000 IU of vitamin D2 or vitamin D3 has been taken by mouth daily, often with calcium for up to 62 months. A dose of 100,000 IU of vitamin D2 has been taken by mouth every three months for up to five years. Single doses of 300,000-500,000 IU have been taken by mouth.
http://www.mayoclinic.org/drugs-supplements/vitamin-d/dosing/HRB-20060400
Vitamin D is found in supplements (and fortified foods) in two different forms: D 2 (ergocalciferol) and D 3 (cholecalciferol). Both increase vitamin D in the blood.
https://ods.od.nih.gov/factsheets/VitaminD-Consumer/
At the end of 2008, the American Academy of Pediatrics doubled its recommended dose of vitamin D for infants, children, and adolescents, raising it from 200 to 400 units per day. Unfortunately, this is still a woefully inadequate recommendation for children.
http://articles.mercola.com/sites/articles/archive/2009/10/10/vitamin-d-experts-reveal-the-truth.aspx#!
For heart disease, 200-2,000 IU or 10-25 micrograms of vitamin D2 or D3 has been taken by mouth daily for 1.4-84 months, with or without calcium. A dose of 100,000 IU of vitamin D2 or D3 has been taken by mouth three times yearly for up to three years.
http://www.mayoclinic.org/drugs-supplements/vitamin-d/dosing/HRB-20060400
I totally agree with your suggestion to take 10,000 IU per day for three months. Then once you get a blood test, stay at that level if you are 50-70 ng/mL and reduce it if you are higher. If you have MS or some other autoimmune disease, starting with 20,000 IU is not a bad idea.
http://articles.mercola.com/sites/articles/archive/2009/10/10/vitamin-d-experts-reveal-the-truth.aspx#!
It is one consequence of not getting enough calcium and vitamin D over the long term. Supplements of both vitamin D 3 (at 700–800 IU/day) and calcium (500–1,200 mg/day) have been shown to reduce the risk of bone loss and fractures in elderly people aged 62–85 years.
https://ods.od.nih.gov/factsheets/VitaminD-Consumer/
Doses of 400-4000 IU vitamin D have been taken by mouth daily for the third trimester or starting the 12th week of pregnancy; other doses were 120,000-600,000 IU of vitamin D taken by mouth monthly at the 5th, 7th, and/or 8th months or the 27th week of pregnancy.
http://www.mayoclinic.org/drugs-supplements/vitamin-d/dosing/HRB-20060400
The upper limit for vitamin D is 1,000 to 1,500 IU/day for infants, 2,500 to 3,000 IU/day for children 1-8 years, and 4,000 IU/day for children 9 years and older, adults, and pregnant and lactating teens and women. Vitamin D toxicity almost always occurs from overuse of supplements.
https://ods.od.nih.gov/factsheets/VitaminD-Consumer/
Recommended Daily Intake for Optimal Health. Based on the most recent research, the current recommendation is 35 IUs of vitamin D per pound of body weight. So for a child weighing 40 pounds, the recommended average dose would be 1,400 IUs daily, and for a 170-pound adult, the dose would be nearly 6,000 IUs.
http://articles.mercola.com/sites/articles/archive/2009/10/10/vitamin-d-experts-reveal-the-truth.aspx#!
Currently, the U.S. RDA for vitamin D is 400 IUs (international units) for the majority of the population. (IU is frequently shortened to just “units.”) This dose was recommended to prevent rickets, which works well, but does nothing to give the far more important protection from cancer, heart disease, and infections.
http://articles.mercola.com/sites/articles/archive/2009/10/10/vitamin-d-experts-reveal-the-truth.aspx#!
how much daily vitamin d
The recommended amount of vitamin D for infants, children, and adolescents is 400 units per day. The daily Vitamin D for infants, children, and adolescents, raising it from 200 to 400 units per day.