Here are some studies demonstrating the inadequacy of traditional vitamin D doses for treating vitamin D-deficiency and it’s related diseases:

The Effect of Various Vitamin D Supplementation Regimens in Breast Cancer Patients (2011)

Conclusion: In an experiment involving 224 women with breast cancer, those given 50,000 IU of vitamin per week experienced much more improved vitamin D levels compared to women given only 1,000 IU daily.


High Prevalence of Hypovitaminosis D in a Swiss Rheumatology Outpatient Population (2011)

Conclusion: 272 Swiss rheumatology patients had their vitamin D levels tested and nearly 90% had low levels. Only 25% of those taking vitamin D supplements (400-800 IU daily) enjoyed adequate vitamin D levels, demonstrating that traditionally recommended doses are not enough.


A 16-Week Randomized Clinical Trial of 2000 International Units Daily Vitamin D3 Supplementation in Black Youth: 25-Hydroxyvitamin D, Adiposity, and Arterial Stiffness (2010)

Conclusion: A 4-month study of 44 black teenagers found that 95% had low vitamin D levels and that supplementing with 2,000 IU of vitamin D daily was effective for reducing arterial stiffness and increasing vitamin D levels. The study also found that the vitamin D levels of the obese subjects rose less than the leaner subjects. Although 2,000 IU daily was effective in raising levels, only 56% achieved sufficient levels after the four months.


Randomized Comparison of the Effects of the Vitamin D3 Adequate Intake Versus 100 mcg (4000 IU) Per Day on Biochemical Responses and the Wellbeing of Patients (2004)

Conclusion: Two randomized trials where participants were either given 600 IU of vitamin D daily or 4,000 IU of vitamin D daily for three months found that those given the higher dose of 4,000 IU had better vitamin D levels and better well-being scores upon evaluation at the end of the trial.


Human Serum 25-Hydroxycholecalciferol Response to Extended Oral Dosing with Cholecalciferol (2003)

Conclusion: 67 men living in Omaha, Nebraska were given varying doses of vitamin D throughout the winter (five months) to see what dose is ideal for helping men maintain adequate vitamin D levels. The study found that men use 3,000-5,000 IU of vitamin D daily and that the historically recommended adult dose of 400 IU is not enough for replenishing this.


Effects of Vitamin D Supplementation on Strength, Physical Function, and Health Perception in Older, Community-Dwelling Men. (2003)

Conclusion: This study found that taking 1,000 IU of vitamin D daily for six months did not improve muscular strength, physical performance, or general health parameters in elderly men. This makes sense as 1,000 IU is an infant-size dose.


Efficacy and Safety of Vitamin D3 Intake Exceeding the Lowest Observed Adverse Effect Level (2001)

Conclusion: Adult men and women were given either 1,000 IU or 4,000 IU of vitamin D3 to take daily for 2-5 months. Not only did 4,000 IU not cause any negative side effects or toxicity, it was also not enough to raise the mean vitamin D level beyond 40 ng/ml (most leading experts recommend 50 ng/ml), suggesting that the average adult needs more than 4,000 IU per day.


Vitamin D Supplementation, 25-Hydroxyvitamin D Concentrations, and Safety (1999)

Conclusion: Contrary to the long-held belief of the medical establishment that adults should take no more than 400 IU of vitamin D daily, this study concludes that adults need at least 4,000 IU of vitamin D daily to achieve sufficient vitamin D levels and that even 10,000 IU of vitamin D daily is safe for adults. It takes long-term dosing of vitamin D in excess of 40,000 IU daily to develop vitamin D toxicity and hypercalcemia in adults. Lifeguards and outdoor workers often obtain very high natural vitamin D levels from their heavy sun exposure that would take long-term daily supplement doses in excess of 10,000 IU to achieve.


Vitamin D Intake is Low and Hypovitaminosis D Common in Healthy 9- to 15-Year-Old Finnish Girls (1999)

Conclusion: This one-year study followed 186 young caucasian Finnish girls aged 9-15, tracking their dietary habits, physical activity habits, measured their vitamin D levels multiples times throughout the year, and tested the effectiveness of supplementing with 400 IU of vitamin D daily for preventing deficiency. The vitamin D level of the group at the beginning of the study in winter was a horribly low 13.5 ng/ml.The group vitamin D level rose significantly during summer to 25 ng/ml, which is still inadequate (and in spite of taking 400 IU per day). At the 12-month testing in the next winter, after taking 400 IU of vitamin D most days, the vitamin D level of the group had barely increased and was still at the deficient level. The findings of this study are: vitamin D levels rise in the summer, vitamin D levels fall in the winter, and not only is 400 IU of vitamin D incapable of preventing vitamin D-deficiency in young girls, this dose barely increases vitamin D levels in young girls at all. Also, even during summer they failed to achieve adequate vitamin D levels. This is probably due to Finland’s very high latitude.


Also see:

Studies Demonstrating Safety of High-Dose Vitamin D Therapy



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