African American asks: How much more Vitamin D should I take?

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My doctor wrote me a prescription for 400 IU of vitamin D3 daily. My blood test results show I am deficient: 17.1. However, I forgot to tell her that I [already] take 2000 IU of vitamin D2 daily. Should the vitamin D3 be in addition to or instead of the supplement I already take?

Age: 32
Ethnicity: African American/Black
Height: 66
Weight: 150 lbs
Conditions: Psoriasis

This is an example of questionable medical advice. The request was seen on another website. The date had to be checked to verify the inquiry was not made in 2001. 400 IU is a very small prescription, basically child level, or an adult level 20 years ago.

The level of 17.1 is also low and prescribing such a low amount for a deficient person makes no sense, especially when the IOM recognizes an upper safety level of 4000 IU per day. (No justification of trying to stay within IOM parameters.)

Many experts now believe that intakes of 25 μg/d (1000 IU) or more may be needed for most people to achieve optimal blood levels of 25(OH)D. This is supported by a study in African American women aged 15–49 who took 10 μg/d (400 IU) of supplemental vitamin D (in addition to dietary vitamin D); 11% of the subjects had 25(OH)D levels ≤37.5 nmol/L, so a much higher percentage clearly had levels below the desirable 75–80 nmol/L range.[1]

Moreover, it is well-established that African Americans may need more vitamin D (a higher percentage are deficient), in part because they need about 5 times as much sun exposure as white people to get the same amount of vitamin D from sunshine.

Furthermore, the patient has psoriasis, which has been resolved for some patients with extra vitamin D.[2] It is not surprising that this person was at 17.1 even while taking 2000 IU daily.

BMI is 24.2, which is just outside of overweight (25.0-30.0). Obese patients (30.0+) would typically be prescribed 2 to 3x more vitamin D.

This patient could take at least 4000 IU of D3 per day, total, assuming no contraindications, or even start taking 6000 IU per day for eight weeks, similar to the Holick Protocol (50,000 IU per week for eight weeks). Then get retested.

Under expert care, with proper monitoring, a higher amount could be supported. For example, in one experiment:

All patients presented low baseline levels of 25(OH)D3 (≤ 30 ng/mL or ≤ 75 nmol/L), with a mean of 14.9 ± 7.4 ng/mL in the psoriasis group… After 6 months of treatment with vitamin D3 (35,000 IU per day), 25(OH)D3 levels increased significantly, to 106.3 ± 31.9 ng/mL in the psoriasis group (p < 0.0001).[3]

  1. Harris S. S. (2006). Vitamin D and African Americans. The Journal of nutrition, 136(4), 1126–1129.
  2. Finamor, D. C., Sinigaglia-Coimbra, R., Neves, L. C., Gutierrez, M., Silva, J. J., Torres, L. D., Surano, F., Neto, D. J., Novo, N. F., Juliano, Y., Lopes, A. C., & Coimbra, C. G. (2013). A pilot study assessing the effect of prolonged administration of high daily doses of vitamin D on the clinical course of vitiligo and psoriasis. Dermato-endocrinology, 5(1), 222–234.
  3. Ibid.

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