Table 2 Vitamin D dosing based on blood level

If vitamin D > 100 ng/ml and elevated calcium (Ca²⁺) > 10.2 mg/dl

 • Call study participant and have them stop vitamin D immediately, increase water intake.

  a. If Ca²⁺ level was 10.2–10.5: call your local physician, or urgent care for guidance.

  b. If Ca²⁺ level was 10.6 or higher: go to the emergency room for evaluation and probable intravenous fluids.

 • Stop or do not start taking the cod liver oil or the multivitamin

 • When vitamin D < 80 ng/ml, resume vitamin D at a reduced dose and cod liver oil and multivitamin per local primary care or neurology guidance

 • Call and notify the study participant’s primary care/neurology team about the high vitamin D level

 • Send letter to participant and primary care/neurologist

If vitamin D > 100 ng/ml and normal calcium Ca²⁺ 8.5–10.2 mg/dl

 • Study staff will call the participant and have them stop all vitamin D supplements. Participant will follow up with their primary care doctor or neurologist.

 • Stop or do not start taking cod liver oil but may continue multivitamin

 • When vitamin D < 80 ng/ml, may resume vitamin D at a reduced dose and cod liver oil and multivitamin per local primary care or neurology guidance

 • Call and notify the study participant’s primary care/neurology team about the high vitamin D level

 • Send letter to participant and primary care/neurologist

If vitamin D between 81 and 100 ng/ml

 • Start or continue taking cod liver oil and multivitamin

 • Reduce total vitamin D intake by 50%

  ∘ The goal is half the dosage from all sources participant was taking at the time the blood measurement was made

  ∘ If the vitamin D₃ supplement dosage was in fractions; then, round it down to the next available pill in the market.

  ∘ E.g., if the total taken is 7000; 1000 from MV, 1000 from calcium/vitamin D₃ supplement and 5000 IU vitamin D₃ we want to halve the dose; then the total amount to take becomes 3500. We will ask the participant to continue calcium/vitamin D₃ (1000 IU), switch to our MV (1000 IU), start cod liver oil (400 IU), which totals 2400. The remaining vitamin D₃ (3500–2400) is 1100 IU (round down to 1000 IU), so we prescribe a 1000-IU pill once daily.

 • Send letter to participant and primary care/neurologist

If vitamin D 40 to 80 ng/ml

 At visits 2, 3, and 4:

  • Start or continue taking cod liver oil and multivitamin which contain about 1400 IU between the two supplements. Keep participant on current dose of vitamin D if in this range.

 At all visits:

  • Do not change vitamin D dose. E.g., if the participant is taking 4000 IU from their personal physician, participant should stay on that dose. If they were taking 5000 IU from their personal physician they should stay on that dose. If participant is taking more than 5000 IU or less than 4000 IU, participant should continue on that dose.

  • No need to start vitamin D₃ supplement if not on any.

If vitamin D value less than 40 ng/ml but more than 20 ng/ml

 If visit 1 blood result:

  • Wait until visit 2.

 At visit 2:

  • If not taking any vitamin D, begin 5000 IU daily. Participant will also begin or continue taking cod liver oil and multivitamin according to the supplement schedule.

  • If taking 4000 IU vitamin D₃ or less daily, participant will be instructed to increase vitamin D₃ to 5000 IU and add or continue taking cod liver and multivitamin according to the supplement schedule.

  • If the participant is already taking 5000 IU but does not take the supplement regularly (i.e., daily) they will be instructed to take the supplement every day and add or continue taking cod liver oil and multivitamin.

  • If taking 5000 IU or more they should add or continue taking cod liver oil and multivitamin. Discuss with Dr. Wahls for further guidance on the appropriate vitamin D dose.^a The patient and primary care/neurology team will be notified by letter of the lab results and the vitamin D, cod liver oil and multivitamin recommendations.

  • Send letter to participant and primary care/neurologist if participant is instructed to change vitamin D intake prescribed by medical personnel

 If visit 2 blood result:

  • Wait until visit 3 blood result.

 If visit 3 or 4 blood result:

  • And participant is taking 5000 IU vitamin D, cod liver oil and the multivitamin, discuss with Dr. Wahls for further guidance.^a An increase in the vitamin D dose will likely be recommended by Dr. Wahls and personalized results letters will be sent separately to the participant and their primary care/neurology team.

If vitamin D value 20 ng/ ml or less

 If visit 1 or 2 blood result:

  • Refer participant back to primary care physician and neurologist, recommending the primary care physician or neurologist prescribe vitamin D₂ 50,000 IU once per week until vitamin D level is greater than 40 ng/ml. Alternatively, the primary care physician may recommend 6000 to 10,000 IU vitamin D₃ daily if preferred over vitamin D₂.

  • Send letter to participant and primary care/neurologist

  • Call and notify participant that vitamin D level is severely low and advise them that a letter is being sent to them and their primary care/neurology team.

 If visit 2, 3, or 4

  • Call participant to clarify if the participant is taking any vitamin D supplements, cod liver oil or multivitamin and discuss with Dr. Wahls for further guidance. If already on vitamin D₃ 5000 IU or a vitamin D₂ supplement per their local medical team, the participant may continue the vitamin D until they see their primary care/neurology team for further guidance. Continue or add cod liver oil and multivitamin as scheduled.

  • Send letter to participant and primary care/neurologist