November 24, 2014

295 Vitamin D – How Much? [24 Nov 2014]

How much vitamin D should we be taking? We have a good idea what blood levels are optimum for health. Dr William Grant of the Vitamin D Council states that 75 nmol/L is “the minimum [vitamin D] concentration associated with optimal health”. The Vitamin D Society, a Canadian non-profit organization, recommends Canadians maintain levels between 100 and 150. But what supplementation do we need to achieve this? Pure North S’Energy Foundation of Calgary carried out a study, published this month, to answer just that.

Over 17,000 healthy adult volunteers of varying BMI (Body Mass Index) were supplemented with different levels of vitamin D for a year, and had their serum D levels measured before and after. On average, 5,000 IU daily achieved a level of about 100 nmol/L; 10,000 about 140; and 20,000 about 150. Note the diminishing returns on increased dosage. Results varied considerably according to the person’s BMI. People of normal weight required about 2,500 IU to reach 100 nmol/L and 10,000 to reach 150. Overweight people required 3,000 and 14,000 respectively; obese people 12,000 and somewhere over 20,000; while underweight people needed only 2,000 and 8,000.

Remember, these figures are for healthy people; people with MS or fighting cancer would want to achieve a higher blood level and would likely need to take a higher dosage to achieve it. A Rosetown woman with MS told me that she was taking 50,000 units for a prolonged period just to keep her vitamin D level in the low end of normal.

Keep in mind that these are all averages and individual results vary considerably so it is important to check your baseline vitamin D levels before beginning (or increasing) supplementation and to have your blood levels monitored regularly.

No adverse side effects were observed in this study, despite supplementation at more than 20,000 IU per day. No cases were reported of hypercalcemia, a concern of critics of high dose D supplementation. This is consistent with other studies which showed no adverse effects with supplementation of up to 50,000 IU.

For more information on this or other natural health topics, stop in and talk to Stan; for medical advice consult your licensed health practitioner


  1. Canada and the USA use different units for vitamin D blood levels.
    Canada uses nmol/L (used in the above article); the US uses ng/ml.
    Conversion: ng/ml X 2.5 = nmol/L or nmol/L divided by 2.5 = ng/ml.

  2. Dr. Rhonda Patrick and Dr William Grant of the Vit D Council agree on these vitamin D blood values. Minimum for health is 30 ng/ml (US) and 75 nmol/L (Can); optimum levels are 40-60 ng/ml or 100-150 nmol/L.