When Should I Take Vitamin D?

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The question is often asked – when should I take my supplements. Most of the time, this is down to a matter of convenience as much as it is to absorption and nutrient availability.  However this is a very valid question in terms of Vitamin D consumption. Vit D levels have attracted lots of attention over the last few years and included with this has been a number of trials and clinical experiences in which there have been differing levels of success based on supplementation in terms of increased blood levels. This paper out in February 2010 in the Journal of Bone Metabolism[1] helps to explain these anomalies.

Many patients treated for vitamin D deficiency fail to achieve an adequate serum level of 25-hydroxyvitamin D [25(OH)D] despite high doses of ergo- or cholecalciferol.

To see if food combinations could influence absorption, a small group of 17 non responding patients were selected. Their mean age (±SD) and sex (F/M) ratio were 64.5 ± 11.0 years and 13 females and 4 males, respectively. The dose of 25(OH)D ranged from 1000 to 50,000 IU daily.

Key Points

  • The mean baseline serum 25(OH)D level (±SD) was 30.5 ± 4.7 ng/mL (range 21.6 to 38.8 ng/mL).
  • The mean serum 25(OH)D level after diet modification (±SD) was 47.2 ± 10.9 ng/mL (range 34.7 to 74.0 ng/mL, p < .01).
  • Overall, the average serum 25(OH)D level increased by 56.7% ± 36.7%.

A subgroup analysis based on the weekly dose of vitamin D was performed, and a similar trend was observed. Thus it is concluded that taking vitamin D with the largest meal improves absorption and results in about a 50% increase in serum levels of 25(OH)D levels achieved.  Similar increases were observed in a wide range of vitamin D doses taken for a variety of medical conditions.


The consumption of a high quality Vit D supplement may well affect the absorption rate over poorer availability supplements, as demonstrated in this study using Biotics Research Vit D in children.[2] Managing food selection as well as supplementation will increase the availability and uptake considerably, especially in those patients that seem to stubbornly resist the increase in serum Vit D levels.


[1] Mulligan GB, Licata A. Taking vitamin D with the largest meal improves absorption and results in higher serum levels of 25-hydroxyvitamin D. J Bone Miner Res. 2010 Apr;25(4):928-30. View Abstract

[2] Gordon CM, Williams AL, Feldman HA, May J, Sinclair L, Vasquez A, Cox JE. Treatment of hypovitaminosis D in infants and toddlers. J Clin Endocrinol Metab. 2008 Jul;93(7):2716-21. Epub 2008 Apr 15. View Full Paper

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