Submitted to: Journal of Bone and Mineral Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/17/2013
Publication Date: 2/20/2013
Citation: Dawson-Hughes, B., Harris, S., Palermo, N., Ceglia, L., Rasmussen, H. 2013. Meal conditions affect the absorption of supplemental vitamin D3 but not the plasma 25-hydroxyvitamin D response to supplementation. Journal of Bone and Mineral Research. 28(8):1778-1783. Interpretive Summary: In the human, it is sometimes assumed that dietary fat is required for vitamin D absorption, although the impact of different amounts and types of dietary fat on vitamin D absorption is not established. In the rat, absorption of vitamin D was enhanced by the presence of small amounts of fat and impaired with larger amounts of fat in the gut. We therefore hypothesized that a low-fat meal would have a more favorable effect on absorption than a high-fat meal. We tested this hypothesis in a study in which changes in vitamin D absorption and in plasma 25-hydroxyvitamin D levels were compared in 62 healthy older adults who were randomly assigned to take supplemental vitamin D each month for 3 months with either: no meal (after a 12 hour fast), a high-fat meal, or a low-fat meal. We found that absorption was significantly greater with the low-fat meal than with no meal (by 20 percent) or with the high-fat meal (by 16 percent), however serum 25-hydroxyvitamin D levels didn’t differ in the three groups at any point during the study. We conclude that metabolism of 25-hydrolyvitamin D level is an important contributor to the circulating 25-hydrolyvitamin D level. More research is needed to define the determinants of 25-hydroxyvitamin D metabolism.
Technical Abstract: It is sometimes assumed that dietary fat is required for vitamin D absorption, although the impact of different amounts of dietary fat on vitamin D absorption is not established. This study was conducted to determine whether the presence of a meal and the fat content of the meal influences vitamin D absorption or the 25-hydroxyvitamin D (25OHD) response to supplemental vitamin D(3). Based on earlier studies in rats we postulated that absorption would be greatest in the low-fat meal group. Sixty two healthy older men and women were randomly assigned to one of three meal groups: no meal, high-fat meal or low-fat meal; each was given a monthly 50,000 IU vitamin D3 supplement with the test breakfast meal (or after a fast for the no-meal group) and followed for 90 days. Plasma vitamin D(3) was measured by LC/MS before and 12 hrs after the first dose; plasma 25OHD was measured by radioimmunoassay at baseline and after 30 and 90 days. The mean 12-hr increments in vitamin D3, after adjusting for age and sex, were 200.9 nmol/L in the no-meal group, 207.4 nmol/L in the high-fat meal group, and 241.1 nmol/L in the low-fat meal group (P = 0.038), with the increase in the low-fat group being significantly greater than the increases in the other two groups. However, increments in 25OHD levels at 30 and 90 days didn’t differ significantly in the three groups. We conclude that absorption was increased when a 50,000 IU dose of vitamin D was taken with a low-fat meal, compared with a high-fat meal and no meal, but that the greater absorption didn’t result in higher plasma 25OHD levels in the low-fat meal group.