16.4: Food sources and dietary intakes (18b.4)
- Page ID
- 117076
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\(\newcommand{\avec}{\mathbf a}\) \(\newcommand{\bvec}{\mathbf b}\) \(\newcommand{\cvec}{\mathbf c}\) \(\newcommand{\dvec}{\mathbf d}\) \(\newcommand{\dtil}{\widetilde{\mathbf d}}\) \(\newcommand{\evec}{\mathbf e}\) \(\newcommand{\fvec}{\mathbf f}\) \(\newcommand{\nvec}{\mathbf n}\) \(\newcommand{\pvec}{\mathbf p}\) \(\newcommand{\qvec}{\mathbf q}\) \(\newcommand{\svec}{\mathbf s}\) \(\newcommand{\tvec}{\mathbf t}\) \(\newcommand{\uvec}{\mathbf u}\) \(\newcommand{\vvec}{\mathbf v}\) \(\newcommand{\wvec}{\mathbf w}\) \(\newcommand{\xvec}{\mathbf x}\) \(\newcommand{\yvec}{\mathbf y}\) \(\newcommand{\zvec}{\mathbf z}\) \(\newcommand{\rvec}{\mathbf r}\) \(\newcommand{\mvec}{\mathbf m}\) \(\newcommand{\zerovec}{\mathbf 0}\) \(\newcommand{\onevec}{\mathbf 1}\) \(\newcommand{\real}{\mathbb R}\) \(\newcommand{\twovec}[2]{\left[\begin{array}{r}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\ctwovec}[2]{\left[\begin{array}{c}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\threevec}[3]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\cthreevec}[3]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\fourvec}[4]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\cfourvec}[4]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\fivevec}[5]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\cfivevec}[5]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\mattwo}[4]{\left[\begin{array}{rr}#1 \amp #2 \\ #3 \amp #4 \\ \end{array}\right]}\) \(\newcommand{\laspan}[1]{\text{Span}\{#1\}}\) \(\newcommand{\bcal}{\cal B}\) \(\newcommand{\ccal}{\cal C}\) \(\newcommand{\scal}{\cal S}\) \(\newcommand{\wcal}{\cal W}\) \(\newcommand{\ecal}{\cal E}\) \(\newcommand{\coords}[2]{\left\{#1\right\}_{#2}}\) \(\newcommand{\gray}[1]{\color{gray}{#1}}\) \(\newcommand{\lgray}[1]{\color{lightgray}{#1}}\) \(\newcommand{\rank}{\operatorname{rank}}\) \(\newcommand{\row}{\text{Row}}\) \(\newcommand{\col}{\text{Col}}\) \(\renewcommand{\row}{\text{Row}}\) \(\newcommand{\nul}{\text{Nul}}\) \(\newcommand{\var}{\text{Var}}\) \(\newcommand{\corr}{\text{corr}}\) \(\newcommand{\len}[1]{\left|#1\right|}\) \(\newcommand{\bbar}{\overline{\bvec}}\) \(\newcommand{\bhat}{\widehat{\bvec}}\) \(\newcommand{\bperp}{\bvec^\perp}\) \(\newcommand{\xhat}{\widehat{\xvec}}\) \(\newcommand{\vhat}{\widehat{\vvec}}\) \(\newcommand{\uhat}{\widehat{\uvec}}\) \(\newcommand{\what}{\widehat{\wvec}}\) \(\newcommand{\Sighat}{\widehat{\Sigma}}\) \(\newcommand{\lt}{<}\) \(\newcommand{\gt}{>}\) \(\newcommand{\amp}{&}\) \(\definecolor{fillinmathshade}{gray}{0.9}\)Natural food sources rich in vitamin D are restricted to fatty fish, organ meats, and UV-exposed mushrooms. In some countries — for example, the United States, Canada, and Finland — fluid milk is fortified with vitamin D. In the United Kingdom and Europe, low amounts of vitamin D can be added to some breakfast cereals, margarine, fat spreads, and vegetable oils, breakfast beverages, and breads (Calvo et al., 2005). In low and medium income countries, fortification of wheat, edible plant-based oil or milk, could reduce vitamin D deficiencies (Cashman and O’Dea, 2019).
Intakes from national nutrition surveys provide data on vitamin D in different countries. They show low (3.0µg/d) vitamin D intakes on average in countries where there is little or no vitamin D fortification, such as the U.K. However in countries such as Japan, fatty fish may be consumed in sufficient quantities to provide vitamin D intakes > 7µg/d (Calvo et al., 2005). Canada, where there is mandatory fortification of milk and margarine, has an average intake of 5µg/d which does not meet the adult US/Canadian Estimated Average Requirement (EAR) of 10µg/d. The Canadian government will double the level of mandatory fortification by 2023 to try to reduce the prevalence of inadequacy (Vatanparast et al., 2020).
High Intakes following self-dosing with excessive amounts of vitamin D supplements have been described, although the dose required to induce vitamin D toxicity is uncertain (Hathcock et al., 2007). Vitamin D intoxication does not arise from the consumption of conventional foods (including fortified foods), nor does excess exposure to UVB through sun or artificial lamps cause toxicity (Marcinowska-Suchowierska et al., 2019). Cases of toxicity have arisen, however, from accidental overfortification of milk with vitamin D3, from uncontrolled use of vitamin D mega-doses, and from inappropriate use of vitamin D metabolites. An increased risk for vitamin D toxicity is also associated with certain diseases, including sarcoidosis, tuberculosis, and genetic disorders of rare polymorphisms of enzymes involved in vitamin D metabolism (e.g., idiopathic infantile hypercalcemia)(Wacker and Holick, 2013). Signs of vitamin D toxicity include hypercalcemia (i.e., elevated serum calcium concentrations) and hypercalciuria (elevated urine calcium levels). Hypercalcemia arises from hyperabsorption of intestinal calcium and, to a lesser degree, from the release of calcium from bone and can lead to calcification of soft tissues such as arteries (arteriosclerosis) and the kidney (nephrocalcinosis). The hypercalciuria associated with vitamin D toxicity reflects the presence of excess calcium in the serum arising from the release of calcium from bone.