31 4.7: Critical Appraisal: The Case of Vitamin D Guidelines
The Case of Vitamin D Guidelines
Vitamin D is an essential micronutrient involved in bone metabolism, serum calcium level management, infectious disease control, and many cellular and immunological processes (Gozdzik, Barta, Wagner, Cole, Vieth & Parra, 2008; Hanley, Cranney, Jones, Whiting, Leslie, Cole & Rosen, 2010; 2020; Mogire, et.al., 2020; Taksler, Cutler, Giovannucci & Keating, 2015). Food sources of vitamin D are minimal (e.g. eggs, fatty fish); subsequently, some governments, including Canada’s federal government, established public health policies and strategies to fortify a variety of foods (e.g. margarine, milk products, milk alternative beverages, juices) to help reduce the risk of deficiency (Health Canada, 2022). Vitamin D deficiency is measured with serum 25-hydroxyvitamin D, which is not a standard or free blood test for most Canadians. As a result, health care providers must be familiar with the nutrition recommendations, signs and symptoms and the risks, including:
- Infants: bone malformation (rickets), seizures and difficulty breathing (World Health Organization, 2023).
- Pregnancy: increased risk of pre-eclampsia, gestational diabetes mellitus, and preterm birth (World Health Organization, 2023).
- Non-pregnant adults: increased risk of cardiovascular disease, cancer, infertility, muscle pain, osteomalacia, rheumatoid arthritis, weakened immune response, autoimmune diseases (Hanley, Cranney, Jones, Whiting, Leslie, Cole & Rosen, 2010; 2020; Taksler, Cutler, Giovannucci & Keating, 2015; Schwalfenberg, Genuis & Hiltz, 2010)
The risks of deficiency include poor sun exposure, vegan or vegetarian diets low in vitamin D-fortified foods and supplementation, chronic renal and liver disease, obesity, breastfeeding, and the use of medications that deplete stores of vitamin D. 1 in 5 people living in Canada are not getting enough vitamin D, and Black people worldwide are more likely to have a deficiency compared to their non-Black counterparts (Ames, Grant& Willett, 2021; Gozdzik, Barta, Wagner, Cole, Vieth & Parra, 2008; Mogire, et.al., Powe, et.al., 2013; Schwalfenberg, Genuis & Hiltz, 2010). Literature recognizes that Black individuals synthesize less vitamin D per unit of sun exposure than white individuals. Yet in Canada, recommendations for supplementation for Black and non-Black people are the same.
Could this be a systemic form of racism that perpetuates high vitamin D deficiency in Black populations and subsequently increased risk of the associated complications?
| Institution |
Guideline |
| Osteoporosis Canada (Osteoporosis Canada, 2023). |
A minimum 400 IU supplement daily along with consuming vitamin D-rich foods to meet the recommended dietary allowance for vitamin D 600 IU/d (age 51–70 yr) and 800 IU/d (age > 70 yr) for males and females. |
| Health Canada
(Health Canada, 2022). |
Between the ages of 2 and 50 years old:
- Eat foods that contain vitamin D every day
OR
- Take a daily supplement containing 400 IU (10 µg) of vitamin D
51 years of age and older:
-
- Take a daily supplement containing 400 IU (10 µg) of vitamin D
- Continue to eat foods that contain vitamin D as part of healthy eating
|
To dismantle Eurocentric assumptions in nutrition science, dietitians must actively evaluate data collection methodologies, nutrition therapies and interventions to identify whether there are biases and forms of structural racism that may impact the data, findings, conclusions and recommendations of a study.
When reviewing nutritional literature or planning a clinical trial, there are tools that you can use to check for structural omissions:
The Critically Appraising Anti-Racism Toolkit and the UK NIHR INCLUDE Project are examples of these evaluation tools. They offer recommendations for improving inclusion of under-served groups in clinical research by encouraging evaluators to:
- Challenge Sample Universality: Check if a study generalizes baseline metrics (e.g., bone density or nutritional markers to all populations when the cohort was overwhelmingly white/Euro-descendent.)
- Evaluate Health Disparity Root Causes: Determine whether an article attributes health disparities solely to genetics or race without accounting for systemic factors (e.g. socioeconomic discrimination).
- Audit Group Categorizations: Ensure demographic options avoid grouping distinct ethnic subsets into single monolithic clusters (e.g., classifying all Black people universally without identifying distinct geographic ancestries).
💻 Active Learning Application Task:
- Select one of the articles below to evaluate. Use either of the appraisal tools listed above to identify structural omissions that may contribute to systemic ABR:
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- Goodwin, P. J., Ennis, M., Pritchard, K. I., Koo, J., & Hood, N. (2009). Prognostic effects of 25-hydroxyvitamin D levels in early breast cancer. Journal of Clinical Oncology, 27(23), 3757-3763.
- Gozdzik, A., Barta, J. L., Wu, H., Wagner, D., Cole, D. E., Vieth, R., Whiting, S., & Parra, E. J. (2008). Low wintertime vitamin D levels in a sample of healthy young adults of diverse ancestry living in the Toronto area: associations with vitamin D intake and skin pigmentation. BMC Public Health., 8(1). https://doi.org/10.1186/1471-2458-8-336
- Højskov, C. S., Heickendorff, L., & Møller, H. J. (2010). High-throughput liquid–liquid extraction and LCMSMS assay for determination of circulating 25 (OH) vitamin D3 and D2 in the routine clinical laboratory. Clinica chimica acta, 411(1-2), 114-116.
- Lee, L. T., Drake, W. M., & Kendler, D. L. (2002). Intake of calcium and vitamin D in 3 Canadian long-term care facilities. Journal of the American Dietetic Association, 102(2), 244-247.
- Liu, B. A., Gordon, M., Labranche, J. M., Murray, T. M., Vieth, R., & Shear, N. H. (1997). Seasonal prevalence of vitamin D deficiency in institutionalized older adults. Journal of the American Geriatrics Society, 45(5), 598-603.
- Mark, S., Gray-Donald, K., Delvin, E. E., O’Loughlin, J., Paradis, G., Levy, E., & Lambert, M. (2008). Low Vitamin D Status in a Representative Sample of Youth From Québec, Canada. Clinical Chemistry., 54(8), 1283–1289. https://doi.org/10.1373/clinchem.2008.104158
- Newhook, L. A., Sloka, S., Grant, M., Randell, E., Kovacs, C. S., & Twells, L. K. (2009). Vitamin D insufficiency common in newborns, children and pregnant women living in Newfoundland and Labrador, Canada. Maternal & child nutrition, 5(2), 186-191.
- Roth, D. E., Martz, P., Yeo, R., Prosser, C., Bell, M., & Jones, A. B. (2005). Are national vitamin D guidelines sufficient to maintain adequate blood levels in children?. Canadian Journal of Public Health, 96(6), 443-449.
- Rucker, D, Allan, J, Fick, G & Hanley, D. (2002). Vitamin D insufficiency in a population of healthy western Canadians. CMAJ Canadian Medical Association Journal, 166(12), 1517-1524. Retrieved from https://ovidsp.ovid.com/ovidweb.cgi?T=JS&PAGE=reference&D=ovftf&NEWS=N&AN=00002792-200206110-00016.
- Rucker, D., Tonelli, M., Coles, M. G., Yoo, S., Young, K., & McMahon, A. W. (2009). Vitamin D insufficiency and treatment with oral vitamin D3 in northern-dwelling patients with chronic kidney disease. Journal of nephrology, 22(1), 75-82.
- Siffledeen, J. S., Siminoski, K., Steinhart, H., Greenberg, G., & Fedorak, R. N. (2003). The frequency of vitamin D deficiency in adults with Crohn’s disease. Canadian Journal of Gastroenterology and Hepatology, 17(8), 473-478.
- Sloka, S., Stokes, J., Randell, E., & Newhook, L. A. (2009). Seasonal variation of maternal serum vitamin D in Newfoundland and Labrador. Journal of obstetrics and gynaecology canada, 31(4), 313-321.
- Vieth, R., Cole, D. E., Hawker, G. A., Trang, H. M., & Rubin, L. A. (2001). Wintertime vitamin D insufficiency is common in young Canadian women, and their vitamin D intake does not prevent it. European journal of clinical nutrition, 55(12), 1091-1097.
- How would you redesign these studies to address the omissions?
