by Marion Nestle
Mar 1 2021

Industry-funded study of the week: vitamin D supplements

The Study:  Maaike J. Bruins and Ulla Létinois. Adequate Vitamin D Intake Cannot Be Achieved within Carbon Emission Limits Unless Food Is Fortified: A Simulation Study.  Nutrients 202113(2), 592;

Conclusion: The present study shows that adequate intakes for vitamin D cannot be achieved with the current diet alone within realistic calorie and carbon emission limits, and additional vitamin D sources are needed to overcome the shortfalls. Universal fortification along with small dietary shifts represents an approach to improve the vitamin D status of the general population, at a high acceptability without affecting the carbon footprint.

Conflicts of Interest: M.J.B. and U.L. are employed by DSM Nutritional Products, a manufacturer of nutritional ingredients.

Comment: Study after study shows that vitamin D supplements do not make healthy people healthier, but the idea persists and supplement companies take advantage of faith in these products.  Well, there isn’t much evidence for harm either, but sunshine on skin is a better source by far.

OK.  I know there’s a big controversy about this.

Here’s a study that shows benefits for patients with COVID; supplements were associated with keeping people out of intensive care.  One of its authors has financial ties to supplement companies, but the study has been criticized on other grounds as has a member of the British Parliament who thinks it provides evidence for supplementing everyone.

And here’s an independently funded study in JAMA shows that vitamin D to have no effect on patients hospitalized with Covid-19.

This one, comes with an editorial.

Given the lack of highly effective therapies against COVID-19, except perhaps for corticosteroids, it is important to remain open-minded to emerging results from rigorously conducted studies of vitamin D (despite smaller sample sizes and important limitations of some studies). However, taken together with existing randomized clinical trials of vitamin D administration in hospitalized patients with respiratory infection and critical illness, the results reported by Murai et al12 do not support routine administration of vitamin D in hospitalized patients with moderate to severe COVID-19.

Fortunately, vitamin D supplements are unlikely to be harmful unless taken in very large doses.

Sunshine, anyone?