The questions come first
Our starting point is the question a reader is trying to answer: what vitamin D does, how food and supplements fit together, or what a test result might mean. We explain technical terms where they appear and distinguish daily nutritional needs from a clinical treatment plan.
How we use evidence
Health claims should have a source close by. We prioritize current public-health guidance, clinical guidelines, systematic reviews, and relevant human studies. We distinguish biological mechanisms from demonstrated clinical effects, and associations from cause and effect. When guidance differs between the United States and Canada, we name that difference.
Meet the team
Zeynep Özdemir, RD; Sevimnur Tas, RD; and Elizabeth Miller, ND, bring their backgrounds in dietetics, nutrition education, and naturopathic medicine to this resource.
Meet our expertsUpdates and corrections
The guide displays its last-updated date. If you notice an error or a source that no longer supports a statement, please contact the editorial team with the page URL and the specific passage.
Education and commercial content
Our editor’s pick is clearly labeled, and our publisher relationship is explained in the footer and the editorial and commercial disclosure. Product information is not used as clinical proof.