Vitamin D is one of the most well-documented players for immune support—an "old-school" nutrient, if you will.* However, it skyrocketed in popularity during the pandemic, after cross-sectional studies found vitamin D deficiency was higher in COVID patients than in the control groups. As such, vitamin D finally got the recognition it deserved—although, says Ferira, it's important to truly digest what you're reading online.
Most of us are deficient in vitamin D, says Ferira. And the research backs it up: 29% of U.S. adults are considered straight-up vitamin D deficient, while 41% are vitamin D insufficient. That's a huge nutrient gap—and yet, most health media outlets provide a single solution: Eat vitamin-D-rich foods.
"That's a huge myth that I'd like to bust," Ferira notes. (She explains her reasoning further here, in case you're curious). "Telling someone to meet their vitamin D requirement through food is like giving you a quart of paint to go repaint your entire house."
Vitamin D is naturally found in small amounts in a handful of foods—which are helpful for preventing extreme vitamin D deficiency and related ailments. For example, 1 cup of milk contains 100 IU of vitamin D. But when it comes to ramping up and maintaining healthy vitamin D status for life, those modest intake levels alone just won't cut it.