While health trends come and go, Vitamin D – particularly Vitamin D3, the form your body naturally produces from sunlight – has remained one of the most consistently recommended nutrients for decades. And, for good reason: a jack of many trades, it supports everything from bone health to immune regulation, mood signaling, and cellular function throughout the body.
But, the reality is that many people who supplement with Vitamin D are still functionally deficient. In fact, research from large population studies suggests that roughly 42% of adults in the United States are deficient (though other studies suggest a much higher percentage).
That’s not because you’re doing something wrong – it’s because most supplements simply don’t provide enough Vitamin D, or the right nutritional context for it to work effectively. And at a time where we’re spending less time outdoors than previous generations and sunscreen-use is more prevalent (important, but also limiting of Vitamin D), millions of people may be struggling with a Vitamin D deficiency. Here are a few warning signs – and what you can do about it.
