You probably already know that vitamin D is important for your health. After all, low vitamin D levels are linked to all sorts of issues, including depression and anxiety, fatigue, changes in metabolism, and hormonal imbalances, according to The Vitamin Shoppe nutritionist Brittany Michels, M.S., R.D.N., L.D.N.
However, in addition to well-known roles in bone health, mood, and energy, vitamin D also has another hugely important role in the body: supporting a healthy immune system.
Seriously, is there anything vitamin D can’t do? If you’ve got questions about how exactly the ‘sunshine vitamin’ does your immunity good, we’ve got answers.
Vitamin D’s Immune Benefits
Never considered vitamin D an immune-booster before? It might be news to you, but researchers have been digging into vitamin D’s immune powers for years now.
“There has been a growing body of research in the last decade exploring and documenting the role vitamin D plays in immune health,” says The Vitamin Shoppe nutritionist Rebekah Blakey, R.D.N. Not only has this research uncovered how vitamin D supports the immune system, but it’s also uncovered that certain health conditions—including respiratory issues or infections—may be associated with low vitamin D, she says.
As a result, many health professionals are leaning more heavily on vitamin D as a tool to support our health and well-being: “Vitamin D is my number one recommendation for immune support year-round,” says Michels. That’s especially true during winter, when decreased sun exposure causes vitamin D levels to dip.
How Exactly Vitamin D Supports Your Immune System
Vitamin D works in our immune systems in multiple ways, all of which are pretty impressive.
“Vitamin D acts as an immune modulator,” says Blakely. “This means it helps boost immune function when needed and protects against unnecessary inflammatory responses.”
One way it does so? By stimulating our immune cells’ production of proteins with antiviral properties, she explains. These cells (known as AMPs) are considered our immune system’s first line of defense.
Vitamin D also helps activate T cells—our immune system’s “fighter” cells—which help identify and fend off infectious pathogens, Blakely adds.
Could Your Immunity Benefit From A Vitamin D Supplement?
Given vitamin D’s important roles in immunity, it’s crucial to maintain adequate levels, says Michels. Unfortunately, though, many people have lower-than-optimal levels. In fact, some estimates suggest up to 42 percent of Americans are vitamin D-deficient.
Ideally we’d get the vitamin D we need from sun exposure. The issue is, most of us don’t get the 15 to 30 minutes of sun exposure daily required to keep vitamin D levels healthy. Plus, vitamin D is pretty hard to come by in food.
That’s where supplements come in. “If you’re unable to maintain those levels from sun exposure and food intake, then supplementation is a must,” says Michels.
This is especially important during the winter and early spring, when most people tend to have lower levels, Blakely adds.
To support health, Blakely recommends healthy adults supplement with 1,000 to 2,000 IU of vitamin D3 daily. Those with compromised health—and/or who get very little to no sunlight exposure—should supplement with up to 4,000 IU daily.
From there, both Blakely and Michels recommend having your vitamin D levels tested regularly. (Michels says maintaining a blood level between 50 and 70 ng/mL is optimal.) That way, you can hone your approach to sunlight, supplements, and diet to keep your immune system—and health—strong.
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