
A Sunny Outlook: Vitamin D and Immunity
Ah, the golden rays of the sun. Nothing feels better, and it’s a beautiful reminder of the changing seasons as we move into warmer, sunnier weather. But the sun’s rays don’t just feel good. The sun, and its vitamin D, can help to boost our mood, improve our wellness and strengthen our immune system. Here’s everything you need to know about vitamin D and immunity, how to figure out how much vitamin D you need, and how to enjoy the sun’s warm rays safely.
Researchers say that just 13 minutes of sun exposure, three times a day, may help you maintain proper, healthy vitamin D levels.
Many people associate vitamin D, the so-called “sunshine vitamin,” with bone health and calcium absorption. And it’s true: Researchers say that Vitamin D is critical for staving off osteoporosis and improving your bone strength.
But that’s just the start.
“Deficiency in vitamin D is associated with increased autoimmunity as well as an increased susceptibility to infection,” explains a study published by the American Federation for Clinical Research. “As immune cells in autoimmune diseases are responsive to the ameliorative effects of vitamin D, the beneficial effects of supplementing vitamin D deficient individuals with autoimmune disease may extend beyond the effects on bone and calcium homeostasis.”
Put in less clinical, simpler words, yes — vitamin D plays numerous important roles in your immune strength and ability to resist disease:
If you love your immune system, make sure you're getting enough vitamin D from the sun and/or from supplements.
According to the Linus Pauling Institute, adult men and women need 600 IU of vitamin D a day. If you're in your 70s or older, your requirement jumps to 800 IU.
Alas, studies have found that nearly half of all American adults don’t get enough of this immune-strengthening nutrient.
Thankfully, the sun is all you need. In a study published in the Journal of Investigative Dermatology, scientists found that just 13 minutes of sunlight exposure three times a week helped adults achieve healthy blood levels of the sunshine vitamin.
However, sun exposure is not without its drawbacks. Too much sun exposure can lead to premature signs of aging in your skin, increased risks of skin cancer, etc. You may wish to wear sunscreen (the American Academy of Dermatology suggests using a sunscreen — remember, natural and organic is always ideal — with a minimum SPF of 30) and avoid sun exposure from 11 a.m. to 3 p.m. when the sun’s ultraviolet rays are at their strongest.
You can also get vitamin D from your diet. Some of the top dietary sources of vitamin D include cod liver oil, salmon, tuna, eggs, fortified dairy products, and mushrooms.
If you prefer to take a vitamin D supplement instead, consider the following tips:
Vitamin D and Immunity

- The cells in your immune system require vitamin D for proper functioning, and for faster responsiveness to infection. (PMC source)
- Vitamin D improves how your T-cells work, which are the immune cells that specifically target invading pathogens in your body. (PMC source)
- Vitamin D helps activate your immune system, reduces inflammation, and promotes the growth of immune cells. (PMC source)
The Right Dose for Vitamin D and Immunity

- Choose vitamin D3. This form of vitamin D is what’s naturally found in your body.
- Check the IU dosage. You’ll want to aim for 600 IU a day.
- Don’t skip other nutrients. Vitamin D doesn’t work in isolation. Research suggests that vitamin K improves absorption, as does magnesium.