How to boost your vitamin D level -- safely -- all year-round

The summer sun can boost your bone health, immune function and glucose control as it tamps down inflammation. How? Its ultraviolet-B rays hit precursor vitamin D in your skin cells, providing the energy needed for your body to synthesize vitamin D2/3.

Unfortunately, the prevalence of an indoor, sedentary, nutritionally poor lifestyle means that 35% of U.S. adults are D-ficient. It's a greater problem among those with darker skin -- they're 15 to 20 times more likely to have severe deficiency. And folks who are obese have a 35% higher prevalence of vitamin D deficiency.

What's the best summertime sun strategy? North of a line that runs through New York City and Sacramento, California, 5 to 15 minutes of midday sunlight on arms, legs and face, three times a week can maintain healthy vitamin D levels in Caucasian adults. Darker-skinned folks should add more time but make sure not to burn. Use sunblock with micronized zinc at all other times and reapply every 10 to 15 minutes.

But what can you do during the winter (or if a blood test shows you're chronically deficient)? A new study reveals that consistently getting aerobic exercise INDOORS prevents your vitamin D level from decreasing during darker days of winter! Study participants did 30-plus minutes four times a week, including one high-intensity interval training session.

Still need a boost? Take D2 or D3 supplements year-round -- 1,000 IU daily is a basic routine. Add vitamin K3 and make sure to eat D-lightful foods like salmon and mushrooms. Recipes are in my "What to Eat When Cookbook."

Health pioneer Michael Roizen, M.D., is chief wellness officer emeritus at the Cleveland Clinic and author of four No. 1 New York Times bestsellers. Check out his latest, "The Great Age Reboot: Cracking the Longevity Code for a Younger Tomorrow," and find out more at www.longevityplaybook.com. Email your health and wellness questions to Dr. Mike at questions@longevityplaybook.com.

(c)2023 Michael Roizen, M.D.

Distributed by King Features Syndicate, Inc.


(c) 2025 Michael Roizen, M.D. Distributed by King Features Syndicate, Inc.