Vitamin D levels can have a big impact on overall health. It is also the number one vitamin deficiency in the U.S. I can attest to that as it’s the most common deficiency that I see as a clinical nutritionist at Nava Health. This “sunshine vitamin” plays an essential role in many aspects of our well-being, from supporting immune function and promoting bone health to mood and hormone regulation.
But as we head into winter, many of us are at risk of a significant dip in vitamin D levels, particularly those living in certain regions of the U.S. Here’s why that happens—and how you can keep your levels up even when the sun is scarce.
Why Vitamin D Is So Important
Vitamin D is unique because it’s a vitamin that our bodies can produce when exposed to sunlight, specifically UVB rays. It acts as a hormone, playing a role in calcium absorption, supporting bone health, regulating the immune system, and even influencing mood and mental health.
Research shows that insufficient levels of vitamin D can lead to a variety of health issues, including:
- Weakened immune function, increasing susceptibility to infections.
- Bone disorders such as osteoporosis and osteomalacia increase the risk of fractures.
- Mood disorders like seasonal affective disorder (SAD) and depression are both linked to low levels of vitamin D.
- Chronic illnesses such as cardiovascular disease and autoimmune disorders.
Ensuring optimal vitamin D levels, especially in winter, is critical to maintaining good health, good mood, and a strong immune system when we need it most.
Why Does Vitamin D Dip in Winter?
Vitamin D production relies heavily on exposure to sunlight, particularly the UVB rays found in direct sunlight. During the winter months, shorter days and less sunlight significantly reduce our ability to naturally synthesize vitamin D.
In some regions, the angle of the sun during winter means that even on a sunny day, the UVB rays aren’t strong enough to stimulate adequate vitamin D production.
If you live in northern U.S. regions—places like the Northeast, Midwest, and Pacific Northwest—you’re at a higher risk of developing a vitamin D deficiency in winter. Residents of cities like Boston, Chicago, and Seattle are especially vulnerable because their winters are long, cold, and often cloudy. In fact, studies show that people living above the 37th parallel (north of cities like San Francisco, St. Louis, and Richmond) struggle the most with maintaining sufficient vitamin D levels in winter.
5 Ways to Boost Vitamin D This Winter
Fortunately, even during the darkest days of winter, there are ways to ensure your vitamin D levels stay in the optimal range. Here are my top five recommendations for boosting your vitamin D level:
1. Get Outside When You Can
Even though UVB rays are weaker in the winter, try to get outside and enjoy natural sunlight whenever possible. Aim for midday exposure when the sun is at its highest. Just 15-20 minutes of outdoor activity a few times a week can help support your body’s vitamin D production. However, this may not be enough for everyone, particularly in regions with heavy cloud cover or those spending most of their days indoors.
2. Eat Vitamin D-rich foods
While sunlight is the primary source of vitamin D, you can also boost your intake through your diet. Some foods are naturally rich in vitamin D, while others are fortified. We focus on functional nutrition here at Nava Health and the approach of diet as a foundation for good health. Here are a few to add to your plate this winter:
- Fatty fish, including salmon, mackerel, sardines, and yes, anchovies
- Egg yolks (pasture-raised)
- Grass-fed whole milk
- Mushrooms (shitake)
- Fortified foods such as cow’s milk, plant-based milk (almond, soy), and cereals
- Cod liver oil
While these foods can help, it’s often challenging to get all the vitamin D you need from diet alone.
3. Consider a High-Quality Supplement
For most people, especially those in high-risk regions, supplementation is the easiest and most reliable way to maintain optimal vitamin D levels in winter. Vitamin D3 (cholecalciferol) is the most effective form, as it’s the same type produced by your skin in response to sunlight. Always consult with a healthcare professional to determine the right dosage for you based on your current levels and needs.
4. Use a UVB Lamp
For those living in areas with very little winter sunlight, a UVB lamp or light box designed to mimic natural sunlight can be a good option. These lamps emit UVB rays, which stimulate vitamin D production in the skin. There are plenty of inexpensive UVB lamp options and, who doesn’t want to spend some quality time with your indoor plant babies and a good book. However, it’s important to use these devices safely and according to manufacturer instructions to avoid skin damage.
5. Stay on Top of Your Health with Regular Testing
The only way to truly know if you’re maintaining optimal vitamin D levels is through regular testing. At Nava Health, we recommend an integrative wellness checkup every three months. Consistent checkups that monitor key biomarkers ensure you are on track holistically and create proactive opportunities to make lifestyle changes or adjustments in supplementation before sub-optimal levels lead to more serious issues.
Don’t Let Winter Steal Your Sunshine
Maintaining healthy vitamin D levels in winter is crucial for overall health, immune resilience, and mental well-being. Whether you’re living in the sunny Boca Raton or braving the long winters in Montvale, New Jersey, taking proactive steps to support your vitamin D levels will help you stay strong and healthy throughout the season.
By combining sunlight exposure, dietary choices, supplements, and regular testing, you can ensure that even when the sun is scarce, your body is getting the vitamin D it needs.
If you’re unsure about your current vitamin D status or want to learn more about how to optimize your health this winter, reach out to your Nava Health integrative team for personalized guidance. Your wellness matters all year round, and we’re here to help you every step of the way.
Nour Amri is a Licensed Integrative Nutritionist, a Certified Nutrition Specialist, and a Certified Ketogenic Nutrition Specialist. She earned her Master’s degree from the Maryland University of Integrative Health. She also received her certification for mind-body medicine facilitation from Georgetown University School of Medicine. In her approach, Nour applies the principles of Integrative and Functional Nutrition, which emphasize healthy eating personalized to the client’s genetics, environment, lifestyle, and health concerns.