Maintaining Adequate Vitamin D in the Fall and Winter

Sunshine does more than brighten your day. When sunlight reaches your skin, your body makes vitamin D, earning it the nickname “sunshine vitamin.” But as fall turns to winter, shorter days and less time outdoors can make it harder to get enough.

Among its many roles, vitamin D promotes healthy immune function, helps your body absorb calcium, and supports strong bones, healthy muscles, and a healthy mood.*

With less opportunity to make vitamin D from sunlight, you may need to rely more on other sources. While certain foods provide vitamin D, getting enough from food alone can be difficult.

When sunlight and food fall short, a vitamin D3 supplement can help you get enough vitamin D for overall wellness throughout the colder months.*

How Sunlight Helps Your Body Make Vitamin D

When ultraviolet B (UVB) rays from sunlight reach your skin, they trigger the production of vitamin D3. Certain foods and many high-quality supplements also provide vitamin D3. However, your body cannot use vitamin D3 as-is. Your liver and kidneys convert it through several steps into calcitriol, the active form your body uses to carry out vitamin D’s many functions.

However, sunlight doesn’t always provide enough UVB rays for your body to make vitamin D. During fall and winter, the sun sits lower in the sky, and its rays travel through more of the atmosphere before reaching your skin. As a result, your body may make less vitamin D, even on a sunny day.

Where you live also matters. In areas farther from the equator, such as the northern United States, winter sunlight may not provide enough UVB rays for your skin to make much vitamin D during certain months.

Several other factors influence vitamin D production throughout the year. Spending more time indoors, wearing clothing that covers your skin, using sunscreen, cloud cover, air pollution, and age can all affect how much vitamin D your body makes.

Skin pigmentation also plays a role. Melanin, the pigment that gives skin its color, absorbs UVB rays. Depending on skin pigmentation, adequate vitamin D production may require anywhere from minutes to hours of sun exposure, with darker skin generally requiring more time. However, during fall and winter, UVB levels may be too low in some areas for the skin to make enough vitamin D, regardless of skin pigmentation.

Can You Get Enough Vitamin D from Food Alone?

Sunlight isn’t your only source of vitamin D, but relatively few foods contain it naturally. Fatty fish, including salmon, trout, sardines, mackerel, and tuna, are among the richest natural sources of vitamin D. Egg yolks and some mushrooms provide smaller amounts.

Fortified foods, including milk, plant-based beverages, breakfast cereals, orange juice, and yogurt, can also provide some vitamin D. However, some contain added sugars or other ingredients you may want to limit, so check the Nutrition Facts label and ingredient list.

Even with these food options, getting enough vitamin D can be difficult, especially during winter when your body makes less from sunlight. As a result, many people may not get enough vitamin D. In a study of nearly 4,500 U.S. adults, researchers found that over 41% had vitamin D deficiency.

Choosing a Vitamin D3 Supplement

When sunshine is in short supply and you’re not getting enough vitamin D from food, a supplement can help fill the gap.*

Vitamin D supplements come in two main forms: D2 (ergocalciferol) and D3 (cholecalciferol). Researchers who analyzed results from multiple randomized controlled trials found that vitamin D3 supplements raise vitamin D status in the blood more effectively than vitamin D2 supplements.*

The recommended dietary allowance (RDA) for vitamin D is 600 IU daily for adults ages 19 to 70 and 800 IU for adults over 70. These amounts include vitamin D from both food and supplements. However, some researchers suggest that these recommendations may not meet everyone’s needs. Because individual needs vary, talk with a qualified health-care practitioner about the amount of vitamin D that may be appropriate for you.*

Keep in mind that vitamin D is fat-soluble, so taking vitamin D supplement capsules with a meal that contains some fat may improve absorption.

When choosing a vitamin D supplement, you may notice that some formulas pair vitamin D3 with vitamin K2. These nutrients play complementary roles in calcium metabolism. Vitamin D helps your body absorb calcium, while vitamin K activates proteins that help your body use calcium to support bone health.*

Keeping Up with Your Vitamin D Needs Year-Round

Your vitamin D needs don’t change with the seasons, but how you meet them may. When sunlight and food aren’t enough, a vitamin D supplement for daily use can help you maintain adequate vitamin D status year-round.*

Because nutritional needs vary from person to person, work with a qualified health-care practitioner when considering dietary supplements. A practitioner can help you determine whether vitamin D supplementation is appropriate and recommend an amount based on your individual needs and health goals.*

Key Takeaways

• Your skin makes vitamin D3 when ultraviolet B (UVB) rays reach it. Your liver, kidneys, and other tissues then convert it into its active form.
• During fall and winter, weaker UVB rays can limit vitamin D production, especially in areas farther from the equator.
• Fatty fish are rich natural sources of vitamin D. Egg yolks, some mushrooms, and fortified foods can also help, but getting enough from food alone can be difficult.
• Vitamin D helps your body absorb calcium and supports strong bones, healthy muscles, and immune function.*
• A vitamin D3 supplement can help you meet your needs when sunlight and food fall short.*

*These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.