Winter changes your daily routine, with earlier sunsets and darker mornings, and the time you do spend outside usually happens bundled up in heavy layers. Those changes can lower your vitamin D levels, since your skin makes vitamin D when it absorbs ultraviolet B (UVB) light and winter offers much less of it.
Vitamin D helps your body absorb calcium, keep bones strong, support muscle function, and maintain normal immune responses. How much your levels shift depends on where you live, what you eat, how often you get outside, and your overall health.
At The Golden Dose, we put this guide together to help you feel confident about your nutrition in every season. In this article, you'll learn why vitamin D in winter can be harder to come by and what you can do to keep your levels steady until spring.
Why Do Vitamin D Levels Drop During Winter?
Vitamin D levels drop during winter because your skin needs UVB rays to produce vitamin D, and winter sunlight carries far less UVB, especially in places farther from the equator. Three seasonal shifts work together to slow that production:
Shorter Days and Lower Sun Angles
Winter brings fewer daylight hours and fewer chances to get outside while the sun is up. The sun also sits lower in the sky, so its rays pass through more of the atmosphere and lose more UVB along the way.
In higher-latitude regions, winter UVB can become too weak for meaningful vitamin D production during parts of the season. A bright, cloudless afternoon can still deliver very little of the UVB your skin needs.
More Time Indoors
Cold weather and early sunsets pull your routine inside, and ordinary window glass blocks UVB, so a sunny window seat does nothing for your vitamin D.
Winter Clothing and Covered Skin
Heavy jackets and gloves keep you warm while limiting how much skin sunlight can reach. Even on clear days, you probably head outside with only your face and hands uncovered. These changes can affect anyone, but some people are more likely to develop low vitamin D levels.
Who Is More Likely to Have Low Vitamin D in Winter?
You're more likely to have low vitamin D in winter if you live far from the equator, spend little time outside, are an older adult, have darker skin, or have a health condition that affects nutrient absorption. Each factor plays out a little differently:
People Living Farther From the Equator
The farther you live from the equator, the bigger the seasonal swing in UVB. Winter sunlight in northern regions may support little vitamin D production for weeks at a time, and no set number of minutes outdoors can guarantee adequate levels.
People With Limited Sun Exposure
If you work indoors or spend most of your day at home, your sun exposure may stay low all year, and the same goes if you regularly keep most of your skin covered. During winter, opportunities for sunlight exposure may become even more limited.
Older Adults and People With Darker Skin
Aging reduces your skin's ability to produce vitamin D. Melanin, the pigment that gives skin its color, also lowers how efficiently skin makes vitamin D from UVB. Darker skin doesn't automatically mean deficiency, though it may mean you need more sun exposure to make the same amount.
People With Certain Health Conditions
Some conditions and treatments make it harder for your body to absorb or use vitamin D, including:
Celiac disease, which damages the lining of the small intestine
Inflammatory bowel disease, such as Crohn's disease
Obesity, since body fat may hold onto vitamin D and keep less of it circulating in your blood
Certain medications, including some steroids
If any of these apply to you, it may be helpful to discuss your vitamin D needs with your healthcare provider.
How Can Low Vitamin D Affect Your Health?
Low vitamin D can weaken your bones and muscles over time and may affect other body systems, although mild deficiency often causes no noticeable symptoms. The effects tend to fall into three areas:
Bone and Muscle Health
Vitamin D helps your body absorb calcium, the mineral that builds your skeleton. When levels stay low for a long time, you may experience:
Bone pain or tenderness
Muscle weakness
Osteomalacia, a softening of the bones in adults
Rickets in children, which can cause soft, misshapen bones
Adequate vitamin D is especially important if you're at risk for osteoporosis, a condition that makes bones thin and fragile.
Immune Function
Vitamin D helps regulate your normal immune responses. Low vitamin D status has been studied in connection with respiratory infections, yet vitamin D supplements haven't consistently been shown to prevent colds or flu. Vitamin D supports your health alongside vaccination and other everyday prevention habits, with no ability to replace them.
Fatigue and Mood Changes
Fatigue and low mood sometimes show up alongside low vitamin D, though both have many possible causes. Shorter days also affect your sleep and circadian rhythm (your body's internal 24-hour clock) on their own, separate from vitamin D. Because these symptoms can have many causes, a healthcare provider can help determine whether vitamin D testing is appropriate.
How Can You Tell If Your Vitamin D Levels Are Low?
A blood test called a 25-hydroxyvitamin D, or 25(OH)D, test is the most reliable way to know, since low vitamin D often causes no obvious symptoms. When deficiency is significant or long-lasting, you may notice signs like these:
Muscle weakness or aches
Bone discomfort
Ongoing fatigue
Routine vitamin D testing isn't generally recommended for healthy adults with no clinical reason for it. Your provider may suggest a test if:
You have risk factors for low vitamin D, such as limited sun exposure
You have a condition that affects nutrient absorption
You show signs of possible deficiency or bone loss
You take medications that interfere with vitamin D
If testing isn't necessary, your focus can shift to everyday habits that keep vitamin D coming in.
How Can You Get Enough Vitamin D During Winter?
You can get enough vitamin D during winter by eating vitamin D foods and getting sensible sun exposure, with a supplement filling any gap that remains. Here's how each source fits in:
Vitamin D-Rich Foods
Relatively few foods naturally contain much vitamin D, so these are good ones to work into your meals:
Fatty fish such as salmon, trout, sardines, and mackerel
Egg yolks
Mushrooms exposed to UV light, which provide vitamin D2
Fortified dairy milk and some plant-based milks
Fortified cereals and certain orange juices
Fatty fish and egg yolks naturally contain vitamin D, while UV-exposed mushrooms provide vitamin D2. Fortified foods have vitamin D added during processing. Fortification amounts vary by brand, and the nutrition label shows how much each product contributes.
Sensible Sun Exposure
Outdoor sunlight may still contribute some vitamin D in winter, depending on where you live. Production depends on latitude, season, time of day, weather, skin tone, and how much skin you expose, which makes a single recommended number of minutes in the sun unreliable. UV exposure also raises your risk of skin damage and skin cancer, so pair time outdoors with sun protection.
Vitamin D Supplements
Supplements give you vitamin D without UV exposure and may be especially relevant if you:
Spend little time outdoors
Follow a vegan diet or avoid fish and dairy
Have specific nutritional needs identified by your healthcare provider
Picking the right amount and form takes a little more thought.
Should You Take Vitamin D Supplements in Winter?
Vitamin D supplements can help in winter if you aren't getting enough from food and sunlight, though the season alone doesn't mean you need one. Your age and current intake shape how much makes sense for you, and the form and dose on the label determine what you're adding:
Recommended Daily Vitamin D Intake
U.S. recommended dietary allowances vary by age:
| Age Group | Recommended Daily Intake |
|---|---|
| Adults 19–70 | 600 IU (15 mcg) |
| Adults 71 and older | 800 IU (20 mcg) |
| Pregnant and breastfeeding adults | 600 IU (15 mcg) |
These figures are general intake recommendations for healthy people, separate from supplement doses or treatment plans for diagnosed deficiency. Food and any multivitamin you take may already cover part of them.
The upper limit for adults is 4,000 IU (100 mcg) per day from all sources combined, unless your healthcare provider directs otherwise. Treat that number as a safety ceiling to stay beneath.
Vitamin D2 vs. Vitamin D3
Vitamin D2 (ergocalciferol) comes mainly from plant and fungal sources, while vitamin D3 (cholecalciferol) is the form your skin makes and the form found in animal foods. Both forms raise the vitamin D in your blood, though D3 may raise levels more effectively and keep them up longer, which makes vitamin D3 in winter a common choice.
Vitamin D is fat-soluble, so taking it with a meal that contains some fat can improve absorption.
Choosing a Vitamin D Supplement
A good supplement fits your needs without pushing your total intake too high, so keep these points in mind as you compare options:
Check the amount of vitamin D per serving, listed in IU, mcg, or both
Add up the vitamin D in your multivitamin and any other supplements you take
Talk with your provider first if you have kidney disease or take medications that may interact with vitamin D
Our Vitamin D3 comes in different IU strengths, so you can match the label to your diet and your provider's guidance. If you prefer a combination formula, our Vitamins A, D3, K2 blend brings those three nutrients together in a single product.
Even with the right product, some common assumptions about winter and vitamin D can lead you astray.
What Are Common Misconceptions About Vitamin D in Winter?
The most common misconceptions about vitamin D in winter overstate how much the season affects everyone and how much extra sun or supplements can help:
Myth #1: Everyone Becomes Vitamin D Deficient in Winter
With winter sunlight dropping so sharply, it seems logical that everyone's levels would crash with it. Your body stores vitamin D in fat tissue and can draw on those reserves after sunnier months. Seasonal dips are possible, but deficiency isn't a given.
Myth #2: More Sunlight Always Means More Vitamin D
Summer teaches many people that more time outside equals more vitamin D. Your skin limits how much vitamin D it makes in a single session, though, and breaks down the excess once it reaches that point. Past that point, extra time outside adds UV exposure without adding much vitamin D. Morning sunlight or any particular time of day also can't guarantee adequate production.
Myth #3: Higher Supplement Doses Work Better
High-dose products line store shelves, so it's easy to assume more vitamin D helps more. Once you're getting enough vitamin D, taking more hasn't been shown to provide additional benefits for most healthy adults. And because vitamin D is fat-soluble, the excess builds up in your body and can raise blood calcium to unsafe levels, which may cause nausea, vomiting, muscle weakness, and kidney problems over time. Stacking several products that each contain vitamin D makes overshooting easy.
How Can You Maintain Healthy Vitamin D Levels This Winter?
You can maintain healthy vitamin D levels this winter by focusing on your individual needs and building a few steady habits around them:
Work vitamin D foods like fatty fish and fortified milk into your weekly meals
Get outside when you can, with sun protection
Choose a supplement strength that fits your total daily intake
Ask your provider about testing if you have risk factors or ongoing symptoms
A steady routine built around your needs can help you stay well supported until the days grow longer.
Support Your Vitamin D Intake This Winter With The Golden Dose
The Golden Dose offers a collection of vitamins and supplements made to fit into your everyday routine. Browse our range for options that support your nutrition through the colder months, and check in with your provider about what's right for you.