Winter and Vitamin D: How Cold Weather Drains Your Sunshine Nutrient

Winter isn’t about chilly winds and fewer hours of daylight. It’s also a time when keeping your vitamin D at healthy levels becomes harder. In summer, your skin makes enough of this vital nutrient on its own, but winter creates the perfect conditions to lower your vitamin D.

Maybe you’ve felt more exhausted during the winter season, had aching bones, or noticed catching colds more often. If so, a lack of vitamin D could be to blame. Around 23% of people face vitamin D deficiency in winter, a noticeable jump from the 12% affected in fall.

The bright side? Knowing how winter messes with your vitamin D and taking a few easy steps can keep you feeling great all winter long.

📌 Key Takeaways

• Vitamin D drops a lot in fall and winter because there is less sunlight.
• Winter has the worst deficiency rate, with 23% of people lacking enough vitamin D.
• Sunlight alone cannot give enough vitamin D during winter.
• Taking Vitamin D3 supplements (1000-2000 IU ) works best in winter.
• Healthy food and spending time outside can help, but they do not replace supplements during winter.

❄️ Why Does Winter Decrease Vitamin D?

Vitamin D is special—your body creates it when sunlight touches your skin. However, winter complicates how this process happens.

The problem with the sun’s angle:

In the winter, the sun stays much lower in the sky. Because of this, sunlight passes through more of the atmosphere before reaching you. Most UVB rays, which are the exact type your skin needs to make vitamin D, get filtered out.

If you are above 37°N latitude (like people in Los Angeles, Atlanta, or southern Spain), staying outside between November and February produces close to no vitamin D. This is true no matter how long you spend in the sun.

Spending more time indoors:

Cold weather makes people head inside more often. When you do go out heavy coats cover most of your skin limiting exposure to sunlight. Even sitting near windows doesn’t work since glass completely blocks UVB rays. That bright sunlight coming in isn’t helping your vitamin D levels either.

Blocking sunlight with clothing:

Unlike summer when your skin is exposed, winter clothes cover almost your entire body. Even if you go out during the sunniest parts of the day, your covered skin cannot produce vitamin D.

These reasons explain why winter often has the highest rates of vitamin D deficiency for all ages and regions.

📉 How Low Vitamin D Affects Your Body

Vitamin D deficiency is more than just a number on a blood test. It leads to real issues that can interfere with your daily life.

Effects on bones and muscles:

Your body needs vitamin D to take in calcium. Without enough of it, your bones lose their strength. Adults with low vitamin D may notice:

• Pain or soreness in bones
• Weak muscles or discomfort
• Fractures happening more after small falls
• Injuries that take longer to heal

In extreme situations, adults may face osteomalacia, which means their bones become soft, while kids might develop rickets. Both conditions can be stopped with proper care.

Effects on the immune system:

Studies say vitamin D helps the immune system work . People with low vitamin D levels seem to catch illnesses like colds more often in winter. Though scientists need to study this link more, it’s clear there’s a trend—cold and flu season matches up with low vitamin D.

Energy and mood changes:

Many who don’t have enough vitamin D feel tired. Different things can lower energy during the colder months, but keeping vitamin D levels healthy helps people stay well overall.

The overlooked issue:

Most people who lack vitamin D show no clear symptoms. You might think you are “okay,” but your body could be struggling without enough vitamin D. This is why checking your vitamin levels is important even if you feel fine.

🌞 How Much Sunlight Do You Need?

It’s simple to get enough vitamin D in the summer. In the winter, it becomes much harder.

Making vitamin D in summer:

When the sun is strong during warmer months, exposing your arms and legs to sunlight for 10 to 15 minutes a few times each week gives most people enough vitamin D. Your skin works very when the conditions are ideal.

Winter challenge:

Research reveals that in winter, you would need about 2 hours of midday sun exposure with lots of skin uncovered to make the same amount of vitamin D. This doesn’t work well for several reasons:

• It’s way too cold to bare that much skin
• Many people stay indoors at work during peak sunlight
• Even those who love sunshine can’t stick to this plan
• The danger of frostbite is greater than the benefit of vitamin D

What does this mean?

You shouldn’t rely on winter sunlight to keep your vitamin d levels up. Spending time outdoors is still good for fresh air, exercise, and lifting your mood, but it won’t fix a vitamin D deficiency in the winter months.

Because of this, taking vitamin D supplements becomes very important during winter.

💊 Vitamin D3 Supplements: A Winter Must-Have

When sunlight fades away during winter, vitamin D supplements come to the rescue. Here’s the basic info you should know.

Why go for vitamin D3:

Vitamin D3 (cholecalciferol) helps improve blood levels better than vitamin D2 (ergocalciferol). When buying a supplement always pick the D3 type.

How much you should take:

During winter:

• Typical daily amount: Between 1000 and 2000 IU
• Lowest helpful amount: 600 to 800 IU —this might not fix winter deficiency
• Maximum safe limit: 4000 IU unless advised by a doctor

Babies expecting moms, and seniors require exact doses—ask your doctor or nurse to figure out the right amount.

When you should take it:

Since Vitamin D mixes better with fat, your body uses it more with foods containing fats. Have your vitamin D pill with food like:

• Avocados or eggs
• Nut spreads or nuts
• Olive oil or similar healthy oils
• Cheese or full-fat yogurt

Swallowing supplements without food makes them harder to absorb so make sure to pair them with a meal. Otherwise, you’re just throwing away money.

Which one to pick:

Fancy brands aren’t necessary. Store-brand vitamin D3 from your local drugstore works just as well as the pricey ones. Choose options that include:

• Look for “Vitamin D3” or “cholecalciferol” on the label
• Each softgel or tablet should contain 1000 to 2000 IU
• Choose USP-verified options if available for quality

A three-month supply costs between $5 and $15 making it one of the cheapest supplements.

🍳 Foods With Vitamin D (And Why They Fall Short)

Foods can help, but they don’t give enough vitamin D in winter.

Best natural sources:

Fatty fish stands out as the best option:

• Salmon (3 ounces): 570 IU
• Mackerel (3 ounces): 400 IU
• Sardines (3 ounces): 160 IU
• Canned tuna (3 ounces): 40 IU

You can get smaller amounts from fortified foods:

• Fortified milk (one cup): 120 IU
• Fortified orange juice (one cup): 100 to 140 IU
• Fortified cereal (a serving): 80 IU

Other food options include:

• Egg yolk (one large): 44 IU
• Mushrooms treated with UV light (half cup): 366 IU
• Cheese (one ounce): 12 IU

The calculations don’t add up:

To get 1000 IU of vitamin D just from food, you would have to eat:

• Almost 2 servings of salmon every day, OR
• Around 8 to 9 cups of fortified milk , OR
• About 23 eggs each day

These amounts are not practical, affordable, or healthy for most people.

Food helps, but it’s not enough:

Try eating foods rich in vitamin D during the winter. They add to your overall nutrition and give you some vitamin D. Still, don’t rely on diet alone to stop winter vitamin D deficiency. Most people will still need supplements.

🧪 Should You Consider a Blood Test?

A lot of people ask if checking their vitamin D levels with a blood test is a good idea.

When a test is worth it:

Think about getting tested if you:

• Feel bone pain have weak muscles, or break bones often
• Struggle with conditions that block your body from absorbing vitamin D like obesity, kidney issues, or digestion problems
• Use medications that mess with vitamin D levels
• Are pregnant or planning to have a baby soon
• Have very dark skin and live in places with less sunlight

When you might skip testing:

Most healthy individuals don’t need regular vitamin D tests. If you’re taking the right supplements in winter and eating well, tests don’t provide much benefit and add to medical bills.

What your results mean:

If you decide to test here’s how to understand the numbers:

• Under 30 nmol/L (12 ng/mL): Lacking
• Between 30-50 nmol/L (12-20 ng/mL): Low levels
• Above 50 nmol/L (20+ ng/mL): Enough for most individuals
• Over 125 nmol/L (50 ng/mL): Think about cutting back on supplements

Speak with your doctor to decide if testing makes sense for you. Avoid testing just to satisfy curiosity—let’s keep healthcare resources focused on those who need them.

👶 Key Points About Kids’ Needs

Kids have different requirements from grown-ups—this is true in winter.

Reasons why kids are at risk:

Kids need enough calcium and vitamin D for growing strong bones. Without these, they may face problems like:

• Slow growth
• Weak or soft bones, which can cause rickets
• Higher chances of breaking bones
• Issues with teeth

Research reveals that 66% of kids lack adequate vitamin D in winter. In some groups, this percentage is even greater.

Babies and breastfeeding:

Breast milk provides very little vitamin D. The American Academy of Pediatrics advises the following:

• Breastfed babies: Give 400 IU of vitamin D drops every day starting soon after birth.
• Formula-fed babies: Extra vitamin D is unnecessary since formula contains it, but always confirm with your pediatrician.
• Keep giving drops until your child drinks enough fortified milk on their own.

Do not skip this step. Infant rickets still happens in wealthy countries in breastfed babies who don’t get vitamin D supplements.

Older kids and teens:

Kids and teens in school need:

• A minimum of 600 IU of vitamin D each day.
• Often around 1000 IU during winter months if they stay indoors often.
• Higher amounts are needed for children with darker skin or those who are obese.

Liquid drops chewable tablets, or gummies can help kids take supplements when they have trouble with regular pills.

Speak with your child’s doctor:

Dosing for kids needs to be very exact compared to adults. Always ask your child’s pediatrician about the proper dose of vitamin D3 based on their age, weight, and specific needs.

👵 Vitamin D and Seniors

Getting older raises the chances of not having enough vitamin D because of multiple factors.

Reasons seniors require more:

As you grow older:

• Your skin makes less vitamin D with the same amount of sun.
• Your kidneys are not as good at turning vitamin D into its active form.
• You stay indoors more often.
• Some medications can mess with how your body handles vitamin D.
• Fragile bones mean bone health is extra important for you.

How much you need:

People over 70 should aim for:

• At least 800 IU every day.
• 1000-2000 IU is needed in the winter months.
• Bigger doses may be necessary if you are deficient, but with a doctor’s advice.

Not just for bones:

Vitamin D can help older adults by:

• Boosting muscle strength and balance so falls happen less.
• Supporting your immune system.
• Helping maintain general health.

Helpful advice:

• Pick vitamin D3 supplements that include calcium if your doctor advises it.
• Take them during your biggest meal of the day.
• Set a daily alert so you don’t forget.
• Don’t just assume your multivitamin has enough—double-check the label.

As you age, falls and fractures can pose greater risks. Keeping your vitamin D levels at a healthy range is a straightforward way to help prevent these issues.

⚠️ Key Safety Tips

Vitamin D3 works well for most people, but there are some things to watch out for.

Is it possible to take too much?

Sure, but using standard doses makes it tough. Vitamin D poisoning happens with high doses, like over 10,000 IU for several months. Signs of this include:

• Feeling sick or throwing up
• Feeling weak
• Problems with kidneys
• Calcium collecting in parts of the body

Taking vitamin D supplements in amounts between 1000-2000 IU is much lower than dangerous levels for most healthy adults.

Medicine interactions:

Certain medicines may react with vitamin D, including:

• Some drugs for cholesterol, like statins
• Steroids
• Medications for weight loss, like orlistat
• Specific drugs for seizures

If you’re on regular meds, ask your doctor if it’s okay to take vitamin D supplements. Never assume all supplements are safe.

When should you skip supplements?

Some should avoid taking vitamin D supplements unless a doctor advises it. These include people who have:

• High calcium levels in their blood
• Kidney problems
• Certain cancers
• Sarcoidosis or other granulomatous diseases

Choose good brands:

Not all supplements are equal. Some brands might not include what they claim on the label. Stick to trusted names or check for USP verification. Consider reputable pharmacy brands too.

🌍 Is where you live important?

Your location plays a big role in how much vitamin D you get during winter.

If you’re in northern areas:

If you live north of 37°N latitude, like in cities such as Boston, Chicago, New York, or Seattle in the United States—or in places like most of Canada, the UK, and northern Europe—your body makes little to no vitamin D from sunlight between November and February.

People in these places often face more cases of vitamin D deficiency. They see the most benefit from taking vitamin D supplements during winter.

Warmer southern areas:

Even in states with lots of sunshine like Florida Texas, or California, winter months reduce how much vitamin D your body can create. While it’s still possible to produce some vitamin D in these regions most people don’t spend enough time under the sun during winter to reach healthy levels without taking supplements.

Spending time indoors matters more than where you live:

Living in sunny places does not guarantee enough vitamin D because modern indoor habits keep many people deficient all year. Spending most of your day inside at work, driving cars, or relaxing indoors in the evening makes your location less important than you might think.

Skin color matters more:

Darker-skinned individuals need a lot more sunlight to make the same amount of vitamin D as those with lighter skin. If you are African American, Hispanic, South Asian, or have lots of melanin, taking supplements during winter is extra important no matter where you live.

🧬 Who’s at the greatest risk?

Certain groups are at a higher risk of lacking vitamin D when it’s colder.

Groups at high risk:

People over 60: As people age, their body produces less vitamin D naturally.

Darker skin individuals: Higher melanin levels block UVB rays, so they need more sunlight to produce vitamin D.

Pregnant or breastfeeding moms: They need extra vitamin D to help develop the baby or support the infant’s growth.

Obese individuals: Body fat traps vitamin D leading to lower levels in the blood.

Individuals with digestion problems: Conditions like Crohn’s and celiac disease make it harder to absorb vitamin D.

Those covering their skin: People who cover up for cultural, religious, or health reasons may lack sun exposure.

Night shift employees: Working at night and sleeping during the day means less time in the sunlight.

People with mobility challenges: Difficulty going outside limits access to sunlight.

Breastfed-babies: Breast milk doesn’t provide enough vitamin D for newborns.

If you belong to any of these groups, you need winter supplements—they aren’t just a choice. Discuss the right dosage with your care provider to suit your needs.

🍽️ Easy Food Tips for the Winter Season

Even though supplements are a must healthy eating helps maintain your overall vitamin D levels.

Weekly meal suggestions:

Monday: Roast some veggies to go with baked salmon
Wednesday: Scramble eggs (include the yolks) and pair them with whole grain toast
Friday: Make a tuna salad sandwich using fortified bread
Daily: Start your day with fortified cereal and fortified milk
Snacks: Try fortified yogurt or enjoy cheese and crackers

Affordable food ideas:

Canned salmon or tuna offers the same vitamin D as fresh fish but is much cheaper. Eggs are one of the most affordable protein options rich in vitamin D. Fortified store-brand milk costs no more than regular milk.

Challenges for vegetarians and vegans:

Few plant-based foods have natural vitamin D. Vegans or vegetarians can:

• Pick fortified plant-based milks like soy, almond, or oat.
• Look for UV-exposed mushrooms (check the packaging).
• Use orange juice with added vitamin D.
• Try plant-based D3 made from lichen.
• Make supplements a must in winter.

Tips for cooking:

Vitamin D can withstand heat so cooking will not ruin it. You can bake, grill, or pan-fry fatty fish without losing its vitamin D content.

🏃 Simple Habits to Boost Vitamin D

Besides eating healthy and taking supplements, some routines help maintain vitamin D levels in the colder months.

Step outside on lunch breaks:

Winter sun may not create much vitamin D, but stepping outdoors still offers these benefits:

• Fresh air and staying active
• Exposure to natural light, which helps regulate your body’s clock
• Improved mood and mental health
• A bit of vitamin D on sunnier days

Put on warm clothes and aim for a short walk of 10 to 15 minutes when possible.

Use natural indoor light:

While bright indoor lights won’t make vitamin D, they help boost mood and energy in the dark winter months. Open your curtains, spend time by windows, and ensure your home is lit.

Stay active:

Exercise keeps bones strong even without vitamin D. Activities like walking, dancing, or lifting weights help maintain bone density when paired with enough vitamin D.

Keep a healthy weight:

Extra body fat stores vitamin D so being overweight raises the amount your body needs. Staying at a healthy weight can make vitamin D work better in your system.

Cut back on alcohol:

Drinking too much alcohol messes up how your body uses vitamin D. To keep good levels, drink moderately or steer clear of it altogether.

🩺 When You Should Visit Your Doctor

You can often handle winter vitamin D levels with basic supplements. Still, get medical help if you:

Notice troubling signs:

• Pain in bones or muscles that does not make sense
• Weak muscles interfering with your daily life
• Break bones or get injured
• Feel tired without any clear reasons

Have specific health issues:

• Kidney or liver problems
• Digestive issues
• Thyroid disorders
• Conditions that block nutrient absorption

Use certain medications:

• Steroids or medications with steroids
• Drugs for lowering cholesterol
• Medicine for seizures
• Pills for reducing weight

Unique circumstances:

• You are pregnant or trying to get pregnant.
• You are breastfeeding right now.
• Your child may have developmental delays.
• You are older than 75 and have trouble with balance or moving around.

Your doctor or healthcare provider can decide if you need to monitor with a blood test or take more supplements based on your needs.

📊 Breaking Down the Numbers

When talking about vitamin D, you might see several terms and ways of measuring it.

How blood levels are measured:

Vitamin D blood tests check 25-hydroxyvitamin D. This is shown as:

• nmol/L (nanomoles per liter) – common in most countries
• ng/mL (nanograms per milliliter) – used in the U.S.

To convert: ng/mL × 2.5 = nmol/L

What the levels indicate:

Blood Level in nmol/Lng/mLHealth StatusDeficient<30<12Needs urgent careInsufficient30-5012-20Below optimal, increase intakeAdequate50-12520-50Ideal for most individualsHigh>125>50Consider lowering supplementationToxic>375>150Risky, stop taking supplements

Supplement measurement units:

Vitamin D supplements use these units:

• IU (International Units) – the most used
• mcg (micrograms) – appearing on newer labels

To convert: 40 IU = 1 mcg

Typical doses:

• 1000 IU equals 25 mcg
• 2000 IU equals 50 mcg
• 4000 IU equals 100 mcg

🌟 The Key Point About Winter and Vitamin D

Winter leads to a lack of vitamin D, but this can be avoided. When sunlight is gone for long periods, your body cannot produce enough of this essential vitamin on its own.

The basic fact:

You cannot count on getting enough vitamin D from winter sunlight or food alone during the fall and winter seasons. For most people in cooler regions, that’s just not enough.

A simple fix:

Taking a daily vitamin D3 supplement of 1000-2000 IU from October to March costs $10 for the whole winter. This small cost helps prevent vitamin D deficiency while improving bone strength immune health, and overall well-being.

What success looks like:

You won’t notice vitamin D “working.” It’s not going to give you instant energy or big changes. Success is quieter—it means keeping good bone health helping your immune system stay strong, and avoiding long-term problems caused by low levels.

Starting today:

Don’t wait until symptoms show up. Vitamin D deficiency sneaks up over time. If you’re not already taking it, start now, stay consistent this winter, and work it into your yearly fall and winter routine.

Managing vitamin D in winter is simple. Take d3 supplements every day with meals that have some fat. Eat foods rich in vitamin D when you can and spend time outside whenever possible. These easy steps help keep you healthy during the darker months without much sun.