Vitamin D Deficiency Symptoms, Sunlight & Supplements

QUICK SUMMARY

What causes vitamin D deficiency? Vitamin D deficiency can happen when you do not get enough sunlight, do not eat enough vitamin D-rich foods, have darker skin, live in a northern climate, spend most of your time indoors, have poor nutrient absorption, take certain medications, or have kidney or liver issues that affect vitamin D metabolism.

Vitamin D plays a vital role in mood, energy, immune resilience, muscle function, calcium absorption, and bone health. Low levels may be subtle, but they are commonly associated with bone pain, muscle weakness, fatigue, low mood, hair loss, immune challenges, and poor bone mineralization.

The best natural strategy is balanced: get wise sunshine without burning, eat nutrient-rich foods, test your 25-hydroxyvitamin D level when needed, and use vitamin D3 with K2 supplementation when sunlight and food are not enough.

Vitamin D is not just another nutrient.

It is a sunshine-connected hormone-like vitamin that touches mood, immunity, bones, muscles, inflammation, and whole-body resilience.

And in a world where many of us spend most of our lives indoors, low vitamin D is not surprising.

But the answer is not fear, megadosing, or reckless sun exposure.

The answer is wisdom.

Get sunlight when you can. Avoid burning. Eat nutrient-rich foods. Test your levels when needed. Supplement with vitamin D3 and K2 when appropriate. Support your bones with movement, minerals, protein, and strength training.

And remember, God made light before He made living creatures.

Your body was designed to live in rhythm with His creation.

A few intentional habits can help restore that rhythm and support the abundant life He calls you to live.

How Much Sun Do You Really Need?

It’s shocking: more than 1 billion people worldwide are estimated to have low vitamin D levels. (1)

Vitamin D plays a vital role in your mood, energy, immune strength, muscle function, and bone health. Yet long work hours indoors, sunscreen use, darker winter months, and colder climates make low vitamin D increasingly common.

The good news?

With a few intentional choices, like safe sun exposure, smart supplementation, and nourishing foods, you can support healthy vitamin D levels naturally and enjoy the benefits of this “sunshine vitamin” year-round.

A little sunshine each day can do wonders for your mood and overall well-being, but how much is enough?

For many people, 10 to 30 minutes of direct sunlight on bare skin may help the body produce vitamin D, depending on skin tone, season, latitude, time of day, cloud cover, age, and how much skin is exposed. Those with darker skin often need more time, while people living in northern regions or going through winter months may not make enough vitamin D from sunlight alone. (2)

Important note: your body may still receive ultraviolet light on cloudy days, but vitamin D production is significantly reduced when UVB rays are limited. More time outdoors may be needed compared with sunny summer days.

Finding the Right Balance

Sun exposure requirements vary by skin tone, latitude, and season.

Outside of summer, vitamin D production drops sharply in many northern climates, making supplementation a smart choice for many adults. Sunscreen and protective clothing help reduce skin damage and sunburn risk, but they also limit vitamin D synthesis.

So what do we do?

We aim for wisdom, not fear.

Get brief, sensible sunlight when appropriate, avoid burning, cover up when exposure will be prolonged, and use supplements or vitamin D-rich foods when sunlight is not enough.

Other Benefits of Sunshine

Beyond vitamin D, sunlight helps regulate your circadian rhythm, supporting better sleep and more stable energy.

Morning sun exposure is especially helpful for setting your internal clock. It signals to the body that the day has begun, supports serotonin rhythms, and helps prepare the body to produce melatonin at night.

This is one reason we love getting outside early in the day.

God designed our bodies to live in rhythm with light and darkness, activity and rest, work and worship.

The Bottom Line

A small dose of daily sunshine can support your health naturally, but more sun is not necessarily better.

Too much exposure can increase your risk of skin damage and burns. Aim for moderation, not excess, and enjoy the many benefits of God’s natural light responsibly.

When sunlight is limited, vitamin D-rich foods and quality supplements can fill the gap safely.

Common Causes of Vitamin D Deficiency

Vitamin D deficiency was much less discussed 100 years ago when people spent more time outdoors, regardless of temperature or weather conditions.

Today, many of us work indoors, commute indoors, exercise indoors, and then relax indoors. Add in winter months, sunscreen, long sleeves, air-conditioned lifestyles, and low dietary intake, and it is easy to see why vitamin D deficiency is so common.

According to the National Institutes of Health Office of Dietary Supplements, vitamin D status is typically evaluated by measuring 25-hydroxyvitamin D, also written as 25(OH)D. Levels below 30 nmol/L, or 12 ng/mL, are considered too low for bone health, and levels of 50 nmol/L, or 20 ng/mL, or higher are generally adequate for most people. (2)

Common causes and risk factors include:

• Lack of sunlight exposure: Your body makes vitamin D when your skin is exposed to UVB rays from sunlight.
• Lack of dietary vitamin D: This may especially affect people who avoid animal foods, since vitamin D is naturally found in fatty fish, egg yolks, liver, and some grass-fed animal foods.
• Darker skin tone: Higher melanin content reduces the skin’s ability to produce vitamin D from sunlight, so people with darker skin may need more sun exposure or supplementation.
• Northern climates and winter months: UVB exposure may not be strong enough for much of the year in some regions.
• Older age: Aging skin is less efficient at producing vitamin D.
• Kidney or liver disease: The body must convert vitamin D into active forms, and kidney or liver issues can interfere with this process.
• Poor food absorption: GI disorders like celiac disease, Crohn’s disease, cystic fibrosis, and inflammatory bowel conditions can prevent proper vitamin D absorption.
• Use of certain medicines: Medications such as anticonvulsants, glucocorticoids, rifampin, and some HIV medications can affect vitamin D metabolism. (2)
• Obesity: Vitamin D is fat-soluble and may become sequestered in body fat, contributing to lower circulating levels.

Also, because of the high content of melanin in the skin, low vitamin D levels are commonly seen in African-American children, especially during winter months.

Application: If you have risk factors for deficiency, ask your practitioner for a 25(OH)D blood test. Guessing is not as helpful as testing, especially if you have fatigue, bone pain, muscle weakness, autoimmune issues, pregnancy, osteoporosis risk, or absorption problems.

Warning Signs of Vitamin D Deficiency

Many people with low vitamin D experience bone pain, joint pain, muscle weakness, or fatigue, but symptoms can be subtle.

Some people have no obvious symptoms at all.

That is called “subclinical” deficiency, meaning vitamin D levels are lower than normal without clear visible signs.

Low vitamin D levels have been associated with a wide range of health concerns, including:

• Bone pain
• Muscle weakness
• Chronic fatigue
• Low mood
• Cognitive changes
• Hair loss
• Low blood calcium levels
• Low blood phosphate levels
• High blood pressure
• Rickets in children
• Osteomalacia in adults
• Bone fragility
• Immune challenges
• Weight gain patterns

To say vitamin D has been thoroughly evaluated is an understatement. PubMed includes tens of thousands of studies referencing vitamin D. (3)

When reviewing the literature, several major health areas stand out.

Cardiovascular Health

Cardiovascular disease is a leading cause of death worldwide, and low vitamin D has been associated with cardiovascular risk factors through pathways involving inflammation, oxidative stress, lipid metabolism, vascular function, and the renin-angiotensin-aldosterone system.

A study in Circulation highlighted vitamin D’s role in vascular repair and endothelial colony-forming cell function, suggesting vitamin D may support vascular regeneration pathways. (4)

This does not mean sunshine or vitamin D is a stand-alone heart treatment. It means vitamin D status is one important piece of a broader heart healthy lifestyle.

Pain and Quality of Life

Pain and quality of life often go hand in hand.

A study in Rheumatology International found that low vitamin D was associated with higher pain intensity and worse quality of life in patients with chronic widespread pain. (5)

This is important for anyone who struggles with chronic pain, fatigue, and low resilience. Checking vitamin D status may be a simple, practical step in a broader healing plan.

Prostate Cancer

Vitamin D has also been studied in relation to cancer risk and cancer biology.

In research involving men from the Selenium and Vitamin E Cancer Prevention Trial and the Prostate Cancer Prevention Trial, investigators examined blood vitamin D levels and prostate cancer risk, including high-grade prostate cancers. (6, 7)

One article noted that plasma 25(OH)D levels were associated with a linear decrease in high-grade prostate cancer risk in African American men. (6)

This is an association, not a stand-alone prevention protocol. Still, it is a compelling reminder that vitamin D status matters deeply, especially for men at higher risk.

Juvenile Idiopathic Arthritis

Low vitamin D levels have been observed in autoimmune and inflammatory conditions, including juvenile idiopathic arthritis.

Italian researchers evaluated children, adolescents, and young adults with JIA and found significantly reduced 25(OH)D levels compared with controls. Patients with active disease or frequent relapses had the lowest vitamin D levels. (8)

This suggests vitamin D status may be an important part of supporting inflammatory balance, especially in children with chronic inflammatory conditions.

Reality check: Vitamin D is powerful, but it is not magic. Low levels should be corrected, but supplementation works best alongside nutrition, sleep, movement, stress reduction, prayer, sunlight, and medical care when needed.

Vitamin D Recommendations & Supplements

First, we need to answer whether vitamin D supplements are really necessary.

For some people, yes.

For others, maybe not year-round.

The NIH lists the Recommended Dietary Allowance for vitamin D as 600 IU daily for most adults ages 19 to 70 and 800 IU daily for adults over 70. (2) The Bone Health & Osteoporosis Foundation recommends 800 to 1,000 IU daily for adults age 50 and older. (9)

The Endocrine Society’s 2024 guideline on vitamin D for prevention of disease suggests empiric vitamin D supplementation for certain groups, including children and adolescents, adults over 75, pregnant people, and adults with high-risk prediabetes, while not recommending routine supplementation beyond usual recommended intake for many otherwise healthy adults under 75. (10)

What does this mean practically?

Supplements are useful when you are deficient, at higher risk, pregnant, older, not getting sunlight, dealing with absorption challenges, or needing practitioner-guided support.

But supplements cannot replace the full design God built into natural rhythms: sunlight, whole foods, outdoor movement, and seasonal living.

Natural vs. Synthetic Vitamin D

Most vitamin D3 supplements are made from lanolin, a natural compound from sheep’s wool that is processed with UV light into cholecalciferol, the same general form of vitamin D3 your body makes from sunlight.

Natural and synthetic forms can be similar in structure and function. However, food-based sources may come with cofactors that support nutrient use. Supplements are still effective for correcting low levels, but they work best as part of a nutrient-rich lifestyle.

When Supplements Matter Most

Routine supplementation is not needed for everyone at the same dose.

The greatest benefits are often seen in people who are deficient, pregnant, elderly, at higher risk, or have absorption issues due to medical conditions.

For most healthy adults, supplements should not be viewed as a replacement for nutrient-rich food or regular, safe sun exposure.

In short, vitamin D supplements are a useful backup plan, but God designed our bodies to thrive best when we get this “sunshine vitamin” through light, whole foods, and time outdoors whenever possible.

D3 + K2

The key to buying the right vitamin D supplement is to make sure it is manufactured in a form your body can absorb and, for many people, paired with vitamin K2.

Vitamin D helps the body absorb calcium. Vitamin K helps activate proteins involved in calcium metabolism, including proteins that help direct calcium into bones and away from soft tissues. (11)

That is why many natural health practitioners recommend taking vitamin D3 and vitamin K2 together.

There are several forms of vitamin K2, including MK-4 and MK-7. MK-7 has a longer half-life and is often used in supplements for steady support.

Application: If you take blood thinners such as warfarin, do not start vitamin K2 without medical guidance.

Note on Bone Health & Steroids

Vitamin D supports calcium absorption, muscle function, and bone health. Deficiency can contribute to rickets in children, osteomalacia in adults, and poor bone mineralization. (2)

Adults taking chronic steroids may need extra attention to bone health because glucocorticoids can increase osteoporosis risk. Professional organizations recommend calcium and vitamin D strategies as part of prevention for glucocorticoid-induced osteoporosis. (12)

For bone health, do not think only about vitamin D.

Think whole lifestyle:

• Vitamin D
• Vitamin K2
• Calcium-rich foods
• Magnesium
• Protein
• Weight-bearing exercise
• Resistance training
• Sunlight
• Avoiding smoking and excess alcohol

How Much Is Too Much?

Vitamin D is fat-soluble, so more is not always better.

The NIH lists the tolerable upper intake level for adults as 4,000 IU per day unless otherwise directed by a healthcare professional. (2)

High-dose supplementation should be guided by testing and follow-up.

Vitamin D-Rich Foods

Sunlight is the most natural source of vitamin D, but food matters too.

Vitamin D-rich foods include:

• Wild-caught salmon
• Sardines
• Mackerel
• Trout
• Pasture-raised egg yolks
• Beef liver
• Grass-fed dairy, if tolerated
• Cod liver oil
• UV-exposed mushrooms
• Fortified foods when needed

We prefer whole-food sources whenever possible, especially wild-caught fish and pastured animal foods.

If you eat a plant-based diet, vitamin D may take more planning. UV-exposed mushrooms can help, but many people still need testing and supplementation, especially in winter.

Application: Pair vitamin D-rich foods with healthy fats because vitamin D is fat-soluble. This helps absorption and makes meals more satisfying.

Vitamin D Deficiency FAQs

What are the most common signs of vitamin D deficiency?

Common signs include fatigue, muscle weakness, bone pain, joint discomfort, low mood, hair loss, frequent illness, and poor bone health. Some people have no obvious symptoms, which is why testing can be helpful.

What blood test checks vitamin D levels?

The standard blood test is 25-hydroxyvitamin D, also written as 25(OH)D. This is the main marker used to evaluate vitamin D status.

What vitamin D level is considered low?

The NIH notes that 25(OH)D levels below 30 nmol/L, or 12 ng/mL, are too low for bone health, while levels of 50 nmol/L, or 20 ng/mL, or higher are generally adequate for most people. (2) Some practitioners prefer higher functional ranges based on individual health goals.

How much sun do I need for vitamin D?

Many people may benefit from 10 to 30 minutes of direct sunlight on exposed skin several times per week, but needs vary by skin tone, season, latitude, time of day, age, and cloud cover. Avoid burning.

Can I get vitamin D on a cloudy day?

Some UV rays still penetrate clouds, but vitamin D production is lower when UVB exposure is reduced. Cloudy days, winter months, and northern climates can make sunlight less reliable for vitamin D.

Can sunscreen cause vitamin D deficiency?

Sunscreen reduces UVB exposure, which can reduce vitamin D production in the skin. However, sunscreen is also important for preventing burns and reducing skin damage during longer sun exposure. The goal is balanced, wise sun exposure without burning.

Is vitamin D3 better than vitamin D2?

Vitamin D3 is generally preferred by many practitioners because it tends to raise and maintain 25(OH)D levels more effectively than vitamin D2 in many studies. Ask your practitioner which form is best for you.

Should I take vitamin D with K2?

Many natural health practitioners recommend vitamin D3 with vitamin K2 because vitamin D supports calcium absorption and vitamin K supports calcium metabolism. If you take blood thinners, ask your practitioner before using K2.

Can too much vitamin D be harmful?

Yes. Vitamin D is fat-soluble, and excessive supplementation can lead to toxicity, high calcium levels, nausea, weakness, kidney problems, and other serious issues. The adult upper limit is generally listed as 4,000 IU daily unless supervised. (2)

Who is most at risk for vitamin D deficiency?

Higher-risk groups include people with limited sun exposure, darker skin, older adults, breastfed infants, people with obesity, people with malabsorption disorders, people taking certain medications, and those with liver or kidney disease.

Resources & References