Vitamin D: Why You Need It and How Your Body Gets It

Vitamin D is essential for strong bones, immune support, mood regulation, and more. Yet many people remain deficient. Understanding how your body absorbs vitamin D—and how to meet your daily needs—can help you stay healthier all year long.

Why Is Vitamin D So Important?

Vitamin D plays a crucial role in helping the body absorb calcium, a key component of bone health. It also supports immune function, reduces inflammation, and has been linked to mental well-being. A deficiency can result in fatigue, bone pain, or more serious complications.

How the Body Absorbs Vitamin D

Vitamin D is unique in that your body can make it on its own. But for that to happen, you need exposure to sunlight—and even then, several factors can affect how much your body actually produces. The rest must come from food or supplements.

Sources of Vitamin D

Your body can absorb vitamin D from three main sources. The key is finding the right balance and ensuring you meet the daily recommended intake for optimal health.

• Sunlight exposure
• Dietary sources
• Vitamin D supplements

Each source plays a role in raising your 25-OH level target, the blood measurement used to assess vitamin D levels.

Sunlight: Nature’s Vitamin D Producer

Your skin makes vitamin D when exposed to UVB rays from the sun. Just 10–30 minutes of midday sun a few times a week may be enough, but it varies greatly by skin type, location, and time of year.

• Darker skin requires more sunlight to produce vitamin D
• Sunscreen can block vitamin D synthesis
• Winter months or northern latitudes reduce UVB availability
• Age and body weight can affect absorption

The sun vs supplement dose question becomes critical in certain climates or for people with limited sun exposure.

Food Sources of Vitamin D

Few foods naturally contain vitamin D, but some are fortified. Diet alone is often not enough to maintain healthy levels, but it can help contribute to your daily intake.

• Fatty fish like salmon, tuna, and mackerel
• Egg yolks and beef liver
• Fortified dairy products and plant milks
• Fortified cereals and orange juice

Still, most diets fall short in providing enough vitamin D – especially for vegetarians or those with dietary restrictions.

Vitamin D Supplements

Supplements are the most reliable way to raise and maintain adequate vitamin D levels, especially for those at risk of deficiency. Most contain either D2 (ergocalciferol) or D3 (cholecalciferol)—with D3 being the preferred form for absorption.

• Available in tablets, softgels, and liquid drops
• Often combined with calcium or other nutrients
• Dosage can range from 400 IU to 5,000 IU or more

Talk to your doctor before starting high-dose supplements. Your dosage should be personalized based on your 25-OH level target, age, and risk factors.

What is the Ideal 25-OH Level Target?

The 25-OH level target refers to the amount of vitamin D in your bloodstream, measured in nanograms per milliliter (ng/mL). This helps determine if you are deficient, sufficient, or at risk for toxicity.

• Deficient: Less than 20 ng/mL
• Insufficient: 21–29 ng/mL
• Sufficient: 30–50 ng/mL
• Possible toxicity: Over 100 ng/mL

Experts often recommend a target level of 30–50 ng/mL for general health. Those with chronic illnesses or bone loss may need higher levels, under supervision.

Sun vs Supplement Dose: What’s Better?

There’s no one-size-fits-all answer to the sun vs supplement dose debate. Sun exposure is natural, but it is unreliable in many regions and during different seasons. Supplements are more consistent but must be taken regularly and responsibly.

• Sunlight provides a free, natural source, but comes with skin cancer risks
• Supplements provide controlled dosing, especially in winter
• People with darker skin or limited sun access often benefit from supplements
• Monitoring your 25-OH level target is key to balancing both

Combining safe sun exposure with a modest supplement dose is often the best approach.

Who’s Most at Risk for Deficiency?

Certain groups are more likely to have low vitamin D and should consider regular testing and supplementation:

• Older adults, especially over age 65
• People with darker skin tones
• Those who use sunscreen daily
• Individuals with obesity or chronic illness
• People who spend most time indoors

For these individuals, reaching and maintaining a healthy 25-OH level target may require year-round supplements.

Maintain a Healthy Level of Vitamin D

Vitamin D is not just a vitamin—it is a hormone that plays a role in nearly every system of the body. Understanding the sun vs supplement dose question and testing your 25-OH level target level helps ensure you stay energized, protected, and strong.

Whether from sunlight, diet, or supplements, maintaining healthy vitamin D levels is one of the simplest ways to improve your long-term health and wellness.

The information provided on this website, including text, graphics, images, and other materials, is intended solely for informational purposes and should not be used as a substitute for professional medical advice, diagnosis, or treatment.