How To Increase Your Vitamin D Levels Through Sunshine, Diet, and Supplements

The Role of Sunlight in Vitamin D Production

One of the most natural ways to maintain healthy vitamin D levels is through sunlight exposure. The body produces vitamin D when the skin is exposed to ultraviolet B (UVB) rays from the sun. However, there are factors that can make it challenging for many people to achieve adequate vitamin D through sunlight alone.

Midday Sun Exposure: The optimal time for vitamin D synthesis is during midday when the sun is at its highest point. Sun exposure to the torso is particularly effective, as this area of the body tends to produce more vitamin D. Ideally, 10-30 minutes of sunlight exposure several times per week is enough to stimulate vitamin D production in most people, depending on their skin type and the intensity of the sun. However, most people are not exposing their torsos to the sun during midday as part of their regular routine.

Latitude and UVB Rays: The geographical latitude also plays a role in UVB exposure. Individuals who live in higher latitudes, especially in the winter months, may not receive enough UVB rays to produce sufficient vitamin D. In these cases, supplementation becomes even more important.


Clothing and Sunscreen: People living in sunny climates often still face difficulties in maintaining adequate vitamin D levels due to clothing that blocks sunlight, how and when they are exposed to sunlight, and the use of sunscreen. Sunscreen with an SPF of 30 or higher can block 95-99% of UVB rays, drastically reducing the skin's ability to synthesize vitamin D. People who are always covered up for cultural, religious, or lifestyle reasons may be at increased risk for deficiency, even in sunny regions.



Additional Factors Affecting Vitamin D Synthesis From the Sun

Cholesterol and Statins: The skin uses cholesterol as a precursor to produce vitamin D, so people with low cholesterol or those taking statin medications may have a reduced ability to produce vitamin D. Statins, which are medications that lower cholesterol levels, may inadvertently impair vitamin D synthesis and lead to lower blood levels of vitamin D.


Age and Skin Tone: Older adults and people with darker skin tones may have a reduced ability to produce vitamin D from sunlight. Melanin, the pigment in the skin, acts as a natural sunscreen and can limit UVB absorption. This makes individuals with darker skin more prone to deficiency, especially if they live in regions with limited sunlight.


Getting Vitamin D From Foods

Getting enough vitamin D from food alone can be challenging, as it’s not naturally abundant in most foods. The best sources are fatty fish like salmon, mackerel, and sardines, as well as liver, mushrooms, and egg yolks. Many people rely on dairy products for their vitamin D intake, but it’s important to note that the vitamin D in dairy is typically added in during processing, just like a supplement. While dairy can be an easy source, it’s not ideal to consume large amounts of dairy daily; it can be an inflammatory food for many, and is a frequent cause of constipation, gas, and bloating. To ensure adequate vitamin D intake, it may be better to focus on fatty fish, liver, and eggs, and consider supplements if needed.

Vitamin D Supplementation: Daily vs. Weekly Doses

Due to the difficulty of getting vitamin D from the sun, and low levels found in food, I recommend most people supplement with vitamin D. The amount needed is a personalized number, and it’s recommended you work with a nutritionist or health care practitioner to determine the appropriate supplementation level for you.

Most functional practitioners (like me!) generally recommend daily doses over one high weekly dose. Daily supplementation provides a more consistent and stable level of vitamin D in the body, which may be more effective for maintaining optimal health. High-dose weekly pills may cause fluctuations in vitamin D levels and are generally not recommended for long-term use (unless told otherwise by your prescriber). High weekly doses may cause stomach upset and other various symptoms as well.

To maximize absorption, it is best to take a vitamin D supplement with a fatty meal or along with a supplemental Omega 3 pill, as vitamin D is fat-soluble and uses fat to be properly absorbed. Some vitamin D supplements will contain fats to help this along, and may be able to be taken without food.