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The Best Time to Take Vitamin D, According to Experts

The Best Time to Take Vitamin D, According to Experts


Did you know that over a billion people worldwide are deficient in vitamin D (1)? Yes, over a billion.

Despite playing a critical role in bone health, immune function, and mental well-being, many people don’t know how to optimize their vitamin D intake.

Recent studies reveal some interesting connections between vitamin D levels and various health outcomes, including its roles in: reducing the risk of chronic disease, reducing the severity of COVID-19 infection, and enhancing mood (2). However, achieving optimal vitamin D levels isn't just about supplementation; timing, season, and even geographical location play important roles in determining who should supplement and when.

In this post, we'll explore the benefits of vitamin D, the best time to take it, discuss how much you should take, and how to avoid deficiency.


The Benefits of Vitamin D

Vitamin D plays an important role across multiple systems, including:

Bone Health: Vitamin D is critical for calcium absorption in the gut and for maintaining normal bone mineralization (3). Without sufficient vitamin D, bones can become thin and brittle. Adequate vitamin D levels can prevent rickets, osteomalacia in adults, and osteoporosis.

Immune System Support: Vitamin D is an important player in the immune system and can reduce inflammation (4). It enhances the body's pathogen-fighting effects, which is particularly important in the context of autoimmune diseases (5).

Mental Health: There is growing evidence that vitamin D plays a role in mental health. It is believed to affect the production of neurotransmitters like serotonin, which regulates mood. Deficiency has been linked to mood disorders like depression (6).

Chronic Disease Prevention: Vitamin D may help reduce the risk of chronic diseases, including cardiovascular disease and diabetes (7). In some cancers, it has been shown to influence the expression of genes that play a role in cancer prevention (8).


The Best Time of Day to Take Vitamin D 

Morning vs. Evening

The timing of vitamin D supplementation can influence how effective it is. Research suggests that taking vitamin D in the morning might be more beneficial compared to the evening. The primary reason is that vitamin D can potentially interfere with the production of melatonin, the hormone responsible for regulating sleep (9). Therefore, taking it late in the day may disrupt sleep patterns.


With a Meal

Vitamin D is a fat-soluble vitamin, meaning it is best absorbed when taken with foods containing fat. Consuming vitamin D with a meal, particularly one that includes healthy fats like avocado, nuts, or olive oil, can enhance absorption significantly (10).


The Best Time of Year for Vitamin D Supplementation

Winter Months vs. Summer Months

Sunlight is the most natural source of vitamin D since ultraviolet B (UVB) rays from the sun stimulate its production in the skin (11). During the summer months, most people can synthesize sufficient vitamin D through moderate sun exposure. However, in the winter, people spend less time outside, the angle of the sun is lower, and UVB rays are less intense, especially at higher latitudes. These seasonal diffferences means that supplementation becomes more critical during the winter months to maintain vitamin D levels.

While obtaining vitamin D through sunlight exposure is ideal, modern lifestyles often limit our time spent outdoors. People who work indoors, use sunscreen diligently, or live in areas with high pollution levels should consider supplementation.


Geographical Considerations

Geographical location plays a significant role in vitamin D synthesis. Individuals living at higher latitudes (closer to the poles) receive less UVB radiation throughout the year, and especially during the winter, so a greater reliance on dietary sources and supplements is usually required (12). Conversely, those living closer to the equator, where UVB radiation is more consistent year-round, might have less of a need for supplementation.


How Much Vitamin D to Take

The recommended daily allowance (RDA) for vitamin D varies based on age, sex, sun exposure, and skin color. For most adults, the RDA is 600 to 800 IU (International Units) per day. However, these values are based on maintaining bone health and may actually be insufficient for the other health benefits mentioned above. Some research has shown that 600 IU of vitamin D supplementation is not enough to increase vitamin D levels (13). The Endocrine Society supports 1,500-2,000 IU/day of supplemental vitamin D to maintain serum vitamin D levels (14). 


Vitamin D can be found in its most bioavailable form at the recommended amount in the plant-based essentials here.


Some groups of people may require higher doses of vitamin D. For instance, older adults often need more vitamin D due to decreased skin synthesis and dietary absorption. One study showed that between 40-80% of older adults are vitamin D deficient (15). Individuals that eliminate animal products from their diet such as those who are vegan or plant-based or individuals with certain medical conditions like osteoporosis or malabsorption syndromes (e.g., Crohn's disease, celiac disease) may also require higher doses.

Blood tests can measure 25-hydroxyvitamin D levels and can help tailor supplementation to your individual needs to prevent both deficiency and toxicity.


Who Should Take Vitamin D

Certain groups at higher risk for vitamin D deficiency that should consider regular supplementation include:

The elderly: Older individuals have reduced skin synthesis and dietary intake of vitamin D 

People with darker skin: An increase in melanin with darker skin reduces the skin’s ability to produce vitamin D

Those who are plant-based/vegan: The most significant dietary sources of vitamin D come from animal-based products, which are eliminated from the diet if vegan or plant-based

Individuals with limited sun exposure: If you receive limited sun exposure, including those living in northern latitudes or those who stay indoors frequently, then regular vitamin D supplementation may be needed

Those with medical conditions: Conditions like osteoporosis, chronic kidney disease, and obesity can impair vitamin D metabolism


How to Avoid Deficiency 

An estimated 42% of Americans are deficient in vitamin D, and this is mostly due to lack of sunlight exposure and our modern lifestyle of spending most of our time indoors. The most common ways to treat or prevent vitamin D deficiency include:

Increase sun exposure: Increasing sun exposure, especially during peak sunlight hours, is the most common way to increase vitamin D levels

Supplementation: Supplementing with vitamin D when you suspect you may be deficient is helpful in mitigating vitamin D deficiency. When purchasing a vitamin D supplement, look for one that has over 100% of the recommended daily allowance and is in the form of D3, the most bioavailable form of vitamin D.


Vitamin D can be found here in the plant-based essentials vegan multivitamin.


Increase dietary sources of vitamin D: Although somewhat limited in amount, vitamin D can be found in foods such as fatty fish, dairy, eggs, and fortified foods, though this should not be the primary source of vitamin D. 

While at-risk groups have a higher necessity for vitamin D, the general population can also benefit from vitamin D supplementation to support overall health, especially during the winter months or in regions with limited sunlight.



Vitamin D is a vital nutrient that supports many bodily functions, from bone health to immune system regulation. Taking vitamin D in the morning, with a meal, and especially during the winter months can help mitigate your risk of vitamin D deficiency.



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