Vitamin D – The Sunshine Vitamin

An essential hormone that plays a vital role in maintaining overall health and wellbeing, including bone health, immunity, and mood regulation.


Vitamin D is a crucial nutrient for overall health and well-being. Known as “the sunshine vitamin,” Vitamin D is produced by the body in response to sunlight exposure. This essential hormone offers a range of benefits, including stronger bones and teeth, improved immunity, and positive feelings of calmness, energy, and mental clarity. Every cell in the body has Vitamin D receptors, highlighting its vital role in various bodily functions.


Vitamin D deficiency is a widespread problem that affects more than 1 in 7 people on the planet, with approximately 50% of people worldwide experiencing insufficient levels of this important nutrient. (1) The primary cause is a lack of sunlight exposure due to spending too much time indoors, living in a location with insufficient sunlight, and possibly by using sunscreen with a high SPF rating (more on that below).

While Vitamin D can be found in dietary sources such as oily fish, eggs, and fortified milk and cereals, these sources typically provide minimal amounts. 

Regular sun exposure is the most natural way to ensure adequate vitamin D levels. For healthy blood levels, aim for 10-30 minutes of midday sun exposure several times a week, adjusting for skin sensitivity. Factors such as skin pigmentation, location, and amount of skin exposed all affect vitamin D production.

Individuals living farther from the equator may require more sunlight and/or vitamin D supplements during winter months. Applying sunscreen after 10-30 minutes of unprotected exposure can help prevent sunburn and skin cancer.

Another way to meet your daily requirements is to take a supplement daily. Consider it your daily dose of sunshine, rain or shine! 

How does Sunscreen affect Vitamin D Production?

Sunscreen is used to protect the skin from sunburns and skin cancer by reflecting, absorbing, or scattering sunlight. However, this can also reduce the amount of UVB rays that are necessary for producing vitamin D. Studies have shown that sunscreen with a high SPF can decrease vitamin D production by up to 92.5%. (2) However, circulating levels were only minimally affected. Despite this, some research indicates that wearing sunscreen has only a minor effect on blood vitamin D levels during the summer. (3) This is likely due to prolonged sun exposure compensating for the reduced UVB absorption. However, the long-term impact of frequent sunscreen use on vitamin D levels is still unclear.

Vitamin D, Depression and Seasonal Affective Disorder

Vitamin D deficiency has been linked to various mood disorders, including Seasonal Affective Disorder (SAD) and depression (4). SAD is a common depressive illness that occurs during the winter months in the northern hemisphere, where there is less sunlight exposure. Studies have found that Vitamin D supplementation often resolves SAD. (5)

Vitamin D plays a crucial role in increasing neurotransmitters. It is converted to active vitamin D (1,25D) which increases the amount of serotonin and dopamine in the brain. (6) It does this by inducing serotonin synthesis, mimicking antidepressants such as SSRIs and MAO inhibitors by reducing the expression of genes that remove serotonin from the synapses and that destroy serotonin and dopamine after use. Unlike antidepressants, Vitamin D does not interfere with the body’s natural processes and does not cause the same side effects or withdrawal syndromes that antidepressants do.

The Role of Vitamin D in Immunity

Vitamin D plays a critical role in supporting the immune system. It helps to activate immune cells such as T-cells and macrophages, which are important for fighting off infections and diseases. Vitamin D also helps to regulate the production of cytokines, which are proteins that are involved in immune responses. (7) Studies have shown that vitamin D deficiency is associated with an increased risk of infections, including respiratory infections, and that supplementation with vitamin D may reduce the risk of developing these infections. (8) Vitamin D deficiency may also be correlated with (but not necessarily causes) many allergic diseases such as asthma, allergic rhinitis, and wheezing, especially in children. (9


To ensure you’re getting the right amount of Vitamin D, it’s recommended to get your levels tested by a physician and track your progress. A blood test can measure your levels of 25-hydroxyvitamin D, which is considered the best indicator of Vitamin D status. Based on the results, your doctor can recommend the appropriate dose of Vitamin D supplement for you.

If you’re taking Vitamin D supplements, it’s best to take them in the morning with a meal that contains some fat, as Vitamin D is fat-soluble and needs dietary fat to be absorbed properly. 

The RDA for vitamin D is 600-800 IU, but many health experts now believe that this may not be enough for optimal health. A study published in The Journal of Clinical Endocrinology & Metabolism (10) found that adults may need at least 1500-2000 IU of vitamin D per day to maintain optimal blood levels. However, according to this same research, some people over the age of 8 years may need up to the maintenance tolerable upper limit (UL) of 4000 IU per day which is not to be exceeded without medical supervision.

Some people may also require higher doses if they have certain medical conditions that affect their ability to absorb or metabolise Vitamin D. In such cases, a doctor may recommend a higher daily dose or periodic high-dose Vitamin D supplementation. 

Supplementing with Vitamin D

In case you need to supplement your Vitamin D intake, there are various forms available. These include Vitamin D3 sourced from lanolin (sheep’s wool), a vegan alternative form of D3 made from lichen, and Vitamin D2 obtained from UV-exposed mushrooms.

Subjective Experiences

Some people (myself included) have reported rare symptoms such as anxiety from standard Vitamin D3 on forums like Reddit, so you might want to experiment with these different types if you react to one form or another. It is unclear what causes Vitamin D3 induced anxiety, but perhaps it is a response to the lanolin from which it is extracted. Personally I have an excellent response to Vitamin D2. Please comment below if you have experience of this rare side effect.


Vitamin D is an essential nutrient that plays a crucial role in many bodily functions, including bone health, immunity, and mental health. While sunlight exposure is the most natural way to get Vitamin D, it’s not always feasible, and many people may not get enough from their diet alone. Vitamin D supplements are a safe and effective way to ensure optimal Vitamin D levels, but it’s important to get your levels tested and consult with a doctor before starting any supplement regimen. With proper supplementation, you can enjoy the many health benefits of Vitamin D and maintain overall wellness.




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