Low Vitamin D and Mental Health: Are Your Genetics a Factor?

Published on: May 8, 2023

What to Know About Vitamin D Deficiency This Mental Health Awareness Month

As Mental Health Awareness Month kicks off and each day brings us a bit more warmth and sunshine (thank you, springtime!!), I’m focusing this month’s blog on one of the most well-known nutrients associated with depression, anxiety, and mood: vitamin D

Appropriately nicknamed “the sunshine vitamin”, our bodies absorb vitamin D from ultraviolet light exposure, certain foods and beverages (particularly fortified foods and animal products), and supplements containing cholecalciferol (vitamin D3) or ergocalciferol (vitamin D2). Still, vitamin D deficiency is among the most common nutrient deficiencies globally. About a billion people worldwide have low vitamin D levels, putting them at risk for physical health issues like bone pain and fatigue and mental health concerns such as depression and mood changes. Risk factors for vitamin D deficiency include genetics, diet, lifestyle, lack of sunlight exposure, and certain medical conditions and malabsorption syndromes.

In this blog post, we’ll take a closer look at how vitamin D deficiency may affect your mental health and well-being, how your genes may be impacting your vitamin D levels, and what you can do to increase your vitamin D levels (no matter the time of year!). 

What is Vitamin D?

Vitamin D is both a hormone and fat-soluble vitamin that’s produced naturally when 7-dehydrocholesterol (7-DHC) in the skin (a precursor of vitamin D) is exposed to ultraviolet B (UVB) rays. UVB rays convert 7-DHC in the skin to 25(OH)D in the liver (this form of vitamin D is also known as 25-hydroxy). Practitioners typically order 25-hydroxy labs when checking a patient’s vitamin D levels, as this test measures the total amount of vitamin D2 and D3 in the body (more on vitamin D2 and D3 below). 

Once the body converts 7-DHC in the skin to 25(OH)D in the liver, there’s still a lot more work to be done! 25(OH)D is then converted to 1.25(OH)D in the kidneys; 1.25(OH)D is the active form of vitamin D, also known as 1,25-dihydroxycholecalciferol or calcitriol

I know this stuff is complex! But the bottom line is this: it’s very difficult — if not impossible — to get enough vitamin D from sunlight alone (especially if you live far north or south of the equator, wear sunscreen, have darker skin, or spend most of your time indoors). And even if you do spend time outdoors year-round, there’s a lot less vitamin D to soak up from the sun during the winter months. 

Is it Better to Take Vitamin D2 or D3? 

While the sun naturally produces both vitamin D2 and D3, there are differences between these two forms of vitamin D. Vitamin D2 is found exclusively in plants, fungi, and fortified foods, while vitamin D3 is produced in humans and animals (including fish). Many experts believe vitamin D3 is more easily absorbed by the body. 

How Does Low Vitamin D Affect Mental Health?

While vitamin D plays a crucial role in skeletal health and the absorption of calcium, the nutrient has also been associated with cancer survival, autoimmune and infectious disease prevention, and positive mental wellness. In addition to seasonal affective disorder, several other mental health conditions associated with vitamin D include obsessive-compulsive disorder (OCD), attention deficit hyperactivity disorder (ADHD), schizophrenia, autism, anxiety, and depression. 

Let’s dive deeper into seasonal affective disorder since this is one of the most common types of depression that I see in my practice!

Low Vitamin D & Seasonal Affective Disorder

It probably comes as no surprise that low vitamin D levels are much more prevalent in winter, or that approximately five percent of the US population suffers from seasonal affective disorder (SAD). In arctic regions that experience Polar Night (for example, Alaska), SAD affects approximately 9.2 percent of the state’s population. 

Also referred to as the “winter blues”, SAD is a seasonal type of depression that’s been linked to vitamin D deficiency and a personal or family history of depression. Using a light therapy lamp in the fall and winter can definitely help to ease feelings of depression until spring rolls around, though sun lamps don’t have an impact on vitamin D levels. As such, it’s important to increase your dietary intake of vitamin D and take a daily supplement as well. Using a vitamin D tracking app like Dminder can also help you to schedule time outdoors when vitamin D levels are highest. 

So, why is direct sunlight exposure so important when it comes to vitamin D absorption? Because “50 to 90 percent of vitamin D is absorbed through the skin via sunlight, while the rest comes from diet”. (Omeed Sizar, et. al., 2023). At least 40 percent of your skin would need to be exposed to sunshine for a minimum of 20 minutes each day in order to prevent vitamin D deficiency through sunlight alone. 

Even this may not be enough if you’re darker-skinned, wear sunscreen or clothing that shields your skin from the sun, have genetic variants associated with low vitamin D (more on these below), or you’re 65 years of age or older. These factors all interfere with the dermal synthesis of vitamin D. 

Vitamin D Levels and Genetics: Tap Into Your Genes to Prevent or Treat Vitamin D Deficiency

Regardless of where you live and whether you’re currently supplementing with vitamin D, I recommend genetic testing for each and every one of my clients struggling with their mental health. Certain genetic variations (also called single nucleotide polymorphisms or SNPs) can impact your need for vitamin D from sunlight, food, and dietary supplements. This is specifically true for variants in the following genes:

  • CYP2R1 – this SNP reduces the ability of the CYP2R1 enzyme to turn vitamin D into its active form, 1,25-dihydroxyvitamin D3 also known as calcitriol. In a nutshell, this gene variant can impact how efficiently our bodies convert vitamin D from sunlight and food into its usable form.
  • GC – this genetic variant encodes for a protein called Vitamin D Binding Protein (DBP) that helps bind and transport the major circulating and active forms of vitamin D in the body (22(OH)D and 1,25(OH)2D). If that’s confusing, don’t worry! Some individuals with certain variants may have a 49% increased likelihood of vitamin D deficiency. This impact on vitamin D is due to issues with transporting vitamin D in the bloodstream to tissues in the body.
  • VDR – is a genetic variant that plays a role in many metabolic pathways (inflammation, insulin-like growth factor signaling, estrogen-related pathways, calcium and vitamin D regulation, and more). VDR requires vitamin D in order to function effectively. This variant is associated with less sensitivity of vitamin D receptors resulting in reduced efficiency of receptors, meaning vitamin D has a harder time doing its job!

Remember that the relationship between these genes, mental health, and vitamin D are complex and not yet fully understood by scientists. However, understanding your genetic makeup through genetic testing can help you make dietary and lifestyle choices that best align with your body’s unique needs. Genetic testing promotes positive mental health and wellness and provides valuable insights into potential health risks.

Food, Sunlight, & Supplements: Easy Ways to Boost Low Vitamin D Levels

If genetic testing reveals you have an increased need for vitamin D, the following can be helpful for preventing and treating a vitamin D deficiency or insufficiency: 

Taking a daily vitamin D supplement

The right vitamin D supplement and dosage depend on genetics, diet, age, and lifestyle. And though the Endocrine Society recommends supplementing with at least 1,500 to 2,000 international units (IUs) of vitamin D daily, higher amounts may be necessary in winter (especially in the case of vitamin D deficiency). Vitamin D toxicity is possible with high-dose vitamin D supplementation (think 10,000 IUs daily or more), but rare. I personally recommend that if you are supplementing with vitamin D, you should also be monitoring your vitamin D levels regularly with blood tests. For those with genetic variations, supplementing with the bioactive form of vitamin D, calcitriol, is recommended for optimal vitamin D metabolism. Additionally, people consuming a vegan, or dairy-free diet may need to consider vitamin D supplementation.

Exposing uncovered skin to sunlight when vitamin D levels are highest

While protecting your skin from the sun’s UV rays is certainly important, exposing uncovered skin to at least 20 minutes of sunlight each day is also essential. As I mentioned earlier, I recommend using a vitamin D tracking app so you can plan your outdoor time when vitamin D levels are highest! But remember, you can’t rely on sunlight alone for vitamin D during the winter months. 

Incorporating more vitamin D-containing animal foods into your diet 

Foods containing vitamin D3 include fatty fish, shellfish, and egg yolks — as well as other animal products like beef liver, cheese, and chicken breast. You can also supplement with vitamin D3 or fish liver oil to increase cholecalciferol levels in your body.

Incorporating more fortified foods and mushrooms into your diet for vitamin D 

Vitamin D2 (ergocalciferol) can be found in fortified foods (like cereals) and in most mushrooms. However, higher levels of vitamin D are present in mushrooms exposed to UV light, and the actual vitamin D content of any mushroom varies widely by mushroom type, producer, and location.

For example, one study found that raw portobello mushrooms contained anywhere from 134 to 835 IU/100 grams of vitamin D2 when exposed to UV light (varying by producer and location). In contrast, the same study found that raw portobello mushrooms contained between two and 31 IU/100 grams when not exposed to UV light. These levels also varied by producer and location.

Lower amounts of vitamin D2 were also found in shiitake, oyster, morel, maitake, enoki, chanterelle, crimini, and white button mushrooms. Of the untreated mushrooms studied, chanterelle and morel mushrooms contained the highest amounts of vitamin D2. 

The Good News About Treating Vitamin D Deficiency

The good news about nutrient deficiencies — including low vitamin D levels and the depressive symptoms associated with vitamin D deficiency — is that they’re often treatable with dietary and lifestyle changes. If you’re looking to give yourself some love and care this Mental Health Awareness Month, apply for coaching. Together, we’ll tap into your unique genes to uncover whether your genetics, diet, or lifestyle could be affecting your mood and mental wellness! 

Additional Resources for Mental Health Awareness Month

This Mental Health Awareness Month, I encourage you to check out some of my other recently published blogs. Each discusses the link between nutrition, genetics, and mental health:

Ready to tap into your genes so you can nourish your unique body, mind, and soul? Get additional support through coaching or sign up to receive emails from me to learn all about holistic mental wellness. You’ll get my FREE Food + Mood Guide for improving your mental wellness just for signing up!



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Howdy! I’m Haley. A registered dietitian nutritionist, yoga teacher, personal trainer, and holistic mental wellness coach on a mission to help you transcend the struggle, stress, and suffering that life can bring. I’ve lived through it and discovered a path to feeling amazing in my mind, body, and soul. Now, I want to help you to live your most fulfilled life too through evidence-based nutrition and lifestyle practices!

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