Everything You Need to Know About Vitamin D

What is it |

How does it work |

What causes deficiencies |

Health benefits

What is Vitamin D? / Where does it come from


you feel sad and unmotivated during the long, dark winter months – you're not alone! This may be due to low levels of vitamin D; a mood-boosting nutrient that you produce when exposed to direct sunlight.

In this article, we explore the health benefits of the "sunshine vitamin" and how you can optimize your levels all year round.

Vitamin D is a fat-soluble nutrient that humans have evolved to produce via sun exposure. When UVB rays from the sun hit the skin, 7-dehydrocholesterol is converted into active vitamin D3 – also known as cholecalciferol. As it's synthesized from cholesterol, vitamin D3 acts more like a hormone than a vitamin in the body.


How Vitamin D Works

Vitamin D3 is involved in many physiological processes and has been found to influence some 3000 genes in the body. Almost all human cells have vitamin D3 receptors, making it a key nutrient for cell differentiation and growth.

One of its most well-known functions is the ability to regulate mineral balance for strong bones. It enhances calcium and phosphorus absorption in the gut and prevents calcium loss (1). This is essential for strengthening bones and teeth, promoting nerve cell activity, and regulating muscle contraction and relaxation.

It's best to consume vitamin D3 with vitamin K2. These two work synergistically to promote healthy calcium metabolism. Vitamin K2 activates the proteins osteocalcin and matrix GLA that bind to calcium and direct it into your bones. Boosting levels of both nutrients may prevent the calcification of blood vessels and other tissues (2).


Sun over mountains with mood boosting vitamin d properties

Symptoms and Risk Factors for Vitamin D Deficiency

Low vitamin D is a global problem as most people are indoors all day and don't spend nearly enough time in direct sunlight. Additional risk factors for vitamin D deficiency include living in a cold climate, having a darker skin tone, struggling with fat malabsorption, and being vegan or vegetarian.
You may have low vitamin D levels if you're struggling with:

  • Frequent infections
  • Fatigue
  • Sore muscles
  • Osteoporosis
  • Bone pain
  • Chronic inflammation
  • Depression
  • Seasonal affective disorder (SAD)

Besides getting more sunlight, the best way to boost vitamin D levels is via diet and supplementation. There are limited dietary sources of vitamin D, but it can be obtained in small amounts from fatty fish, grass-fed butter, cheese, egg yolks, organ meats, and fortified cereals. However, most people require extra support from a vitamin D3 supplement.


Health Benefits of Vitamin D

Here are 4 science-based benefits of supplementing with vitamin D3.

Supports Bone Health

As mentioned, vitamin D3 – when used in conjunction with vitamin K2 – maintains healthy calcium and phosphorus levels necessary to promote strong bones and prevent fractures. It's particularly beneficial for older people, who are at increased risk for low bone mineral density, osteoporosis, and fractures. A study on men aged 65 years and older found that blood levels of vitamin D below 20 ng/ml were detrimental to hip bone mineral density (3).

Boosts Immunity

Vitamin D3 is a great supplement to keep on hand during cold and flu season! Receptors on immune cells allow vitamin D3 to interact closely with your immune system and strengthen your defenses.

A 2017 systematic review found that supplementing with vitamin D daily or weekly reduced the risk of acute respiratory tract infections − particularly for vitamin D deficient people (4).

Another interesting 2020 study found that lower levels of vitamin D3 were associated with poor COVID-19 outcomes (5)

Regulates Mood

Vitamin D3 supports brain function and mental well-being. This is likely why seasonal affective disorder (SAD), characterized by low mood and motivation, is common during northern hemisphere winters when vitamin D3 levels plummet.

Research on adults has found that low vitamin D is associated with mood disorders and poor cognitive performance (6). Fortunately, regular vitamin D3 supplementation boosts blood levels and improves symptoms of depression, especially when taken during the winter months (7).

Supports Muscle Strength and Fitness

D3 supplementation promotes muscle strength and performance, allowing you to stay fit as you age.

Healthy vitamin D levels are associated with greater physical performance, improved muscle tissue composition, and may even help to reduce the likelihood of falls in older people (8).



healthy happy running woman in sun getting vitamin d cup of coffee next to a spoon

Make Vitamin D Part of Your Daily Diet

Okay you knew it was coming... time for a shameless plug.  Do you think the benefits of adding vitamin d to your daily diet could help?  Create a personalized daily vitamin pack that includes vitamin d and any other vitamins, minerals or supplements you think could help.  Start by adding vitamin d to your Kit here!

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