6 Essential Things to Know About Vitamin D: High Foods, Why It is Important, Vitamin D Deficiency Symptoms & Can DNA Health Tests Help

6 Essential Things to Know About Vitamin D: High Foods, Why It is Important, Vitamin D Deficiency Symptoms & Can DNA Health Tests Help

In 30 seconds...Sunlight is just the start; fatty fish, egg yolks, and certain mushrooms are nature's pantry for Vitamin D. But it's not just about intake; genes like the GC and CYP2R1 influence how we absorb and utilise this crucial nutrient. Feeling unusually tired or noticing hair loss? These could be silent signals of a Vitamin D deficiency. Dive deeper to explore the genetic intricacies, the vital role of Vitamin D during pregnancy, and how DNA health tests can reveal your unique Vitamin D blueprint.


In the vast realm of nutrition, Vitamin D stands out as a unique player. Often dubbed the "sunshine vitamin", its significance goes beyond just bone health. From the foods we eat to the very genes that make us who we are, Vitamin D intertwines with various facets of our health. Why is Vitamin D important? It's not just about strong bones; it's about overall well-being. In this comprehensive guide, we'll delve deep into the world of Vitamin D, exploring its sources, benefits, and the silent signs of its deficiency. Moreover, we'll uncover how DNA health tests can offer a personalised window into our Vitamin D health.

Vitamin D: Not Just a Vitamin, But a Hormone!

When we think of Vitamin D, the immediate association is often with bone health and its role in aiding calcium absorption. However, referring to it merely as a 'vitamin' might be a bit of an understatement. In reality, Vitamin D functions more like a hormone in our body, and its impact is vast and multifaceted.

Why is Vitamin D Considered a Hormone?

  1. Production and Activation: Unlike other vitamins that we must obtain from food, Vitamin D can be synthesised by our bodies. When our skin is exposed to sunlight, specifically UVB rays, it produces a form of Vitamin D called cholecalciferol (Vitamin D3). However, this form is inactive. It travels to the liver, where it's converted into 25-hydroxyvitamin D, and then to the kidneys, where it's transformed into its active form, 1,25-dihydroxyvitamin D. This multi-step process of production and activation is characteristic of many hormones.
  2. Receptors in Various Tissues: The active form of Vitamin D binds to Vitamin D receptors (VDR) found in various cells throughout the body, much like how hormones bind to their specific receptors. These receptors are present in numerous tissues, including the intestines, bones, brain, and immune cells, underscoring Vitamin D's wide-ranging effects.
  3. Regulation of Gene Expression: Once bound to its receptor, Vitamin D can influence the expression of over 1,000 genes. This ability to modulate gene activity is a hallmark of steroid hormones.

Implications of Vitamin D's Hormonal Action

  1. Bone Health and Beyond: While it's well-known for its role in regulating calcium and maintaining bone health, Vitamin D's hormonal action means it also influences cell growth, immune function, and inflammation.
  2. Mood and Brain Health: There's evidence to suggest that Vitamin D can influence neurotransmitters and protect the brain, potentially influencing mood and cognitive health.
  3. Immune System Regulation: Vitamin D plays a pivotal role in bolstering our immune system, helping to fend off infections and even playing a role in autoimmunity.
  4. Endocrine System Interactions: Vitamin D interacts with other hormones, including parathyroid hormone, influencing calcium metabolism and bone turnover.

The Sunlit Nutrient: How Vitamin D is Produced and Absorbed

How Vitamin D is Produced and How Vitamin D is Made

Every time you bask in the sunlight, your skin is doing something remarkable. It's producing Vitamin D. When UVB rays from the sun hit our skin, they interact with a form of cholesterol present in the skin, converting it into Vitamin D. This naturally produced Vitamin D then undergoes further transformations in the liver and kidneys to become the active form that our body utilises.

How Vitamin D is Absorbed and Where Vitamin D is Found

Apart from sunlight, Vitamin D can also be absorbed from the foods we consume and the supplements we take. Are Vitamin D tablets good for you? They can be, especially if you live in areas with limited sunlight. Once ingested, it's absorbed in the small intestines alongside dietary fats. This is why it's often recommended to take Vitamin D supplements with a meal containing healthy fats to enhance absorption.

Why It is Important? What Vitamin D Does for the Body

Beyond Bone Health

While Vitamin D is renowned for its role in calcium absorption and bone health, its benefits extend much further:

  • Immune System Regulation: It plays a pivotal role in bolstering our immune system, helping to fend off infections.
  • Mood and Brain Health: There's growing evidence linking Vitamin D levels with mood regulation and a reduced risk of depression.
  • Support During Pregnancy: Adequate Vitamin D levels are crucial during pregnancy, ensuring the development of healthy bones in the baby and reducing complications.

Vitamin D in Pregnancy

During pregnancy, the body's demand for nutrients, including Vitamin D, escalates. It aids in the formation of the baby's skeleton and regulates the levels of calcium and phosphate in the body. A deficiency during this critical period can lead to complications such as gestational diabetes and preeclampsia. Moreover, it's essential for ensuring the baby's teeth, bones, and kidneys develop healthily.

The Culinary Boost: Vitamin D High Foods and Sources

Natural Sources: Where Vitamin D is Found

While sunlight is a primary source, certain foods are naturally rich in Vitamin D. Here's a list of Vitamin D high foods:

  • Fatty fish like salmon, mackerel, and sardines
  • Cod liver oil
  • Egg yolks
  • Beef liver
  • Cheese
  • Mushrooms exposed to sunlight

Vitamin D Supplements & Sprays: Which Vitamin D Should I Take?

For those who can't get enough Vitamin D from natural sources, supplements come to the rescue.

Which Vitamin D should you take?

The two main forms are Vitamin D2 (ergocalciferol) and Vitamin D3 (cholecalciferol). Of the two, D3 is more effective and is the same form produced by our skin. It's available in various forms, including tablets, capsules, and even Vitamin D sprays.

Vitamin d is low: Recognising Vitamin D Deficiency Symptoms

Common Symptoms and Their Impact

A lurking danger with Vitamin D deficiency is that in its early stages, symptoms can be subtle or even non-existent. However, as the deficiency becomes more pronounced, signs begin to emerge:

  • Tiredness and Fatigue: One of the most common yet overlooked symptoms. Can Vitamin D deficiency cause tiredness? Absolutely.
  • Bone and Back Pain: Given its role in bone health, deficiency can lead to chronic pain.
  • Depression: Especially in older adults, low Vitamin D levels have been linked to a higher risk of depression.
  • Hair Loss: Severe deficiency can lead to hair loss, often mistaken for ageing. Can Vitamin D deficiency cause hair loss? Yes, it's one of the lesser-known symptoms.
  • Muscle Pain: There's a connection between chronic muscle pain and low Vitamin D levels.

Why Vitamin D Deficiency Occurs

Several factors can lead to Vitamin D deficiency:

  • Limited exposure to sunlight
  • Darker skin (melanin reduces the skin's ability to produce Vitamin D from sunlight)
  • Kidney and liver diseases
  • Certain genetic factors affecting Vitamin D metabolism

Vitamin D and Testosterone: An Intriguing Connection

Vitamin D, often hailed for its role in bone health and immune function, has a lesser-known yet significant connection to testosterone, the primary male sex hormone. This relationship has been the subject of numerous studies, and the findings offer intriguing insights into men's health.

The Link Between Vitamin D and Testosterone Levels

  1. Clinical Observations: Several observational studies have noted a positive correlation between Vitamin D levels and testosterone levels in men. Men with sufficient Vitamin D levels often have higher testosterone levels compared to those with a Vitamin D deficiency.
  2. Seasonal Variations: Testosterone levels in men tend to fluctuate seasonally, with peaks often observed in the summer months and troughs in the winter. Interestingly, this pattern mirrors the seasonal variations of Vitamin D levels, which are influenced by sunlight exposure.
  3. Supplementation Studies: Some clinical trials have shown that Vitamin D supplementation can lead to a modest increase in testosterone levels in men with low Vitamin D status. However, it's worth noting that not all studies have found this effect, and more research is needed to establish a definitive link.

Potential Mechanisms of Action

  1. Vitamin D Receptor (VDR) in Testes: The testes, where testosterone is produced, contain Vitamin D receptors. It's hypothesised that Vitamin D might influence testosterone synthesis by binding to these receptors.
  2. Influence on Sex Hormone-Binding Globulin (SHBG): Vitamin D might influence the levels of SHBG, a protein that binds to testosterone in the blood. By affecting SHBG levels, Vitamin D could indirectly influence the amount of free, bioavailable testosterone.
  3. Protection of Leydig Cells: Leydig cells in the testes are responsible for testosterone production. Some animal studies suggest that Vitamin D might play a role in protecting these cells from oxidative stress, potentially supporting their function.

Implications for Men's Health

  1. Holistic Health Approach: While the relationship between Vitamin D and testosterone is still being explored, it underscores the importance of a holistic approach to men's health. Ensuring adequate Vitamin D levels might be one piece of the puzzle in maintaining optimal testosterone levels and overall well-being.
  2. Consideration for Supplementation: Men with low testosterone and Vitamin D deficiency might benefit from Vitamin D supplementation. However, it's essential to consult with a healthcare professional before starting any supplementation regimen.
  3. Lifestyle Factors: Beyond supplementation, lifestyle factors such as regular sunlight exposure, a balanced diet rich in Vitamin D sources, and maintaining a healthy weight can support both Vitamin D and testosterone levels.

The Genetic - Vitamin D Connection

DNA and Vitamin D Health

Our DNA, the intricate code that defines our very being, has a profound influence on how our bodies interact with various nutrients, including Vitamin D. This connection between our genes and Vitamin D is not just about absorption but also about metabolism, storage, and even how our body responds to Vitamin D levels.

3 Key Genes & Their Roles in Vitamin D Absorption and Metabolism

1. GC Gene and Vitamin D Binding Proteins

The GC gene, also known as the Vitamin D binding protein gene, plays a pivotal role in how Vitamin D is transported and stored in our body. This gene produces a protein that binds to Vitamin D in the bloodstream. Variations in this gene can influence the amount of binding protein available, which in turn can affect the levels of free, unbound Vitamin D in the blood. Some genetic variants might lead to higher levels of Vitamin D binding proteins, potentially reducing the amount of active Vitamin D available for the body to use.

2. CYP2R1 Gene and Vitamin D Activation

The CYP2R1 gene is responsible for the initial step of Vitamin D activation in the liver. It converts the Vitamin D we get from the sun or our diet into a form that the body can start to use. Genetic variations in the CYP2R1 gene can affect how efficiently this conversion process happens. Some people might have a version of this gene that converts Vitamin D more slowly, making them more prone to deficiencies even if their intake is adequate.

3. VDR Gene and Vitamin D Response

The Vitamin D Receptor (VDR) gene produces a protein that binds with the active form of Vitamin D. This binding activates the receptor, allowing it to regulate the expression of other genes. Variations in the VDR gene can influence how our bodies respond to Vitamin D, affecting bone health, immune function, and more.

Should I do a Vitamin D Health Tests?

Understanding our genetic predisposition related to Vitamin D can offer invaluable insights. For instance, someone with a genetic variant that affects Vitamin D activation might need to be more vigilant about their Vitamin D intake or consider supplementation. On the other hand, those with variants in the VDR gene might require different levels of Vitamin D to achieve the same health benefits.

Short answer, Yes.

In the age of personalised medicine, recognising these genetic nuances can help tailor dietary and lifestyle recommendations, ensuring that each individual's unique needs are met. DNA health tests can provide these insights, offering a roadmap to optimised Vitamin D health.

Personalised Insights: Why Everyone's Vitamin D Needs are Different

Just as we all have unique fingerprints, our nutritional needs, influenced by our genes, are also distinct. This is where DNA health tests come into play. By analysing specific genetic markers, these tests can provide insights into how efficiently you metabolise Vitamin D, your risk of deficiency, and even how your genes can influence your Vitamin D requirements.

Taking Charge of Your Health: The Next Steps

The Benefits of DNA Health Tests

In the age of personalised medicine, DNA health tests offer a window into our unique genetic makeup. They can provide actionable insights, helping you make informed decisions about your health. For instance, understanding your genetic predisposition to Vitamin D deficiency can guide dietary choices, sunlight exposure, and supplement intake.

Actionable Takeaways

  • Sunlight Exposure: Aim for 10-30 minutes of midday sunlight several times a week.
  • Dietary Choices: Incorporate more Vitamin D high foods into your diet.
  • Supplementation: If you're at risk of deficiency, consider supplements after consulting with a healthcare professional.
  • DNA Health Test: Consider taking a DNA health test to gain a deeper understanding of your Vitamin D health and other vital metrics.


Vitamin D, often overlooked, plays a pivotal role in our overall health. From the foods we eat to the very genes that define us, understanding Vitamin D is crucial. As we move towards more personalised healthcare, tools like DNA health tests offer invaluable insights, empowering us to take charge of our health.