Unveiling the Sun Vitamin: A Lifelong Journey with Vitamin D

Vitamin D, often referred to as the “sunshine vitamin,” is a crucial nutrient that transcends age boundaries, offering a plethora of benefits across the lifespan. From supporting bone health to influencing mood and immune function, let’s explore the remarkable journey of vitamin D through the various stages of life.

Why It's Important

Vitamin D plays a crucial role in maintaining optimal health.  Vitamin D can enter the nucleus of the cell and is responsible for interaction with over 900 genes! This includes genes for inflammation, bone metabolism, brain synapses, and tumor growth.1 One of its primary benefits lies in supporting bone health by aiding the absorption of calcium, which is essential for bone strength and development. Additionally, vitamin D contributes to immune system function and helping the body defend against infections and illnesses.2

Signs and Symptoms of Deficiency

A deficiency in vitamin D can manifest through various signs and symptoms. Fatigue is a common indicator, as the vitamin plays a role in energy metabolism. Bone pain and muscle weakness may occur due to impaired calcium absorption, leading to issues with bone density and muscle function. Athletes who suffer from stress fractures often are found to have a vitamin D deficiency. Inadequate levels of vitamin D have also been linked to an increased risk of infections, as the immune system may not function optimally without sufficient vitamin D. Some of these infections associated with vitamin D deficiency are the flu, common cold , bronchitis, and pneumonia.3

How Our Bodies Get Vitamin D

Warning: chemistry incoming!

Vitamin D absorption from sunlight involves a fascinating process within our skin. When exposed to ultraviolet B (UVB) rays from the sun, a precursor molecule in the skin (7-dehydrocholesterol) undergoes a photochemical reaction. This process converts 7-dehydrocholesterol into pre-vitamin D3.

Following this conversion, pre-vitamin D3 undergoes a thermal isomerization process, transforming into vitamin D3, also known as cholecalciferol. This newly formed vitamin D3 is not yet fully active; it requires further processing to become biologically active.

The liver plays a crucial role in this activation process. This inactive form of Vitamin D3 is transported to the liver, where it undergoes hydroxylation, resulting in the formation of 25-hydroxyvitamin D [25(OH)D]. This compound serves as the major circulating form of vitamin D in the bloodstream and is likely the form of Vitamin D tested in your bloodwork.

The final activation step occurs in the kidneys. 25(OH)D undergoes another hydroxylation, this time in the kidneys, to form the biologically active 1,25-dihydroxyvitamin D [1,25(OH)2D], also known as calcitriol. Calcitriol is the form of vitamin D that interacts with various target tissues, such as the intestines, bones, and immune cells, to exert its physiological effects.

It’s important to note that factors such as skin pigmentation, geographic location, time of day, and sunscreen use can influence the efficiency of vitamin D synthesis from sunlight. While sunlight is a natural and valuable source of vitamin D, individuals should balance sun exposure to avoid skin damage and consider alternative sources, such as diet and supplements, to ensure adequate vitamin D levels!3 Some great food options that are high in Vitamin D are mushrooms, eggs, sardines, and salmon.

Benefits of Vitamin D

Why is Vitamin D So Critical For Bone Health?​

The synergy between calcium and vitamin D is fundamental to maintaining optimal bone health. Calcium, a key mineral in bone structure, relies on vitamin D for efficient absorption from the intestines into the bloodstream.
  • Once absorbed, calcium is deposited into the bones, where it contributes to bone mineralization, ensuring the formation of a robust bone structure. Vitamin D plays a pivotal role in this process by regulating the balance of calcium and phosphorus within the bones → essential for maintaining bone density and strength.4
  • Vitamin D also aids in calcium resorption from bone tissue when dietary intake is inadequate, ensuring normal calcium levels in the bloodstream. This delicate balance is crucial for preventing bone loss and fractures.
  • Furthermore, vitamin D influences bone remodeling, promoting the activity of bone-forming osteoblasts while inhibiting bone-resorbing osteoclasts, ensuring the continuous renewal of bone tissue.
  • Additionally, vitamin D indirectly enhances bone health by promoting muscle strength and balance, reducing the risk of falls and fractures, particularly in older adults.
Without Vitamin D, calcium would be useless to the bones!5, 6

Vitamin D's Role in Skeletal Muscle

Vitamin D plays a pivotal role in skeletal muscle health. It exerts its influence through vitamin D receptors (VDRs) present in skeletal muscle tissue. These receptors, when activated by vitamin D, contribute to various processes crucial for muscle function.
  • Muscle Contraction and Strength: Vitamin D is involved in the regulation of calcium, a mineral essential for muscle contraction. It facilitates the entry of calcium into muscle cells, promoting proper contraction and strength. This mechanism is vital for overall muscle performance and physical function.7
  • Protein Synthesis: Vitamin D is associated with increased protein synthesis in muscle cells. This is crucial for maintaining and repairing muscle tissue, especially after exercise or injury. Adequate vitamin D levels contribute to an optimal environment for muscle protein synthesis, supporting muscle growth and recovery.
  • Inflammation and Muscle Function: Vitamin D possesses anti-inflammatory properties that can positively impact muscle function. Chronic inflammation is often associated with muscle wasting, and by modulating inflammatory responses, vitamin D may help mitigate muscle damage and preserve muscle mass.4, 7

Role in Cognition and Memory: How to Help Prevent Neurodegenerative Diseases

Vitamin D has a role in maintaining brain synapses and reducing inflammation, two huge factors associated with cognitive decline. During the onset of Alzheimer’s disease, brain synapses are destroyed which can be a byproduct of suboptimal vitamin D levels. Therefore, reduced vitamin D levels are associated with cognitive decline. 1

Vitamin D and Heart Health

Vitamin D deficiency causes  cardiovascular disease through direct and indirect mechanisms.8

Direct effects include:

  • Decrease in build up of atherosclerotic plaque
  • Prevention of calcification of the plaque in the artery walls
  • Calming of low grade inflammation associated with vascular walls in cardiovascular disease

Vitamin D deficiency has also been associated with hypertension, diabetes, obesity, insulin resistance, and obesity which are all risk factors for cardiovascular disease.8

Vitamin D is increasingly recognized for its involvement in metabolic processes, and its relationship with diabetes mellitus, a group of metabolic disorders characterized by elevated blood sugar levels. Several mechanisms highlight the impact of vitamin D on metabolic health, particularly in the context of diabetes:

  • Insulin Sensitivity: Vitamin D is believed to enhance insulin sensitivity, the ability of cells to respond to insulin. Improved insulin sensitivity is crucial for the efficient uptake of glucose by cells, helping to regulate blood sugar levels. Deficient vitamin D levels may contribute to insulin resistance, a key factor in the development of type 2 diabetes. When our cells become insensitive  to insulin our bodies cannot recognize the rise and fall in blood sugar and therefore causes diabetes related side effects.
  • Pancreatic Function: The pancreas is the organ that produces and secretes insulin. Vitamin D receptors are present in the pancreas. Adequate vitamin D levels may support optimal pancreatic function and insulin secretion. Dysfunction in these processes is associated with the progression of diabetes.
  • Inflammation Regulation: Chronic inflammation is linked to insulin resistance and diabetes. Vitamin D possesses anti-inflammatory properties, and by modulating inflammatory responses, it may help mitigate inflammation-related complications in metabolic disorders.

While these observations suggest a potential link between vitamin D and metabolic health, it’s crucial to approach diabetes management comprehensively. Lifestyle factors, dietary choices, and individual health conditions should be the first line of defense against metabolic conditions! Individuals with diabetes or at risk should always consult healthcare professionals.5

FAQs: What else do I need to know?

  1. Preventing Sarcopenia: Sarcopenia, the age-related loss of muscle mass and function, is a common concern for older adults. Vitamin D’s role in promoting muscle protein synthesis and calcium regulation can aid in preventing or mitigating sarcopenia, contributing to better mobility and functionality through the life span.
  2. Reducing Falls and Fractures: Adequate vitamin D levels are linked to improved bone health. As bones and muscles are interconnected, preserving skeletal muscle density can enhance stability and reduce the risk of falls and fractures, which are major concerns for the elderly. According to the Centers for Disease Control and Prevention (CDC), approximately 20% of older adults who experience a hip fracture die within 1 year of the injury. Maintaining bone health, to decrease risk and development of osteoporosis is contributing to longevity!
  3. Enhancing Physical Function: Maintaining optimal vitamin D levels may enhance physical performance in older adults, supporting activities of daily living and overall quality of life. This is crucial for independent living and a proactive approach to healthy aging.

In conclusion, vitamin D’s impact on skeletal muscle extends beyond basic function, influencing processes critical for muscle health. For older adults, maintaining sufficient vitamin D levels can be a valuable strategy to combat age-related muscle loss and its associated consequences. Regular monitoring and supplementation, when necessary, are advisable to support overall musculoskeletal well-being in aging populations.5

To prevent deficiency, it’s important to ensure an adequate intake of vitamin D through sources like sunlight exposure, dietary supplements, or foods rich in vitamin D, such as fatty fish, fortified dairy products, and eggs. Sunlight is the most efficient way for our body to obtain Vit D, but there some ways to make the process more efficient. First, try to get sunlight at the beginning of your day, as well as the strongest part of the day (around noon). Also, make sure to expose as much skin as possible! The more skin exposed to sunlight, the more Vit D you get! (Fun fact: this is part of the reason why we often get sick in the winter- we’re too covered up to receive adequate amounts of Vitamin D!) Regular monitoring of vitamin D levels and consulting healthcare professionals for personalized advice are advisable for maintaining overall well-being.

Vitamin D toxicity is rare and usually occurs with extremely high doses, often well above the recommended daily allowances. If considering vitamin D supplementation, it’s advisable to consult with healthcare professionals to determine appropriate doses tailored to individual needs and health conditions. Regular monitoring of vitamin D levels can also help prevent potential harm. Always consult your physician!

While vitamin D is crucial for various bodily functions, but it is essential to be aware of potential harm, especially from high doses of vitamin D supplements. Here are some aspects to consider:

Hypercalcemia
The most significant risk associated with excess vitamin D is hypercalcemia, the medical term for too much calcium in the blood. Vitamin D enhances calcium absorption, and an overdose can lead to excessive calcium accumulation, causing symptoms such as nausea, vomiting, weakness, and in severe cases, kidney damage.

Kidney Damage
Prolonged hypercalcemia can strain the kidneys as they work to excrete the excess calcium. This can result in kidney damage or the formation of kidney stones. Individuals with pre-existing kidney conditions should be particularly cautious with vitamin D supplementation. It is important to note that there is no evidence that vitamin D contributes to kidney stone formation for those with no existing kidney conditions.

Soft Tissue Calcification
Excessive vitamin D can lead to the deposition of calcium in soft tissues such as the heart, lungs, and blood vessels. This calcification can impair the normal function of these tissues and potentially lead to cardiovascular issues.

GI Distress
High doses of vitamin D may cause gastrointestinal symptoms like nausea, vomiting, and diarrhea. This can be an early sign of vitamin D toxicity.

Weakened Bones
Interestingly enough, excessive vitamin D can lead to weakened bones. This is because hypercalcemia interferes with the normal balance of calcium and phosphorus in bones, potentially contributing to bone loss and fractures.

Interactions with Medications
Vitamin D supplements can interact with certain medications, such as certain diuretics and heart medications. This can exacerbate the risk of hypercalcemia or interfere with the effectiveness of medications. Always consult your physician before beginning a new vitamin or supplement.

So What Dose of Vitamin D Should I Be Taking?

It is typically recommended that you only take between 1000-2000 IU of vitamin D3 per day. However, if you know your blood vitamin D levels, you can much more accurately determine what your optimal dose should be. To raise your blood vitamin D3 by 10ng/dl, you need to take 1000 IU.
  • For example, if my blood vitamin D is 30ng/dl and I want it to be 50ng/dl, I should take 2000 IU.
Formula: how much you want to raise your blood level by (in ng/dl) x 100 = dose in IU 
  • On your bloodwork, your vitamin D level might appear “in range” for levels around 35 to 40 ng/dl. However, many functional health experts agree that this range is still not optimal. 
“Optimal” ranges are typically considered 50 to 70 ng/dl, and no higher than 80 ng/dl1, 6

My Two Cents!

In the scary world of sun damage, Vitamin D can be hard to get in adequate amounts. Sunscreen greatly impacts the amount we can absorb from the sun, but how can we get enough vitamin D while protecting ourselves from the sun? In my opinion, supplementation is a great way to combat deficiency. Make sure to look for high quality sources of vitamin D3 when choosing your supplement! Do you live in a cold climate in the winter? Do you wear sunscreen when you go to the beach/for a walk in the sun? Do you work inside all day? If you answered yes to any of these questions, you likely would benefit from increasing your vitamin D levels through supplementation or diet. Watch your immune system soar through winter or observe the disappearence of the mid-day slump due to loss of energy when you start to increase your vitamin D! Let us know if this article inspired you to incorporate a vitamin D supplement to your daily routine. 

Interested in reading more? Here's our references!

  1. Bredesen, D. The End of Alzheimer’s: The first program to prevent and reverse cognitive decline.1st ed. Thorndike Press, a Cengage Company; 2017: 126.
  2. Holick MF. Vitamin D deficiency. N Engl J Med. 2007;357(3):266-281. doi:10.1056/NEJMra070553
  3. National Institutes of Health. Vitamin D: Fact Sheet for Health Professionals. Updated September 23, 2021. Accessed January 30, 2022. https://ods.od.nih.gov/factsheets/VitaminD-HealthProfessional/
  4. Institute of Medicine (US) Committee to Review Dietary Reference Intakes for Vitamin D and Calcium; Ross AC, Taylor CL, Yaktine AL, et al., editors. Dietary Reference Intakes for Calcium and Vitamin D. National Academies Press; 2011. Accessed January 30, 2022. https://www.ncbi.nlm.nih.gov/books/NBK56061/
  5. Annweiler C, Dursun E, Féron F, et al. “Vitamin D and cognition in older adults”: Updated international recommendations. J Intern Med. 2015;277(1):45-57. doi:10.1111/joim.12279
  6. Hyman M. Before the Diet, the Detox. In: Hyman M. Food: What the Heck Should I Eat?. 1st ed. New York, NY: Little, Brown and Company; 2018: 285.
  7. Shuler FD, Wingate MK, Moore GH, Giangarra C. Sports health benefits of vitamin d. Sports Health. 2012;4(6):496-501. doi:10.1177/194173811246162
  8. Nitsa A, Toutouza M, Machairas N, Mariolis A, Philippou A, Koutsilieris M. Vitamin D in Cardiovascular Disease. In Vivo. 2018;32(5):977-981. doi:10.21873/invivo.11338
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