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Vitamin D: A Comprehensive Guide

18 Mar, 2024
Vitamin D the sunshine vitamin - Sunrise over a vibrant sunflower field

Top Ten FAQ's - Vitamin D

What is vitamin D?

Vitamin D is a fat-soluble vitamin that is essential for calcium absorption, maintaining the health of bones and teeth, and supporting the health of the immune system, brain, and nervous system.1

How can we obtain vitamin D?

Vitamin D can be obtained from sunlight exposure, dietary sources like fatty fish and fortified foods, and supplements.2

What are the benefits of vitamin D?

Benefits of vitamin D include regulation of calcium and phosphate in the body, which are needed for healthy bones, teeth, and muscles. It also helps with inflammation and immune function and may play a role in protecting against certain diseases.2

What are the symptoms of vitamin D deficiency?

The recommended dietary allowance (RDA) for most adults is 600-800 IU per day, but some individuals may need more depending on their health status and exposure to sunlight.1

How much vitamin D should you take daily?

Some studies suggest that 5-HTP may help control appetite and support weight loss, but more research is needed3. 5-HTP should only be used as a complement to diet and exercise, not as a sole method of weight loss.

Can you get vitamin D through a window?

No, you cannot effectively get vitamin D through a window. The reason for this is that the ultraviolet B (UVB) rays necessary for the skin to produce vitamin D are mostly blocked by glass.

Can vitamin D improve mood?

Some studies suggest that vitamin D might play a role in mood regulation and may help improve symptoms of depression, especially in those who are deficient in the fat-soluble vitamin.4 However, more research is needed.

What are the signs of too much vitamin D?

Signs of vitamin D toxicity include nausea, vomiting, confusion, abdominal pain, weakness, dehydration, and more serious complications like kidney damage.5

Can vitamin D affect sleep?

Some research suggests that adequate levels of vitamin D may support healthy sleep patterns, but the relationship is not fully understood.6

What foods are high in vitamin D?

Foods high in vitamin D include fatty fish like salmon and mackerel, beef liver, cheese, egg yolks, and foods fortified with vitamin D such as certain dairy products and cereals.7

Vitamin D, often hailed as the 'Sunshine Vitamin,' is a unique nutrient that holds a venerable spot in the realm of health and wellness.

Unlike other vitamins, vitamin D functions like a hormone, and nearly every single cell in your body has a receptor for it.8 This essential vitamin is synthesised by our bodies when sunlight hits our skin, and yet, in our modern indoor lifestyles, vitamin D deficiency has become a silent epidemic.3

The Vital Roles of Vitamin D 

Vitamin D’s claim to fame is its crucial role in bone health. It facilitates the absorption of calcium and phosphorus, minerals critical for building bone. This is not just important during our growing years but also throughout our adulthood and into old age, where sufficient vitamin D levels can help prevent osteoporosis, falls, and fractures.1

Beyond bones, vitamin D has an expansive influence. It’s instrumental in muscle growth, function, and regeneration.9 There’s also growing evidence that vitamin D plays a role in immune function, with some studies suggesting it may help fend off infections like the flu and reduce the risk of chronic diseases, including multiple sclerosis and certain types of cancer.10

Person with arms wide open amidst a blooming field at sunrise, feeling invigorated by Lily & Loaf's natural wellness products.

Sources of Vitamin D 

The most efficient way to get vitamin D is through sunlight, which triggers the synthesis of vitamin D3 in the skin. About 10-30 minutes of midday sun exposure most days of the week may suffice for most people to maintain adequate vitamin D levels, though this varies widely depending on skin colour, location, and lifestyle.11 For many, particularly those living in less sunny climes, this natural process alone isn’t enough.

Diet can help bridge the gap, with fatty fish such as salmon, mackerel, and sardines being among the richest natural sources. Egg yolks, beef liver, and cheese provide smaller amounts, while many countries fortify foods like milk, orange juice, and cereals with vitamin D.7

For those who struggle to get enough vitamin D from sunlight and diet alone, supplements may offer a practical solution. Vitamin D supplements are widely available and may help raise and maintain adequate levels in the blood, especially during the darker winter months.7

How Much Do You Need? 

The Recommended Dietary Allowance (RDA) for vitamin D is around 600 to 800 International Units (IU) per day for most adults, but this is a general guideline. Factors like age, skin colour, location, and health status may increase vitamin D needs.1 Some experts may suggest higher supplement doses, especially for those with little sun exposure or older adults.

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The Perils of Deficiency 

A shortfall of vitamin D may lead to a spectrum of health issues. In children, severe vitamin D deficiency causes rickets, a condition characterised by soft bones and skeletal deformities. In adults, deficiency may result in osteomalacia, leading to bone pain and muscle weakness.3

The symptoms of a mild deficiency are more insidious and can be easily overlooked. Fatigue, aches, and pains, and a general sense of malaise are often attributed to the stresses of daily life but may be a cry for more vitamin D for some people.3

Vitamin D and Mental Health 

Vitamin D’s influence extends to the brain. Studies have linked adequate levels of vitamin D to a reduced risk of depression, and supplementation has shown promise as a part of depression treatment. The exact mechanisms are not yet clear, but vitamin D receptors in the brain suggest it may play a role in mood regulation.4

Joyful woman feeding a happy dog in the park, symbolizing the wholesome life Lily & Loaf advocates for pets and owners.

Navigating Supplementation 

If you opt for supplements, it’s important to talk to a healthcare provider, as vitamin D can interact with certain medications and conditions. More isn’t always better; excessive intake of vitamin D supplements can lead to toxicity, with symptoms like nausea, vomiting, and serious complications such as kidney damage.5

Vitamin D is a shining example of how traditional wisdom and modern science converge. The advice to "get a little sunshine" has never been more pertinent in our increasingly indoor-centric world. By ensuring you receive adequate amounts of this vital nutrient, you support a foundation for robust health. Whether it’s taking a lunchtime walk in the sun, tweaking your diet, or considering a supplement, small steps can lead to big leaps in your overall well-being. Remember, when it comes to vitamin D, every ray of sunshine counts!



  1. National Institutes of Health – Office of Dietary Supplements. Vitamin D: Fact Sheet for Health Professionals.
  2. MedlinePlus. Vitamin D.
  3. Płudowski P, Kos-Kudła B, Walczak M, et al. Guidelines for Preventing and Treating Vitamin D Deficiency: A 2023 Update in PolandNutrients. 2023;15(3):695. doi:10.3390/nu15030695
  4. Akpınar Ş, Karadağ MG. Is Vitamin D Important in Anxiety or Depression? What Is the Truth?. Curr Nutr Rep. 2022;11(4):675-681. doi:10.1007/s13668-022-00441-0
  5. Marcinowska-Suchowierska E, Kupisz-Urbańska M, Łukaszkiewicz J, Płudowski P, Jones G. Vitamin D Toxicity-A Clinical PerspectiveFront Endocrinol (Lausanne). 2018;9:550. poi:10.3389/fendo.2018.00550
  6. Abboud M. Vitamin D Supplementation and Sleep: A Systematic Review and Meta-Analysis of Intervention StudiesNutrients. 2022;14(5):1076. doi:10.3390/nu14051076
  7. National Health Service. Vitamin D.
  8. Bikle DD. Extraskeletal actions of vitamin DAnn N Y Acad Sci. 2016;1376(1):29-52. doi:10.1111/nyas.13219
  9. Latham CM, Brightwell CR, Keeble AR, et al. Vitamin D Promotes Skeletal Muscle Regeneration and Mitochondrial HealthFront Physiol. 2021;12:660498.  doi:10.3389/fphys.2021.660498
  10. Prietl B, Treiber G, Pieber TR, Amrein K. Vitamin D and immune functionNutrients. 2013;5(7):2502-2521. doi:10.3390/nu5072502
  11. Srivastava SB. Vitamin D: Do We Need More Than Sunshine?. Am J Lifestyle Med. 2021;15(4):397-401. doi:10.1177/15598276211005689