Am I Getting Enough Vitamin D?
Vitamin D, commonly known as the "Sunshine Vitamin", is a unique nutrient vital for maintaining overall health and well-being.* Unlike other vitamins, Vitamin D is also a hormone, and many of the organs and tissues in your body have a receptor for it.1 This comprehensive post explores the nature of Vitamin D, its crucial role in our health, how to assess adequate intake, signs of deficiency, and dietary recommendations to maintain optimal levels.*
What is Vitamin D?
Vitamin D is a fat-soluble vitamin, which means it is transported and absorbed in a manner similar to fats. Vitamin D is also stored in the body's fat cells and processed in the liver.2 It's unique among vitamins because your body can produce it when exposed to sunlight. There are two main forms: Vitamin D2 (ergocalciferol) and Vitamin D3 (cholecalciferol).1
Vitamin D3 vs Vitamin D2
In the realm of dietary supplements, two distinct forms of vitamin D are available: vitamin D3, known as cholecalciferol, and vitamin D2, referred to as ergocalciferol. Each form possesses the ability to help raise 25-hydroxyvitamin D (25(OH)D), sometimes referred to as serum vitamin D, levels within the body.3 However, a majority of healthcare professionals tend to favor vitamin D3. This preference is attributed to a lower bioavailability of Vitamin D2 than its counterpart, which is readily usable by the body.*4 Intriguingly, vitamin D3 is synthesized naturally by animals, including humans, and can be found in some vegan sources such as lichen, while vitamin D2 is found predominantly in plant sources.5
Assessing Your Vitamin D Levels
To determine if you're getting enough Vitamin D, a 25-hydroxyvitamin D blood test is the recommended method.
- Levels below 30 nmol/L (12 ng/mL) are too low and might weaken your bones and affect your health.*3
- Levels of 50 nmol/L (20 ng/mL) or above are adequate for most people for bone and overall health.*3
- Levels above 125 nmol/L (50 ng/mL) are too high and might cause health problems.*3
Signs of Vitamin D Deficiency
Vitamin D deficiency is a common global issue. About 1 billion people worldwide have vitamin D which are considered too low, while only 50% of the population has an adequate amount of vitamin D.6 However, in the US, 18% had vitamin D levels that were slightly low (30-49 nmol/L or 12-19.6 ng/mL), and 5% had very low levels (below 30 nmol/L or 12 ng/mL), putting them at risk of deficiency. Additionally, 4% had vitamin D levels that were higher than recommended (above 125 nmol/L or 50 ng/mL).3
A lack of Vitamin D, which can lead to deficiency, can manifest in various ways, and the symptoms are often subtle. They can include:
- Fatigue.6
- Osteomalacia, a disorder that causes bone pain and muscle weakness.3
- In children, deficiency can cause rickets, a disease where bones become soft, weak and deformed.3
- Mood changes with an increased risk for depression.3
Who Is Most At Risk of Vitamin D Deficiency?
Aside from medical conditions that can lead to vitamin D deficiency, biological and environmental factors that put someone at an increased risk of vitamin D deficiency include:
Diet: Dietary habits significantly impact vitamin D levels, particularly in individuals who consume insufficient foods that contain vitamin D like trout, salmon, mushrooms, and fortified dairy products and cereals.7
Lifestyle factors: Lifestyle choices also play a crucial role. Individuals who spend limited time outdoors due to occupational demands, health issues, lack of green spaces in their living environments or those who wear long robes, dresses or head coverings for religious reasons may experience reduced sunlight exposure, affecting vitamin D synthesis.7
Geographical factors: Geographical location is another key factor. Residents of regions like Northern Canada, Alaska, or extremely hot climates might have less exposure to the sun's UVB rays, the latter due to avoiding intense heat and sunlight.7
Pollution: Environmental pollution can hinder UVB ray penetration, affecting vitamin D production. This is particularly true for individuals living in heavily polluted areas, who might also choose to spend less time outdoors due to air quality concerns.7
Skin type: Skin pigmentation affects vitamin D synthesis. Those with darker skin require longer sun exposure to produce the same amount of vitamin D as individuals with lighter skin.7
How Do I Get More Vitamin D?
When the sun’s rays hit the skin, processes inside the tissues start making vitamin D.
People do not need to get a tan or burn to get vitamin D from the sun. The body will make all the vitamin D it needs for a day in about half the time it takes the skin to burn.*8
Many factors affect how much vitamin D a person gets from the sun, such as:
Time of day - The production of vitamin D in the skin is most efficient around midday, when the sun is at its peak.* During these hours, the sun's rays are most direct. However, it's important to balance sun exposure with safety measures such as applying sunscreen and staying hydrated, especially when exposed to the hot midday sun for extended periods.8
Amount of skin exposed - The extent of skin exposure also influences vitamin D synthesis. Exposing larger areas of skin, like the back, can significantly increase vitamin D production compared to limited exposure such as only the hands and face.* This is because more skin surface area is available to interact with sunlight, thereby producing more vitamin D.8
Vitamin D can be obtained through dietary sources, a convenient option for those who may have limited sun exposure. Certain foods naturally contain vitamin D, while others are fortified with this essential nutrient.
Regular consumption of these foods can help maintain adequate vitamin D levels:9
Fatty fish: Options like salmon, mackerel, tuna, and sardines.
Mushrooms: Some varieties, particularly those exposed to UV light, contain Vitamin D - usually as vitamin D2.
Fortified foods: Dairy products, plant-based milks, orange juice, and cereals often have added Vitamin D.
Egg yolks: Eggs from hens raised outdoors or fed Vitamin D-enriched feed can provide more of this vitamin.
For those who cannot get enough Vitamin D from sunlight and food, supplements are an effective alternative.* Vitamin D3 supplements are generally recommended because they are effective at raising and maintaining Vitamin D levels in the blood.* But despite supplementation being an effective way to add vitamin D to your diet, you should always verify with your healthcare provider if you need to obtain additional vitamin D through supplementation prior to adding any supplement to your regimen.
The Recommended Dietary Allowance is one of the values developed by expert committees to ensure the average daily levels of intake is sufficient to meet the nutrient requirements for nearly all healthy individuals.3
Recommended Daily Allowance (RDA)3:
- Birth to 12 months = 10 mcg (400 IU)
- Children 1–13 years = 15 mcg (600 IU)
- Teens 14–18 years = 15 mcg (600 IU)
- Adults 19–70 years = 15 mcg (600 IU)
- Adults 71 years and older = 20 mcg (800 IU)
- Pregnant and breastfeeding teens and women = 15 mcg (600 IU)
Tolerable Upper Intake Levels (ULs):
The Tolerable Upper Intake Level is the maximum daily intake unlikely to cause adverse health effects.3
- Birth to 6 months = 25 mcg (1000 IU)
- Infants 7-12 months = 38 mcg (1500 IU)
- Children 1-3 years = 63 mcg (2500 IU)
- Children 4-8 years = 75 mcg (3000 IU)
- Children 9-18 years = 100 mcg (4000 IU)
- Adults 19 years and older = 100 mcg (4000 IU)
- Pregnant and breastfeeding teens and women = 100 mcg (4000 IU)
Conclusion
Vitamin D is a key nutrient for maintaining bone strength, supporting immune function, and contributing to overall health.* Ensuring adequate Vitamin D intake through sunlight exposure, diet, and supplements is vital for good health.* Be sure to consult with a healthcare provider to do blood work before increasing Vitamin D intake or adding any new supplement to your regimen.
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*These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure or prevent any disease. |
REFERENCES:
- Harvard T.H. Chan School of Public Health. (2023). Vitamin D. The Nutrition Source. Retrieved from https://www.hsph.harvard.edu/nutritionsource/vitamin-d/ (Accessed 6 December 2023)
- National Research Council (US) Committee on Diet and Health. Diet and Health: Implications for Reducing Chronic Disease Risk. Washington (DC): National Academies Press (US); 1989. 11, Fat-Soluble Vitamins. Available from: https://www.ncbi.nlm.nih.gov/books/NBK218749/ (Accessed 4 January 2024)
- Office of Dietary Supplements. (2023). Vitamin D - Health Professional Fact Sheet. Retrieved from https://ods.od.nih.gov/factsheets/VitaminD-HealthProfessional/#h36 . (Accessed 4 January 2024)
- Lehmann U, et al. (2013). Bioavailability of vitamin D(2) and D(3) in healthy volunteers, a randomized placebo-controlled trial. J Clin Endocrinol Metab. 98(11): 4339-45.
- Bilezikian, J. (2022). What's the Deal with Vitamin D? Columbia University Irving Medical Center. Available at: https://www.cuimc.columbia.edu/news/whats-deal-vitamin-d# (Accessed 6 December 2023)
- Cleveland Clinic. (2022, August 2). Vitamin D Deficiency: Causes, Symptoms & Treatment. Retrieved from https://my.clevelandclinic.org/health/diseases/15050-vitamin-d-vitamin-d-deficiency. (Accessed 7 December 2023)
- Medical News Today. (2019). Why am I not getting enough vitamin D?. Available at: https://www.medicalnewstoday.com/articles/318060#causes. (Accessed 7 December 2023)
- Medical News Today. (2021). How to get more vitamin D from the sun. Available at: https://www.medicalnewstoday.com/articles/326167#boosting-vitamin-d. (Accessed 8 December 2023)