Vitamin D deficiency causes a number of illnesses. Not just rickets (a bone deforming disease, first discovered in the mid-1600s), but there is also a growing body of evidence that Vitamin D helps against high blood pressure, cancer and multiple sclerosis (1).
So, if Vitamin D is so important, what causes Vitamin D deficiency?
You Don’t Have Enough Sun Exposure
The number one reason in what causes Vitamin D deficiency is not enough sun exposure. Vitamin D is also called the sun vitamin. Your body produces vitamin D when your skin is exposed to sunlight. The sun emits two types of sun lights (rays), UVA and UVB. Your body requires UVB for Vitamin B production (2), and your body doesn’t need much time for that.
Fair skinned people only need about 10 to 20 minutes to get all the sun they need for that day. The best time for getting UVB sun light while minimizing the risk of getting skin cancer is around noon (4). This is the time frame when you can get the most UVB from sun rays.
Impact of Darker Skin, Age and Sunscreen Use
If you have darker skin or are older, you will need more time in the sun (3). Dark skin reduces the amount of UVB that makes it through the skin, and also as you get older, your organs (including your skin) become less effective in producing Vitamin D.
If you use sun screen during sun exposure, you can end up reducing the production of Vitamin D by up to 99%. Having said that, it is recommended that you put sun screen on your face or protect your face, since the skin on your face is quite thin and constant sun exposure of your face can lead to cosmetic damage.
You Don’t Eat Enough Foods Rich in Vitamin D
The number two reason in what causes deficiency of Vitamin D is not eating enough foods rich in Vitamin D. Depending on where you live, getting enough Vitamin D through sun exposure may not always be an option. Until the 1960s, whale liver oil was used as a major dietary source of Vitamin D (5), and from everything you can read about it, the taste was nasty. Luckily, today there are more tastier food options available, such as sardines, salmon, mackerel, tuna, and fortified milk.
You Have A Liver, Kidney or Digestive Illness
If your primary source for Vitamin D is food, any digestive illness (Crohn’s disease, Ulcerative Colitis, etc.) that would limit your colon’s ability to extract Vitamin D from the food that you eat, could also cause Vitamin D deficiency. Liver disease (6) and kidney disease (7) can also cause Vitamin D deficiency.
Vitamin D Deficiency Treatment
Now that you know what causes Vitamin D deficiency, the question is what should you do? If you have an illness, you will need to discuss your Vitamin D strategy with your doctor. If you are otherwise healthy, you have several options. You can increase your sun light exposure, you can eat more foods rich in Vitamin D, and you can take Vitamin D as a supplement.
According to the Office of Dietary Supplements from the National Institute of Health, the recommended daily amount of Vitamin D varies by age (8):
The recommended upper safe limit for vitamin D is 1,000 to 1,500 IU/day for infants, 2,500 to 3,000 IU/day for children 1-8 years, and 4,000 IU/day for children 9 years and older, adults, and pregnant and lactating teens and women.
Vitamin D supplement comes in two forms, D2 and D3. Look for supplements that provide D3 (cholecalciferol) rather than D2 (ergocalciferol).
If you take Vitamin D3, there is growing evidence that it should be taken together with the MK-7 version of Vitamin K2 (9) as the combination can also protect against arterial calcification, whereas vitamin D alone does not. According to the Office of Dietary Supplements from the National Institute of Health, the recommended daily intake for Vitamin K2 is about 100 mcg for adults.
An easy way to start is get out in the sun when it’s sunny! A little bit of sun is not harmful and actually necessary for your health.
(1) WebMd; Vitamin D: Vital Role in Your Health – https://www.webmd.com/food-recipes/features/vitamin-d-vital-role-in-your-health#1
(2) Sunlight and Vitamin D – https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3897598/
(3) J Pharmacol Pharmacother; Vitamin D: The “sunshine” vitamin.- https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3356951/
(4) At what time should one go out in the sun? – https://www.ncbi.nlm.nih.gov/pubmed/18348449
(5) Encyclopedia Britannica; Whale Oil – https://www.britannica.com/topic/whale-oil
(6) Gastroenterol Hepatol; Vitamin D Deficiency and Liver Disease – https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2950664/
(7) Vitamin D and Chronic Kidney Disease – https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2878736/
(8) Office of Dietary Supplements from the National Institute of Health; Vitamin D – https://ods.od.nih.gov/factsheets/VitaminD-Consumer/
(9) Nephrology Dialysis Transplantation; Epidemiology – cardiovascular outcome – https://academic.oup.com/ndt/article/28/suppl_1/i352/1838602/Epidemiology-cardiovascular-outcomes#42763848