What causes vitamin D deficiency?


The reason for Vitamin D deficiency can be due to non-proper exposure to sunlight, insufficient production in the skin, not having enough vitamin D in your diet, and health issues such as liver diseases, renal diseases, and gastrointestinal disorders.

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People who are at a high probability of getting a vitamin D deficiency disease-

1. People with Darker skin

Melanin is a group of natural pigments found in our skin. Melanin has properties to absorb UV rays from the sun which lower the skin’s capacity to produce vitamin D3 by 95%-99%. Dark-colored skinned people have more melanin than those with lighter skin. Therefore, dark-skinned people have natural sun protection and need to be at least 3-5 times longer exposures than white-skinned people to consume the same amount of vitamin D. 

Africans (Dark-skinned people) have a level of 16ng/mL, whereas Americans (white-skinned people) have a level of 26ng/mL.

2. Overweight

If you are overweight, you may put yourself at high risk for a vitamin D deficiency. Your diet and less sun exposure might affect your vitamin D level. For blood level testing of vitamin D, both obese and non-obese groups were put into sun exposure in subjects. At first, it was found an equal rise in vitamin D levels due to the similar capacity of the skin to produce the vitamin. But, after 24 hours, there were 57% less vitamin D levels in the blood of the obese group. Therefore being obese can put you at high risk of causing vitamin D deficiency disease.

3. Less exposure to the sun

For avoiding and protecting your body from skin cancer we use sunscreen. This might decrease your vitamin D levels. Sunscreen protects your body against UV-B rays with SPF of 30 which decreases vitamin D production in the skin by more than 95%. Plus, we mostly spend our maximum time indoors. The total amount of vitamin D your body produces varies according to the time of the day, season, ozone amount, and a cloudy sky.

By increased Vitamin D level, you also have a reduced risk of burning and damaging your skin with short sun exposures.


When the UV index is 3 or above – Sunscreen protection is recommended. 

When the UV index is below 3– Sunscreen protection is not recommended.

Click to know- How to increase vitamin d levels quickly?  


Who is at risk for vitamin D deficiency?

It is found in –

• Older adults 

• Adults (with BMI > 30 kg/m2)

• Obese children 

• Pregnant women 

• Hispanic children and adults

• African-American

• Lactating women

Also, people who are suffering from a disease like-

• Musculoskeletal diseases

• Chronic kidney disease

• Hepatic failure

• Malabsorption syndromes

• Malabsorption

People suffering from malabsorption syndromes and people who have had bariatric surgery are not able to absorb vitamin D.

It has been found that as we grow old, our body decreases the ability to synthesize vitamin D from sun exposure. Therefore, there is about 25% reduced production over the age of 70.