Why Are So Many People Deficient in Vitamin D?

Hey Angels and Alphas,

Vitamin D is an essential nutrient that plays a crucial role in bone health, immune function, and many other physiological processes. Despite the importance of this vitamin, studies have shown that a large percentage of the population is deficient in vitamin D.

According to the National Institutes of Health, an estimated 40% of people in the United States are deficient in vitamin D, and this number increases to 70% in certain high-risk populations, such as older adults, people with darker skin, and those who are overweight or obese.

Globally, it is estimated that more than one billion people have insufficient levels of vitamin D, making it one of the most common nutrient deficiencies worldwide. Given the crucial role of vitamin D in maintaining overall health, these statistics highlight the need for increased awareness and action to address this issue.

In this post, we’ll explore some of the reasons why so many people are deficient in vitamin D.

Lack of Sun Exposure

One of the primary sources of vitamin D is sunlight. When the skin is exposed to UVB radiation, it produces vitamin D3, which is then converted into its active form by the liver and kidneys.

However, many people spend a significant amount of time indoors or wear clothing that covers their skin, which can limit their exposure to sunlight. Additionally, people who live in northern latitudes or areas with less sunlight are at higher risk of vitamin D deficiency.


While sunlight is the primary source of vitamin D, some foods are also rich in this nutrient. However, many people do not consume enough vitamin D-rich foods, such as fatty fish (salmon, tuna, mackerel), egg yolks, and fortified dairy products. Vegetarians and vegans are also at risk of vitamin D deficiency, as few plant-based foods contain significant amounts of this nutrient.


Obesity has been linked to vitamin D deficiency, as excess body fat can sequester vitamin D and make it less available to the body. This is because vitamin D is a fat-soluble vitamin, meaning it is stored in fat cells. Studies have shown that obese individuals have lower blood levels of vitamin D than those with a healthy weight.


As we age, our skin becomes less efficient at producing vitamin D in response to sunlight. Additionally, older adults may not consume enough vitamin D in their diet and may spend less time outdoors. These factors can increase the risk of vitamin D deficiency in older adults.

Dark Skin

Melanin, the pigment that gives skin its color, can reduce the skin’s ability to produce vitamin D in response to sunlight. This means that people with darker skin may require more sun exposure to produce the same amount of vitamin D as someone with lighter skin. This can put them at higher risk of vitamin D deficiency, especially if they live in areas with less sunlight.

Medical Conditions

Certain medical conditions can interfere with the body’s ability to absorb and utilize vitamin D. These conditions include inflammatory bowel disease, celiac disease, and cystic fibrosis, among others. Additionally, people with conditions that affect the kidneys or liver may have difficulty converting vitamin D into its active form.

In summary, there are several reasons why so many people are deficient in vitamin D, including lack of sun exposure, diet, obesity, age, dark skin, and medical conditions.

If you’re concerned about your vitamin D levels, talk to your healthcare provider. They can recommend a blood test to check your vitamin D status and suggest ways to increase your intake of this essential nutrient.

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