Low vitamin D levels can stem from several factors. It's not a single cause, but rather a combination of contributing elements.
Insufficient Sunlight Exposure
One primary reason for low vitamin D is inadequate sun exposure. Our bodies produce vitamin D when exposed to ultraviolet B (UVB) radiation from sunlight. People who live in areas with limited sunshine, spend most of their time indoors, or consistently use sunblock may not synthesize enough vitamin D. Darker skin pigmentation also reduces the body's ability to produce vitamin D from sunlight. (Source: People who don't have adequate levels of vitamin D may be deficient for any of these reasons: Not enough exposure to sunlight. Darker skin pigment. Malnutrition.)
Dietary Deficiencies
Malnutrition and a diet lacking in vitamin D-rich foods are also major contributors to low levels. While some foods are fortified with vitamin D, many people do not consume sufficient quantities of these foods. (Source: People who don't have adequate levels of vitamin D may be deficient for any of these reasons: ... Malnutrition.) Breast milk naturally contains low levels of Vitamin D, and many infant formulas are not sufficiently fortified, leaving infants vulnerable. (Source: ... low vitamin D levels because of inadequate vitamin D intake. Human breast milk contains low levels of vitamin D, and most infant formulas do ...)
Obesity
Obesity has been linked to lower vitamin D levels. This is thought to be due to vitamin D being stored in fat cells, making it less readily available to the body. (Source: Obesity: A body mass index greater than 30 is associated with lower vitamin D levels. Fat cells keep vitamin D isolated so that it's not released.) A study suggests that volumetric dilution, rather than sequestration within fat cells, may better explain this observation. (Source: Volumetric dilution, rather than sequestration best explains the low ...)
Other Contributing Factors
Several other factors may contribute to vitamin D deficiency, including:
- Certain medical conditions: Some diseases and medications can interfere with vitamin D absorption or metabolism.
- Age: Older adults often have difficulty producing and absorbing vitamin D.
- Gastrointestinal disorders: Conditions affecting nutrient absorption in the gut, like Crohn's disease or celiac disease, can lead to vitamin D deficiency.
- Genetic factors: Individual genetic variations influence the body's response to sun exposure and vitamin D absorption. (Source: These data suggest that variable responsiveness to UVB radiation is evident among individuals, causing some to have low vitamin D status despite abundant sun exposure ...)
Symptoms of Low Vitamin D
Low vitamin D can manifest in various ways, including:
- Bone pain: Weak and painful bones are classic signs of vitamin D deficiency. This can lead to conditions like osteomalacia (soft bones) in adults and rickets in children. (Source: In adults, severe vitamin D deficiency leads to osteomalacia. Osteomalacia causes weak bones, bone pain, and muscle weakness.) (Source: Vitamin D Deficiency Symptoms · Weak, sore, and painful muscles (with mild deficiency) · Incorrect growth due to bowed or bent bones · Muscle ...)
- Muscle weakness and pain: Muscle weakness, aches, and pain are common symptoms. (Source: Symptoms include muscle pain, bone pain, tingly sensation in hands or feet, muscle weakness ...) (Source: Symptoms when vitamin D is low · Fatigue · ... Bone pain or achiness · ... Muscle weakness · ...)
- Fatigue: Feeling constantly tired and lacking energy is another symptom. (Source: Symptoms when vitamin D is low · Fatigue · ...)
- Mood changes: Depression and sadness are linked to vitamin D deficiency. (Source: Symptoms when vitamin D is low · ... Depression or feelings of sadness · ...)
- Hair loss: While less common, hair loss can also occur. (Source: Symptoms when vitamin D is low · ... Hair loss · ...)
