Vitamin D deficiency is one of the most common vitamin deficiencies across the globe and arises when a person does not get enough vitamin D from either the sunlight or their diet. Although this may seem minor in the short term, the long-term implications can be catastrophic and result in a loss of bone density, osteoporosis, and an increased risk of broken bones. The prevalence of vitamin D deficiency is on the rise, with current estimates suggesting that approximately 40% of the population is deficient on some level, with 13% severely deficient (Cashman et al., 2016). But why is this deficiency on the rise?
There are several risk factors for low vitamin D levels that cannot be modified, such as older age, female gender, lower latitudes, skin pigmentation, and winter season. However, there are several modifiable risk factors, including sunlight exposure, dietary habits, and the lack of vitamin D fortification in common foods (Mithal et al., 2009). In recent years, there has been a substantial increase in urbanization, with more and more people living and working indoors. Additionally, cultural practices have seen trends of sun avoidance, which has resulted in people receiving limited sun exposure. Collectively, this, paired with the growing demand for fast and limited nutritious foods has caused a spike in the number of people with vitamin D deficiencies.
Testing for a vitamin D deficiency
The goal of a vitamin D test is to screen for low levels of this nutrient in the blood so the deficiency can be appropriately treated. Most people do not regularly test their vitamin D levels unless an issue arises, such as a bone disorder development, or they experience specific symptoms. Likewise, as vitamin D is involved in several processes in the body, vitamin D levels are tested in those with other chronic and long-term medical conditions. In these cases, vitamin D levels still do not need to be check routinely as it can take up to six months for a deficiency to alleviate once treatment has been started. It is, therefore, recommended that vitamin D levels be checked six months after starting vitamin D supplementation.
There are several methods to test for a vitamin D deficiency; however, the most prevalent and most accurate way is the 25-hydroxy vitamin D blood test. This measures the exact volume of this nutrient in the blood, with a result between 20ng/mL and 50ng/mL considered within a healthy range. A result below 12ng/mL indicates vitamin D deficiency (Kennel, Drake, & Hurley, 2010). Given the increased prevalence of vitamin D deficiency in recent years, it comes as no surprise that testing has also increased. Although the exact figures on the global increase in testing are not available, figures from the United Kingdom suggest that testing rose from 0.029% of the general population in 2005 to 1.61% in 2015 (Crowe et al., 2019).
Symptoms of vitamin D deficiency
The challenge with noticing vitamin D deficiency is that symptoms often do not present for several months or even years. In some instances, symptoms might not present at all. However, there are some clear indicators that warrant doing a 25-hydroxy vitamin D blood test. The first and most prominent symptom is persistent fatigue and tiredness. Unlike other more common symptoms of fatigue, like stress, depression, and insomnia, low vitamin D levels are often overlooked (Pennisi et al., 2019).
The second characteristic sign of vitamin D deficiency is bone and back pain. Vitamin D plays a crucial role in the maintenance of bone health by assisting in the absorption of calcium. Hence, disruption to vitamin D levels can have significant implications on the skeletal system, causing arthritis, muscle pain, and osteoporosis. This symptom ties in with the third symptom of vitamin D deficiency, bone loss. Beyond calcium absorption, vitamin D facilitates bone metabolism. Therefore, vitamin D deficiency and low bone mineral density go hand-in-hand, increasing the risk of fractures (Lips & van Schoor, 2011).
Other symptoms include depression, hair loss, muscle pain, weight gain, anxiety, and impaired wound healing.
Benefits of good vitamin D levels
The benefits of maintaining healthy vitamin D levels are substantial due to the wide array of roles that vitamin D plays in the human body. These include but are not limited to the regulation of calcium and phosphate in the body, keeping the bones, teeth, and muscles healthy, facilitation of a normal immune system function, and growth and development (Nair & Maseeh, 2012).