Vitamin D has become an extremely popular vitamin, partly because there is growing recognition that a vast number of people may be vitamin D deficient. In fact, this pattern is so prevalent that vitamin D deficiency may be a hidden epidemic.
Such an epidemic might seem strange, especially if people do often ask, what are the symptoms of a vitamin D deficiency?
One problem is that the symptoms of vitamin D deficiency can seem fairly vague and generic, so they’re easy to overlook.
Now, low levels of vitamin D are particularly concerning because vitamin D plays a number of key roles in the body. Furthermore, vitamin D deficiency may be linked to a number of chronic diseases, including both cancer and cardiovascular disease (1).
At the same time, vitamin D is actually a hormone, even though we call it a vitamin. Because of this, there are receptors for vitamin D in the cells across your entire body, which is part of the reason that vitamin D is so critical for health.
Estimations of the prevalence of vitamin D deficiency vary dramatically but one study indicated that vitamin D deficiency was present in 41.6% of the American population and is especially common among people with poor overall health and as high as 82% for African Americans (2).
However, there remains considerable debate about how much vitamin D humans need. Official recommendations tend to suggest that people get between 400 and 800 IU of vitamin D each day (3), although other estimates suggest anywhere from 1,000 IU (4) to 5,000 IU or higher (5) to get the best health benefits.
Regardless of the ideal amount of vitamin D that we need, it’s clear that many people simply aren’t getting enough of this critical hormone. One of the reasons for this is that people often assume they have enough vitamin D. After all, vitamin D is produced in the presence of sunlight and many foods are also fortified with vitamin D.
So, it’s easy to be unaware that you could be deficient, especially if you need to ask, what are the symptoms of vitamin D?
To help you figure out whether you are deficient, here are 7 key symptoms of a vitamin D deficiency.
None of these symptoms will prove that you have vitamin D deficiency, as they are also associated with other conditions or health issues. However, if you experience a number of these problems, vitamin D deficiency may be the underlying cause.
1. Tiredness or Fatigue
Many of us feel tired or fatigued on an almost daily basis. In fact, this problem is so common that people often dismiss it as a simple fact of life. Yet, feeling consistently fatigued can be an indication of a health problem, especially if you are already getting enough sleep.
To make matters worse, fatigue is often poorly characterized in patients that experience it and many people don’t find solutions. This can have dramatic impacts on quality of life.
The connection between vitamin D and fatigue may seem unusual but there is evidence supporting it. For example, research has shown that those with higher levels of vitamin D in their blood were less likely to experience fatigue than those with lower levels of vitamin D (6).
Indeed, the connection between vitamin D deficiency and fatigue is so strong that sometimes low vitamin D is misdiagnosed as fibromyalgia, which is a chronic condition that shares a number of symptoms of a vitamin D deficiency, including fatigue and pain.
It’s also worth noting that tiredness and fatigue can cause a circular pattern with vitamin D deficiency.
In particular, if you are constantly tired, this will often decrease how often you go outside and how much time you spend in the sun. Doing so can make issues of vitamin D deficiency worse as you aren’t synthesizing as much.
Vitamin D supplements can offer an appealing way to get around this, especially for people who do not have the time or the energy to get outside as often as they would like.
There are many possible causes of tiredness and fatigue beyond simply not getting enough sleep - and vitamin D deficiency is high on that list
2. Aches and Pains
Another extremely generic set of symptoms for vitamin D deficiency is the presence of overall aches and pains, particularly in the muscles but also in the joints and bones (9,10) . This pattern is another reason why vitamin D deficiency is often confused with fibromyalgia.
Research into the mechanism for this effect is still in its early stages but there is evidence that there is a vitamin D receptor in nerve cells, which have the ability to sense pain. As such, a deficiency in vitamin D does have the potential to increase sensitivity and lead to generalized aches and pains (11).
Observational studies have also indicated that vitamin D deficiency was present in 71% of patients with chronic pain, while an additional 21% had insufficient levels of vitamin D.
The use of vitamin D therapy or supplementation has been proposed as a way to reduce these symptoms, particularly for people with chronic pain, and some studies have found promising outcomes (14,15). Some research has also shown that such treatment can significantly reduce pain, such as in children experiencing growing pains (16).
Persistent pain in muscles or in bones is also associated with vitamin D deficiency, even though many people don't realize this
Vitamin D deficiency has also been linked to depression. This relationship has mostly been found in observational studies and appears to be especially common in older adults, who are also a high-risk group for vitamin D deficiency (17,18,19).
However, results from experimental studies are less clear, with some studies finding that vitamin D supplementation can help to fight depression in patients with vitamin D deficiency and other studies failing to find that outcome (20,21,22).
Studies do suggest that supplementing with vitamin D may be particularly relevant for fighting depression in the winter months when people often experience seasonal vitamin D deficiency (23)
There are also other related health connections. For example, one study found that young women in Australia experienced simultaneous issues with poor mental health, bone density and vitamin D levels.
Those connections highlight the importance of ensuring a sufficient intake of vitamins and minerals through the diet and via supplements if necessary.
Not only is vitamin D deficiency connected to depression, supplementing with vitamin D may even help to improve outcomes
4. Loss of Bone Density
Speaking of the connections between vitamin D and other compounds, another one of the symptoms of vitamin D deficiency is the loss of bone density.
This occurs because vitamin D plays a role in bone metabolism overall and the absorbance of calcium. As such, a person who is supplementing with calcium may not see many benefits for their bone health if they are deficient in vitamin D (25).
A loss of bone density can exhibit in a number of ways, such as brittle fingernails, decreased grip strength, bone pain and even muscle aches (26).
However, these can also be symptoms of conditions like osteoporosis, so if you do have some of these symptoms it’s important to talk to your doctor.
Even though a loss of bone density is connected to vitamin D deficiency, taking high dose supplements doesn’t appear to help resolve this issue (27).
Nevertheless, it's likely that having adequate vitamin D could help to prevent bone loss from occurring. This makes it important to keep both your vitamin D and your calcium levels high to reduce the chance of bone loss, especially as you age.
Loss of bone density is often associated with calcium but the interaction between calcium and vitamin D means that you should consider your vitamin D intake as well
5. Hair Loss
In most cases, hair loss tends to get attributed to genetic factors or to stress. However, sometimes nutrient deficiency can also be a cause, including vitamin D deficiency.
There is some evidence that low levels of vitamin D are associated with hair loss in women, although there hasn’t been much research on the topic (28).
One particular disease that is connected to hair loss is alopecia areata, which is an autoimmune disease (29). Vitamin D deficiency may act as a risk factor for this disease, as many patients with it are deficient in vitamin D (30,31,32).
Additionally, some research has found a correlation with hair loss in alopecia areata, where vitamin D levels are inversely correlated with the amount of hair loss. So, lower levels of vitamin D tend to be associated with a greater amount of hair loss (33).
In some cases, hair loss can be connected to vitamin D deficiency, although there hasn't been a lot of research on the topic
6. Slow Wound Healing
One unexpected symptom of vitamin D deficiency is slower-than-normal wound healing. This action may be connected to the role that vitamin D has in controlling inflammation, although the precise mechanism is not known (34).
Additionally, a test tube study suggested that vitamin D can have a positive interaction with other factors in the wound healing process (35).
Potentially, this pattern means that increasing vitamin D levels in vitamin D deficient patients can help to speed up the process of wound healing.
This is not an area that has been studied in much detail.
However, one study did note that they found low levels of vitamin D in most patients with leg ulcers and that those with higher vitamin D levels experienced better healing, although the effect appears to have been non-significant (36).
Slower wound healing may not be extremely obvious but it is another vitamin D deficiency symptom to watch out for
7. Compromised Immune System
Your immune system plays a critical role in protecting you from disease and in fighting off harmful microbes.
Our immune systems are complex and involve many different components, but vitamin D does play a role in their effectiveness (37). As such, vitamin D deficiency can mean that your immune system does not function as well.
When this happens, you may end up becoming sick more often, especially with colds and other easy to contract illnesses.
For example, observational research has suggested that vitamin D deficiency is linked to higher levels of respiratory tract infections (38) and pneumonia (39), although not all research studies have found the same outcomes.
Some studies also indicate that taking vitamin D supplements can help to reduce the risk of respiratory tract infections (40). However, more research is still needed.
However, this pattern does strongly suggest that people who are deficient in vitamin D may contract illnesses more often.
Because vitamin D interacts with your immune system, vitamin D deficiency can potentially decrease the effectiveness of your immune system and increase how often you get sick
Diagnosis and Treating Vitamin D Deficiency
Despite increasing awareness, vitamin D deficiency continues to be surprisingly prevalent. The generalized nature of these symptoms of a vitamin D deficiency is a key reason why. Additionally, doctors often don’t test vitamin D levels unless you specifically request a test.
Thankfully, vitamin D deficiency is easy to detect and treat.
The best place to start is your doctor, who can determine your vitamin D level through a blood test. If possible, I recommend getting the doctor to tell you your actual vitamin D levels, rather than just whether you are deficient or not.
After all, there are varying opinions on what constitutes vitamin D deficiency and research does suggest that higher levels of vitamin D may offer more benefits.
In some cases, you may simply be able to get enough vitamin D by modifying your diet and by getting more sun exposure.
However, that may not always be enough, especially if you are considerably deficient in vitamin D.
As such, supplements are often the most reliable and practical way to increase your vitamin D levels, particularly in the winter months.
Whatever approach you take, resolving your vitamin D deficiency can be relatively simple and is well worth doing for improving your overall health and well-being.
Many people do find dramatic benefits from resolving a vitamin D deficiency and you may even find that your quality of life improves considerably.
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