If you have any medical questions or concerns, please talk to your healthcare provider. The articles on Health Guide are underpinned by peer-reviewed research and information drawn from medical societies and governmental agencies. However, they are not a substitute for professional medical advice, diagnosis, or treatment.
Vitamin D is a bit like NASA. We know they both do great things, even if we’re unsure what exactly those things are, and we talk about them as one unit. But just as there are people who work at NASA, what you know as “vitamin D,” or calcifediol, is actually a collection of fat-soluble steroids. These steroids act like hormones in your body, and vitamin D2 (ergocalciferol) and D3 (cholecalciferol) are especially vital for humans.
Despite its importance in our bodies for creating strong bones, cutting our risk of heart disease, and potentially increasing our immunity, 41.6% of adults in the United States don’t get enough (Forrest, 2011). And since pale skin produces more of this “sunshine vitamin” with sun exposure to ultraviolet light (UV light), people with dark skin have a higher chance of deficiency. If you’re African American or Hispanic, your risk of vitamin D deficiency leaps to 82.1% and 69.2%, respectively. (These numbers are using a cutoff value of ≤50 nmol/L to define what counts as a deficiency.) Public health experts believe a rise in concern over skin cancer has diminished the already small amount of time we spent in the sun. Coupled with a shift to more office work, and we’re simply not in a place for adequate vitamin D production. This isn’t an excuse to skimp on sunscreen (more on that later).
- 41.6% of adults in the United States don’t get enough vitamin D, and people with dark skin have more likely to be deficient.
- That’s because pale skin produces more of this “sunshine vitamin” vis-a-vis exposure to ultraviolet light (UV light)
- People living north of Atlanta, GA, are more likely to be D deficient in the winter months.
- Medical problems such as Crohn’s disease, celiac disease, and cystic fibrosis because they may cause malabsorption of vitamin D in their intestines.
Other causes of vitamin D deficiency
A deficiency doesn’t always come through a lack of vitamin D-rich foods or sunlight exposure, either. Both vitamin D3 and D2 have to be converted into their active forms by both the liver and the kidneys, and this process may be impaired in some people due to health problems. Other risk factors include medical problems such as Crohn’s disease, celiac disease, and cystic fibrosis because they may cause malabsorption of vitamin D in their intestines.
Signs and symptoms of vitamin D deficiency
A vitamin D deficiency can be hard to catch, which is why we’re glad you’re reading up on the common symptoms. Noticing the signs can help you advocate for yourself or at least start a discussion with your healthcare provider about how you’re feeling. “I don’t think most people would notice they are vitamin D deficient,” Dr. Dana Hunnes, senior dietitian at Ronald Reagan UCLA Medical Center, says. “A lot of its signs and symptoms (not having done a blood test) are relatively nonspecific and also can be confounded by other nutritional deficiencies or conditions.”
And, take note: You don’t have to have a deficiency to suffer. Even low blood levels of vitamin D have been associated with increased risk of cardiovascular disease, asthma in children (Ali, 2017), and cognitive impairment in older adults (Kent, 2009).
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Weakened immune system/Getting sick often
Children suffering from lower respiratory tract infections had lower vitamin D levels than their healthy counterparts, one study found (Jat, 2016). Another observed a connection between vitamin D levels and pneumonia in their participants (Pletz, 2014)—not just whether they had it, but also the severity of their illness.
Symptoms of vitamin D deficiency can look like the effects of everyday life. “Most people who have vitamin D insufficiency or deficiency may not automatically know it or even notice it since a lot of us are run down anyway from childcare or work, or insufficient sleep,” Dr. Hunnes explains. “Yes, it might affect your ability to do your job, but so might any of these things listed above.” Dr. Hunnes adds that “it would be important to identify the root cause of these signs and symptoms,” which is why you should start a conversation with a medical professional, even if you think you’re just worn down.
Dr. Hunnes identifies bone pain as one of the most common and severe symptoms of vitamin D deficiency. This is also likely to be experienced specifically as back pain, one study found (E Silva, 2013) They looked at over 9,000 participants and found an association between back pain and vitamin D deficiency.
Other factors can confound some signs of a vitamin D deficiency. You might feel muscle weakness because you’ve been working out or restricting your calories to lose weight. Perhaps you haven’t been sleeping enough. But if you’re feeling your muscle strength suffer, mention it when you talk to a medical professional, especially if you’re experiencing it along with other symptoms on this list.
Is it seasonal affective disorder or not enough vitamin D? It can be hard to tell. Researchers have found a connection between vitamin D deficiency and anxiety and depression (Armstrong, 2006), though they couldn’t say for sure that one caused the other. But another study might have helped clarify that (Jorde, 2008). People suffering from depression reported an alleviation of their symptoms when researchers gave them vitamin D supplements.
If there’s one role of vitamin D that most people know, it’s that the Ds support bone health by preventing bone loss through conditions like osteoporosis. That’s because vitamin D boosts your gut’s calcium absorption and plays an integral role in how bone is remodeled. Researchers also found a strong link between low blood serum levels of vitamin D and low bone mineral density in a large observational study of women either in menopause or postmenopause (Bener, 2015). Vitamin D deficiency can also cause osteomalacia, or a softening of the bones, in older adults (Sitta, 2009).
Although more research needs to be done in this area, low levels of vitamin D do seem associated with hair loss (Rasheed, 2013). There’s also an association between low D and alopecia areata, an autoimmune disease associated with rickets and characterized by severe loss of hair (Mahamid, 2014). One study looked even closer at the connection between vitamin D and hair loss, specifically in patients with alopecia areata. Researchers found that the more severe hair loss, the lower the patient’s blood levels of vitamin D were (Aksu Cerman, 2014).
Inability to heal wounds
If even minor scrapes and cuts take forever to heal, it might be a sign to get your D levels checked. When researchers looked at this vitamin’s ability to maintain glucose homeostasis, they also found that it indirectly helped with wound healing (Razzaghi, 2017). The sunshine vitamin increased study participants’ glycemic control, which quelled inflammation and allowed their foot ulcers to heal.
Getting enough vitamin D might take some planning, but it’s worth the effect. One study found that people with anxiety disorders had lower vitamin D blood levels than those who didn’t suffer from these conditions within the same age group (Bičíková, 2015). And although the study was done only on women with type 2 diabetes and anxiety, researchers found that vitamin D supplementation helped improve their mood (Penckofer, 2017).
Your lack of vitamin D may be showing up on the scale. There’s an association between lower levels of vitamin D and an increase in belly fat and waist circumference, research presented in 2018 found (Rafiq, 2018). But other recent studies indicate that correcting our low vitamin D levels may also help the weight come off. Waist circumference, hip circumference, weight, and BMI all decreased in participants given vitamin D supplements in a study (Khosravi, 2018).
Although bone health was a primary focus of vitamin D studies for a long time, researchers are now looking at vitamin D receptors and the effects of vitamin D on inflammation and immunity. A review of clinical trials in this area outlines vitamin D’s ability to decrease the risk of catching a cold or the flu or developing asthma (Hughes, 2009). And a 2019 study found that supplementation could even reduce some symptoms of chronic obstructive pulmonary disease (COPD) (Jolliffe, 2019).
Research is torn here, and more work needs to be done to clarify the connection, but some studies do show a connection between a higher vitamin D blood serum level and higher chances of pregnancy through IVF (Farzadi, 2015) (Paffoni, 2014). Getting the amount of vitamin D you need might also help you have a healthy pregnancy, as lower levels have been associated with bacterial vaginosis (Bodnar, 2009), gestational diabetes (Zhang, 2015), and preterm birth (Bodnar, 2015).
Researchers have noticed time and again, the protective quality of vitamin D against cardiovascular disease (CVD), even if they’re unclear on what mechanism makes that happen (Giovannucci, 2008) (Anderson, 2010). But you don’t need to understand how it works to know that not getting much vitamin D can up your odds for developing CVD, coronary artery disease (Anderson, 2010), and heart failure as well as having a heart attack (Lund, 1978).
Getting the right amount of vitamin D may help prevent muscular sclerosis (MS), a systematic review of past studies found (Sintzel, 2017). It also found that vitamin D may also alter disease activity in patients with MS, although the reviewers believe we need more research done in these areas.
Low levels of vitamin D are also associated with an increased risk of hypertension (high blood pressure). In fact, a meta-analysis found that the sunshine vitamin does indirectly modulate blood pressure, and the researchers think it has to do with D’s role in parathyroid hormone performance (Mehta, 2017). Studies have been mixed, but some have found that supplementing with vitamin D decreased blood pressure in those already low in the vitamin (Larsen, 2012).
Of note, people who are vitamin D deficient may have all, some, or none of these symptoms. This represents what some of the research says, but in actuality, each person may present with unique symptoms.
Treatment of vitamin D deficiency
If you suspect you have low vitamin D values, go see your healthcare provider. They’ll be able to run a blood test to identify your D levels and prescribe a course of treatment. “The gold standard test for vitamin D levels is a 25-hydroxy vitamin D test otherwise known as vitamin D hydroxyl,” says Dr. Hunnes. Once you take in vitamin D, your body converts it to a chemical called 25-hydroxyvitamin D, or calcidiol. This blood test checks your serum 25-hydroxyvitamin d (which you may see abbreviated as 25(OH)D).
Deficiency sometimes requires a short-time regimen of high-dose vitamin D supplementation that should be monitored by a medical professional. Dr. Hunnes explains that it can take longer to build up stories of vitamin D because it’s fat-soluble, so she’ll typically give patients a 12-week supplement regimen and retest their levels at the end. Severe vitamin D deficiency can require 50,000 international units (IU) of ergocalciferol (D2) weekly or 2,000-4,000 IU cholecalciferol (D3) daily for 12 weeks. Make sure you’re working with a medical professional, as taking too much can cause vitamin D toxicity.
How to prevent a vitamin D deficiency
Although we’re spending more time indoors away from the sunlight, which decreases our ability to produce vitamin D, it also lowers one risk factor for skin cancer. That’s important, especially for groups of people with darker skin who would need longer exposure to produce the same amount. And with other ways of getting vitamin D, potentially dangerous time in direct sunlight without sunscreen isn’t necessary. The safest and easiest method of prevention may be in the kitchen.
Stock your kitchen with good food sources of vitamin D such as fatty fish (like sockeye salmon, mackerel, cod liver oil, and herring), egg yolks, beef liver, dairy products, and fortified foods such as orange juice and certain breakfast cereals. Just don’t go too crazy, or add a supplement to your regimen, unless you’ve had your vitamin D status checked. Your vitamin D intake may be sufficient if you’re eating several of these foods, as the recommended dietary allowance for adults (600 IU for those between 1 and 70, 800 IU for those 71 and older) can be hit through from food sources alone.