26 Symptoms of Low Vitamin D You Need to Know About
Vitamin D deficiency may be linked to several conditions, from depression to cancer.
By Lauren Oster Updated on August 5, 2022
We get vitamin D from a great source: the sun. But it's still possible to not get enough vitamin D—which can lead to negative health consequences. According to the National Library of Medicine, vitamin D deficiency can lead to a loss of bone density, which can contribute to osteoporosis and fractures (broken bones). Severe vitamin D deficiency can also lead to other diseases. And researchers are studying vitamin D for its possible connections to several medical conditions, including diabetes, high blood pressure, cancer, and autoimmune conditions such as multiple sclerosis.
The good news? It's relatively easy to get enough vitamin D. Certain foods, including fatty fish, can help you increase your levels, as can sunlight. Specifically, 15 minutes of sunlight on your hands and face each day can do the trick, Donald Ford, MD, a family medicine doctor at Cleveland Clinic, told Health. (Also worth noting, if it's raining one day, you can make up for it by spending 30 minutes in the sun the next.)
Here are 26 reasons you should consider spending more time outdoors if your doctor mentions that your vitamin D levels are low.
Obese men, women, and children are 35% more likely to be vitamin D deficient than non-obese people and 24% more likely to be D deficient than overweight people, according to a 2015 meta-analysis published in Obesity Reviews. According to a 2019 Cochrane Database of Systematic Reviews review, the accumulation of vitamin D in the adipose tissue might explain why obese people have low vitamin D blood levels since fat cells hold on to vitamins and don't release them efficiently. Translation: Obesity could actually make vitamin D deficiency worse.
People with diabetes or prediabetes have lower vitamin D levels than those with normal blood sugar levels, according to a Spanish study published in 2015 in the Journal of Clinical Endocrinology & Metabolism. The link is held for folks across the BMI spectrum. In fact, both lean and severely obese people with diabetes or prediabetes had significantly lower D than their nondiabetic counterparts. The study's authors believe that vitamin D deficiency and obesity "interact synergistically" to increase the risk of diabetes and other metabolic disorders.
Heart disease and vitamin D deficiency are known to go hand in hand. One 2022 study appearing in the European Heart Journal found evidence that vitamin D deficiency can increase blood pressure and the risk of cardiovascular disease.
However, experts say there isn't evidence of a direct link between higher vitamin D levels and lower cardiovascular risk. A 2019 meta-analysis published in JAMA Cardiology looked at more than 83 000 participants and vitamin D supplementation. Study researchers found vitamin D supplementation was not associated with reduced risks of major adverse cardiovascular events, myocardial infarction, stroke, or cardiovascular disease mortality.
Lupus, a chronic inflammatory disease in which the body's immune system attacks its own organs and tissues, is frequently associated with vitamin D deficiency—in part because lupus patients are often advised to stay out of the sun (the source of 90% of our vitamin D), and may be prescribed corticosteroids, which are also linked to low levels of D, according to the Lupus Foundation of America.
A 2022 study in the British Medical Journal found that vitamin D supplementation for five years taken with or without fish oil (Omega 3 fatty acid) may help reduce autoimmune diseases, such as lupus. Researchers found the autoimmune disease was reduced by 22% in those who took the increased levels of vitamin D with or without fish oil.
In a 2015 study published in Obstetrics and Gynecology, more than 2,000 mothers-to-be, women with higher levels of 25-hydroxy vitamin D (an indicator of our bodies' vitamin D stores, measurable with a blood test) had a lower risk of giving birth before 37 weeks. The authors suggested that D could have a protective effect by reducing bacterial infection in the placenta, which can cause preterm birth.
In a 2014 study in the American Journal of Epidemiology, researchers who examined data from the Collaborative Perinatal Project (a study of more than 42,000 women) reported that among nonwhite mothers, higher concentrations of 25-hydroxy D were associated with a reduced risk of birth before 35 weeks.
In 2013, an international team of researchers examined data from 465 people with early-stage MS, an often-disabling autoimmune disease that affects the central nervous system. As published in JAMA Neurology, researchers reported that higher levels of 25-hydroxy D measured at the onset of symptoms (and then 6, 12, and 24 months later) predicted a slower rate of disease progression. Subjects with higher levels of D had a slower increase in brain lesion volume, fewer new lesions, lower brain volume loss, and lower disability levels than those with low levels of D.
High-dose vitamin D supplementation was found to reduce the prevalence of PMS and dysmenorrhea (severe and frequent menstrual cramps and pain during your period, according to Johns Hopkins Medicine) in a 2017 study published in Gynecological Endocrinology. Vitamin D also had positive effects on the physical and psychological symptoms of PMS.
Non-steroidal anti-inflammatory drugs like ibuprofen and naproxen are still the first line of therapy for PMS symptoms, but researchers believe vitamin D supplements are a promising alternative.
Inflammatory Bowel Disease
Vitamin and mineral deficiencies, including D deficiency, are extremely common for people with gastrointestinal health issues that affect their body's ability to absorb nutrients. Patients with active ulcerative colitis, a type of inflammatory bowel disease (IBD), especially those who take corticosteroids, are often deficient in D, a 2013 tudy in Digestive Diseases and Sciences suggested. In addition, some researchers believe deficiency could have a role in increasing the risk of developing IBD and determining the severity of a person's symptoms, as a 2013 study in Alimentary Pharmacology and Therapeutics found.
Alopecia and Hair Loss
Women with female pattern hair loss had significantly lower levels of vitamin D than those without hair loss, a 2013 study in Skin Pharmacology and Physiology found. The vitamin is crucial for hair cycling and helps push the hair from its resting phase to the growing phase. Turkish researchers found that patients with alopecia areata, an autoimmune disease that attacks follicles and can cause hair loss all over the body, had significantly lower levels of 25-hydroxy vitamin D than folks without the condition, according to a 2014 study in the British Journal of Dermatology. Researchers also noted the lower their D levels, the more severe their disease.
Insulin resistance, which leads to glucose buildup in the blood, and type 2 diabetes and prediabetes, has been linked to vitamin D deficiency for quite some time. A 2019 study on Nutrients concluded that vitamin D deficiency is one of the factors accelerating insulin resistance formation. However, researchers noted that it is not fully recognized how vitamin D may reduce the risk of metabolic disorders development (such as type 2 diabetes).
In addition, researchers in Iran found that vitamin D supplements had no effect on insulin sensitivity in pre-diabetic patients, as published in a 2013 study in the Journal of Research in Medical Science.
Vitamin D is known to have a regulatory influence on both the immune system and skin barrier function, both critical in the development of eczema. Research suggests a link between vitamin D and eczema, specifically lower serum vitamin D levels associated with increased incidence and severity of eczema symptoms, according to a 2015 study in the Journal of Clinical Medicine.
Supplementing with vitamin D in pill form can improve winter-related eczema, one 2014 study published in the Journal of Allergy and Clinical Immunology found.
Tooth Decay in Infants and Toddlers
Vitamin D is crucial both to our dental health and the formation of our teeth in the first place—yet another reason taking prenatal vitamins is so important. A 2014 study in Pediatrics measured the blood levels of vitamin D in pregnant women, then checked their babies' teeth at one year old. Researchers found that mothers of children with weak enamel and tooth decay had significantly lower vitamin D levels during pregnancy compared to moms of children with healthy teeth.
Gum Disease and Tooth Loss
Because vitamin D helps your body absorb calcium, it's essential for healthy teeth and gums, says the National Library of Medicine.
When vitamin D levels are unregulated, it weakens your teeth, making you susceptible to cavities, fractures, and decay. A 2020 study in the journal Oral Diseases looked at over 4200 US adults and found that vitamin D levels are significantly associated with the occurrence of cavities.
Additionally, a 2020 study published in the Journal of Periodontal Research found lower vitamin D levels are linked with an increased risk of periodontitis, possibly because of its connection to the immune system. Vitamin D seems to positively impact inflammation and mineralization effects on the tissue surrounding your teeth.
Alzheimer's and Dementia
Studies have linked low vitamin D to abnormalities in brain structure, cognitive decline, and dementia. In a 2015 study in JAMA Neurology, which measured vitamin D and cognitive function each year in an ethnically diverse group of elderly patients (about half of whom had some form of cognitive impairment at the start of the study), lower levels of D were associated with accelerated cognitive decline.
A 2021 review in Nutrients concluded that, though there is a certainty that vitamin D is involved in normal brain function and that low vitamin D concentrations can occur in patients with dementia, there is no clear evidence that supplementation with vitamin D can prevent or modify the course of cognitive decline and dementia.
Vitamin D helps prevent infection by helping our bodies produce natural antibiotics. A 2014 study in the Archives of Disease in Childhood found that D deficiency is a risk factor for urinary tract infections in children, especially girls. It's a bit too soon to call vitamin D the new cranberry juice, but low levels are associated with UTIs for adults, too. A 2013 International Journal of Infectious Disease study of women who suffered from recurrent UTIs found that they had lower levels of vitamin D than women who didn't.