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Top Signs of Vitamin D Deficiency

Vitamin D deficiency is common and can affect energy, mood, and bone health. Here are the top signs to watch for and what to do next.
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Vitamin D Deficiency
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Vitamin D is often called the “sunshine vitamin” because our bodies make it when skin is exposed to sunlight. However, despite its natural source, vitamin D deficiency is surprisingly common worldwide. According to the National Institutes of Health (NIH), low levels of this nutrient affect millions of people, especially in regions with limited sun exposure or in those with restricted diets [1].

Because vitamin D supports bone strength, muscle function, immunity, and mood, a deficiency can have wide-reaching effects on health. The challenge, however, is that the symptoms are often subtle and easy to overlook. Let’s explore the most common signs of vitamin D deficiency and why it’s important to recognize them early.

Why Your Body Needs Vitamin D

Vitamin D is a fat-soluble vitamin that acts more like a hormone in the body. Once activated, it regulates calcium and phosphorus absorption, which are vital for strong bones and teeth. Beyond that, research shows vitamin D also plays a role in immune defense, muscle function, and even mood regulation (NIH, 2022) [1].

Without enough of it, your body struggles to function at best. That’s why spotting the signs of vitamin D deficiency can be an important step toward maintaining long-term health.

Top Signs of vitamin D Deficiency

1. Frequent Illness or Infections

If you seem to catch every cold that comes your way, low vitamin D may be part of the problem. Vitamin D helps regulate immune cells, and studies in the British Medical Journal (2017) found supplementation reduced the risk of respiratory infections, particularly in those with low levels [2].

2. Fatigue and Low Energy

Persistent tiredness—even after a full night’s sleep—can be a sign of deficiency. While fatigue has many causes, some research suggests that correcting low vitamin D levels improves energy and reduces feelings of exhaustion [3].

3. Bone or Back Pain

Vitamin D is essential for calcium absorption. When levels drop, bones and joints may suffer. Adults with vitamin D deficiency often report bone pain, lower back discomfort, or muscle aches. Over time, deficiency can contribute to conditions like osteoporosis or osteomalacia.

4. Muscle Weakness

Feeling weaker than usual, or struggling with tasks that used to be easy, could be linked to low vitamin D. The nutrient plays a role in muscle contraction and strength, and deficiency has been associated with an increased risk of falls in older adults.

5. Mood Changes or Depression

Low vitamin D has been linked to mood disorders, including depression. A review in the Journals of Gerontology (2017) found a correlation between low vitamin D levels and depressive symptoms [4]. While supplementation isn’t a replacement for therapy or medication, it may help support emotional well-being.

6. Slow Healing Wounds

If cuts or bruises seem to linger longer than they should, this may point to low vitamin D. The vitamin helps regulate inflammation and supports tissue repair, which are crucial for wound healing.

7. Hair Loss

Although hair loss has multiple causes, severe vitamin D deficiency has been linked to alopecia areata and general thinning. Because vitamin D affects hair follicle growth, restoring adequate levels may support healthier hair.

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Who’s Most at Risk?

Certain groups are more likely to experience vitamin D deficiency, including:

  • People with limited sun exposure: Those living in northern climates or who spend little time outdoors.

  • Individuals with darker skin: Higher melanin levels reduce vitamin D production from sunlight.

  • Older adults: Aging skin produces less vitamin D, and kidneys may convert less to its active form.

  • People with digestive disorders: Conditions like celiac or Crohn’s can impair absorption.

  • Vegetarians and vegans: Vitamin D3 is found mostly in animal-based foods, so plant-based eaters may rely heavily on fortified foods or supplements.

What to Do If You Suspect a Deficiency

If you recognize several of these signs, the first step is to ask your healthcare provider for a blood test. The 25-hydroxyvitamin D test is the standard way to measure vitamin D status. Depending on the results, lifestyle adjustments, dietary changes, or supplements may be recommended.

It’s important not to self-diagnose since the symptoms overlap with other health conditions. A medical professional can provide guidance on safe and effective dosing if supplementation is needed.

Conclusion

Vitamin D deficiency is far more common than many realize, and its symptoms—ranging from fatigue and mood changes to bone pain—can easily be dismissed as everyday issues. Yet, addressing it can make a major difference in overall health.

If you suspect you’re not getting enough, the next step is learning more about this vital nutrient. Be sure to check out our article on “Vitamin D: Benefits, Sources, and Daily Essentials” to deepen your understanding. You can also explore our guide on “Vitamin D3 and K2: Benefits and How They Work Together,” which includes our top supplement picks for optimal support.

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Disclaimer: This content is for informational purposes only and should not be considered medical advice. Always consult a qualified healthcare provider before making dietary changes.

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About the Author

Jalaine McCaskill, founder of Tweaksly, offers practical, research-based nutrition tips and reviews to make healthy eating simple and achievable.

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References:

  1. National Institutes of Health (NIH). (2022, November 08). Vitamin D: Fact Sheet for Consumers. Retrieved from National Institutes of Health (NIH): https://ods.od.nih.gov/factsheets/VitaminD-Consumer/

  2. al., M. A. (2017, February 15). Vitamin D Supplementation to Prevent Acute Respiratory Tract Infections: Systematic Review and Meta-Analysis of Individual Participant Data. BMJ, 356. doi:https://doi.org/10.1136/bmj.i6583

  3. Roy, S., Sherman, A., Monari-Sparks, M. J., Schweiker, O., & Hunter, K. (2014). Correction of Low Vitamin D Improves Fatigue: Effect of Correction of Low Vitamin D in Fatigue Study (EViDiF Study). North American journal of medical sciences, 6(8), 396–402. https://doi.org/10.4103/1947-2714.139291

  4. de Oliveira, C., Hirani, V., & Biddulph, J. P. (2018). Associations Between Vitamin D Levels and Depressive Symptoms in Later Life: Evidence From the English Longitudinal Study of Ageing (ELSA). The journals of gerontology. Series A, Biological sciences and medical sciences, 73(10), 1377–1382. https://doi.org/10.1093/gerona/glx130