8 Health Dangers of Low Vitamin D Levels

Doctor William C Lloyd Healthgrades Medical Reviewer
Medically Reviewed By William C. Lloyd III, MD, FACS
Written By Sarah Lewis, PharmD on July 4, 2021

Vitamin D is the sunshine vitamin. Ultraviolet sunlight stimulates the skin to produce it. This is important because very few foods naturally contain vitamin D. Moderate exposure to sunlight—15 minutes three times a week—gives most adults enough vitamin D to make up for low dietary levels. Most U.S. adults don’t need to worry about low levels. But there are people at risk, including breastfed infants, older adults, people with dark skin, and those with kidney or liver problems.

Most people associate vitamin D with bone health. Vitamin D promotes bone formation and helps maintain proper levels of calcium and phosphorus. But vitamin D also plays a role in insulin production and immune system function. It regulates cell growth, muscle function, and inflammation. Its role in these various systems means low levels may be linked to health problems.

  • Woman holding a glass of Milk
    1. Osteoporosis
    Osteoporosis is thinning of the bones resulting in fragile bones that fracture easily. The risk of osteoporosis increases as you age. Your body needs both calcium and vitamin D to maintain bone mass. Studies of osteoporosis and its prevention use both calcium and vitamin D. So it’s hard to separate one from another. But doctors know you need adequate vitamin D in your system for optimal bone health. Women especially may benefit from vitamin D supplementation to strengthen bones.
  • radiologist viewing x-ray of broken leg
    2. Fractures
    Vitamin D’s benefits go beyond strengthening your bones. It also helps strengthen your muscles. The combination of strong bones and strong muscles helps prevent falls and fractures. Research suggests regular supplementation with moderate doses is most effective for bone and muscle strength. Normal doses range from 1,000 to 2,000 IU per day. Very high doses of vitamin D may actually increase the risk of bone fractures.
  • Heart Health Concept
    3. Heart Disease
    Your heart is a muscle. So it makes sense that vitamin D levels could affect it. In fact, several studies have found a connection between low vitamin D levels and an increased risk of heart attack, heart failure, and death. Researchers are still studying whether vitamin D supplements can decrease your risk of heart disease. In the meantime, doctors know vitamin D is necessary for overall health and recommend maintaining healthy levels.
  • biologist holding a flask containing stem cells
    4. Cancer
    Many years ago, researchers found a link between low vitamin D levels and cancer. They noticed people living at higher latitudes—such as northern states—were more likely to die of colon cancer. Since then, researchers have linked low vitamin D levels to the risk of developing dozens of cancers. This includes colon, breast, prostate and pancreatic cancers. They are still looking at whether vitamin D supplementation will decrease the risk of these cancers or help treat them.
  • Hospital phlebotomist preparing to collect blood donation from patient
    5. Immune Function
    Vitamin D helps regulate your immune system. Scientists are looking at the role of vitamin D in autoimmune diseases. This includes multiple sclerosis, type 1 diabetes, rheumatoid arthritis, and Crohn’s disease. Many of these diseases have higher rates among people who live in northern latitudes. It’s unclear whether supplementation helps prevent them.
  • Pensive Senior Man
    6. Dementia and Alzheimer’s Disease
    A recent study found elderly people with low levels of vitamin D were more than twice as likely to develop dementia. Even people with moderately low levels had an increased risk of developing these problems. Researchers are currently studying whether taking vitamin D supplements can delay or prevent dementia. It’s important to understand that a link with low vitamin D levels doesn’t mean low vitamin D levels caused the problem. This is true with many of these health problems.
  • woman using diabetes test kit
    7. Type 2 Diabetes
    In the past, studies found people with low vitamin D levels were more likely to be obese. And obesity is a risk factor for diabetes. Researchers recently found evidence linking low vitamin D levels directly to problems with glucose metabolism. The results were independent of how much a person weighed. This is important because it clarifies the understanding of vitamin D and type 2 diabetes. Vitamin D is related to glucose problems in general and not just to obesity.
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    8. Depression
    Researchers have long suspected a link between depression and vitamin D levels. A recent study found low levels of vitamin D predicted depression symptoms in a group of 185 women. There’s definitely a connection, but again it’s not clear if low vitamin D actually causes depression. Scientists need to study whether vitamin D supplementation improves depressive symptoms.
  • Woman and Doctor
    Talk with your doctor about testing your vitamin D levels.
    Symptoms of vitamin D deficiency include bone pain, muscle aches, and muscle weakness. But most people aren’t deficient. Still, given the health concerns linked to low vitamin D levels, it’s reasonable to think about testing. A simple blood test accurately measures your levels. Your doctor may recommend a supplement if your vitamin D level is at the low end of normal. The recommended daily allowance (RDA) for most adults is 600 IU. This increases to 800 IU after age 70. Talk with your doctor about your vitamin D needs.
8 Health Dangers of Low Vitamin D Levels

About The Author

Sarah Lewis is a pharmacist and a medical writer with over 25 years of experience in various areas of pharmacy practice. Sarah holds a Bachelor of Science in Pharmacy degree from West Virginia University and a Doctor of Pharmacy degree from Massachusetts College of Pharmacy. She completed Pharmacy Practice Residency training at the University of Pittsburgh/VA Pittsburgh Healthcare System. 
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  6. Vitamin D. National Institutes of Health Office of Dietary Supplements. http://ods.od.nih.gov/factsheets/VitaminD-HealthProfessional/#h5 
  7. Vitamin D and Health. Harvard School of Public Health. http://www.hsph.harvard.edu/nutritionsource/vitamin-d/ 
  8. Vitamin D and the Heart. The Johns Hopkins University. http://www.hopkinsmedicine.org/heart_vascular_institute/clinical_services/centers_excellence/womens_... 
  9. Vitamin D Deficiency Linked More Closely to Diabetes than Obesity. Endocrine Society. https://www.endocrine.org/news-room/current-press-releases/vitamin-d-deficiency-linked-more-closely-...
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Last Review Date: 2021 Jul 4
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