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What Happens to Your Body If You Don't Get Enough Vitamin D, Doctors Say

This common deficiency can cause a wide range of health woes.

When it comes to most nutrients, it's possible to get everything you need by eating a wide variety of whole foods—but vitamin D is a rare exception to the rule. Though experts recommend that adults aim for 600 IU of the vitamin daily, it's found in only a narrow selection of foods such as fatty fish, eggs, mushrooms, and fortified milks and cereals, making it difficult to reach the recommended amount through diet alone. Instead, most people get it through direct skin exposure to natural sunlight, or through supplements. However, many people still struggle to get enough vitamin D on a daily basis.

In fact, a widely cited 2011 study published in the journal Nutrition Research reports that 42 percent of adults in the U.S. are vitamin D deficient—and though it's a common problem, the consequences can be troubling. Read on to learn what happens to your body if you don't get enough vitamin D, and how one method of getting your vitamin D can seriously backfire if you're not careful.

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You may develop muscle cramps.

woman rubbing her legs
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One of the most common symptoms of a vitamin D deficiency is having muscle cramps or muscle weakness. "A lack of vitamin D can lead to a loss of muscle mass and strength, resulting in muscle weakness. This is because vitamin D regulates calcium homeostasis, which is necessary for proper muscle contraction and relaxation," explains Denise Pate, MD, a board-certified physician and Medical Director with Medical Offices of Manhattan.

Erika Aragona, MD, a board-certified family medicine physician and wellness expert for BioShell, tells Best Life that this is because the vitamin is essential for your body to absorb calcium and phosphorus. "If your calcium level falls, your body may try to compensate by making another gland, your parathyroid, increase its function in attempts to balance out the low calcium," she says. "When these levels are abnormal, and your body notices chronic low calcium and high parathyroid hormone levels, you can experience several symptoms including, but not limited to, muscle cramps and muscle weakness." Ultimately, this can lead to an increased incidence of fall injuries—particularly in the elderly, Pate adds.

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Your bones may weaken.

man with broken arm
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Having a vitamin D deficiency can also harm your bone health, both doctors say. "A weakening of the bones, which can result in osteoporosis and an increased risk of fractures, is one of the most typical symptoms of vitamin D insufficiency," explains Pate.

Aragona says this occurs because when vitamin D is low and calcium is not absorbed as well in your body, this can cause your bone mineralization to worsen. Though a deficiency can affect your bone health at any age, children are susceptible to the most severe outcomes. "When children do not have enough vitamin D, they may have poor development of their bones and it can lead to deformities in their bone structure," Aragona notes.

You may be at higher risk of depression.

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Aragona says that those with a deficiency of this particular vitamin may be at higher risk of depression, though she notes that studies suggesting as much have stopped short of establishing causation. "A direct link is not yet known, but several different theories exist. One is that people already suffering with mental health conditions may be more withdrawn, tired, and less likely to go outside and have sun exposure. They also may be less likely to eat well-balanced meals that contain enough vitamin D."

"Another theory is that low vitamin D causes poor absorption of many more nutrients than just calcium, and as malnutrition increases, mood disorders also can increase," she adds.

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You may be at higher risk of certain illnesses.

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Besides being crucial for helping you maintain healthy bones, muscles, and teeth, Pate points out that having a vitamin D deficiency is linked with several chronic illnesses. In particular, a 2017 study published in the medical journal Aging and Disease found that vitamin D insufficiency plays a role in the development and progression of several chronic diseases, such as cardiovascular disease, diabetes, and certain cancers.

Your immune system may also suffer, Pate says. "Vitamin D is essential for regulating the immune system and promoting immune function. The vitamin has been shown to have immune-modulatory properties, and a lack of it has been linked to an increased risk of autoimmune diseases and infections," she adds.

However, doctors warn against this one mistake.

doctor talking and explaining test result and diagnosis to demoralized elderly patient in hospital hallway
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When you expose your skin to sunlight, your body is able to make its own vitamin D. "We each have vitamin D receptor cells that, through a chain of reactions starting with conversion of cholesterol in the skin, produce vitamin D3 when they're exposed to ultraviolet B (UVB) from the sun," explained dermatologist David J. Leffell, MD, chief of Dermatologic Surgery while speaking with Yale Medicine. However, this poses a serious dermatological threat, since one in five Americans will develop skin cancer in their lifetime and more than one million Americans are living with melanoma, a potentially life-threatening form of skin cancer.

Aragona agrees that too many people jeopardize their health by sunbathing in the name of vitamin D. "Remember, tanning beds and sun lights are not advised as a good source for getting your vitamin D, and with the alarming number of skin cancer diagnoses worldwide, maximizing your sun exposure for increasing your vitamin D is not the best way doctors advise you get proper vitamin D intake," says Aragona. Instead, she recommends maximizing your intake of foods that are rich in the nutrient, and talking to your doctor about whether supplements might be right for you.

Best Life offers the most up-to-date information from top experts, new research, and health agencies, but our content is not meant to be a substitute for professional guidance. If you have specific health questions or concerns, always consult your healthcare provider directly.

Lauren Gray
Lauren Gray is a New York-based writer, editor, and consultant. Read more