Vitamin D deficiency can have many impacts on your body. But to understand why, you should first understand what vitamin D is and how it works in your body. “Like all vitamins, vitamin D is a compound that acts to help the body accomplish a particular set of normal functions. Vitamin D is made by the skin when the skin is exposed to sunlight,” says Dr. Jason Prescott, MD, an endocrinologist and associate chief of surgery, research, and academic Affairs at NYU Langone Hospital in Brooklyn. “Vitamin D is then transported through the blood to the liver and to the kidneys, both of which then activate vitamin D, allowing it to carry out its normal functions.” The main job of activated vitamin D is to help the body absorb calcium from food and otherwise maintain normal body calcium levels. “Calcium plays a critical role in the normal activities of many organs, including the bones, the muscles, and the brain,” adds Dr. Prescott. “When vitamin D levels are low, these organs (in particular, the bones) may not function normally or may, over time, sustain damage.” But it also plays a role in many functions in your body. “There are many other roles that vitamin D likely plays, including reducing inflammation, maintaining cell growth, promotion of good nerve and immune function and regulating glucose metabolism,” says Dr. Cory Fisher, DO, a family medicine physician at Cleveland Clinic.
What does it mean to be vitamin D deficient?
Unfortunately, this is a very common problem, with over 40% of people in the United States, for example, suffering from vitamin D deficiency. “The most important first step is to visit your doctor to see if your vitamin D levels are low. This can be done with a simple and quick blood test,” says Dr. Prescott. Your blood test, called a 25-hydroxy vitamin D test, will tell you where your vitamin D levels fall. “There are a lot of conflicting opinions out there about what an appropriate level of vitamin D should be,” says Dr. Fisher. “In general, a ’normal’ vitamin D level is between 30-80 ng/mL (depending on the lab reference range). Anything below 30 ng/mL is considered a deficiency, and anything below 20 ng/mL is considered a severe deficiency.”
The #1 sign you’re deficient in vitamin D is…
According to experts, it’s fatigue. “Fatigue, most commonly defined by people visiting their doctor as tiredness or a state of ‘low energy’, is very common, impacting approximately one-third of people in the United States,” says Dr. Prescott. “Multiple studies have shown a relationship between low body vitamin D levels and fatigue, with some reports identifying fatigue in 75% or more of people who also have low vitamin D levels.” More important, he says, “these studies demonstrate, overall, that fatigue among people who have also been diagnosed with vitamin D deficiency improves with vitamin D supplementation.” Unfortunately, we still don’t know exactly why low vitamin D levels contribute to fatigue. “We suspect that this may be related to a role vitamin D plays in controlling normal body pathways related to inflammation and sleep (which may be disrupted when vitamin D levels are low),” adds Dr. Prescott. “Vitamin D also appears to play an important role in maintaining normal muscle strength/health, which may be compromised in vitamin D deficiency.”
How to get more vitamin D
If your vitamin D levels are low, there are several simple things you can do to raise your levels.
Get out in the sun
“Your skin needs UVB radiation to create vitamin D in your skin. This type of radiation is present only in the mid-portion of the day (it varies by latitude) in the summer months,” saysDr. Annette Faller, MD, Internal Medicine at Mayo Clinic Health System in La Crosse, Wisconsin. “Spending 20 or so minutes in the sun without sunscreen on during the summer months a few times a week is helpful. From November to March, for most of the United States, there is limited UVB radiation.” Adds Dr. Prescott, “In fact, any light source that produces ultraviolet B rays (UVB) will stimulate vitamin production by your skin (including most light therapy lamps). This being said, exposure to UVB also increases your risk of developing skin cancer, so it is important to keep your sun exposure moderate and, certainly, to avoid being in the sun long enough to develop a sunburn.”
Take a supplement
“Vitamin D3 comes in varying doses. I usually recommend around 4,000 IU (this is higher than the RDA) to ensure that your levels are sufficient to fight off infection, protect your bones and improve energy,” says Dr. Faller. “Getting your level checked can be helpful when it comes to making recommendations about the dose of vitamin D to take, so talk with your doctor about this. I believe a healthy level is over 50 ng/mL.”
Eat foods rich in vitamin D
“Consume more foods that contain vitamin D3, such as fatty fish (salmon, sardines, tuna), mushrooms, eggs (the yolks!) and fortified beverages such as milk,” says Dr. Faller. Next up: Could Wearing Sunblock Cause Vitamin D Deficiency?
Sources
Dr. Annette Faller, MD, Internal Medicine at Mayo Clinic Health System in La Crosse, WisconsinDr. Cory Fisher, DO, a family medicine physician at Cleveland ClinicDr. Jason Prescott, MD, an endocrinologist and associate chief of surgery, research, and academic Affairs at NYU Langone Hospital in Brooklyn
