A quick vitamin D primer
You walk in the sunshine every day (wearing your SPF, of course). You eat right. You get enough sleep. But even if you’re doing all the right things, you still may be missing something—vitamin D.
Though rare, severely low levels of vitamin D can cause rickets in children and osteomalacia (softening of the bones) in adults. Left untreated, these conditions can lead to bone pain, and thin, brittle, or misshapen bones, according to the National Institutes of Health. But recent research has suggested a connection between even moderately low levels of vitamin D and a number of surprising health conditions, including diabetes, osteoarthritis, and cancer.
There are a number of sneaky signs that can point to a vitamin D deficiency, so if you’re suffering from any of them, talk with your healthcare provider, who will likely recommend a blood test. This is really the only way to accurately determine your vitamin D level. Then you can discuss ways to boost them, usually by taking an over-the-counter supplement.
You’re tired all the time
If you aren’t getting enough vitamin D, you may feel completely exhausted, even if you get plenty of sleep. “There is mounting evidence that vitamin D deficiencies are associated with fatigue and sleep disorders,” says Catherine G. R. Jackson, PhD, a professor of kinesiology and exercise science at California State University in Fresno. A study in the North American Journal of Medical Sciences found that people who felt tired had low levels of vitamin D, but raising their vitamin D to normal levels significantly reduced feelings of fatigue. Not the problem for you? Here are other reasons you’re tired all the time.
You’re depressed
Having the blues may be linked to an insufficient amount of vitamin D. According to the Vitamin D Council, vitamin D receptors have been found in many parts of the brain, including in areas linked to depression. Results from studies have been mixed—some researchers have found significant improvements in mood after supplementing with D, while others have not—but that could depend on the severity of the depression as well as the vitamin D deficiency. For example, researchers from Columbia University found that taking vitamin D supplements was effective for those who suffered from clinically significant depression. See the everyday habits that could increase your risk for depression.
Your bones hurt
Adults who don’t get enough vitamin D often have aches and pains in their muscles and bones, especially in the winter. Their joints are also a little stiffer in the morning. “Many aches and pains are symptoms of the classic vitamin D deficiency, osteomalacia,” says Sonya Angelone, MS, RDN, spokesperson for the Academy of Nutrition and Dietetics. Soft bones are more likely to bow and fracture than ones that are healthy and hard.
You’re prone to stress fractures
“Most people think of a lack of calcium when talking about bone health, which is true. However, without vitamin D, calcium doesn’t get absorbed properly,” says Jennifer Giamo, a nutritionist, certified personal trainer, and founder of New York City-based Trainers in Transit. “Vitamin D, specifically D3, which increases calcium absorption, is critical to preventing bones from becoming thin and brittle.” A study in The Journal of Foot and Ankle Surgery found that people who participate in higher-impact activities may need greater levels of vitamin D to reduce their risk of stress fractures. Note, people with high levels of calcium in their bodies due to underlying illness may need to use low doses of vitamin D as a supplement, or avoid it altogether. In addition to the vitamin D deficiency symptoms that can put you at risk, make sure you know these signs of a calcium deficiency.
Your athletic performance could be better
Insufficient vitamin D may affect your fitness levels and muscle function. “You may not even realize you’re not performing at your best,” says Paige Waehner, a certified personal trainer and author of The About.com Guide to Getting in Shape. Giamo agrees. “Vitamin D deficiency is linked to increased inflammation. And after intense exercise, the body is inflamed,” she says. “If adequate amounts of vitamin D are already in the bloodstream, then the speed of recovery from intense exercise is increased.” Giamo warns, though, not to take vitamin D supplements if you aren’t deficient in the nutrient because it’s unlikely you’ll improve your athletic performance or recovery rate. “Since vitamin D is a fat-soluble hormone that doesn’t get excreted by the body, it could be potentially harmful if you take too much,” says Giamo. Thankfully, it’s hard to develop vitamin D toxicity if you are being prudent about dosage, so consult your doctor or pharmacist. (Psst: These foods can help reduce inflammation and joint pain.)
You can’t get a good night’s sleep
Researchers found that people with sleep disorders who took vitamin D supplements improved the quality of their z’s—they fell asleep faster and slept longer, according to a study published in the journal Nutritional Neuroscience.
Psst: Check out the myths and truths about vitamin D.
You catch everything going around
Colds, viruses, the flu: You name it, you get it. But you might not have known that these could actually be vitamin D deficiency symptoms. “Vitamin D deficiencies are associated with depressed immune systems,” says Dr. Jackson. “You’ll catch whatever is going around if your immune system isn’t functioning properly.” A study published in the journal Nutrients found that adults who have low levels of vitamin D had a 58 percent higher chance of catching an acute respiratory infection. Higher levels of vitamin D may also help decrease recovery time from the flu.
Next, read about why you should talk to your doctor before taking supplements.