5 Sneaky Signs You Might Have a Vitamin D Deficiency

As far as nutrients go, vitamin D has been pretty on-trend. This could be due to the robust research behind all of its potential health benefits, from supporting healthy bones and reducing inflammation to lowering the risk of depression. But what actually is vitamin D? And how do you know if you're falling short on your needs? Here we dive into the science behind how much vitamin D you actually need, plus five sneaky signs that indicate you might be deficient.

5 Signs You Might Have a Vitamin D Deficiency

1. You're Feeling Depressed

According to a 2020 review published in the Indian Journal of Psychological Medicine, researchers concluded that serum vitamin D levels inversely correlated with clinical depression, meaning the lower your vitamin D levels, the more likely you were to be depressed. Vitamin D deficiency might be a factor if you are feeling down more often than usual, especially during the winter months (looking at you, seasonal affective disorder). The good news is that upping your intake might help improve some symptoms.

Your baseline vitamin D status may also impact how well an increase in vitamin D will impact your symptoms of depression. Researchers found that in individuals who had low vitamin D levels, but not critically low, vitamin D supplementation helped alleviate symptoms, according to a 2024 review published in Journal of Affective Disorders. Other reviews have had inconclusive results, so more research is needed to clarify vitamin D's relationship with mental health, according to a 2021 review published in the Journal of Clinical Medicine. As always, talk with your doctor before starting any new supplement. Your doctor can perform a blood test to check your serum vitamin D levels to see if you're deficient.

2. You Live in a Cold-Weather Climate

As mentioned, our bodies can make vitamin D from exposure to the sun. However, the sun has to have a high enough UV index in order for our bodies to be able to do this. The UV index changes depending on location, time of year and the surface on the ground—for example snow and sand reflect more UV light, according to 2024 research published in Scientific Reports. We also have to have enough skin exposed—which doesn't often happen in the winter. In places with a long, cold winter, say, Vermont, there are only a few months of the year where making enough vitamin D from the sun is viable. If you are curious about this, the app Dminder can help you track the specific amount of vitamin D you are getting from the sun based on the UV index, time of day, amount of sun exposure and more.

3. You Have Weak Bones

This could be the most obvious sign that you might not be meeting your vitamin D needs. Vitamin D helps our bodies absorb calcium—the mineral that helps build and maintain strong bones, according to the National Institute of Arthritis and Musculoskeletal and Skin Diseases. Frequent bone breaks or stress fractures could be a sign that your vitamin D levels are low. If you are experiencing any of these symptoms, talk to your doctor to see the best course of treatment and to learn if a vitamin D supplement could be right for you.

4. You Have High Blood Pressure

While the connection between vitamin D and bone health is well established, the connection between vitamin D and heart health is less clear. Research looking into the link between vitamin D status and high blood pressure found that lower vitamin D levels were associated with the development of hypertension after an 8-year follow-up, according to a 2021 study published in Medicina. Other studies have not found the same association, according to a 2023 review published in International Journal of Molecular Sciences. More research is needed to clarify the relationship between vitamin D and blood pressure. If you have high blood pressure and think you might be deficient in vitamin D, talk to your doctor to see if testing your vitamin D levels is appropriate.

5. You Follow a Vegan Diet

Unfortunately, most food sources of vitamin D come from animal products such as eggs, fish and dairy. Avoiding these foods can put you at a higher risk of deficiency, however it's not impossible to meet your needs if you follow a vegan diet. It might take some extra planning, but there are plant-based ways to get your 600 IUs in every day. Include vegan-friendly food sources of vitamin D such as UV-exposed mushrooms, fortified orange juice and fortified breakfast cereals. Also, try to spend some time outdoors each day, especially if you live in a warmer climate.

What is Vitamin D?

Vitamin D is a nutrient our body can make when exposed to sunlight. It is considered a fat-soluble vitamin because you need fat to absorb vitamin D—the other fat-soluble vitamins are vitamins E, K and A. Vitamin D helps the body absorb calcium, which is important for healthy bones and muscles. It also can help reduce inflammation, support a healthy immune system and more, according to the National Institutes of Health (NIH).

How Much Vitamin D Do You Need Each Day?

It is recommended that adults between ages 19 and 70 get 600 IUs (or 15 mcg) of vitamin D per day, according to the NIH. One of the main ways we get this vitamin is through sun exposure. Our skin can create sufficient vitamin D from approximately 5 to 30 minutes of sun exposure to our face, arms, hands and legs daily (or at least twice per week), but this can vary significantly based on where you live.

There are also several food sources of vitamin D, including eggs, salmon, sardines, yogurt, milk, tuna, UV-exposed mushrooms and fortified foods (like orange juice and breakfast cereal). Additionally, vitamin D supplements may help you meet your needs.

The Bottom Line

Vitamin D is involved in various important body functions, from bone health to brain health and more. But meeting your needs can be easier said than done, especially if you follow a vegan diet or live in a colder-weather climate. Feeling more depressed than usual or having high blood pressure might be symptoms of an underlying deficiency. If you are concerned about your vitamin D levels, talk to your doctor or a dietitian about a serum vitamin D test or to see if supplementation is right for you.