Vitamin D — often called “the sunshine vitamin” — plays many essential roles in your body. You can get it from your diet, and your body can its own make vitamin D (when exposed to sunlight). Still, many people have low levels.
Vitamin D deficiency symptoms are often hard to detect. Learn if you might be at risk and the warning signs of vitamin D deficiency.
What Does Vitamin D Do?
Vitamin D is well-known for its role in building strong, healthy bones. It helps you absorb calcium and get it into your bones. And it helps maintain healthy levels of calcium and phosphorus in your blood.
Besides bone health, scientists have learned that vitamin D plays many other roles in your health. Although they’re still doing research, it appears that vitamin D supports these and other functions:
- It helps your muscles and nerves work normally. Healthy vitamin D levels might help keep your muscles stronger as you age.
- It supports your immune system, helping immune cells fight infections and reduce inflammation. People with low vitamin D levels seem to have a higher risk of viruses and certain autoimmune diseases, like multiple sclerosis.
- It may play a role in reducing the risk of some types of cancer. Studies in animals (but not necessarily people) suggest that vitamin D might reduce cancer risk and slow the growth of cancer tumors.
- It’s needed for normal blood sugar metabolism. People who develop type 2 diabetes tend to have lower vitamin D levels.
- It’s vital for brain health and mood support. Low vitamin D levels are more common in people with depression and older adults with dementia.
Vitamin D Deficiency Symptoms in Adults
About 25% of people in the U.S. are deficient in vitamin D. Another 40% have borderline low levels.
A true vitamin D deficiency causes bone problems. Children who don’t get enough vitamin D will develop a bone condition called rickets — soft, often deformed bones.
In adults, vitamin D deficiency causes osteomalacia. Signs include weak bones that can break easily. You may also have bone or joint pain or muscle weakness.
Vitamin D deficiency symptoms also include dental problems and weak teeth.
You might not know if you have borderline low vitamin D levels because the symptoms are harder to detect. That’s because they are often non-specific, meaning they aren’t limited to bones or any one part of your body.
Borderline low levels of vitamin D might cause these and other symptoms:
- Fatigue.
- Problems sleeping.
- Achiness or back pains.
- Frequent illnesses or infections.
- Feelings of sadness.
- Loss of appetite.
“Vitamin D deficiency is quite common, especially in Pennsylvania and Pittsburgh areas. Even if you do not have symptoms, I recommend that patients discuss this topic with their primary care provider during their wellness exams,” saysAlexandra Potock, MD, of Northern Medical Associates. “This helps to assess for risk factors and provides guidance on whether starting a vitamin D supplement is right for you, Dr. Potock adds.
Who Is at Risk of Low Vitamin D?
Vitamin D comes from a few select foods. If you don’t eat these foods often, you might not get enough vitamin D:
- Fish, like salmon, rainbow trout, and sardines.
- Fortified milk. Cow’s milk always has vitamin D added, but not all plant milk does.
- Breakfast cereals with added vitamin D.
- Fortified orange juice.
- Egg yolks.
Your body also makes vitamin D when you’re in the sun — hence the name “sunshine vitamin.”
You might risk a deficiency or borderline low vitamin D if you:
- Eat a vegan diet, or don’t eat many vitamin D-rich foods.
- Live in the northern part of the U.S. (or far from the equator), where there is less sunlight during the winter.
- Avoid sun exposure on your skin, or always wear a high-SPF sunscreen. Note that windows in your car, house, or office block UV rays, so they don’t count toward sun exposure.
- Are over 40 years old. As you age, your body is less effective at making vitamin D from the sun.
- Have dark skin. Dark skin has more melanin, which blocks some of the sun’s rays.
- Are overweight or obese. You store vitamin D in your fat, so you may have less available throughout your body.
- Had weight loss surgery or have a health condition (like celiac disease) that affects how well you absorb nutrients. Both can reduce the amount of vitamin D you absorb from foods or supplements.
- Have liver or chronic kidney disease. Your liver and kidneys help turn vitamin D into a form your body can use. If these organs aren’t working right, they may not do this job as well.
- Take medications like a statin (for high cholesterol) or a steroid (like prednisone). These can affect how your body absorbs or uses vitamin D.
Your doctor can measure your vitamin D level with a blood test, so tell them if you have any risk factors for vitamin D deficiency. Sometimes people have low levels because of a combination of these factors.
How to Get More Vitamin D
The daily recommended amount for vitamin D for adults and children aged one and older is 15 mcg (600 IU). Adults over 70 should get 20 mcg (800 IU) daily. But depending on how well your body makes and absorbs vitamin D, you may need more than this.
The only sure way to know if you’re getting enough vitamin D is to have your health care provider do a blood test. You shouldn’t rely on symptoms alone. Your doctor can tell you if you need more vitamin D.
You might meet your needs by eating several vitamin D-rich foods daily. But if you’re borderline low or have a deficiency, your doctor might recommend a supplement.
Most people can safely take 25 mcg (1,000 IU) of vitamin daily, but you may need more depending on your levels. Your health care provider will advise you of the best dose.
Vitamin D supplements are available in two forms — D2 and D3. Vitamin D2 comes from plants, while vitamin D3 is animal-based. Your body absorbs and uses both forms, but vitamin D3 seems to do a better job of raising low levels.
If you prefer a plant-based supplement, you can use vitamin D2. Just be aware that you may need a higher dose. If your doctor recommends a supplement, let them know if you take the D2 form.
Note that vitamin D from a supplement is better absorbed if you take it with a meal that has some fat.
Can you get too much?
Because your body stores vitamin D, it can build up. So it’s important not to go overboard with supplements.
It’s rare to overdose on vitamin D from food or sunlight because your body regulates these. But you can get too much vitamin D from supplements.
You shouldn’t take more than 100 mcg (4,000 IU) a day unless your doctor tells you to. Getting too much vitamin D puts you at risk for these health problems:
- Nausea and vomiting.
- Muscle weakness.
- Loss of appetite.
- Dehydration.
- Kidney stones.
- Kidney failure.
- Irregular heartbeat.
If you’re concerned about a potential vitamin D deficiency, ask your doctor about testing your vitamin D levels at your wellness exam. Because this vitamin has wide-reaching effects on your health, it’s good to identify the problem so you can take steps to treat it.