Vitamin D is a nutrient that’s important for bone health, inflammation, and immune function. Vitamin D is also needed for red blood cell production. As a result, a low level may lead to anemia. It’s an indirect, but important, relationship.

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Vitamin D is an essential nutrient that’s essential for bone health, proper immune function, regulating inflammation, and several other body functions. Vitamin D deficiency is quite common, affecting about 35% of adults in the United States.

Anemia occurs when your level of red blood cells is lower than normal. Red blood cells carry oxygen around your body. Blood loss, low iron or B12 levels, or some health conditions and medications can cause anemia. In the United States, it’s estimated that 6.86% of the population has anemia.

At first glance, anemia and vitamin D deficiency seem to be unrelated, but there’s a potential association. Vitamin D has several roles that help maintain normal red blood cell levels. Also, people with low levels of vitamin D are more likely to have anemia.

Researchers have been exploring how vitamin D and anemia are connected. This connection is directly related to the levels of a hormone called hepcidin.

About hepcidin

Hepcidin is a hormone that helps control the amount of iron available in your body. Iron is essential for making red blood cells. When you don’t have enough iron, you can’t make enough red blood cells. Iron deficiency is the number one cause of anemia.

Hepcidin also protects your body by blocking the absorption of too much iron. High iron levels can be harmful to your organs. When there’s inflammation in your body, hepcidin levels go up. It’s a protective measure when your body is dealing with infection or inflammation.

High hepcidin levels mean that less iron is available to make new red blood cells. This can cause red blood cell levels to drop, resulting in anemia.

Vitamin D and hepcidin

Research suggests that low vitamin D levels can also increase hepcidin levels. This reduces red blood cell production. When vitamin D levels are increased, levels of hepcidin have been shown to go down in a small study. This allows more iron to be available to build new red blood cells.

Vitamin D may also help reduce inflammation. When inflammation decreases, it lowers hepcidin levels, and your body can make more red blood cells again.

There’s also emerging evidence that vitamin D plays a more direct role in the production of red blood cells. Vitamin D may support the normal growth of the cells that produce red blood cells.

It’s important to remember that it’s not just low levels of vitamin D that can lead to anemia. Your body also needs other nutrients, including iron and B12, to create red blood cells.

Typically, our main source of vitamin D has been sunlight. Our bodies create vitamin D from sun exposure. With the risk of skin cancer and winter conditions in colder areas, it’s not always possible to get enough vitamin D from the sun.

Many people take vitamin D supplements to ensure they’re meeting their daily vitamin D needs.

Adults up to 70 years or age need 15 micrograms (mcg) (600 international units, or IU) of vitamin D daily. For adults over 70, the recommendation goes up to 20 mcg (800 IU) of vitamin D daily.

If you have low vitamin D levels, you may need a higher amount of vitamin D at first to get your levels back into a normal range.

Normal vitamin D levels support lower levels of hepcidin in the body. This allows iron to be available to create red blood cells. Vitamin D also supports the normal development of the stem cells that build red blood cells.

Sources of vitamin D

There are only a few food sources of vitamin D. It’s hard to get enough from diet alone. Food sources include:

  • milk fortified with vitamin D
  • fatty fish
  • egg yolks
  • mushrooms treated with ultraviolet (UV) light
  • other foods fortified with vitamin D, including cereal and yogurt

Sunlight is a major source of vitamin D. You need about 20 minutes daily outside in the sun with at least 40% of your skin exposed to prevent vitamin D deficiency.

There are a lot of variables, though, depending on the climate where you live. People with darker skin and older adults have a harder time getting enough vitamin D from the sun.

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Many of the symptoms of anemia are due to lower oxygen levels in the blood. There are many causes of anemia, but the symptoms will be similar.

Typical symptoms of anemia include:

If you’re experiencing symptoms of anemia, the next step is to get a blood test.

The blood test results will provide information about the health of your red blood cells. Iron and B12 levels are often checked at the same time. Low levels of these nutrients can cause anemia. Vitamin D isn’t usually checked when you’re screened for anemia. You can discuss with a healthcare professional whether your vitamin D levels should also be checked.

Untreated anemia can cause anemia symptoms to get worse. Feeling tired, light-headed, and short of breath can make daily activities more difficult. In cases of severe anemia, a lack of oxygen may cause headaches, damage to the heart, and developmental delays in children. It may also make some chronic conditions worse.

Treatments for anemia include:

  • Iron supplements: Oral supplements are typically the first-line treatment for iron-deficiency anemia. There are many types and doses available.
  • B12 supplements: If low B12 levels are contributing to anemia, oral B12 supplements or B12 shots can help increase levels.
  • Intravenous (IV) iron: This is a way to quickly boost iron levels in severe anemia or if oral iron supplements aren’t an option.
  • Blood transfusions: This may be an option if blood loss is the reason for low red blood cells. It can also be used in cases of severe anemia to help normalize levels.

Vitamin D deficiency happens when levels of vitamin D are low in your body. It’s a common deficiency, affecting about 35% of adults in the United States. Anemia, which can have many causes, is when red blood cell levels are too low.

Researchers have discovered a link between low vitamin D levels and anemia. Low vitamin D levels may affect your body’s ability to make new red blood cells. This could lead to anemia.

Regular blood work is the best way to monitor your vitamin D levels and screen for anemia. While there are no standard guidelines to monitor the association between vitamin D levels and anemia, your vitamin D levels can still be an indicator of your overall health. Vitamin D deficiency and anemia are both treatable conditions.