A vitamin D deficiency means you don't have enough vitamin D in your body. A lack of vitamin D makes bones weak. But the link between vitamin D and blood pressure isn't clear.

In general, vitamin D may change how some body chemicals control blood pressure. The vitamin also seems to keep the lining of blood vessels flexible and healthy. If you have low vitamin D, your arteries can become stiff. This makes it harder for blood to flow.

Research about vitamin D and heart health has been mixed. Here's what studies say so far:

• A low vitamin D level seems to increase the risk of heart disease and death due to the condition.
• A low vitamin D level may make a person more likely to have high blood pressure and diabetes. These conditions are risk factors for heart disease.
• It's unclear whether a daily vitamin D supplement protects against heart attacks and strokes. It may only help those with severely low vitamin D levels.

Still, vitamin D is needed for overall good health. The daily recommended amounts from the National Academies of Sciences, Engineering, and Medicine are as follows:

• Adults ages 19 to 70 should get 600 international units (IU) of vitamin D a day.
• Adults over 70 should try to get 800 IU a day.

Remember, more of a vitamin isn't always better. Adults should not take more than 4,000 IU a day.

If you're worried that you're not getting enough vitamin D, talk to your health care provider. A blood test can be done to check your vitamin D level.

Screening for vitamin D deficiency is especially important in those with brown or Black skin, which has higher levels of the substance that gives skin its color. This substance is called melanin. The more melanin you have, the harder it is for your skin to make vitamin D from the sun.

Others who may benefit from vitamin D screening are:

• People who don't spend a lot of time in the sun.
• Older adults.
• People with certain health conditions that make it difficult to absorb vitamin D.