The connection between vitamin D and our overall health and wellness is complex enough that researchers have studied it in great detail—and continue to study its effects on the body and potential health conditions.
How Vitamin D Benefits the Body
Vitamin D plays many roles in how your body functions, the most important of which relates to your bone health.
When you think of your bones and keeping them healthy, calcium probably comes to mind. “Got Milk” commercials and your pediatrician shared the message that you need calcium to help your bones grow and stay strong.
That’s true—you do need calcium for healthy bones. But without vitamin D, that calcium would be ineffective. Your body needs vitamin D to absorb calcium properly, and the two nutrients work together to help prevent osteoporosis and bone fractures.
Vitamin D has other critical jobs in the body, too. Along with helping your body absorb calcium, it also helps the body absorb phosphorus, another essential nutrient.
Research has also found that vitamin D helps reduce cancer cell growth, limits infections by boosting the immune system, reduces inflammation, promotes muscle movement, and helps the nerves carry essential messages between the brain and the body.
Signs You May Be Vitamin D-Deficient
When your body doesn’t get enough vitamin D, that’s known as a vitamin D deficiency. A deficiency in vitamin D can cause various adverse health issues, putting you at risk for problems related to the skeletal system, immune system, nervous system and muscular system.
If you’re vitamin D-deficient, you may experience a range of symptoms, including:
- Back pain
- Bone pain
- Bone loss
- Depression or mood changes
- Excessive fatigue
- Frequent illness
- Hair loss
- Muscle pain, weakness or cramps
- Non-healing or slow-healing wounds
Vitamin D Deficiency Research
In recent years, there’s been a good deal of research about what happens to the body when a person has a vitamin D deficiency. Some of that research is inconclusive, but there has been some evidence of a connection between not getting enough vitamin D and developing prediabetes and Type 2 diabetes. Other recent research looked into whether supplementation with vitamin D might help lower the risk of becoming infected with COVID-19.
Promising research recently published in Science Advances found that a lack of vitamin D seemed to increase the risk of opioid addiction in mice, offering the potential for vitamin D supplementation as a preventive measure.
Low levels of vitamin D may also increase a person’s risk of developing heart disease, some types of cancer and multiple sclerosis. Falls, which are very common in adults over age 65, are even more common in those who are vitamin D-deficient.
How Much Vitamin D Do You Need?
The amount of vitamin D you need each day depends on your age, and in some cases, your gender. Age is a particularly important factor since both infants and older adults often don’t get enough vitamin D. In breastfed babies, this is because breast milk isn’t a good source of vitamin D, while in older adults, the skin doesn’t make vitamin D as efficiently.
The National Institutes of Health recommends the following daily intake, measured in International Units:
- Children from birth to age 1—400 IU
- Children ages 1 to 13—600 IU
- Teens ages 14 to 18—600 IU
- Pregnant and breastfeeding teens and women—600 IU
- Adults ages 19 to 70—600 IU
- Adults ages 71 and older—800 IU
These are general guidelines, but your doctor can recommend an amount of vitamin D that’s appropriate for your health and specific needs. This may vary based on your risk factors and whether you have or are at risk of osteoporosis and certain other medical conditions.
Other factors, including any medications you take, can also play a role in determining how much vitamin D you need. Certain medications, including steroids, cholesterol-lowering drugs and seizure control medications, can lower your vitamin D levels.
Wondering how much you need? To make a recommendation, your doctor will verify the amount of vitamins in your body using a blood test. Guided by your vitamin D level and other knowledge about your health, he or she will recommend how much vitamin D you need.
Where to Find Vitamin D
Vitamin D is both a nutrient in the foods you eat and a hormone produced by your body. Production of vitamin D in the body is stimulated by exposure to the sun.
But when you’re exposed to sunlight, you’re also exposed to the sun’s harmful ultraviolet rays. There are three types of ultraviolet rays, two of which make it to the earth’s surface—UVA and UVB rays. UVA rays primarily cause premature skin aging, but UVB rays can lead to sunburn and increase your risk of skin cancer.
If you’re out in the sun for more than a few minutes, experts recommend wearing sunscreen with an SPF of at least 30, which limits your body’s ability to produce vitamin D.
Because of that, if you are vitamin D-deficient, your doctor will likely recommend that you take a vitamin D supplement. Vitamin D can be found both as a supplement by itself and in multivitamin formulas.
There are also two forms of vitamin D:
- D2, or ergocalciferol
- D3, or cholecalciferol
Both will help increase the amount of vitamin D in your blood, but vitamin D3 raises it higher and for longer.
You can also seek out vitamin D in the foods you eat, though getting enough vitamin D through food sources is challenging. Few foods contain vitamin D naturally, but an increasing number are fortified with the essential nutrient.
Vitamin D occurs naturally in fatty fish, such as salmon and tuna. Beef liver, cheese, egg yolks and mushrooms also contain small amounts of vitamin D. Milk, breakfast cereals and other products, such as orange juice and yogurt, are often fortified with some amount of vitamin D.
While it’s important to maintain adequate levels of vitamin D in your blood, it’s also important to know that you can get too much vitamin D. Getting too much of the nutrient is called vitamin D toxicity—a condition that can damage the kidneys and increase the levels of calcium in your blood. High levels of calcium can disrupt your heart’s rhythm and cause other health issues.
If you’re on vitamin D supplements, avoid taking too much by ingesting only the amount suggested by your doctor.
