Getting enough vitamin D helps the growth and development of bones and teeth. It may also provide improved resistance to certain diseases.
Vitamin D is a fat-soluble vitamin in a family of compounds that includes vitamins D1, D2, and D3.
Your body produces vitamin D naturally when it’s directly exposed to sunlight. You can also get vitamin D from certain foods and supplements to ensure adequate levels of the vitamin in your blood.
Vitamin D has several important functions. Perhaps the most vital are regulating the absorption of calcium and phosphorus and healthy immune system function.
Getting enough vitamin D is important for the typical growth and development of bones and teeth and for improving resistance to certain diseases.
Here is more information about the benefits of vitamin D, its downsides, how much you need, and foods with vitamin D.
1. Vitamin D may fight disease
In addition to its primary benefits, research suggests that vitamin D may also play a role in:
Reducing the risk of multiple sclerosis (MS): A 2017 review
of population-based studies found that low levels of vitamin D are linked with an increased risk of MS.
Decreasing the chance of heart disease: Low vitamin D levels have been linked to increased risk of heart diseases such as hypertension, heart failure, and stroke. However, it’s unclear
whether vitamin D deficiency contributes to heart disease or indicates poor health when you have a chronic condition.
Reducing the likelihood of severe illnesses: Although studies
are mixed, vitamin D may make severe flu and COVID-19 infections less likely. A recent review found that low vitamin D levels contribute to acute respiratory distress syndrome.
Supporting immune health: People who do not have adequate vitamin D levels might be at increased risk of infections and autoimmune diseases, such as rheumatoid arthritis, type 1 diabetes, and inflammatory bowel disease.
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2. May regulate mood and reduce depression
Research has shown that vitamin D might play an important role in regulating mood and decreasing the risk of depression. A review of 7,534 people found that those experiencing negative emotions who received vitamin D supplements noticed an improvement in symptoms. Vitamin D supplementation may help people with depression who also have a vitamin D deficiency.
Another study identified low vitamin D levels as a risk factor for more severe fibromyalgiasymptoms, anxiety, and depression.
3. May support weight loss
People with higher body weights have a greater chance of low vitamin D levels, and some studies suggest there may be a link between vitamin D and obesity, though more research is needed to verify this.
In an older study, people taking daily calcium and vitamin D supplements lost more weight than subjects taking a placebo supplement. The researchers suggest that the extra calcium and vitamin D may have had an appetite-suppressing effect.
Current research doesn’t support the idea that vitamin D causes weight loss, but there appears to be a relationship between vitamin D and weight.
Vitamin D deficiency
Several factors can affect your ability to get adequate vitamin D from sunlight alone.
You may be less likely to absorb enough vitamin D from the sun if you:
live in an area with high pollution
use sunscreen
spend most of your time indoors
live in a big city where buildings block sunlight
have darker skin (The higher the levels of melanin, the less vitamin D your skin can absorb.
These factors can increase your risk of vitamin D deficiency, so it’s important to get some of your vitamin D from sources other than sunlight.
What are the signs you need vitamin D?
The symptoms of a vitamin D deficiency in adults may include:
tiredness, aches, and pains
severe bone or muscle pain or weakness
stress fractures, especially in your legs, pelvis, and hips
A healthcare professional can diagnose a vitamin D deficiency by performing a simple blood test.
If you have a deficiency, your doctor may order X-rays to check the strength of your bones.
Is it good to take vitamin D every day?
If you receive a diagnosis of vitamin D deficiency, a healthcare professional will likely recommend that you take vitamin D supplements. If you have a severe deficiency, they may instead recommend high dose vitamin D tablets or liquids.
You should also make sure to get vitamin D through sunlight and the foods you eat.
Risks of getting too much vitamin D
If you take excessive amounts of vitamin D supplements, you may get too much of it. However, this is unlikely to happen through diet or sun exposure because your body regulates the amount of vitamin D produced through sun exposure.
Vitamin D toxicity can lead to an increase in your blood calcium levels. This can result in a variety of health issues, such as:
frequent urination
apathy
vomiting
abdominal pain
dehydration
confusion
increased thirst
What food is highest in vitamin D?
Some foods contain vitamin D naturally, and others are fortified with it. You can find vitamin D
in the following foods:
sardines
herring
canned tuna
cod liver oil
beef liver
egg yolk
regular mushrooms and those treated with ultraviolet light
milk (fortified)
certain cereals and oatmeals (fortified)
yogurt (fortified)
orange juice (fortified)
It can be hard to get enough vitamin D each day through sun exposure and food alone, so taking vitamin D supplements could help.
How much do you need?
There has been some debate over the amount of vitamin D required for optimal functioning. Recent studies indicate that we need more vitamin D than previously thought.
Some of the main controversies surrounding vitamin D
are:
standardization of methods for measuring vitamin D levels
the difference between free and total vitamin D testing
defining low vitamin D status (insufficiency versus deficiency)
screening versus treatment
vitamin D threshold for the general population relative to a particular condition (such as pregnancy or nursing) and health issues (such as kidney failure or osteoporosis)
Blood serum levels considered adequate range from 50–100 nanomoles per liter (nmol/L). Depending on your blood level, you may need more vitamin D.
The Recommended Dietary Allowances for vitamin D are as follows:
infants (0–12 months): 10 micrograms (mcg) or 400 international units (IU)Trusted Source
children and teens: 15 mcg (600 IU)
adults ages 18–70: 15 mcg (600 IU)
adults over age 70: 20 mcg (800 IU)
pregnant people or those who are breastfeeding to chestfeeding: 15 mcg (600 IU)
Frequently asked questions
What does vitamin D help with the most?
Vitamin D mainly helps the body absorb and retain calcium and phosphorus, which are crucial for maintaining strong bones. This means it’s really important for bone health.
How can I raise my vitamin D level quickly?
To increase your vitamin D levels, you can spend more time in the sun, take a supplement, and include certain foods in your diet. If you spend more time outdoors, make sure to use sunscreen.
Just one thing
Try this today: Add fish to your diet a couple of times per week to help boost your vitamin D intake. Try salmon in a mustard sauce, grilled sardines, or canned tuna on a salad to create different meal options.
The bottom line
Vitamin D has many potential benefits. It may reduce the risk of certain diseases, help improve mood reduce depression symptoms, and help with weight management.
It’s hard to get enough vitamin D through your diet alone, so you may want to ask a healthcare professional for a blood test and consider taking a vitamin D supplement.
25-Hydroxy Vitamin D Test
Doctors use the 25-hydroxy vitamin D test to monitor your vitamin D levels. Low levels can mean you need to spend more time outdoors or adjust your diet. But it can also occur with certain medical conditions.
Vitamin D helps your body absorb calcium and maintain strong bones throughout your entire life. Your body produces vitamin D when the sun’s UV rays contact your skin. Other good sources of the vitamin include fish, eggs, and fortified dairy products. It’s also available as a dietary supplement.
Vitamin D must go through several processes in your body before your body can use it. The first transformation occurs in the liver. Here, your body converts vitamin D to a chemical known as 25-hydroxyvitamin D, also called calcidiol.
The 25-hydroxy vitamin D test is the best way to monitor vitamin D levels. The amount of 25-hydroxyvitamin D in your blood is a good indication of how much vitamin D your body has. The test can determine if your vitamin D levels are too high or too low.
The test is also known as the 25-OH vitamin D test and the calcidiol 25-hydroxycholecalcifoerol test. It can be an important indicator of osteoporosis (bone weakness) and rickets (bone malformation).
Why is a 25-hydroxy vitamin D test done?
Your doctor may request a 25-hydroxy vitamin D test for several different reasons. It can help them figure out whether too much or too little vitamin D is causing bone weakness or other abnormalities. It can also monitor people who are at risk for having a vitamin D deficiency.
Those who are at high risk of having low levels of vitamin D include:
people who don’t get much exposure to the sun
older adults
people with obesity
babies who are breastfed only (formula is usually fortified with vitamin D)
people who have had gastric bypass surgery
people who have a disease that affects the intestines and makes it difficult for the body to absorb nutrients, such as Crohn’s disease
Your doctor may also want you to do a 25-hydroxy vitamin D test if they’ve already diagnosed you with a vitamin D deficiency and want to see if treatment is working.
How is the 25-hydroxy vitamin D test performed?
Your doctor will tell you not to eat anything for four to eight hours before the test.
The 25-hydroxy vitamin D test requires a common blood test. Your healthcare provider will draw blood from a vein in your arm using a needle. A quick finger prick will more than likely provide enough for a blood sample in children and infants.
Evaluating the results of a 25-hydroxy vitamin D test
Results will depend on your age, sex, and the testing methods used. Results can also slightly vary from lab to lab.
According to the Office of Dietary Supplements (ODS), levels of vitamin D are measured by the 25-hydroxy level in nanomoles/liter (nmol/L) or nanograms/milliliter (ng/mL). The results can indicate the following:
deficiency: less than 30 nmol/L (12 ng/mL)
potential deficiency: between 30 nmol/L (12 ng/mL) and 50 nmol/L (20 ng/mL)
normal levels: between 50 nmol/L (20 ng/mL) and 125 nmol/L (50 ng/mL)
high levels: higher than 125 nmol/L (50 ng/mL)
If your vitamin D levels are low and you’re having symptoms of bone pain, a doctor may recommend a special scan to check bone density.
Doctors use this painless scan to evaluate a person’s bone health.
Low blood levels of 25-hydroxy vitamin D usually mean one (or more) of the following:
you aren’t eating a balanced, complete diet
your intestines aren’t absorbing the vitamin properly
you’re not spending enough time outside to absorb adequate vitamin D levels through sun exposure
Some evidence links vitamin D deficiency to a higher risk of certain cancers, immune diseases, and cardiovascular disease.
High vitamin D blood levels generally result from taking too many vitamin pills and other nutritional supplements. High doses of vitamin D can result in a condition called hypervitaminosis D. Hypervitaminosis is a rare but serious condition that could put you at risk for liver or kidney problems.
High levels are rarely due to consuming too much of the vitamin through foods or sun exposure.
Your doctor will help explain the results of your test and determine if you have a vitamin D deficiency.
Risks of a 25-hydroxy vitamin D test
As with any routine blood test, risks of the 25-hydroxy vitamin test are minimal and include:
excessive bleeding
lightheadedness
a slight chance of infection where the needle pierces your skin
Outlook
Vitamin D is vital to the body. Deficiencies at any age can cause problems.
Your doctor may recommend supplements or other treatment options if you’re very deficient. Eating foods that contain vitamin D in addition to adding supplements to your regimen can help keep your vitamin D levels stable.
