Vitamin D is essential for immune system function and bone health. It may also influence mood regulation and reduce the risk of several chronic health conditions, but more research is needed to better understand these links.
Vitamin D is a fat-soluble vitamin that has two primary forms: vitamin D2 (ergocalciferol), found in plants, and vitamin D3 (cholecalciferol), found in animal tissues. The body produces vitamin D when exposed to sunlight, but it may also be acquired through foods and supplements.
In the United States, the Food and Drug Administration (FDA) does not regulate supplements the way it regulates prescription drugs. That means some supplement products may not contain what the label says. When choosing a supplement, look for independently tested products and consult a healthcare provider, registered dietitian nutritionist (RD or RDN), or pharmacist.
Benefits
Vitamin D has several important functions in the body, including:
- Bone and teeth health: Vitamin D helps the body retain and absorb calcium and phosphorus, which are important for building and maintaining healthy bones and teeth. Vitamin D deficiency may lead to decreased bone density, which can cause osteoporosis and broken bones.
- Nerve function: Nerves need vitamin D to carry messages between the brain and other parts of the body.
- Immune health: The body’s immune system needs vitamin D to fight off viruses.
- Mood regulation: Studies have shown that vitamin D may affect a person’s mental health by reducing negative emotions. Researchers have found that individuals with major depressive disorder and vitamin D deficiency are most likely to benefit from supplementation.
- Disease prevention: While more research is needed, several studies link vitamin D deficiency to several health conditions, including diabetes, some types of cancer, hypertension (high blood pressure), and multiple sclerosis.
- Weight management: Some studies have found a link between obesity and low levels of vitamin D. However, more research is needed to clarify what role the nutrient plays in weight.
Does Vitamin D Give You Energy?
Vitamin D deficiency can cause tiredness. Studies have shown that vitamin D supplementation may improve fatigue in otherwise healthy individuals with a vitamin D deficiency.
Vitamin D Sources
Your body makes vitamin D when it’s exposed directly to sunlight. However, prolonged sun exposure is advised against because it can increase your risk of other ailments, such as premature aging and skin cancer. Additionally, most people get less vitamin D during the winter months because of insufficient exposure to sunlight.
This makes it necessary to get vitamin D from other sources. Dietary sources of vitamin D include:
- Fatty fish, such as tuna, salmon, and mackerel
- Mushrooms
- Egg yolks
- Beef liver
- Cheese
- Fortified dairy products
- Fortified breakfast cereals and orange juice
Signs of Low Vitamin D
Vitamin D deficiency is relatively common in the United States and many people with it have no symptoms. However, signs of low vitamin D may include the following:
- Muscle pain
- Muscle weakness
- Dental problems
- Fatigue
- Bone pain
- Depression
- Cognitive impairment
Risk Factors of Developing Vitamin D Deficiency
Someone may have a greater risk of developing vitamin D deficiency if they take medications that interfere with vitamin D metabolism or if they have the following conditions:
- A history of gastric bypass surgery (a type of weight-loss surgery)
- Celiac disease (an immune reaction to the protein gluten found in wheat, barley, and rye)
- Osteoporosis (reduced bone mineral density causing weak and brittle bones)
- Chronic kidney or liver disease
- Crohn’s disease (an inflammatory bowel disease causing chronic inflammation of the digestive tract)
- Sarcoidosis (an autoimmune disease that causes collections of inflammatory tissue in parts of the body)
- Histoplasmosis (an infection caused by breathing in fungal spores)
- Tuberculosis (an infectious lung disease mainly caused by a bacterium)
- Hyperparathyroidism (a condition where the parathyroid glands release too much hormone, raising calcium levels)
How Much Vitamin D Do You Need?
Vitamin D intake is measured in international units (IU) and micrograms (mcg). The amount of the nutrient you need depends on your age and other health factors.
The daily vitamin D requirements are as follows:
| Life Stage | Daily Recommended Amount |
|---|---|
| Birth to 12 months | 400 IU (10 mcg) |
| Children 1–18 years old | 600 IU (15 mcg) |
| Adults age 19–70 | 600 IU (15 mcg) |
| Adults over age 70 | 800 IU (20 mcg) |
| Pregnant and breastfeeding people | 600 IU (15 mcg) |
Vitamin D Supplements
Your healthcare provider can order a blood test to measure the level of vitamin D in your blood. If your levels are low, your provider will likely recommend you take a vitamin D supplement to correct the deficiency.
When selecting a vitamin D supplement, you may want to choose D3 over D2. Both are easily absorbed by the body, but research suggests that vitamin D3 increases blood levels of the nutrient more and keeps those levels elevated longer than vitamin D2.
You should take a vitamin D supplement as directed by your healthcare provider, likely every day or week, based on the formulation. Because vitamin D is a fat-soluble vitamin, it is best taken with meals or snacks containing fat, so the body can better absorb the nutrient.
Side Effects of High Vitamin D Levels
Vitamin D toxicity is unlikely to occur from diet or excess sun exposure since your body can control the amount of vitamin D it makes from the sun. In most cases, toxicity occurs due to the overuse of vitamin D supplements.
The main side effect of vitamin D toxicity is a condition called hypercalcemia, in which too much calcium builds up in the blood, causing symptoms like:
- Nausea, vomiting
- Confusion
- Muscle weakness
- Decreased appetite
- Generalized pain
- Excessive thirst and urination
- Dehydration
- Kidney stones
Extremely high vitamin D levels can cause more serious side effects, including irregular heartbeat, kidney failure, and death.
Interactions
Some medications may interact with vitamin D supplements, decreasing their effectiveness or causing side effects. If you take any medications, check with your healthcare provider before taking a vitamin D supplement.
Drugs that vitamin D supplements interact with include:
- Orlistat (Xenical, Alli): These weight-loss drugs may reduce the absorption of vitamin D.
- Statins: High-dose vitamin D supplements may decrease the effectiveness of cholesterol-lowering drugs like atorvastatin (Lipitor), lovastatin (Altoprev and Mevacor), and simvastatin (FloLipid and Zocor).
- Corticosteroids: Drugs like prednisone (Deltasone, Rayos, and Sterapred) may decrease levels of vitamin D in the blood.
- Diuretics: When taken with a vitamin D supplement, thiazide diuretics (like Hygroton, Lozol, and Microzide) can cause dangerously high levels of calcium in the blood.
People with hyperparathyroidism, kidney disease, or hypercalcemia (high blood calcium) should also speak with their healthcare provider before taking a vitamin D supplement.
Summary
Vitamin D is involved in many bodily functions and plays a vital role in immune health and maintaining healthy bones and teeth. It may also help improve mood and protect against certain diseases.
Vitamin D is found in some foods, such as fatty fish and fortified dairy products. The potential benefits of vitamin D supplementation are more significant in people with a confirmed deficiency of the nutrient. You can increase your vitamin D intake by spending a safe amount of time in the sun, eating a balanced diet, and taking supplements.
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