Vitamin D is one of many vital nutrients your body needs to stay healthy. It helps with calcium absorption and bone health. Without enough vitamin D, you may be at risk for bone loss and deformations. Other benefits of vitamin D include inflammation regulation, immune system support, muscle function, and glucose metabolism.

Most people can get enough vitamin D through sun exposure, diet, or supplements. However, some people may be at a higher risk for vitamin D deficiency.

1. Get Safe Sun Exposure

Sun exposure can help most people boost their vitamin D levels.

Your body makes vitamin D when cells in your skin come into contact with ultraviolet rays from the sun. After sun exposure, these cells begin a process that results in active vitamin D in the form of cholecalciferol, or vitamin D3.

Studies estimate sun exposure can provide about 80% of your vitamin D needs. However, some people may not get as much vitamin D from the sun as others.

For example, people with darker skin tones make less vitamin D from the sun’s ultraviolet rays due to higher levels of melanin in their skin. Those living in regions with less sunlight or climates that require skin covering may also struggle to get vitamin D through sun exposure.

Sunscreen is only thought to reduce vitamin D production minimally.

2. Eat Fish and Seafood

Various types of fish and seafood are some of the best food sources of vitamin D.

Fish are believed to get vitamin D from the food chain, which starts with plankton. Phytoplankton and zooplankton are organisms that float near the surface of water and absorb UV rays from the sun, increasing their vitamin D content.

Oily fish and seafood are exceptionally high in vitamin D.

The vitamin D content of a 3-ounce serving of the following fish is:

• Rainbow trout: 645 international units (IU)
• Salmon: 383 to 570 IU
• Canned tuna: 231 IU
• Herring: 182 IU
• Canned sardines: 164 IU
• Tilapia: 127 IU
• Flounder: 118 IU

3. Try Fortified Foods

Some foods may be fortified with vitamin D and other nutrients to enhance their nutritional value.

Cow’s milk, breakfast cereals, and margarine were first fortified with vitamin D in the 1930s to reduce the risk of rickets (a bone disease that may occur due to a vitamin D deficiency).

Vitamin D is most commonly added to dairy products like milk and yogurt. However, other foods and beverages may also be fortified with it.

4. Consider Fortified Dairy-Free Options

You may obtain vitamin D from fortified nondairy foods if dairy is not in your diet.

To increase nutrient density, beverages like orange juice, soy milk, almond milk, and rice milk are often fortified with vitamin D. Many breakfast cereals also contain vitamin D.

You may find other dairy-free foods and drinks fortified with vitamin D. If vitamin D is present, the food’s nutrition label will indicate it.

5. Add Mushrooms to Your Regimen

Mushrooms are a unique, natural source of vitamin D that can fit into a plant-based diet.

When exposed to the sun, mushrooms can synthesize vitamin D in the form of vitamin D2 (ergocalciferol). Mushrooms and other fungi can make vitamin D from the sun due to ergosterol, a cholesterol-like substance found in cell walls.

Because they are grown in labs, button mushrooms often found in retail stores typically contain less vitamin D than wild mushrooms. Dried mushrooms are another option because the drying process preserves vitamin D content. Research also shows that the vitamin D2 found in mushrooms is as bioavailable as vitamin D2 found in supplements.

6. Optimize Your Absorption

You may optimize vitamin D absorption either through sunlight exposure or food.

Experts recommend going outside for five to 30 minutes without sunscreen between 10 a.m. and 4 p.m. to enhance vitamin D synthesis from sun exposure.

Otherwise, eating certain foods may help increase vitamin D absorption, including:

• Healthy fats: Vitamin D is a fat-soluble vitamin, which means it dissolves in fat. Therefore, consuming vitamin D alongside healthy fats is thought to optimize absorption. In one study, adults who took a vitamin D supplement with a fat-containing meal had a 32% higher absorption rate than adults who took vitamin D with a fat-free meal.
• Zinc: Zinc and vitamin D have a relationship in which one helps regulate the other. Research shows that zinc supplementation may increase vitamin D levels, which may help reduce the risk of vitamin D deficiency. Studies have also found that zinc plays a role in activating vitamin D.
• Magnesium: Research has found that magnesium supplements may increase vitamin D absorption. In one study of adults, a supplement that contained both magnesium and vitamin D increased vitamin D levels better than a vitamin D supplement alone. These effects may be due to magnesium’s important role in vitamin D metabolism.
• Vitamin K: Vitamin K is a fat-soluble vitamin that has an important relationship with vitamin D. Though vitamin K may not increase vitamin D absorption, research shows that vitamin K may help vitamin D work properly when absorbed. Specifically, vitamins K and D work together to maintain bone and heart health.

7. Consider a Vitamin D Supplement

Some people may benefit from taking a vitamin D supplement to meet their health needs, such as the following:

• Supplement forms: Dietary supplements may contain vitamin D in either D2 or D3 form. Both forms have been found to help increase vitamin D levels in the blood. However, some research indicates that vitamin D3 may be more effective at correcting a deficiency than vitamin D2.
• Cod liver oil: You may also consider cod liver oil. Cod liver oil contains both omega-3 fatty acids and vitamin D3. There are 400 IU of vitamin D in 5 milliliters (mL) of cod liver oil.
• Recommended Dietary Allowance (RDA): Adults over 19 need 600 IU of vitamin D daily. However, those 70 years and older need 800 IU of vitamin D daily to reduce the risk of age-related bone loss.
• Precautions: Vitamin D supplements are considered safe for most people, but some people may need to take precautions. People who are pregnant or breastfeeding or those with kidney disease, thyroid disease, or high blood calcium (hypercalcemia) levels may need to avoid vitamin D supplements. You should also avoid vitamin D supplements if you are allergic to any of their ingredients.

Vegan Options

There are various vegan options for vitamin D supplements. Supplements may contain vitamin D2 or vitamin D3, the former of which typically comes from plant-based sources.

Vitamin D2 often comes from mushrooms and other types of fungi or yeasts. On the other hand, vitamin D3 typically comes from animal sources. However, some supplements may contain plant-based vitamin D3 made from lichen, a type of algae.

When looking for vegan supplements, check the product label. Any vegan vitamin D supplement should be appropriately marked on the label.

Can You Get Too Much Vitamin D? (Toxicity Risks)

Getting too much vitamin D is possible and may lead to toxicity.

Vitamin D toxicity (hypervitaminosis D) may occur if you take very high doses of vitamin D.

Though most adults need 600 IU of vitamin D daily, taking vitamin D in doses as high as 2,000 IU per day is believed to be safe. Toxicity may occur if you take 10,000 IU of vitamin D or more.

Symptoms of too much vitamin D may include:

• Constipation
• Low appetite
• Dehydration
• Fatigue and muscle weakness
• Irritability
• Vomiting

Too much vitamin D may also lead to high blood calcium levels (hypercalcemia), a serious condition marked by:

• Bone pain
• Digestive symptoms
• Increased thirst and urination
• Muscle twitches

To avoid vitamin D toxicity, take supplements only as directed and never exceed a recommended dose.

Symptoms of Vitamin D Deficiency

Vitamin D deficiency may occur if you aren’t getting enough vitamin D from your diet or sun exposure. Some people may also become deficient in vitamin D due to poor absorption.

Without enough vitamin D, your body may not be able to absorb enough calcium to keep your bones healthy. Other critical bodily functions in your muscles, nervous system, and immune system may also be compromised if you don’t get enough vitamin D.

Vitamin D deficiency symptoms may include:

• Bone deformities
• Bone pain
• Seizures
• Muscle spasms
• Dental abnormalities

Vitamin D deficiency may lead to rickets in children and osteomalacia in adults. These conditions can cause bone loss and deformities.

To reduce the risk of vitamin D deficiency, eat foods rich in vitamin D and get plenty of safe sun exposure.

Summary

Vitamin D is an essential, fat-soluble vitamin that plays many vital roles in your body. Without enough vitamin D, you may be at risk for bone loss and calcium deficiency. Most people can increase their vitamin D status by eating vitamin D-rich foods, getting safe sun exposure, and optimizing absorption. For some people, a vitamin D supplement may be necessary.

Talk with your healthcare provider to learn more about how to take vitamin D supplements safely.