June 13, 2024

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Vitamin D3: Health Benefits and Supplementation

8 min read

Vitamin D3 (cholecalciferol) has a few health benefits, including helping the body absorb calcium. Fish, beef liver, eggs, and cheese naturally contain vitamin D3. It can also be produced in the skin following exposure to ultraviolet (UV) radiation from the sun.

Supplement forms of vitamin D3 are also available and may be used for general health, as well as the treatment or prevention of vitamin D deficiency.

Vitamin D3 is one of two types of vitamin D. It differs from vitamin D2 (ergocalciferol) in both its structure and sources.

The article explains what vitamin D supplements do and the benefits and drawbacks of vitamin D3 specifically. It also lists other essential sources of vitamin D3.

Olga Shumitskaya / Getty Images

Why You Need Vitamin D

Vitamin D, also called calciferol, is a fat-soluble vitamin (which is broken down by fat and oils in the gut). It is commonly referred to as the “sunshine vitamin” because the D3 type can be naturally produced in the body following exposure to the sun.

Vitamin D has many functions in the body, chief of which include:

Not getting enough vitamin D can lead to an array of health concerns, including:

How Much Vitamin D Do I Need?

Current guidelines from the National Institutes of Health recommend that people ages 1 to 70 get 600 international units (IUs) of vitamin D daily from all sources. Adults over 70 need 800 IUs daily.

How Do I Know If I Need More Vitamin D?

If you do not obtain enough vitamin D to meet the body’s needs, you are considered to have a vitamin D deficiency. This can be diagnosed through blood testing.

However, the U.S. Preventive Services Task Force does not recommend routine vitamin D screening in adults without symptoms of deficiency.

Not everyone low in vitamin D experiences symptoms. Those who do may notice:

  • Muscle and/or bone pain
  • Muscle weakness
  • History of fractures
  • Muscle twitching

If you suspect you could be vitamin D deficient, ask your healthcare provider to test your blood levels or take an at-home test.

Causes for vitamin D deficiency are many, including diseases or conditions that limit fat absorption and the breakdown of vitamin D in the gut. As such, you are at greater risk for vitamin D deficiency if you have:

Older people who are housebound or have dark skin are also more vulnerable to vitamin D deficiency.

Vitamin D deficiency affects almost 50% of the population worldwide. Both vitamin D2 and D3 can be used to treat this, with vitamin D3 generally being the preferred choice.

There are some at-home tests that can measure the amount of vitamin D in your blood. All you need to do is place a drop of blood on a test strip and mail it to the test’s manufacturer or designated lab for processing.

Vitamin D3 vs. Vitamin D2

Vitamin D2 and vitamin D3 are chemically similar and are both well-absorbed in the gut. Where they differ significantly is in their sources:

  • Vitamin D2 is naturally found in mushrooms, including shiitake, Portobello, and crimini mushrooms. The vitamin D content increases when these mushrooms are exposed to UV radiation.
  • Vitamin D3 is naturally found in animals and animal-derived products like milk. It is also directly synthesized in the skin when it is exposed to ultraviolet B (UVB) radiation.

Aside from the fact that vitamin D3 is likely easier to consume in your day-to-day diet, unless you are a vegetarian or vegan, vitamin D3 has proven superior to vitamin D2 in two other important ways:

  • Vitamin D3 has better bioavailability, meaning more of the vitamin enters the bloodstream and can be used by the body
  • Vitamin D3 has a better half-life, meaning it stays in circulation for longer

On the downside, vitamin D3 in supplements has historically been synthesized using lanolin derived from sheep’s wool. This makes it unsuitable for those who choose to avoid animal-based products.

With that said, some manufacturers have been able to synthesize vitamin D3 from algae and lichen.

A lack of vitamin D can cause you to feel lethargic. Supplementing with D3 could, over time, help you feel more energetic, but only if you have a deficiency.

Vitamin D3 For Those Without Deficiency

Beyond its use in treating vitamin D deficiency, vitamin D3 may offer health benefits to certain people without such deficiency—in particular, those with high blood pressure or osteoporosis.


Hypertension, more commonly known as high blood pressure, is cardiovascular disease commonly seen in people with vitamin D deficiency.

Recent studies suggest that vitamin D3 may help lower blood pressure in people with hypertension and vitamin D deficiency as well as certain groups of people with hypertension only.

According to a 2019 review of studies in the journal Medicine involving 1,687 people, vitamin D3 was able to significantly reduce systolic (“top number”) blood pressure in people over the age of 50 and those with obesity.

This is important because isolated systolic hypertension can increase the risk of stroke, heart disease, and chronic kidney disease over time.


Osteoporosis is a frequent consequence of long-term vitamin D deficiency, so common wisdom would suggest that vitamin D supplements may help prevent or slow the progression of this common, aging-related bone disease. There is some evidence to support this claim.

Researchers found that giving Vitamin D3 supplements in addition to calcium supplements can reduce the incidence of hip fractures and non-vertebral fractures in older people.

Unproven Benefits

Despite claims to the contrary, there is no evidence that vitamin D3 supplements can reduce the risk of cancer, coronary heart disease, or stroke. With that said, the supplements pose little, if any, harm if taken at the prescribed dose.

Sources of Vitamin D3

Whether you are nutritionally deficient or simply want to meet your recommended daily allowance (RDA) of vitamin D, you can obtain ample supplies of vitamin D3 from animal-based foods, dietary supplements, and sun exposure.

Dietary Sources

Food should always be the first source of vitamin D. Here are some of the best dietary sources of vitamin D3 to bolster your intake:

Food IU Serving size % RDA
Beef liver 42 3 ounce 5%
Butter 9 1 tablespoon 1%
Cereal 80 1-1/2 ounce 10%
Cheese 12 1 ounce 2%
Cod liver oil 1,360 1 tablespoon 170%
Egg yolks 44 1 yolk 6%
Fresh salmon 570 3 ounce 71%
Halibut 384 1/2 fillet 48%
Mackerel 360 1/2 fillet 45%
Milk, fortified 120 1 cup 15%
Sardines 46 2 fish 6%
Trout 645 3 ounce 81%
Tuna 40 3 ounce 5%

Some manufacturers of fruit juices, dairy products, margarine, and plant-based milk add vitamin D3 to boost their product’s nutritional value, as well.


As convenient as they are, supplements should never be your primary source of vitamin D (or any nutrient, for that matter). They are only intended when you are not getting enough from your diet.

Vitamin D3 is readily available in supplement form and sold as capsules, softgels, gummies, and liquid drops. Most are formulated in doses higher than you need per day—between 2,000 and 10,000 IUs—but this is not a concern as only a portion will be absorbed. The rest will be passed in urine.

Talk to your healthcare provider about the best dose based on age and medical history.

Vitamin D3 is a fat-soluble vitamin. This means that taking it with fat helps it absorb better. It doesn’t matter what time of day you take it, but you should eat fat-containing food when you do.

Sun Exposure

Vitamin D3 is unique in that (unlike vitamin D2) you can get it from the sun.

When exposed to UVB light, an organic compound in the skin called 7-dehydrocholesterol activates and starts churning out vitamin D3. The rate of production can vary by age and skin tone, with older people and those with darker skin getting the least benefit.

Sunscreen can also decrease production by blocking both UV rays.

Getting sunlight daily can help you maintain your vitamin D levels, but it’s not the safest or most reliable way to get it, given the risk of skin cancer.

Possible Risks

Vitamin D3 is generally considered safe, but it can occasionally cause toxic effects if you take too much. This is referred to as hypervitaminosis D.

With vitamin D toxicity, the balance of minerals like calcium and potassium is upset. This can lead to a condition known as hypercalcemia, in which too much calcium builds up in the body. This can lead to symptoms like:

  • Stomach upset
  • Nausea
  • Vomiting
  • Constipation
  • Bone pain
  • Muscle weakness
  • An increased risk of bone fractures

People with hyperparathyroidism, kidney disease, or hypercalcemia (high blood calcium) should typically avoid vitamin D3 supplements. Certain medications can also interact with vitamin D. Speak with your healthcare provider or pharmacist before starting any supplement. 

Vitamin D toxicity was common in the 1940s when daily doses of 200,000 to 300,000 IUs per day were commonly recommended to treat chronic illnesses like tuberculosis and rheumatoid arthritis. Today, vitamin D toxicity is considered a rare occurrence.

Recent studies have shown that vitamin D3 doses of 20,000 IUs per day are tolerable in adults with no signs of toxicity.


Vitamin D helps you absorb calcium and phosphate from food. It is important for bone and muscle strength and immune function, and it may also help prevent inflammatory disease.

There are two types; vitamin D3 is more efficient in terms of how it can be used in the body than vitamin D2. You can get vitamin D from food or supplements, and your body can make D3 when exposed to sunshine.

Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. National Institutes of Health Office of Dietary Supplements. Vitamin D: fact sheet for health professionals.

  2. US Preventive Services Task Force, et al. Screening for vitamin D deficiency in adults: US Preventive Services Task Force recommendation statement. JAMA. 2021;325(14):1436-1442doi:10.1001/jama.2021.3069

  3. Yale Medicine. Vitamin D Deficiency.

  4. Cui A, Zhang T, Xiao P, Fan Z, Wang H, Zhuang Y. Global and regional prevalence of vitamin D deficiency in population-based studies from 2000 to 2022: A pooled analysis of 7.9 million participants. Front Nutr. 2023;10:1070808. doi:10.3389/fnut.2023.1070808

  5. Tripkovic L, Lambert H, Hart K, et al. Comparison of vitamin D2 and vitamin D3 supplementation in raising serum 25-hydroxyvitamin D status: a systematic review and meta-analysis. Am J Clin Nutr. 2012 Jun;95(6):1357–64. doi:10.3945/ajcn.111.031070

  6. McCullough PJ, McCullough WP, Lehrer D, Travers JB, Repas SJ. Oral and topical vitamin d, sunshine, and uvb phototherapy safely control psoriasis in patients with normal pretreatment serum 25-hydroxyvitamin d concentrations: a literature review and discussion of health implications. Nutrients. 2021;13(5):1511. doi:10.3390/nu13051511

  7. Nowak A, Boesch L, Andres E, et al. Effect of vitamin D3 on self-perceived fatigue: A double-blind randomized placebo-controlled trial. Medicine (Baltimore). 2016;95(52):e5353. doi:10.1097/MD.0000000000005353

  8. He S, Hao X. The effect of vitamin D3 on blood pressure in people with vitamin D deficiency: a system review and meta-analysis. Medicine (Baltimore). 2019 May;98(19):e15284. doi:10.1097/MD.0000000000015284

  9. Manoj P, Derwin R, George S. What is the impact of daily oral supplementation of vitamin D3 (Cholecalciferol) plus calcium on the incidence of hip fracture in older people? A systematic review and meta-analysis. Int J Older People Nurs. 2023;18(1):e12492. doi:10.1111/opn.12492

  10. Zhang R, Zhang Y, Liu Z, et al. Association between vitamin D supplementation and cancer mortality: a systematic review and meta-analysis. Cancers (Basel). 2022;14(15):3717. doi:10.3390/cancers14153717

  11. National Institutes of health Office of Dietary Supplements. Vitamin D.

  12. Marcinowska-Suchowierska E, Kupisz-Urbańska M, Łukaszkiewicz J, Płudowsk P, Jones G. Vitamin D toxicity–a clinical perspective. Front Endocrinol (Lausanne). 2018;9:550. doi:10.3389/fendo.2018.00550

Additional Reading

  • National Institutes of Health, Office of Dietary Supplements. Vitamin D fact sheet for consumers.

Yvelette Stines

By Yvelette Stines

Stines is a Michigan-based health writer, book author, and communications specialist.


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