The difference between vitamin D2 and D3 and which one you should choose as a supplement

 

• The difference between vitamin D2 and vitamin D3 is that whereas animals produce vitamin D3, plants produce vitamin D2.
• When choosing a supplement, opt for vitamin D3 since it is better absorbed by your body.
• Vitamin D can boost your immune system, help your body absorb calcium, and may even help prevent cancer.

This article was medically reviewed by Julia Blank, MD, family medicine physician at Providence Saint John's Health Center in Santa Monica, California.

You may know vitamin D as an essential nutrient that helps you absorb calcium and keep bones strong, but vitamin D is actually a category that includes several different chemical compounds. The most common vitamin D compounds are vitamin D2 and vitamin D3, which come from different natural sources.

Doctors generally prescribe vitamin D2 supplements if you have a vitamin D deficiency, but some experts say that vitamin D3 is easier for your body to absorb and may work better to boost your health. Here's what you need to know about the differences between vitamin D2 and D3.

What is vitamin D?

Vitamin D is not actually a vitamin, but a hormone that affects many of your body's important functions.

It "is essential for good health," says Susan Lanham-New, a professor of human nutrition at the University of Surrey. 

About 10% of your vitamin D comes from the foods you eat in the form of D2, while 90% is produced within your own body as D3. 

Benefits of vitamin D

Both D2 and D3 offer the same important health benefits.  

Helps absorb calcium: Your kidneys convert vitamin D to its active form, which plays an important role in regulating calcium levels in your blood. Vitamin D helps your body absorb calcium and phosphorus — which are both necessary minerals for building healthy bones and reducing the risk of osteoporosis (decreased bone density) later in life.

Boosts immune system: Vitamin D is also important for your immune system's functioning – people with insufficient vitamin D have a harder time fighting infections and may be more likely to suffer from autoimmune disorders.

May help prevent cancer: Some studies have linked higher vitamin D levels to a lower risk of colorectal cancer. However, more research is needed to see how vitamin D affects cancer risk.

Vitamin D2 vs. D3

Both humans and plants produce vitamin D when they are exposed to sunlight. But while animals produce vitamin D3, plants produce vitamin D2.  

When deciding whether to take vitamin D2 or D3 as a supplement, Lanham-New says that it is always best to choose vitamin D3. "It is more effective in raising vitamin D levels in the blood," Lanham-New says.  

This is because your body breaks down vitamin D2 more quickly, so it does not remain in the body for as long.  

A small 2011 study published in the Journal of Clinical Endocrinology & Metabolism found that vitamin D3 was 87% more potent in raising vitamin D levels in the blood of 33 healthy adults, compared with D2. Vitamin D3 was also stored more effectively in the body's fat cells.  

Another small study in 2015 published in the European Journal of Clinical Nutrition found that while vitamin D2 and D3 were both effective in boosting vitamin D levels, people who took vitamin D3 kept up higher blood levels of vitamin D 77 days after stopping the supplements.  

Sources of Vitamin D2 and D3

Though most of our vitamin D comes from the sun, we can also get some vitamin D through our diets. "There are relatively few dietary sources of vitamin D3," says Lanham-New, but you can find vitamin D3 in certain foods, including:  

Fish – particularly trout, salmon, sardines, and cod liver oil

Egg yolk

Beef liver

Vitamin D2 can be found in:

Mushrooms like portabella and shitake, particularly mushrooms that have been exposed to high levels of UV radiation

Foods that are fortified with vitamin D such as milk and fortified cereals

The bottom line

You are unlikely to get enough vitamin D from your diet alone and it isn't always possible to get regular sunlight. If you want to take a supplement to boost your vitamin D levels, vitamin D3 may be a better choice, as it can have a stronger and longer-lasting effect on your vitamin D levels. Though you need to be careful not to overdo, as too much Vitamin D supplementation can result in vitamin D toxicity, which can lead to nausea and vomiting, kidney problems, depression, and calcium buildup in blood vessels and vital organs.  

"Everyone should be taking vitamin D during the winter," Lanham-New says, adding that a daily maintenance dose should be about 600 IU. This is particularly important for people "who are most at risk of vitamin D deficiency such as the elderly, ethnic groups with darker skin, pregnant and lactating women."