Vitamin D Vs. D3: What’s the Difference? Dietitians Explain

Vitamin D is the all encompassing name for a family of similar chemical components needed in the human body, said Courtney Pelitera, M.S., R.D.N., C.N.S.C., registered dietitian and owner of Devour Your Life Nutrition Coaching. The two most common forms of vitamin D that you will see on supplement shelves are vitamin D2 and vitamin D3 (though some products will just say vitamin D).

Vitamin D is a fat-soluble vitamin which plays a major role in bone health, immunity, and nerve communication between the brain and muscle cells, explained Pelitera. “It is essential for calcium absorption as well, and in this way, it helps to prevent bone diseases such as osteoporosis,” she noted. Along with calcium, vitamin D also helps our bodies absorb magnesium and phosphate, added Melissa Mroz-Planells, D.C.N., R.D.N., national media spokesperson for the Academy of Nutrition and Dietetics.

Boosting your vitamin D intake has been shown to produce significant health benefits, like reducing your risk of heart attack and helping to prevent the development of type 2 diabetes.

Vitamin D3, also called cholecalciferol, is what gives the “sunshine” vitamin its name. D3 is produced in our body from exposure to sunlight, Mroz-Planells explained. It is also found in animal-based foods such as butter, oily fish, egg yolks, and liver. Vitamin D3 is an inactive form of vitamin D, meaning the body needs to convert it into calcitriol, which is the form of vitamin D that the body can then use.

What about vitamin D2?

Vitamin D2, also called ergocalciferol, is another inactive form of vitamin D. It can be found in both food and supplements, said Mroz-Planells. She notes that this form is found in plant foods like mushrooms, yeast, and fortified foods.

If you’ve determined that you need to supplement with vitamin D, you’ll be choosing between D2 and D3—even if the label says vitamin D on the front, the ingredient list will say either D2 or D3. Here is some important information to know about each.

Uses

Both vitamin D2 and vitamin D3 will help to increase vitamin D levels in the blood, said Pelitera. However, some studies have shown that supplementing with vitamin D3 does a little bit better of a job at increasing levels.

Dosage

According to the National Institutes of Health (NIH), the recommended intake of vitamin D for healthy adults is 600 to 800 IU. This intake can be achieved by consuming either vitamin D2 or D3, from any combination of food sources, sun exposure, and supplements.

Efficacy

Research has shown that vitamin D3 tends to be more effective than vitamin D2 supplementation when trying to increase serum vitamin D levels, said Pelitera. “In bloodwork, we measure Vitamin D status through something called 25-OH Vitamin D, or ‘serum,’” she noted. When these levels are low, supplementation of vitamin D3 is often recommended due to its effectiveness.

Still, more research is needed to confirm if one is better than the other for serum vitamin D, said Mroz-Planells. “If you have low serum vitamin D levels, your provider may start with a higher dose of vitamin D2 for a set number of weeks, and then switch you to a lower maintenance dose of vitamin D3,” Mroz-Planells explained.

In adults who are deficient in vitamin D, we may see a condition called osteomalacia, which is a softening of the bones and can lead to osteoporosis, Mroz-Planells said.

Per Pelitera, other symptoms of a vitamin D deficiency may include:

• Muscle or bone pain
• Increased sensitivity to pain
• Tingling feeling in the hands or feet
• History of frequent broken bones
• Muscle twitches or spasms
• Muscle weakness

Infants and children with severe vitamin D deficiency are at risk for a condition called Rickets, added Mroz-Planells. “This is where the arms and legs can become bowed from the bones not being able to properly grow.”

There are many risk factors for vitamin D deficiency, such as limited sun exposure, older age, certain health conditions, and skin pigmentation, said Mroz-Planells. If you have reason to believe that you might not be getting enough of the sunshine vitamin, “talk with your provider about getting your serum vitamin D level checked,” Mroz-Planells advised.

Some medications may interact with vitamin D supplements, and they may need to be avoided or taken separately from vitamin D, said Mroz-Planells. Vitamin D supplementation could interact with some medications such as a statin (cholesterol reducing medication), orlistat (a weight loss drug), steroids (such as prednisone), and some types of diuretics, Pelitera warned. “You should consult your doctor before starting any new supplement or medication,” she advised.

The best way to get Vitamin D is through daily sun exposure, said Pelitera. However, we know that in some places and with some lifestyles, it is not always possible to get enough vitamin D from the sun alone.

Therefore, foods high in vitamin D will be the best ways to prevent a deficiency, said Mroz-Planells. Some of the best food sources of vitamin D, according to Mroz-Planells, include:

• Salmon
• Mackerel
• Sardines
• Eggs
• Mushrooms
• Fortified foods like milk and cereal

Supplements can also be a great way to add vitamin D to the diet when necessary, said Pelitera, and research does not strongly recommend one form of the vitamin over the other. “Both D2 and D3 can be used as a supplement to treat low serum vitamin D…and we get exposure to both versions through our diet and time in sunlight,” said Mroz-Planells. Still, if the goal is to try and increase a low level of vitamin D, vitamin D3 supplementation may be the most effective choice between the two, noted Pelitera. But you should always consult your doctor before adding any new supplements to your regimen.

Dietary supplements are products intended to supplement the diet. They are not medicines and are not intended to treat, diagnose, mitigate, prevent, or cure diseases. Be cautious about taking dietary supplements if you are pregnant or nursing. Also, be careful about giving supplements to a child, unless recommended by their healthcare provider.