What's the difference between vitamin D and vitamin D3?

Vitamin D is an essential vitamin for your health. It has a wide range of benefits, including supporting your bones, muscles, nerves, and immune system. It comes in different forms: D1, D2, and D3.

The difference between vitamin D and vitamin D3 is a matter of specificity. You can talk about vitamin D as a general term for the nutrient from all sources, but you would discuss vitamin D3 when referring to the specific form found in supplements.

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What is vitamin D?

Vitamin D is an essential nutrient for your health. It can be found in different foods, but it’s most known as the vitamin that your body produces in sunlight. It’s also known as calciferol, and you can get it in supplement form if your body isn’t getting enough from other sources.

Being deficient in vitamin D, meaning you don’t have enough of it, is common — around 1 billion people worldwide have a vitamin D deficiency, while 50% of the population have an insufficiency, which is slightly less severe than a deficiency.

One of vitamin D’s main roles is helping the body absorb calcium, which is essential for bone and tooth health.

It also supports your immune system, which can help stop you from getting sick. One 2020 review suggests that vitamin D deficiency is linked with an increased risk of infections and autoimmune diseases like inflammatory bowel disease.

Other benefits include:

• supporting muscle health
• reducing inflammation
• aiding cell growth

Dietary sources of vitamin D are generally quite limited, but some common sources include:

• fish liver oils
• the flesh of some wild fish, like tuna or mackerel
• egg yolks
• some mushrooms
• yeast
• dark chocolate

Some foods, known as fortified foods, also have vitamin D added to them. Milk and dairy products are common examples.

What is vitamin D3?

Vitamin D3, also known as cholecalciferol, is just one form of vitamin D. Once you consume it, your body converts it into the active form of vitamin D, calcitriol, in your liver and kidneys.

D3 is the form of vitamin D your body creates through outdoor sunlight exposure — not through a window. Most people get at least some of their necessary vitamin D this way. Experts recommend around 5 to 30 minutes of sunlight exposure at least twice a week, but preferably daily, to meet your vitamin D needs.

Vitamin D3 is also the form of vitamin D found in animal sources, like fatty fish and egg yolks. Vitamin D2 is the kind found in plant sources.

One key aspect of vitamin D3 is that it’s available in supplement form — in solid tablet form and liquid formulations. Research suggests that vitamin D3 supplements increase blood vitamin D levels higher and for longer than other forms of vitamin D.

Experts strongly recommend vitamin D3 supplementation if you aren’t getting enough from your diet and sunlight because deficiency is so common, especially in winter.

Taking vitamin D3 supplements is very safe, even with long-term daily use. In fact, one 2018 study comparing lower daily and higher monthly administration of vitamin D3 found the two to be similarly safe and effective, with no negative events.

However, it’s important to take into account your individual circumstances and follow the recommended daily amounts for vitamin D3 supplements. Most adults need 15 micrograms (mcg) of vitamin D per day, but the maximum limit is 100 mcg from all sources of vitamin D, including both supplements and food.

Key differences between vitamin D and vitamin D3

The main difference between vitamin D and vitamin D3 is that vitamin D is an umbrella term for all sources of vitamin D, whereas vitamin D3 is a specific form of the nutrient that is often found in supplement form. Vitamin D3 can be converted into the active form of vitamin D in your liver and kidneys.

It’s important to note that vitamin D and vitamin D3 aren’t exactly different substances. You will likely hear vitamin D discussed as an overarching term for all forms of the nutrient, including vitamin D3. However, the term vitamin D3 can’t be used for all forms of vitamin D.

Vitamin D2 and vitamin D3 are two forms of vitamin D that have key differences. The main difference is that D2 is mostly found in plant sources like fungi, while D3 can be made by the body through sunlight exposure and is also found in animal sources like fish.

Many of the vitamin D supplements available over the counter will contain vitamin D3, but they may be marketed simply as “vitamin D.” If you have any concerns about your vitamin D levels, speak with a doctor. They will be able to advise you on what supplement is best for your situation.

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Summary

Vitamin D is an essential nutrient you can get through sunlight, some dietary sources, and even dietary supplements. Vitamin D3 is just one form of vitamin D.

Vitamin D deficiency is very common worldwide, so experts often recommend dietary supplements, which are commonly in the form of vitamin D3. Supplementation is considered safe, with a low chance of side effects if you take it according to your needs and daily recommendations.

Always check with a doctor before starting a new supplement.

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