What Is The Difference Between Vitamin D And Vitamin D3

Have you ever noticed multiple forms of vitamin D on supplements - like vitamin D2, vitamin D3, and simply vitamin D? What do these different labels mean and what are the differences between them? Vitamin D nutrition can be confusing, but understanding the distinctions between these common forms can help ensure you get the right type of this essential vitamin.

Vitamin D is often referred to as the "sunshine vitamin" because sun exposure allows our bodies to produce it naturally. But it also exists in food sources and dietary supplements in multiple forms, including vitamin D2 and vitamin D3. Let's break down the similarities and differences between these two common types of vitamin D.

Vitamin D2 vs D3 - The Functional Difference

While both vitamin D2 and D3 increase vitamin D levels in the body, there are some distinctive differences in their chemical structure and origin:

• Vitamin D2, also called ergocalciferol, is derived from plant sources. It comes from fungi and yeasts.
• Vitamin D3, also called cholecalciferol, is the form produced by the human body when skin is exposed to sunlight. It is also found in animal sources.
• The chemical structure of D2 contains a double bond between carbons 22 and 23. D3 contains a double bond between carbons 5 and 6.
• In the liver, vitamin D is converted to 25(OH)D. The metabolites of D2 and D3 differ slightly in structure.

While these structural variations seem subtle, they can significantly impact the relative potency and bioavailability of the two forms. Studies show vitamin D3 tends to be more effectively absorbed and utilized than D2.

Why Is Vitamin D3 Potentially Better?

Research has found that vitamin D3 may have advantages over vitamin D2 when it comes to raising blood levels of vitamin D and maintaining those levels over time. For example:

• A study found 70% higher serum 25(OH)D levels with D3 compared to D2 at 11 weeks.
• A meta-analysis reported a mean increase in serum 25(OH)D of 50% more for D3.
• One trial saw 25(OH)D return to baseline levels more rapidly after stopping D2 compared to D3.

The superior bioavailability of D3 may relate to structural differences that impact binding to vitamin D carrier proteins. This allows more D3 to circulate in the bloodstream. D3 is also more stable and less likely to degrade with time and heat.

Given the accumulating research, experts tend to recommend vitamin D3 over D2, especially for those correcting deficiencies. The Endocrine Society clinical practice guidelines suggest vitamin D2 should no longer be regarded as equivalent to D3 in terms of potency.

Food Sources of Vitamin D2 vs D3

When it comes to food, vitamin D3 tends to be the form found in animal sources naturally, while D2 occurs in fungi exposed to UV light:

• Vitamin D3 is found in fatty fish, fish liver oils, and egg yolks.
• Vitamin D2 is found in mushrooms exposed to UV light, alfalfa, and yeast.

Milk and plant milks like soy, almond, and oat milk are sometimes fortified with vitamin D2. Beef liver, cheese, and other dairy contain naturally-occurring D3.

So animal-based foods tend to provide more bioavailable vitamin D3, while plant sources provide D2. Consuming a variety of vitamin D-rich foods can help meet your daily needs for this nutrient.

Factors Impacting Recommended Intake

When it comes to how much vitamin D you need each day, there are some factors to consider:

• Age - Older adults need more vitamin D due to less efficient absorption and synthesis.
• Sun exposure - People who get minimal sun need more vitamin D from food/supplement sources.
• Latitude - Populations farther from the equator produce less vitamin D from sun exposure.
• Skin tone - Darker skin tones absorb less UVB radiation needed for vitamin D synthesis.

Based on these factors, global recommendations for vitamin D intake range from 400-800 IU per day for children and 600-2000 IU per day for adults. Reaching the higher end of the range may be best for those with deficiencies.

Supplementing with Vitamin D2 or D3

Both vitamin D2 and D3 can be found in supplemental forms like multivitamins, gummy vitamins, and single-ingredient tablets. Vitamin D3 supplements tend to be preferred due to greater potency and more sustained improvements in vitamin D status, based on research.

Cod liver oil is a common supplement containing D3. Vegan supplements will contain vitamin D2 from lichens rather than animal sources. Prescription strength doses like 50,000 IU capsules are usually vitamin D2.

When choosing a vitamin D supplement, opt for a moderate daily dose of D3 in the range of 1000-4000 IU, unless under medical guidance to take higher therapeutic doses. Combine with food sources like fatty fish, liver, and egg yolks for comprehensive vitamin D intake.

Who May Benefit From Supplemental D3?

Vitamin D deficiency is very common worldwide. Certain groups are at high risk of deficiency and may benefit from D3 supplementation, including:

• Older adults - Absorption decreases with age.
• Nursing home residents - Get less sun exposure.
• People with dark skin tones - Produce less vitamin D from sunlight.
• Those who live farther from the equator - Less intense UVB exposure.
• People with digestive disorders - May not absorb it as well from food.
• Vegans and vegetarians - Lower vitamin D intake.
• Night shift workers - Less sun exposure.
• Obese individuals - Vitamin D can become trapped in fat.

A blood test can confirm vitamin D status. Your doctor may recommend more aggressive D3 supplementation to restore healthy levels if deficient.

Vitamin D3 (cholecalciferol) tends to be more effective than vitamin D2 based on clinical research. Vitamin D3 raises blood levels higher and keeps levels elevated for a longer period of time.

Animal foods like fatty fish, egg yolks, liver, and dairy products contain vitamin D3 naturally. Vitamin D2 comes from sun-exposed yeasts and fungi.

When correcting deficiency, vitamin D3 is preferred. For maintenance, aim for 600-2000 IU of vitamin D3 from a combination of sun, food, and supplements daily.

Choosing vitamin D3 provides the vitamin D that is closest to what the human body makes naturally. Pairing D3 from fish, eggs, liver and moderate sunlight gives you active, highly useful vitamin D for optimal health.

I hope this overview has helped explain the key differences between the common forms of supplements - vitamin D2 and vitamin D3. Let me know if you have any other questions!