Vitamin D is unique. It belongs to a family of vitamins and nutrients that share similar structures, and yet, it really isn’t a vitamin at all, but acts more like a prohormone. There are five forms of Vitamin D which include Vitamins D1, D2, D3, D4, and D5. However, the main forms of Vitamin D are Vitamin D2 (ergocalciferol) and Vitamin D3 (cholecalciferol). The fascinating fact about Vitamin D is that it is the only vitamin that is synthesized through the skin, from exposure to sunlight. We are going to cover the significant differences between Vitamin D and Vitamin D3 that you should know when searching for the best supplement to increase your Vitamin D levels.

What Is Vitamin D?

Vitamin D is classified as a fat-soluble vitamin yet acts like a prohormone. Fat-soluble vitamins are best absorbed and provide more bioavailability when taken with foods higher in fat. When these specific vitamins are not taken with enough fat, they pass through the GI tract without much effect or absorption. Swolverine encapsulates its Vitamin D3 in Olive Oil, to provide healthy essential fats to optimize absorption and provide maximum potency. Vitamin D promotes calcium absorption, regulates bone growth, and plays a pivotal role in your immune system. Studies show that Vitamin D may also assist in the prevention of chronic disease states as well as help regulate mood.

How Does Vitamin D Work? 

When your skin is exposed to sunlight, specifically ultraviolet B (UVB) rays, your body naturally produces Vitamin D3. D2 is created in a similar fashion yet through the synthesis of sunlight by mushrooms and plants. There are three ways you can obtain vitamin D for your body. These ways include from the sun, vitamin D supplements, and from food, preferred in that exact order. Wow, supplements over the food you say? Yes, exactly. The reason is simple: most individuals aren’t exposed to UVB rays for at least 15 minutes a day, uncovered and unprotected (that means no sunscreen, makeup, or clothing). Foods fortified with Vitamin D2 also don’t contain enough vitamin D to provide the body with the recommended daily intake (RDI) of Vitamin D [R]. For these reasons, vitamin D3 supplementation is the most effective way to get the daily recommended amount of vitamin D. 

It’s estimated that nearly 1 billion people or 50% of the world population are vitamin D deficient. Low vitamin D levels can result in abnormalities in bone metabolism, slow wound healing, chronic fatigue, depressed mood states, muscle weakness, and depression [R, R, R].

According to a national nutrition examination survey 41.6% of US adults exhibited vitamin D deficiency, with the highest rate seen in African Americans at 82.1% followed by those of Hispanic descent at 69.2% [R].

Is Vitamin D3 The Same As Vitamin D?

The term Vitamin D itself is a bit misleading since you won’t find a vitamin D product in the supplement aisle, but rather Vitamin D2 or Vitamin D3. Generally speaking, when someone mentions the term Vitamin D, then Vitamin D2 is implied. Vitamin D3 does not go by any aliases and is simply referred to as Vitamin D3. 

What Are The Differences Between Vitamin D And Vitamin D3? 

Both Vitamin D and Vitamin D3 are processed in the body by the liver to 25-hydroxyvitamin D, which increases 25D levels.

Vitamin D2 referred to as Vitamin D, is largely human-made and derived from plant sources. Vitamin D is produced by plants when they’re exposed to UV light (similar to the way we explained earlier that humans produce Vitamin D3).

Vitamin D2 is commonly found in fortified foods, such as milk and cereal products, or in supplement form. While this form is often pressed into a tablet supplement and consumed by people adhering to restricted diets, your body doesn’t actually produce this form of vitamin D naturally, making it a poor-quality nutrient when it comes to fulfilling your daily requirement of vitamin D [R]. 

In food, vitamin D is measured in micrograms with the suggested daily intake of 25-100 micrograms per day needed to maintain optimal blood levels (that’s 1000-4000 IU in supplement talk).

Examples of Foods High in Vitamin D:

• Fatty Fish (salmon, trout, swordfish) = 9-17 micrograms per 3oz serving
• Mushrooms (portabella, exposed to UV light) = 7.9 micrograms per ½ cup serving
• Whole Milk = 3.2 micrograms per 1 cup serving
• Orange Juice (fortified) = 2.5 micrograms per 1 cup
• Eggs (hard-boiled) = 1.1 micrograms per 1 large egg  

As you can see from the examples above, even the best food source of vitamin D doesn’t contain nearly enough micrograms (remember, you need up to 100 micrograms per day) to provide sufficient delivery and function within the human body. Vitamin D2 is used as an inexpensive, low-quality, and less effective option to boost nutrient quality as compared to Vitamin D3 [R].

Vitamin D3 is obtained through animal sources such as fatty fish (salmon, tuna, mackerel), egg yolks, and liver. Studies have shown that Vitamin D3 is the preferred form to elevate vitamin D blood concentration. In fact, research evaluating the effects of both Vitamin D and Vitamin D3 on serum d concentration indicates that Vitamin D3 is 85% more effective at raising Vitamin D concentration and provides 300% greater storage of Vitamin D than Vitamin D2 [R, R].

Frequently Asked Questions About Vitamin D vs Vitamin D3

Which Vitamin D Should You Take? 

According to the research, it’s clear that Vitamin D3 is the preferred source of Vitamin D supplementation since your body naturally synthesizes Vitamin D3 from exposure to sunlight. Clinical studies have proven that Vitamin D3 can increase 25-hydroxyvitamin D levels more than Vitamin D.

Do I Need Vitamin D or Vitamin D3?

Vitamin D3 increases vitamin D concentrations more so than vitamin D alone, therefore, if you’re choosing a supplement, the best choice is Vitamin D3.

What Are The Side Effects Of Vitamin D3?

There are no common side effects with Vitamin D2 or Vitamin D3 supplementation. If too much Vitamin D is taken, an extremely rare condition Hypervitaminosis D may occur. Mega-doses of vitamin D can lead to high levels of calcium in the blood, which can lead to vomiting, nausea, and increased urination, and lead to the calcification of organs and soft tissue.

What Are The Symptoms Of Low Vitamin D?

Signs and symptoms of Vitamin D deficiency in adults may include:

• Chronic Fatigue
• Muscle Atrophy
• Muscle Pain
• Weakened Immune System Health
• Depressed Mood State
• Back Pain
• Impaired Wound Healing

If you’re exhibiting any of these signs or symptoms, consult your physician and have a blood panel done. Chances are you have low vitamin D levels. By adding a high-quality vitamin D3 supplement to your daily routine, you may be able to improve your immune health, relieve chronic fatigue, and improve your overall quality of life. Vitamin D deficiency affects more than 1 billion people or 50% of the world's population. Oftentimes, obtaining the recommended amount of vitamin D through sun exposure and diet alone does not suffice.

RELATED ARTICLE 7 Signs & Symptoms Of Low Vitamin D

What Is The Best Time To Take Vitamin D?

Vitamin D is a fat-soluble vitamin. Therefore it’s recommended to take Vitamin D or D3 with a meal, for proper absorption. If your Vitamin D or D3 supplement is suspended in an oil, or fat, then you can take your vitamin D at any time.

Vitamin D vs Vitamin D3: Takeaway

Studies suggest that Vitamin D3 is the preferred form of vitamin D supplementation. When you’re searching for the best vitamin D supplement, it’s important to find a supplement that is paired with fat to maximize absorption and potency. If you’re not sure if you need a vitamin D supplement, it’s important to consult your physician. The recommended dose is dependent upon your 25-hydroxyvitamin D levels, obtained from a blood panel. This will determine which form and dose is best for you.

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References 

Institute of Medicine (US) Committee to Review Dietary Reference Intakes for Vitamin D and Calcium; Editors: A Catharine Ross, Christine L Taylor, Ann L Yaktine, and Heather B Del Valle. 

Chun RF, Hernandez I, Pereira R, et al. Differential Responses to Vitamin D2 and Vitamin D3 Are Associated With Variations in Free 25-Hydroxyvitamin D. Endocrinology. 2016;157(9):3420-3430. doi:10.1210/en.2016-1139

Romagnoli E, Mascia ML, Cipriani C, et al. Short and long-term variations in serum calciotropic hormones after a single very large dose of ergocalciferol (vitamin D2) or cholecalciferol (vitamin D3) in the elderly. J Clin Endocrinol Metab. 2008;93(8):3015-3020. doi:10.1210/jc.2008-0350

Albert Shieh, Rene F. Chun, Christina Ma, Sten Witzel, Briana Meyer, Brandon Rafison, Leon Swinkels, Tonnie Huijs, Sam Pepkowitz, Brett Holmquist, Martin Hewison, John S. Adams, Effects of High-Dose Vitamin D2 Versus D3 on Total and Free 25-Hydroxyvitamin D and Markers of Calcium Balance, The Journal of Clinical Endocrinology & Metabolism, Volume 101, Issue 8, 1 August 2016, Pages 3070–3078.