Confused Over Vitamin D vs D3? Here’s How to Decide!

Vitamin D is an essential nutrient for immunity, bone strength, physical fitness, and many other functions. However, deficiencies are common, especially in colder climates.

With different sources using different names, what is the difference between vitamin D vs. D3? Short answer: both vitamin D3 and vitamin D2 are forms of vitamin D. It’s crucial to know the difference between vitamin D2 and D3, as some supplements use the less effective form or a blend of the two.

This article will discuss the differences between the two forms of vitamin D and explore top vitamin D supplements like the one from Akasha Naturals. Let’s dig in!

What Is Vitamin D?

Vitamin D is a fat-soluble nutrient that your body can produce from cholesterol or get through food consumption. It shares similarities with steroids in the chemical structure, hormone-like function and endocrine role but unlike steroids it is not produced in the adrenal glands or gonads.

But apart from these basics, let’s take a closer look at how the vitamin D forms, D2 and D3, respectively, differ:

Vitamin D2 vs D3

Vitamin D3 specifically refers to cholecalciferol, the animal forms our bodies produce. Animal cells convert this type of cholesterol into vitamin D3. This not only gives your skin some protection against Ultraviolet B (UVB) light, but most of your cells have vitamin D receptors [1].

The term “vitamin D” is sometimes used to refer to vitamin D2, the plant, yeast, and fungal form. When mushrooms are described as a vegan-friendly source of vitamin D, it normally refers to vitamin D2. However, our bodies do not use it efficiently [1].

One study on older women showed that the area under the curve (AUC), a measure of your vitamin D levels over time, was cut in half if they took vitamin D2 or D3. Women taking vitamin D3 had an AUC of 3,193ng x d/mL, but women given vitamin D2 had an AUC of 1,820 [2].

In the following sections we’ll refer to vitamin D2 as vitamin D; so when we say vitamin D vs D3 what we actually mean is vitamin D2 vs D3.

Vitamin D Health Benefits

When comparing vitamin D vs D3 benefits, you can expect to be much stronger if you focus on taking D3 alone. The vitamin D2 vs D3 debate is not a close call, with D3 leading in terms of efficacy. However, we’ll explore the benefits of taking both vitamin D2 and D3.

Immune System Function

The question of “What does vitamin D do?” is often first answered by addressing its immunity benefits. Vitamin D can strengthen appropriate immune responses to infection and dial down excessive reactions to allergens.

In one trial, taekwondo athletes were given 5,000 IU of vitamin D3 daily for a month during winter. The supplementation group had a much lower average score of respiratory tract infections, at just 7.7 compared to 13.0. They also had higher levels of protective antibodies in their mouths, which were responsible for some of the benefits experienced [3].

Vitamin D may tone down an overactive immune response by regulating gut bacteria populations and improving the integrity of the intestinal wall. These abilities can reduce the immune cells’ overactivity in allergic reactions [4].

Bone Health and Osteoporosis

Another popular use for vitamin D vs D3 is its potential to improve bone strength and healing time.

It may be even more effective alongside nutrients such as vitamin K2 and calcium. A trial involving people who had spinal fusion surgery demonstrated a complete fusion rate of 91% after 6 months. The group that only took calcium and vitamin D3 had a fusion rate of 71%, suggesting that a combination is best. Both groups also had far better pain scores afterward [5].

Muscle Function and Performance

Improved physical strength is a lesser-known benefit of vitamin D. However, a review of clinical trials showed that it could improve strength by anywhere from 1.37% to 18.75%. Vitamin D2 showed no effect on muscle function and performance; all of these gains were thanks to vitamin D3 [6].

Vitamin D may support both muscle size and function. It activates processes that stimulate muscle cell growth, supports the connection between muscle fibers and nerves, and protects against exercise-induced damage. Athletes may notice improved muscle power, recovery times, and testosterone production; it can also be effective in older adults with severe muscle loss [6].

Glycemic Control and Diabetes

Type II diabetes is a common chronic illness, with weight management supplements and a healthy diet two of the best preventive measures to take. However, vitamin D may also help prevent people with prediabetes from developing the disease. If you already have diabetes, optimal vitamin D levels can cut your risk of eye problems in half and almost halve your risk of kidney damage [7].

Some people see greater benefits from higher vitamin D levels than others. Those taking high doses for a short period, non-obese people, people with Middle Eastern heritage, and people with low starting levels of vitamin D seem to benefit the most [8].

Vitamin D may stimulate insulin production and improve insulin sensitivity in muscle and liver cells. Lab studies also show that its anti-inflammatory properties could protect metabolic health [8].

Maternal and Child Health

Vitamin D seems to benefit people of all ages, including newborns. Supplementation may reduce the risk of low birth weight by up to 60%. Another potential benefit is the lower risk of preterm births [9].

Healthy vitamin D levels could also prepare babies for better brain development. A trial comparing 400, 2,000, and 4,000 IU of vitamin D daily during pregnancy showed improved language development with the 2,000 IU dose [10]. Although 400-800 IU is enough under normal circumstances, pregnancy is a time of rapid growth and increased nutrient demand.

All-Cause Mortality

Some research has found that vitamin D may help reduce your overall chance of dying from any cause. One large population study involving over 4,500 people found an impressive 50-60% drop in all-cause mortality among people with higher vitamin D levels compared to levels under 25nmol/L. While 58 out of 136 people (42.6%) with levels under 25nmol/L died during the study period, only 510 out of 1,579 people (32.2%) with levels between 50-75nmol/L died. Men may benefit more than women, too [11].

Research on vitamin D and all-cause mortality gives mixed results, but gene variations may have the answer. Another paper revealed that vitamin D deficiency or insufficiency increased all-cause mortality by 36%, but only among people with low klotho levels. The klotho gene has gained attention from the life extension field thanks to its broad anti-aging properties [12].

What Are the Best Sources of Vitamin D?

You can get vitamin D from sunlight, food, and quality supplements. The “best” source depends on where you live, your health status, and your dietary requirements.

Sunlight

Sunlight is the best source of vitamin D. You don’t have to worry about whether you will absorb it or how much of it your body will absorb. However, people living close to the equator must be careful to avoid sunburn. Regardless of where you live, vitamin D production is highest between 11 am and 2 pm because of the sun’s angle [1].

Sun exposure does not always trigger vitamin D production. If you live at a latitude that’s over 50 degrees north or south of the equator, you are likely unable to produce significant amounts of vitamin D for 6 months every year. Research in Boston, which sits at 42 degrees north, shows that people cannot produce vitamin D during sun exposure from November to February [1].

To produce significant amounts of vitamin D, it seems best to spend 10-20 minutes in the sun without sunscreen between 10 a.m. and 3 p.m. Unless you are very fair and live in a region with a very thin ozone layer, do not wear SPF 30-50 sunscreen for incidental sun exposure (5-10 minutes) [1].

Diet

There aren’t many foods that contain substantial amounts of vitamin D. The best sources are oily fish, with rainbow trout having an estimated 645 IU per 3 ounces. Sockeye salmon isn’t far behind at 570 IU per 3 ounces, similar to some supplements. White, raw mushrooms exposed to sunlight can give you 366 IU per half cup, but only as vitamin D2 [13].

Additionally, some countries add vitamin D to packaged foods such as cereals, margarine, orange juice, and milk. If you buy these, check the labels to ensure they contain vitamin D [1].

Supplements

Supplementation can be the best way to get enough vitamin D3 if producing it in sunlight isn’t possible for months on end. The best vitamin D3 supplements contain significant doses of fat-soluble carrier ingredients. Many have supporting active ingredients such as vitamin K2 and calcium.

Vitamin D Dosage

When it comes to vitamin D prescription and dosage, vitamin D supplements should aim for a dose of 500 and 5,000 IU. Lower doses are best for everyday use, while high doses are often your better choice during winter if you live far from the equator.

Vitamin D3 Dosage

If your supplement of choice contains a high 5,000 IU dose, save it for the colder months and switch to a 500 IU amount during spring and summer. Experts recommend anywhere between 400 IU and 2,000 IU, depending on factors such as latitude and age [1].

Vitamin D3 is over twice as effective as vitamin D2, so you don’t need megadoses with a quality supplement. Studies show that vitamin D3 can be anywhere from 2 to 9.5 times more effective than D2 when increasing your levels of active vitamin D [13].

Just note that vitamin D builds up in the body, so you need to be careful with the dosages you take to prevent side effects.

Vitamin D Side Effects

Side effects from either form of vitamin D are usually associated with taking very high doses of supplements for extended periods and are rare when getting vitamin D from food or sunlight. Vitamin D toxicity can lead to buildup of calcium in your blood, also known as hypercalcemia, which can cause the following side effects:

• Nausea and vomiting

• Poor appetite

• Constipation

• Diarrhea

• Weakness and fatigue

• Confusion, disorientation, and difficulty thinking

• Frequent urination and excessive thirst

• Bone pain

That said, keep in mind that there’s little practical difference between D2 and D3 when it comes to side effects at high doses.

Signs of Vitamin D Deficiency

Severe vitamin D deficiency in children can cause rickets, which causes the bones to become soft and deformed. If their deficiencies are severe enough, teenagers and younger adults can develop osteomalacia, which has similar symptoms to rickets, including pain in the bones and dental problems [14].

A discussion on Reddit’s r/Supplements forum revealed various symptoms associated with low vitamin D. Symptoms reported included dry skin, depression, acne, insomnia, lack of motivation, extreme joint pain, and even tooth decay.

One Redditor observed that their skin improved dramatically after taking vitamin D supplements [15]. TokkiJK linked their depression, skin problems, sleep issues, and low motivation to low vitamin D levels, which improved with supplementation and sun exposure [16]. Another Redditor, riddikulus13_2, experienced severe joint pain and tooth decay, which their dentist correctly attributed to a vitamin D deficiency [17].

Vitamin D Deficiency Risk Factors

Some people, especially older adults and people with darker skin are at a higher risk of vitamin D deficiency. Let’s take a look at other risk factors synonymous with vitamin D deficiency.

Age

Older adults are more likely to be vitamin D deficient because they spend less time outdoors and convert cholesterol to vitamin D less efficiently. Some recommendations list the ideal vitamin D intake as between 800 and 2,000 IU for adults over 65. Many also take statins, which reduce cholesterol production and can, therefore, affect vitamin D levels.

Sunlight Exposure

Sun exposure is the most readily available way to get vitamin D3, but an inability to spend enough time in the sun can lower your vitamin D levels for some time. If you live further from the equator, this shortens the length of time per year and per day that you can make enough vitamin D. This is because less UVB reaches your body when the sun appears lower in the sky [1].

A UK study demonstrated that vitamin D deficiency rates were twice as high in winter and spring when they were just starting to go outside again. While just 13% of people were deficient during summer and fall, 30% were deficient in winter or spring [18].

Skin Pigmentation

Skin pigmentation blocks some UV light to protect against its damaging effects. With less UVB light reaching the deeper layers of skin, people with darker complexions need more sun exposure to make enough vitamin D. Some experts even recommend doses of up to 4,000 IU per day [19].

On the other hand, people with lighter skin need to ensure they aren’t spending too much time in sunlight. You do not need to spend as much time outside to receive the same benefits or expose as much skin.

Diet

If you are vegan or vegetarian, the lack of oily fish in your diet can raise your risk of deficiency without enough sun exposure. Avoiding packaged food such as cereals, margarine, and orange juice may reduce your vitamin D intake even more, meaning that sun exposure or supplements are essential if you eat whole foods and follow a plant-based diet.

BMI

Body weight can affect your vitamin D requirements, but it’s more a question of body composition than weight. Vitamin D is stored in fat tissue, so overweight and obese people need larger amounts to increase their blood levels. Low body fat could also affect vitamin D production.

Specific Medical Conditions and Medications

Certain medication conditions and even a few medications can increase your personal vitamin D requirements.

For example, medical conditions that affect your mobility may increase your risk of deficiency, as you would likely spend less time outside. Issues that reduce nutrient absorption, such as recently diagnosed celiac disease, inflammatory bowel disease, and cystic fibrosis, may impair your vitamin D absorption [20].

Corticosteroids, HIV medication, some antifungal drugs, anti-seizure medications, and cholestyramine are medications that affect vitamin D production and metabolism. We couldn’t find conclusive information, but reduced nutrient absorption and food intake may mean that GLP-1 medications like semaglutide affect vitamin D levels.

Lifestyle

With sun exposure being the best way to get vitamin D, lifestyle is a critical factor. Your vitamin D production will be much lower if you spend almost all of your time indoors or only go outside before 9 a.m. and after 3 or 4 p.m. You may even benefit from a short walk outside during a break at work or outdoor outings on your days off.

Expert Insights

The expert consensus on vitamin D varies. However, professionals now recognize the importance of maintaining healthy levels of vitamin D to prevent or manage a range of health problems.

An October 2024 consensus statement published in Endocrine Reviews states:

“Beyond the well-known skeletal features, interest in vitamin D’s extraskeletal effects has led to clinical trials on cancer, cardiovascular risk, respiratory effects, autoimmune diseases, diabetes, and mortality. The initial negative results are likely due to enrollment of vitamin D-replete individuals.

Subsequent post hoc analyses have suggested potential benefits in reducing cancer incidence, autoimmune diseases, cardiovascular events, and diabetes. Oral administration of vitamin D is the preferred route” [21].

FAQs on Vitamin D vs D3

Here are common questions you may have about which vitamin D to take and its benefits.

Is Vitamin D the Same as Vitamin D3?

Vitamin D3 is often written as vitamin D, but so is the less efficient D2 form. The conversion of vitamin D2 to D3 doses may have up to a nine-fold difference, so ensure that “vitamin D” means D3.

What Is Vitamin D Good For?

Vitamin D may help regulate the immune system, improve cardiovascular health, and strengthen your bones and muscles. Some research studies also point to better brain development in childhood and improved blood sugar control.

Can You Take Too Much Vitamin D?

It is possible to take too much vitamin D. Kidney stones and other issues from high blood calcium levels are the usual results of excessive intake. However, you are only at risk if you take 5,000-10,000 IU or more per day for several months.

When Is the Best Time to Take Vitamin D?

You can take vitamin D at any time of the day as long as it helps you build a routine. However, it’s best to take vitamin D with meals that contain fat, as this boosts absorption. Plus, fat-soluble vitamins (like A, D, E, and K) take longer to build up in your system and might take weeks or months to show noticeable effects.

How Long Does It Take for Vitamins to Work?

If you’re keen on taking them, then you must have been curious at some point to find out how long it takes for vitamins to work. To see any significant changes, it takes a couple of weeks to a few months of consistent use for a vitamin to take full effect on your overall health, so consistency is key.

Can I Take 5000 IU of Vitamin D3 Every Day?

Vitamin D3 is not a supplement you should take daily. We only recommend taking 5,000 IU of vitamin D3 daily for a short period, such as during the darkest and coldest part of the year. If you continue past this, your risk of excessive calcium levels and consequences such as kidney stones may increase.

How Can I Increase My Vitamin D Levels Quickly?

Taking around 5,000 IU of vitamin D for a week or two can quickly restore your levels during winter.

Vitamin D vs D3: Final Word

Vitamin D3 and D are used interchangeably; the D3 form is more efficiently activated. This is most likely because it is the animal form, while vitamin D2 is made by fungal and plant cells for their own needs.

If you live in a colder climate, this difference is even more important. With vitamin D3 being anywhere from 2 to 9.5 times more effective than the D2 form, it’s best to rely on oily fish. And when considering supplements, choose the ones specifically labeled as containing vitamins D3 or cholecalciferol, like the one from Akasha Naturals.

References

1. Wacker, Matthias, and Michael F Holick. “Sunlight and Vitamin D: A global perspective for health.” Dermato-endocrinology vol. 5,1 (2013): 51-108. doi:10.4161/derm.24494

2. Romagnoli, Elisabetta 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.” The Journal of clinical endocrinology and metabolism vol. 93,8 (2008): 3015-20. doi:10.1210/jc.2008-0350

3. Jung, Hyun Chul et al. “Vitamin D₃ Supplementation Reduces the Symptoms of Upper Respiratory Tract Infection during Winter Training in Vitamin D-Insufficient Taekwondo Athletes: A Randomized Controlled Trial.” International journal of environmental research and public health vol. 15,9 2003. 14 Sep. 2018, doi:10.3390/ijerph15092003

4. Murdaca, Giuseppe et al. “Vitamin D and Microbiota: Is There a Link with Allergies?.” International journal of molecular sciences vol. 22,8 4288. 20 Apr. 2021, doi:10.3390/ijms22084288

5. Zhang, Wencan et al. “Concurrent Treatment with Vitamin K2 and D3 on Spine Fusion in Patients with Osteoporosis-Associated Lumbar Degenerative Disorders.” Spine vol. 47,4 (2022): 352-360. doi:10.1097/BRS.0000000000004309

6. Chiang, Chien-Ming et al. “Effects of Vitamin D Supplementation on Muscle Strength in Athletes: A Systematic Review.” Journal of strength and conditioning research vol. 31,2 (2017): 566-574. doi:10.1519/JSC.0000000000001518

7. Sacerdote, Alan et al. “Type 2 Diabetes Mellitus, Insulin Resistance, and Vitamin D.” Current diabetes reports vol. 19,10 101. 10 Sep. 2019, doi:10.1007/s11892-019-1201-y

8. Li, Xinyi et al. “The Effect of Vitamin D Supplementation on Glycemic Control in Type 2 Diabetes Patients: A Systematic Review and Meta-Analysis.” Nutrients vol. 10,3 375. 19 Mar. 2018, doi:10.3390/nu10030375

9. Thorne-Lyman, Andrew, and Wafaie W Fawzi. “Vitamin D during pregnancy and maternal, neonatal and infant health outcomes: a systematic review and meta-analysis.” Paediatric and perinatal epidemiology vol. 26 Suppl 1,0 1 (2012): 75-90. doi:10.1111/j.1365-3016.2012.01283.x

10. Rodgers, Megan D et al. “Vitamin D and Child Neurodevelopment-A Post Hoc Analysis.” Nutrients vol. 15,19 4250. 3 Oct. 2023, doi:10.3390/nu15194250

11. Wang, Jing et al. “Vitamin D Status and Risk of All-Cause and Cause-Specific Mortality in Osteoarthritis Patients: Results from NHANES III and NHANES 2001-2018.” Nutrients vol. 14,21 4629. 3 Nov. 2022, doi:10.3390/nu14214629

12. Chen, Zhuohui et al. “Serum Klotho Modifies the Associations of 25-Hydroxy Vitamin D With All-Cause and Cardiovascular Mortality.” The Journal of clinical endocrinology and metabolism vol. 109,2 (2024): 581-591. doi:10.1210/clinem/dgad480

13. National Institutes of Health. “Vitamin D.” National Institutes of Health, 18 Sept. 2023, ods.od.nih.gov/factsheets/VitaminD-HealthProfessional/.

14. Armas, Laura A G et al. “Vitamin D2 is much less effective than vitamin D3 in humans.” The Journal of clinical endocrinology and metabolism vol. 89,11 (2004): 5387-91. doi:10.1210/jc.2004-0360

15. dasdab. “What Were Your Low Vitamin d Symptoms?” Reddit.Com, https://www.reddit.com/r/Supplements/comments/1ch6jdi/comment/l213s5r/. Accessed 3 Jan. 2025.

16. dasdab. “What Were Your Low Vitamin d Symptoms?” Reddit.Com, https://www.reddit.com/r/Supplements/comments/1ch6jdi/comment/l20ynkf/. Accessed 3 Jan. 2025.

17. dasdab. “What Were Your Low Vitamin d Symptoms?” Reddit.Com, https://www.reddit.com/r/Supplements/comments/1ch6jdi/comment/l2b52og/. Accessed 3 Jan. 2025.

18. Pludowski, Pawel et al. “Clinical Practice in the Prevention, Diagnosis and Treatment of Vitamin D Deficiency: A Central and Eastern European Expert Consensus Statement.” Nutrients vol. 14,7 1483. 2 Apr. 2022, doi:10.3390/nu14071483

19. Giustina, Andrea et al. “Consensus Statement on Vitamin D Status Assessment and Supplementation: Whys, Whens, and Hows.” Endocrine reviews vol. 45,5 (2024): 625-654. doi:10.1210/endrev/bnae009

20. Wong, Samford et al. “Prevalence of vitamin D deficiency in patients with spinal cord injury at admission: a single-centred study in the UK.” Journal of nutritional science vol. 12 e24. 20 Feb. 2023, doi:10.1017/jns.2023.12

21. Giustina, Andrea, et al. “Consensus Statement on Vitamin D Status Assessment and Supplementation: Whys, Whens, and Hows.” Endocrine Reviews, vol. 45, no. 5, 2024, pp. 625–654, doi:10.1210/endrev/bnae009.

This article appears in Dec 18, 2024 – Jan 16, 2025.