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Vitamin D (Ergocalciferol): Benefits & Risks

Key Takeaways

  • Vitamin D2 (ergocalciferol) is used to treat hypoparathyroidism (low parathyroid hormone) and rickets, which are soft or weak bones caused by vitamin D deficiency or hypophosphatemia (low phosphate levels).

  • Vitamin D is made by the body when the skin is exposed to sunlight. However, depending on diet and environmental factors, a vitamin D supplement may be necessary for some people. 

  • While vitamin D supplements are widely available over-the-counter (OTC), you should always check with your healthcare provider to make sure vitamin D supplements are safe for you.

The two commonly known types of vitamin D are vitamin D2 (ergocalciferol) and vitamin D3 (cholecalciferol). They are commonly found in foods and are available as OTC supplements. Belonging to the same family, vitamin D2 and vitamin D3 share similar chemical structures. However, they each have different characteristics that make them different.

Vitamin D deficiency is also attributed to certain types of diets that don’t provide enough vitamin D, as well as lifestyle and environmental factors such as limited sun exposure.  

Please continue reading to learn more about certain forms of vitamin D, ergocalciferol (vitamin D2), and cholecalciferol (vitamin D3), including their benefits and risks.

How much vitamin D do you need?

Vitamin D is a family of fat-soluble nutrients which helps calcium absorption in the gut. Having enough vitamin D in the body is essential for strong bones. In addition to bone mineralization, vitamin D also plays a role in neuromuscular function, cell growth, immune function, and glucose metabolism. 

According to the National Institute of Health (NIH), the recommended intake of vitamin D in international units (IU) is as follows:

  • Children below 1 year of age: 400 IU per day /10 micrograms (mcg)

  • People 1 to 70 years of age: 600 IU per day /15 mcg

  • Adults over 70 years of age: 800 IU per day /20 mcg

This includes dietary and supplementary sources. People who do not obtain enough vitamin D from their diet may benefit from taking it in the form of dietary supplements.

You can increase your vitamin D level by safely increasing the consumption of vitamin D-rich food. Also, Vitamin D3 is made by the body when the skin is exposed to sunlight. However, in many cases, a vitamin D supplement may be necessary in some people to prevent growth problems or treat certain bone disorders.  

Why do doctors prescribe vitamin D2 instead of D3?

There are a few different forms of vitamin D, with Vitamin D2 (ergocalciferol) and vitamin D3 (cholecalciferol) being the main forms. These vitamin D analogs have similar chemical structures. Both forms are absorbed in the small intestine and can be used to increase your vitamin D level. 

Both vitamin D2 (ergocalciferol) and vitamin D3 (cholecalciferol) are available as nutritional supplements to treat a deficiency, but D3 may be more effective than D2. However, vitamin D2 is taken once daily, while vitamin D3 can be prescribed at higher doses taken once weekly.  

What is vitamin D2 ergocalciferol used for?

Vitamin D2 (ergocalciferol) is used to treat 

  • Hypoparathyroidism (low levels of parathyroid hormone).

  • Familial hypophosphatemia (an inherited condition with impaired vitamin D metabolism and low phosphate levels, causing rickets or osteomalacia, i.e., weak or soft bones in children and adults, respectively).

  • Refractory rickets (soft or weak bones that are unresponsive to treatment).

Vitamin D3 (cholecalciferol) is used to treat:

  • Not enough vitamin D in the diet.

  • Bone diseases such as rickets and osteomalacia (soft and weak bones in children and adults, respectively, caused by a lack of vitamin D).

  • Osteoporosis (weak, porous, and brittle bones that fracture easily due to the decline in bone mineral density). 

What are the symptoms of vitamin D deficiency?

Some of the signs and symptoms of vitamin D deficiency include fatigue, sleep problems, bone pain or achiness, muscle weakness, hair loss, loss of appetite, pale skin, depression, and falling sick more often. 

Keep in mind that these are non-specific symptoms that can occur for many different reasons. If you suspect you have low levels of vitamin D, your healthcare professional can do a blood test and prescribe vitamin supplements if needed.

Who needs to take calcium and vitamin supplements?

People who are at risk of low vitamin D levels may need to take supplements. This includes elderly patients, infants fed with breast milk, menopausal and postmenopausal women, obese individuals, dark-skinned people, those who work indoors and have limited sun exposure, and people with gastrointestinal conditions such as celiac disease and Crohn's disease that can affect the absorption of vitamin D from the gut.

Is 50,000 IU (international units) of vitamin D2 a lot?

Yes, 50,000 IU is a high ergocalciferol dose, but it is acceptable to treat certain health conditions as instructed by your doctor. For most people, the recommended dietary allowance of vitamin D is 400-800 IU, which is equivalent to about 2,800-5,000 IU per week. However, your healthcare professional may prescribe higher doses of up to 50,000 IU if you have a severe deficiency of vitamin D and need higher than normal doses to achieve normal blood levels of this vitamin. 

Vitamin D2 (ergocalciferol) 50,000 IU can be prescribed to be taken by mouth once daily for certain cases of hypothyroidism and persistent rickets. It is very important to keep in mind that vitamin D3 (cholecalciferol) is also prescribed at 50,000 IU, but it should be taken by mouth once weekly. Ask your doctor or pharmacist if you are not sure which vitamin D product you are prescribed and how often you should take it. 

The high dosage may be taken for a period of 6 to 12 weeks. Your doctor may lower the dose after this period if your reports show an adequate improvement in your vitamin D levels. 

How to take vitamin D?

While vitamin D2 and vitamin D3 are the two major forms found in food, dietary preferences may be a barrier to consuming enough vitamin D-rich food for many.

If you want to increase vitamin D intake, you can get vitamin D2 from plant sources and different fortified foods.

Vitamin D3 (cholecalciferol), however, is strictly from animal-based sources, such as oily fish like salmon, mackerel, sardines, egg yolk, and liver. 

Vitamin D comes as a tablet, capsule, gel capsule, liquid, or chewable to take by mouth.

  • Give your doctor a complete list of your other drugs, including prescription medicines, over-the-counter medicines, and herbal products. This will help avoid drug interactions between vitamin D and your other medications.

  • Vitamin D is available both over-the-counter and by prescription. Read the prescription label or product package carefully and take only the recommended dose because too much vitamin D can be harmful. 

  • Take vitamin D with healthy fats (avocado, nuts, seeds, fatty fish, full-fat dairy) for maximum absorption.

  • Talk to your doctor about dietary changes, including taking calcium supplements while on vitamin D. You need to eat enough calcium for vitamin D to work properly.

  • Keep all your medical and lab appointments. Your doctor may order certain lab tests during treatment.

  • If you miss a dose of vitamin D, take it as soon as you remember. But if it is almost time for the next dose, skip the missed dose and go back to your regular dosing schedule. Do not take extra medicine to make up for a missed dose.

  • Store vitamin D in a tightly closed container, safely out of reach of children.

  • Call your doctor immediately or call the National Poison Control Center at 1-800-222-1222 in case of an overdose. 

What are the side effects of vitamin D?

Most people tolerate vitamin D well, but some people can have an abnormal sensitivity to this vitamin. Call your doctor for medical advice if you develop drowsiness, unusual tiredness, difficulty thinking, nausea, vomiting, constipation, loss of appetite, weight loss, pale skin, increased thirst, increased urination, muscle weakness, muscle aches, or muscle stiffness. Seek emergency medical care if you develop signs and symptoms of an allergic reaction (skin rash, hives, itching, swelling, difficulty breathing).

Who should not take ergocalciferol?

People with the following conditions should not take oral vitamin D:

  • Allergic reactions to vitamin D2 (ergocalciferol) and D3 (cholecalciferol) or any of the inactive ingredients in vitamin D formulations, for example, certain food dyes. 

  • A medical problem such as hypervitaminosis D (high levels of vitamin D in the body) or hypercalcemia (high levels of calcium in the blood).

  • A gastrointestinal condition or malabsorption syndrome that affects the body’s ability to absorb nutrients from food.

Make sure you follow your doctor’s instructions to get the maximum benefit and lower your risk of side effects and complications. 

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  1. https://ods.od.nih.gov/factsheets/VitaminD-HealthProfessional/#:

  2. https://medlineplus.gov/druginfo/meds/a616042.html

  3. https://medlineplus.gov/druginfo/meds/a620058.html