Vitamin D3 is the common name for cholecalciferol.
Vitamin D3 can be taken as a supplement to improve overall health or used to treat osteoporosis.
It can also be used to treat conditions in which vitamin D3 levels may be low, such as in people who have underactive parathyroid glands, low levels of phosphate in the blood, or hereditary conditions in which the body doesn’t respond to the parathyroid hormone.
Vitamin D3 also encourages the kidneys to recycle phosphate back into the blood, which helps the blood stay at the right pH.
Vitamin D3 is available for purchase over-the-counter (OTC).
Vitamin D3 Deficiency
Historically, vitamin D3 loss has been associated with rickets, a disease caused by low levels of vitamin D3 that commonly affects children.
Children with rickets and adults who had rickets as children often have legs that are bow-shaped.
However, while adults who are deficient in vitamin D3 do not typically develop rickets disease, their bones may start to become softer — a condition known as osteomalacia.
People with digestive problems like celiac disease, liver problems, or Crohn’s disease are more likely to have low levels vitamin D3.
Sunlight is a natural source of vitamin D3, and people who rarely or never go outside (for example, those in nursing homes or bedridden hospital patients) are most likely to be deficient in it.
Also, the darker your skin, the more sunlight you need to keep vitamin D3 at healthy levels.
This is because the extra melanin found in darker skin slows the absorption of vitamin D3.
Some studies suggest that the time of day when you receive sunlight affects how well your body absorbs vitamin D3.
While many experts advise people to avoid sunlight between the hours of 10 AM and 2 PM or 3 PM to help protect their skin from cancer, data shows the body actually absorbs vitamin D3 better during this time.
The Difference Between Vitamin D2 and Vitamin D3
There are two forms of vitamin D: Vitamin D2, or ergocalciferol, is commonly found in foods.
Vitamin D3 is made by the body naturally when skin is exposed to the sun.
Although there is some debate, most experts currently believe that the best form of vitamin D supplement to take is vitamin D3.
It’s thought that D3 is more natural and easier for the body to absorb.
Also, the body does not allow as large a concentration of D3 to circulate in the bloodstream as it does D2, so it’s considered safer.
Vitamin D Foods
Oily fish like salmon, codfish, mackerel, and blue fish are great natural sources of vitamin D.
Fortified foods — such as milk and cereal — along with egg yolks and raw shiitake mushrooms also contain vitamin D.
Vitamin D3 and Acne
There is some debate about whether vitamin D3 works to treat acne.
The Vitamin D Council website states that lack of sunlight may increase acne, and some people notice their acne worsening during the winter and improving during the summer.
Still, there aren’t any clinical studies supporting the use of vitamin D3 for acne.
There’s also very little evidence supporting the use of vitamin D in preventing acne.
However, some anecdotal reports claim that acne improved after taking vitamin D supplements or applying it (in oil form) to their skin.
Vitamin D3 Levels and Weight
Recent studies show that people who are overweight may have higher levels of vitamin D.
The reason is thought to be because vitamin D is an oily substance that tends to get stored in the body’s fat tissue.
So, the more body fat you have, the more easily the body can store vitamin D.
If you are underweight, your levels may be lower than you’d expect because you have less body fat in which to store extra vitamin D.
Vitamin D3 Warnings
Talk to your doctor before taking vitamin D3 if you:
- Are taking bile acid sequestrants like Welchol (colesevelam), Colestid (colestipol) Locholest, Prevalite (cholestyramine)
- You are taking the weight-loss drug Alli or Xenical (orlistat)
Pregnancy and Vitamin D3
It’s unclear whether vitamin D3 might harm your unborn baby.
Talk to your doctor if you are pregnant or plan to become pregnant before taking this medication.
You should also tell your doctor if you are breastfeeding or plan to breastfeed.
Vitamin D3 passes into breast milk and is therefore not recommended for breastfeeding mothers.
Vitamin D3 Side Effects
In general, side effects from taking vitamin D3 tend to be rare.
Serious side effects of vitamin D3 include but are not limited to:
- Allergic reactions like rash or itching
- Swelling of the face, throat, and tongue
- Severe dizziness
- Trouble breathing
- Changes in heart rhythm including irregular or racing heart beat
Rare Side Effects
Although it doesn’t happen very often, vitamin D can cause:
- Dry mouth
- Weakness and lack of energy
Vitamin D3 Interactions
It’s always important to share with your doctor and pharmacist all of the medications you are taking.
This includes prescriptions and over-the-counter medications, supplements like vitamins and other dietary supplements (nutritional shakes, protein powders, etc.), herbals, and any illegal or recreational drugs.
You should avoid taking vitamin D3 if you are taking the following drugs:
- Zemplar (paricalcitol)
- Donovex or Sorilux (calcipotriene)
- Hectorol (doxercalciferol)
- Mineral oil
- Alli or Xenical (orlistat)
Bile acid sequestrants like Welchol (colesevelam), Colestid (colestipol), Locholest or Prevalite (cholestyramine)
Drugs like Alli or Xenical, or bile acid sequestrants like those listed above, can decrease or prevent your body from absorbing vitamin D and other fat-dependent vitamins, namely vitamins A, E, and K.
You should separate vitamin D from these medications by at least 2 hours or take your vitamin D at bedtime to allow enough time to avoid interactions.
Also, be careful with drugs like:
- Aluminum hydroxide
- Water pills like chlorthalidone, hydrochlorothiazide, and chlorothiazide
- Magnesium hydroxide and magnesium citrate
Vitamin D3 and Alcohol
You should avoid or limit alcohol consumption while taking vitamin D3 because alcohol can decrease its absorption.
Vitamin D3 Dosage
Vitamin D3 is available as a tablet in doses of 400 IU and 1000 IU.
You can also buy vitamin D3 combined with calcium in a single pill.
You should not take more than 4,000 IU a day of vitamin D3 unless your doctor tells you otherwise.
In general, it’s best to take vitamin D with food. This may vary with prescription forms of vitamin D, so talk to your doctor or pharmacist about what’s right for you.
If you have osteoporosis and are over 50 years old, you should take 800 to 1000 IU (20 to 25 mcg) a day of vitamin D with calcium.
If you are taking vitamin D because of an underactive parathyroid, your doctor will determine the dose that’s right for you.
For treating vitamin D-resistant rickets in children, your doctor may tell you to give your child anywhere between 12,000 and 500,000 IU (0.3 to 12.5 mg a day).
Vitamin D3 Overdose
If you suspect an overdose, you should contact a poison control center or emergency room immediately.
Missed Dose of Vitamin D3
If you miss a dose of Vitamin D3, try to take it as soon as you remember.
If it’s almost time for the next dose, skip the missed dose and take your next dose at the regular time.
Do not take two doses of the medication at the same time.