- What to Know
- Daily Recommended Intake
- Safe Levels
- Cancer-Fighting Properties
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When it comes to raising levels of vitamin D in the body, studies have shown that vitamin D3 is better for you than vitamin D2. Reasons why vitamin D3 is superior to vitamin D2 include the following:
- Vitamin D3 is naturally produced in the human body, whereas vitamin D2 cannot be manufactured by the body.
- Vitamin D3 supplementation has shown to provide higher levels of the active form of vitamin D (called 25-hydroxyvitamin D or calcifediol) in the blood.
- Vitamin D3 helps sustain elevated levels of the active form of vitamin D (25-hydroxy vitamin D) longer than vitamin D2.
What to know about vitamin D supplements
Vitamin D is a family of fat-soluble vitamins that the body obtains from fortified foods, sun exposure, and over-the-counter and prescribed supplements. Though most people do not get enough vitamin D through diet alone, you should not take vitamin D supplements without first talking to your doctor.
Vitamin D consumed in any form is biologically inert and undergoes two chemical changes (hydroxylation) in the body before activation:
- The first change occurs in the liver, which converts vitamin D to 25-hydroxyvitamin D [25(OH)D], also called “calcifediol.”
- The second change occurs in the kidneys and forms the physiologically active 1,25-dihydroxyvitamin D [1,25(OH)2D], also called “calcitriol.”
- Whether you consume vitamin D2 or D3 supplements, both are ultimately converted in the body into 25-hydroxyvitamin D [25(OH)D].
Vitamin D supplements may contain either vitamin D2 (called ergocalciferol), D3 (called cholecalciferol), or both. D3 is mainly obtained from animal sources, such as fish oils, liverm and egg yolk, whereas D2 is of plant origin (mushrooms and fortified foods). The FDA has suggested using vitamin D3 for food fortification (milk, cheeses, butter) over D2.
How much vitamin D should you have daily?
Age | Male | Female | Pregnancy | Lactation |
---|---|---|---|---|
0 to 12 months | 10 mcg (400 international units or IU) | 10 mcg (400 IU) | ||
1 to 13 years | 15 mcg (600 IU) | 15 mcg (600 IU) | ||
14 to 18 years | 15 mcg (600 IU) | 15 mcg (600 IU) | 15 mcg (600 IU) | 15 mcg (600 IU) |
19 to 50 years | 15 mcg (600 IU) | 15 mcg (600 IU) | 15 mcg (600 IU) | 15 mcg (600 IU) |
51 to 70 years | 15 mcg (600 IU) | 15 mcg (600 IU) | ||
Older than 70 years | 20 mcg (800 IU) | 20 mcg (800 IU) |
Whether you take D2 or D3 supplements, the serum concentration of 25(OH)D is currently the main indicator of vitamin D levels. The circulating 1,25(OH)2D is generally not a good indicator of vitamin D level because:
- It has a short half-life measured in hours.
- Its serum levels are variable and dependent on blood parathyroid hormone as well as calcium and phosphate levels.
- Levels of 1,25(OH)2D do not typically decrease unless there is a severe vitamin D deficiency.
nmol/L | ng/mL | Health indications |
---|---|---|
Less than 30 | Less than 12 | Associated with severe vitamin D deficiency |
30 to less than 50 | 12 to less than 20 | Vitamin D insufficiency |
Less than or equal to 50 | Less than or equal to 20 | Adequate levels |
Greater than 125 | Greater than 50 | Toxic levels |

QUESTION
Next to red peppers, you can get the most vitamin C from ________________. See AnswerCan taking too much vitamin D be harmful?
The safe upper intake level of vitamin D is 100 mcg per day (4000 IU per day).
Taking too much vitamin D carries risks such as:
- Nausea and vomiting
- Increased blood calcium levels
- Calcinosis (deposit of calcium crystals in soft tissues, such as the kidneys, heart, or lungs)
- Organ dysfunction
- Toxicity (risk is higher with vitamin D supplementation rather than dietary intake)
Excessive sun exposure does not cause vitamin D toxicity. However, too much sun exposure can cause skin damage and raise the risk of skin cancer.
Does vitamin D have cancer fighting properties?
Emerging research suggests that vitamin D may have a role in combating colorectal, breast, prostate, and pancreatic cancers
The effect of vitamin D supplements on cancer may be due to the physicochemical effect of vitamin D on immune cell function and its hormone-like effect on the cells. However, the following factors are unknown:
- Appropriate dose of vitamin D for cancer prevention
- From what age the supplementation should begin for cancer prevention
- How long to ingest the vitamin to potentially see benefits
- Whether there are any potential drug-vitamin D interactions
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National Institutes of Health. Vitamin D. https://ods.od.nih.gov/factsheets/VitaminD-HealthProfessional/
National Institutes of Health. Vitamin D and Cancer Prevention. https://www.cancer.gov/about-cancer/causes-prevention/risk/diet/vitamin-d-fact-sheet
Harvard T. H. Chan. Vitamin D. https://www.hsph.harvard.edu/nutritionsource/vitamin-d/
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