Vitamin D
The fat-soluble vitamin D’s most important role is maintaining blood levels of calcium, which it accomplishes by increasing absorption of calcium from food and reducing urinary calcium loss. Both effects keep calcium in the body and therefore spare the calcium that is stored in bones. When necessary, vitamin D transfers calcium from the bone into the bloodstream, which does not benefit bones. Although the overall effect of vitamin D on the bones is complicated, some vitamin D is necessary for healthy bones and teeth.
When "D” is used without a subscript it refers to either D2 or D3, the two primary forms used as supplements.
- Reliable and relatively consistent scientific data showing a substantial health benefit.
- Contradictory, insufficient, or preliminary studies suggesting a health benefit or minimal health benefit.
- For an herb, supported by traditional use but minimal or no scientific evidence. For a supplement, little scientific support.
Our proprietary “Star-Rating” system was developed to help you easily understand the amount of scientific support behind each supplement in relation to a specific health condition. While there is no way to predict whether a vitamin, mineral, or herb will successfully treat or prevent associated health conditions, our unique ratings tell you how well these supplements are understood by the medical community, and whether studies have found them to be effective for other people.
For over a decade, our team has combed through thousands of research articles published in reputable journals. To help you make educated decisions, and to better understand controversial or confusing supplements, our medical experts have digested the science into these three easy-to-follow ratings. We hope this provides you with a helpful resource to make informed decisions towards your health and well-being.
This supplement has been used in connection with the following health conditions:
| Used for | Amount | Why |
|---|---|---|
Crohn’s Disease | 1,000 to 1,200 IU daily under medical supervision |  [3 stars] Vitamin D malabsorption is common in Crohn’s and can lead to a deficiency of the vitamin. Supplementation can help prevent bone loss in cases of deficiency. |
Cystic Fibrosis | 1,000 to 2,000 IU daily | [3 stars] The fat malabsorption associated with cystic fibrosis often leads to a deficiency of fat-soluble vitamins, such as vitamin D. Supplementation can help counteract the deficiency. |
Neuropathy | 7,100 IU daily or 50,000 IU weekly of vitamin D3 for eight to twelve weeks, followed by 2,000 to 4,000 IU daily long term | [3 stars] Supplementing with vitamin D3 daily or weekly can help reduce symptoms of diabetic neuropathy. |
Obesity | 2,000–7,000 IU per day | [3 stars] Vitamin D insufficiency and deficiency are common in people with overweight and obesity; restoring sufficient levels with vitamin D supplements is likely to improve the response to weight loss efforts. |
Osteoporosis | 400 to 800 IU daily depending on age, sun exposure, and dietary sources | [3 stars] Vitamin D increases calcium absorption and helps make bones stronger. Vitamin D supplementation has reduced bone loss in women who don’t get enough of the vitamin from food and slowed bone loss in people with osteoporosis and in postmenopausal women. It also works with calcium to prevent some musculoskeletal causes of falls and subsequent fractures. |
Rickets | Consult a qualified healthcare practitioner | [3 stars] Vitamin D supplements may be helpful in preventing and treating rickets. |
Type 1 Diabetes | Many doctors recommend a dose of 2,000 to 4,000 IU vitamin D daily, especially in the winter months | [3 stars] Vitamin D is needed to support healthy immune and pancreatic function. Supplementing with vitamin D may improve blood sugar control in those with type 1 diabetes, especially in those with low vitamin D levels. |
Asthma | 1,200 IU per day for 15 to 17 weeks |  [2 stars] One study found that daily supplementation with vitamin D during the winter months significantly reduced the amount of times the children experienced asthma attacks. |
Autism | Refer to label instructions | [2 stars] In a preliminary study and a follow-up double-blind study of autistic children, daily supplementation with vitamin D was associated with improvements in various symptoms of autism. |
Burns | 200 to 600 IU day in cases of extensive burns | [2 stars] People with a history of an extensive burn might benefit from vitamin D supplementation, since the skin may not be as effective at manufacturing vitamin D from sunlight. |
Celiac Disease | Consult a qualified healthcare practitioner | [2 stars] Malabsorption-induced vitamin D deficiency can lead to bone weakening in people with celiac disease. Supplementing with vitamin D may help increase bone density.
|
Common Cold and Sore Throat | 300 IU per day for three months in winter | [2 stars] Research suggests that supplementing with vitamin D may prevent upper respiratory tract infections in people who are deficient in the vitamin, but not in those who have normal vitamin D status. |
Congestive Heart Failure | Refer to label instructions | [2 stars] In preliminary research, the prevalence of vitamin D deficiency was significantly higher in patients with congestive heart failure than in patients without it. |
Depression | 400 to 800 IU daily | [2 stars] Some studies have shown that supplementing with vitamin D leads to improved mood. |
Eczema | Refer to label instructions | [2 stars] In one preliminary trial, eczema significantly improved in people who had very low blood levels of vitamin D after supplementing with vitamin D. |
Epilepsy | Refer to label instructions | [2 stars] In a preliminary study, correcting vitamin D deficiency resulted in a decrease in the number of seizures in patients with epilepsy who had failed to respond adequately to medications. |
Fibromyalgia | Refer to label instructions | [2 stars] In a double-blind study of women with fibromyalgia who had low or moderately low blood levels of vitamin D, supplementing with vitamin D improved pain, compared with a placebo. |
Hypertension | 800 to 2,000 IU daily, ideally based on blood levels; up to 7,000 IU per day temporarily to reverse deficiency | [2 stars] Vitamin D may reduce blood pressure in hypertensive people with vitamin D deficiency. |
Influenza | 800 IU per day for two years; then 2,000 IU per day after that | [2 stars] In one study, long-term vitamin D supplementation for three years significantly reduced flu and cold symptoms.
|
Influenza and Children | 1,200 IU per day for 15 to 17 weeks | [2 stars] A study of Japanese children found that daily supplementation with vitamin D during the winter months significantly reduced the amount of times the children developed the flu.
|
Low Back Pain | Refer to label instructions | [2 stars] In people with muscle pain associated with vitamin D deficiency, supplementing with the vitamin may improve pain.
|
Lupus | Refer to label instructions | [2 stars] In a double-blind trial, people who took vitamin D daily experienced a decrease in disease activity and flare-ups. |
Metabolic Syndrome | 3 to 4,000 IU of vitamin D3 daily | [2 stars] Vitamin D deficiency increases the risk of metabolic disorders. |
Seasonal Affective Disorder | Refer to label instructions | [2 stars] Supplementing with vitamin D may improve SAD in people with low levels of the vitamin. |
Tension Headache (Calcium) | 1,000 to 1,500 mg per day (plus the same amount of calcium) | [2 stars] In preliminary research, people with chronic tension-type headaches who were also suffering from severe vitamin D deficiency experienced an improvement in their symptoms after supplementing with vitamin D and calcium.
|
Type 2 Diabetes | 1,332 IU daily | [2 stars] 4,000 IU per day |
Type 2 Diabetes and Diabetic Neuropathy | 2,000 IU of vitamin D daily for three months | [2 stars] In a preliminary trial, supplementing with vitamin D per day significantly improved pain by almost 50% in patients with diabetic neuropathy. |
Vaginitis | Refer to label instructions | [2 stars] In one double-blind trial, women with vaginitis who were not experiencing any symptoms were given vitamin D daily and had a higher cure rate than the control group. |
Alcohol Withdrawal | Refer to label instructions |  [1 star] If deficient, supplementing with this vitamin may help prevent bone loss and muscle weakness.
|
Amenorrhea and Osteoporosis (Calcium) | Refer to label instructions | [1 star] Despite the lack of evidence that calcium and vitamin D supplements alone are helpful to amenorrheic women, they are still generally recommended to prevent the added burden of calcium and vitamin D deficiency from further contributing to bone loss. |
Breast Cancer | Refer to label instructions | [1 star] Vitamin D from supplements and from exposure to the sun both appear to protect against breast cancer. |
Cardiac Arrhythmia | Refer to label instructions | [1 star] One case report described relief from a type of arrhythmia after supplementing with vitamin D.
|
Colon Cancer | Refer to label instructions | [1 star] People who take vitamin D supplements have been shown to be at low risk for colon cancer. |
Dysmenorrhea | Refer to label instructions | [1 star] In a double-blind trial, women with dysmenorrhea received a placebo or a single administration of a large amount of vitamin D, which appeared to significantly diminish menstrual pain. This should only be done under doctor supervision.
|
Hepatitis and Hepatitis C | Refer to label instructions | [1 star] In a study of people with hepatitis C who were being treated with standard medication, vitamin D supplementation increased the proportion of patients who had undetectable levels of the virus after 24 weeks of treatment. |
Migraine Headache | Refer to label instructions | [1 star] Taking large amounts of the combination of calcium and vitamin D has been reported to produce a marked reduction in the incidence of migraines in several women. |
Multiple Sclerosis | Refer to label instructions | [1 star] Studies suggest that vitamin D may help reduce the number of MS attacks and may protect against the development of the disease. |
Parkinson’s Disease | Refer to label instructions | [1 star] Vitamin D deficiency is common in Parkinson’s disease and may increase the risk of hip fracture due to osteoporosis. This risk may be reduced by taking vitamin D. |
Prostate Cancer | 2,000 IU daily | [1 star] Where sun exposure is low, the rate of prostate cancer has been reported to be high. |
Restless Legs Syndrome | Refer to label instructions | [1 star] In one small study, in people with a vitamin D blood level below 20 ng/ml, vitamin D supplementation decreased the severity of restless legs syndrome. |
Urinary Incontinence | Refer to label instructions | [1 star] Higher blood levels of vitamin D are associated with lower risk of urinary incontinence in women.
|
Vitiligo | Refer to label instructions | [1 star] When used in combination with sun exposure, a form of vitamin D called calcipotriol may be effective in stimulating repigmentation in children with vitiligo. |
Copyright © 2025 TraceGains, Inc. All rights reserved.
Learn more about TraceGains, the company.
The information presented by TraceGains is for informational purposes only. It is based on scientific studies (human, animal, or in vitro), clinical experience, or traditional usage as cited in each article. The results reported may not necessarily occur in all individuals. Self-treatment is not recommended for life-threatening conditions that require medical treatment under a doctor's care. For many of the conditions discussed, treatment with prescription or over the counter medication is also available. Consult your doctor, practitioner, and/or pharmacist for any health problem and before using any supplements or before making any changes in prescribed medications. Information expires December 2025.