Vitamin D

What is it?

Vitamin D is an essential vitamin that helps regulate calcium and phosphorus in the body. It also plays a role in maintaining proper bone structure.

There are different forms of vitamin D, including ergocalciferol (vitamin D2) and cholecalciferol (vitamin D3). Vitamin D is found in fish, eggs, and fortified milk. It’s also made in the skin when exposed to sunlight. During periods of sunlight, vitamin D is stored in fat and then released when sunlight is not available.

Vitamin D supplements are commonly used to treat and prevent vitamin D deficiency. People who don’t get enough sun and people who are 65 years or older are at risk for deficiency. People also use vitamin D for weak and brittle bones, heart disease, asthma, hay fever, and many other conditions, but there’s no good scientific evidence to support many of these uses. There is also no strong evidence to support using vitamin D supplements for COVID-19. But it is important to maintain healthy levels of vitamin D. This can be done by taking 400-1000 IU of vitamin D daily or spending 15-30 minutes in the sun each day.

Is it effective?

NatMed Pro rates effectiveness based on scientific evidence according to the following scale: Effective, Likely Effective, Possibly Effective, Possibly Ineffective, Likely Ineffective, Ineffective, and Insufficient Evidence to Rate.

Effective for …

A rare, inherited bone disorder marked by low levels of phosphate in the blood (familial hypophosphatemia). Taking specific forms of vitamin D, called calcitriol or dihydrotachysterol, by mouth along with phosphate supplements is effective for treating bone disorders in people with low levels of phosphate in the blood.
Underactive parathyroid (hypoparathyroidism). Taking specific forms of vitamin D, called dihydrotachysterol, calcitriol, or ergocalciferol, by mouth is effective for increasing calcium blood levels in people with low parathyroid hormone levels.
Softening of the bones (osteomalacia). Taking vitamin D3 by mouth is effective for treating this condition.
A bone disorder that occurs in people with kidney disease (renal osteodystrophy). Taking a specific form of vitamin D, called calcitriol, by mouth helps to manage low calcium levels and prevent bone loss in people with kidney failure.
Rickets. Taking vitamin D by mouth is effective for preventing and treating rickets. A specific form of vitamin D, called calcitriol, should be used in people with kidney failure.
Vitamin D deficiency. Taking vitamin D by mouth is effective for preventing and treating vitamin D deficiency.

Probably Effective for …

Bone loss in people taking drugs called corticosteroids. Taking vitamin D by mouth prevents bone loss in people taking drugs called corticosteroids. Also, taking vitamin D alone or with calcium seems to improve bone density in people with existing bone loss caused by using corticosteroids.
Weak and brittle bones (osteoporosis). Taking vitamin D3 by mouth along with calcium seems to help prevent bone loss and bone breaks in people with osteoporosis.
Psoriasis. Applying vitamin D in the form of calcitriol, calcipotriene, maxacalcitol, or paricalcitol to the skin can help treat plaque-type psoriasis. Applying vitamin D along with corticosteroids seems to work better than applying vitamin D or corticosteroids alone. But taking vitamin D by mouth doesn’t seem to help.

Possibly Effective for …

Hay fever. Taking vitamin D by mouth seems to reduce symptoms of hay fever in adults and children. But it isn’t clear if taking vitamin D during pregnancy can help to prevent hay fever in the child after birth.
Cavities. Taking vitamin D2 or D3 by mouth reduces the risk of cavities by 36% to 49% in infants, children, and adolescents.
Heart failure. Taking vitamin D by mouth can help reduce the risk of developing heart failure in some people. But it doesn’t seem to help patients who already have heart failure.
Bone loss in people with overactive parathyroid (hyperparathyroidism-related bone loss). Taking vitamin D3 by mouth seems to reduce parathyroid hormone levels and bone loss in people with a condition called hyperparathyroidism.
Infection of the airways. Taking vitamin D by mouth helps prevent respiratory infections in children. But taking vitamin D by mouth during pregnancy doesn’t seem to reduce the risk of these infections in the child after birth. It also doesn’t help prevent infections in adults.
Preventing tooth loss (tooth retention). Taking calcium and vitamin D3 by mouth appears to prevent tooth loss in elderly people.

Possibly Ineffective for …

Heart disease. Taking a vitamin D supplement by mouth doesn’t seem to prevent heart disease, heart attack, stroke, or other serious heart-related events in most people.
Critical illness (trauma). Giving vitamin D to people with low vitamin D levels who are in the hospital with a critical illness doesn’t make them more likely to live.
Fractures. Taking vitamin D by mouth doesn’t seem to prevent fractures in older people who do NOT have osteoporosis.
High blood pressure. Taking vitamin D by mouth doesn’t seem to lower blood pressure in most people with high blood pressure. But it might help people who have very low blood levels of vitamin D.
A mental disorder marked by hallucinations and delusion (psychosis). Taking vitamin D by mouth doesn’t seem to improve symptoms of psychosis in adults.
Prostate cancer. Taking vitamin D by mouth doesn’t seem to reduce cancer progression or death from prostate cancer.
Tuberculosis. Most research shows that taking vitamin D by mouth doesn’t help to cure tuberculosis or make it less severe.

There is interest in using vitamin D for a number of other purposes, but there isn’t enough reliable information to say whether it might be helpful.

Is there concern for the safety of its use?

When taken by mouth: Vitamin D is likely safe when taken in recommended amounts. Most people don’t experience side effects with vitamin D, unless too much is taken. Some side effects of taking too much vitamin D include weakness, dry mouth, nausea, vomiting, and others. Taking vitamin D for long periods of time in doses higher than 4000 IU (100 mcg) daily is possibly unsafe and may cause very high levels of calcium in the blood.

Special Precautions & Warnings:

Pregnancy and breast-feeding: Vitamin D is likely safe during pregnancy and breast-feeding when used in daily amounts below 4000 IU (100 mcg). Do not use higher doses unless instructed by your healthcare provider. Vitamin D is possibly unsafe when used in higher amounts during pregnancy or while breast-feeding. Using higher doses might cause harm to the infant.

Children: Vitamin D is likely safe in children when taken by mouth in recommended amounts. But it is possibly unsafe to take vitamin D in higher doses, long-term. Infants from 0-6 months should not take more than 1000 IU (25 mcg) daily. Infants aged 6-12 months should not take more than 1500 IU (37.5 mcg) daily. Children aged 1-3 years should not take more than 2500 IU (62.5 mcg) daily. Children aged 4-8 years should not take more than 3000 IU (75 mcg) daily. Children aged 9 years and older should not take more than 4000 IU (100 mcg) daily.

Hardening of the arteries (atherosclerosis): Taking vitamin D could make this condition worse, especially in people with kidney disease.

A type of fungal infection called histoplasmosis: Vitamin D might increase calcium levels in people with histoplasmosis. This could lead to kidney stones and other problems. Use vitamin D cautiously.

High levels of calcium in the blood: Taking vitamin D could make this condition worse.

Over-active parathyroid gland (hyperparathyroidism): Vitamin D might increase calcium levels in people with hyperparathyroidism. Use vitamin D cautiously.

Lymphoma: Vitamin D might increase calcium levels in people with lymphoma. This could lead to kidney stones and other problems. Use vitamin D cautiously.

Kidney disease: Vitamin D might increase calcium levels and increase the risk of “hardening of the arteries” in people with serious kidney disease. Calcium levels should be monitored carefully in people with kidney disease.

A disease that causes swelling (inflammation) in body organs, usually the lungs or lymph nodes (sarcoidosis): Vitamin D might increase calcium levels in people with sarcoidosis. This could lead to kidney stones and other problems. Use vitamin D cautiously.

Tuberculosis: Vitamin D might increase calcium levels in people with tuberculosis. This could lead to kidney stones and other problems. Use vitamin D cautiously.