Vitamin D is a fat-soluble vitamin that helps the body absorb dietary calcium and phosphorus from the intestines. Vitamin D also suppresses the release of parathyroid hormone, a hormone that causes bone resorption.
Vitamin D is produced in the skin when it is exposed to sunlight. Vitamin D also occurs naturally in certain foods such as fatty fish, cod liver oil, and eggs. It is also found in fortified foods such as cow’s milk.
In the body, vitamin D assists with the following functions:
- Bone health and reduced risk of osteoporosis
- Strengthens muscles
- Helps with immune system function
- Reduces inflammation
- Aids in glucose (sugar) metabolism which may help prevent diabetes
- Helps promote heart health and lowers the risk of cardiovascular disease
- Lowers the risk of tooth decay and gum disease
Vitamin D may also help:
- Reduce the risk of death from breast, colorectal, pancreatic, and prostate cancers
- Treat high blood pressure (hypertension)
- Treat depression
- Reduce the risk of contracting multiple sclerosis (MS) and, once MS is present, decrease the risk of relapse and slow the disease’s progression
- With weight loss
What Is Vitamin D Deficiency?
Symptoms of vitamin D deficiency (low levels of vitamin D) include:
- Bone problems
- Fractures
- Pain due to softening of bones (osteomalacia)
- Bone deformities such as rickets in children
- Abnormal bone growth in children aged 1 to 4 years, causing scoliosis, bowlegs, or knock-knees
- Muscle weakness
- Muscle aches or cramps
- Muscle spasms
- Fatigue
- Cognitive impairment in older adults
- Severe asthma in children
- Cancer
Are There Risks of Taking Vitamin D Supplements?
Excess amounts of vitamin D are toxic. Vitamin D toxicity is unlikely to occur from too much sun exposure or by eating foods high in vitamin D, but toxicity may occur from taking vitamin D supplements inappropriately or in excessive amounts. Too much vitamin D can lead to high blood calcium levels (hypercalcemia) and high calcium levels in the urine (hypercalciuria).
Hypercalcemia can cause symptoms such as:
- Nausea
- Vomiting
- Muscle weakness
- Kidney stones
- Pain
- Loss of appetite
- Dehydration
- Increased urine production
- Excessive thirst
- Neuropsychiatric disturbances
Severe cases of vitamin D toxicity can lead to:
- Kidney failure
- Calcification of soft tissues throughout the body (including in coronary vessels and heart valves)
- Irregular heartbeats (cardiac arrhythmias)
- Death
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