Benefits of vitamin D

The human body produces vitamin D when exposed to sunlight.

Vitamin D has many functions in the body. It helps:

• Promotes healthy bones and teeth
• Supports immune, brain and nervous system health
• Regulate insulin levels and support diabetes management
• Supports lung function and cardiovascular health
• Influences the expression of genes involved in cancer development

Healthy bones

Vitamin D plays an important role in regulating calcium and maintaining phosphorus levels in the blood. These factors are essential for maintaining healthy bones.

People need vitamin D to stimulate and absorb calcium in the intestines and to recycle calcium that would otherwise be excreted by the kidneys.

Vitamin D deficiency in children can cause rickets, a severe bow-legged appearance due to softening of the bones.

Similarly, in adults, vitamin D deficiency manifests as osteomalacia, or softening of the bones. Osteomalacia causes poor bone density and muscle weakness.

Vitamin D deficiency can also manifest as osteoporosis, for which more than 53 million people in the United States seek treatment or are at increased risk.

Reduce the risk of influenza

A 2018 review of existing research shows that some studies have found that vitamin D has a protective effect against influenza viruses.

However, the authors also looked at other studies in which vitamin D had no such effect on influenza and flu risk.

Therefore, further research is necessary to confirm the protective effect of vitamin D against influenza.

Healthy baby

Vitamin D deficiency is linked to high blood pressure in children. A 2018 study found a possible connection between low vitamin D levels and stiffness of arterial walls in children.

The American Academy of Allergy, Asthma and Immunology (AAAAI) states that there is evidence of a link between low vitamin D exposure and an increased risk of allergic sensitization.

An example of this is that children who live near the equator have lower rates of hospitalization for allergies and fewer prescriptions for epinephrine auto-injectors. They are also less likely to be allergic to peanuts.

AAAAI also highlights Australian research on egg intake. Eggs are a common early source of vitamin D. Children who start eating eggs after 6 months are more likely to develop food allergies than children aged 4-6 months.

In addition, vitamin D can enhance the anti-inflammatory effects of glucocorticoids. This benefit makes it potentially useful as supportive therapy for people with steroid-resistant asthma.

Healthy Pregnancy

A 2019 review suggests that pregnant women who are vitamin D deficient may be at greater risk of developing preeclampsia and premature birth.

Doctors have also linked poor vitamin D status to gestational diabetes and bacterial vaginosis in pregnant women.

It's also important to note that in a 2013 study, researchers linked high vitamin D levels during pregnancy to an increased risk of food allergies in babies during the first two years of life.

Although the body can produce vitamin D, there are many causes of vitamin D deficiency.

Reasons

Skin type: For example, darker skin and sunscreen can reduce the body's ability to absorb ultraviolet radiation B (UVB) rays from the sun. Absorbing sunlight is essential for the skin to produce vitamin D.

Sunscreen: Sunscreen with a sun protection factor (SPF) of 30 can reduce the body's ability to synthesize vitamins by more than 95%. Covering the skin with clothing can also inhibit the production of vitamin D.

Geographical location: People who live in northern latitudes or areas with high pollution, work night shifts, or are homebound should get as much vitamin D as possible from food.

Breastfeeding: Babies who are exclusively breastfed need vitamin D supplements, especially if they have dark skin or have little sun exposure. The American Academy of Pediatrics recommends that all breastfed infants receive 400 international units (IU) of oral vitamin D daily.

While people can take vitamin D supplements, it is best to get any vitamin or mineral from natural sources whenever possible.

Symptoms

Symptoms of vitamin DD deficiency may include:

• Frequently sick or infected
• Fatigue
• Bone and back pain
• Depressed
• Impaired wound healing
• Hair loss
• Muscle pain

If vitamin D deficiency persists for a long time, it may lead to complications such as:

• Cardiovascular disease
• Autoimmune issues
• Nervous system diseases
• Infection
• Pregnancy complications
• Certain cancers, especially breast, prostate, and colon cancer.

Getting enough sunlight is the best way to help your body produce enough vitamin D. Rich food sources of vitamin D include:

• Fatty fish such as salmon, mackerel and tuna
• Egg yolk
• Cheese
• Beef liver
• Mushrooms
• Fortified milk
• Fortified cereals and juices

People can measure vitamin D intake in micrograms (mcg) or international units (IU). One microgram of vitamin D equals 40 IU.

The recommended daily intake of vitamin D is as follows:

• Infants 0-12 months: 400 IU (10 mcg).
• Children 1-18 years: 600 IU (15 mcg).
• Adults under 70 years of age: 600 IU (15 mcg).
• Adults 70 years and older: 800 IU (20 mcg).
• Pregnant or nursing women: 600 IU (15 mcg).

Most people can produce enough vitamin D with 5-10 minutes of reasonable sun exposure on bare skin 2-3 times a week. However, vitamin D breaks down very quickly, which means storage may be reduced, especially in the winter.

The upper limit of vitamin D recommended by health care professionals is 4,000 IU per day for an adult. However, the National Institutes of Health (NIH) states that vitamin D toxicity is unlikely at intakes of less than 10,000 IU per day.

Excessive intake of vitamin D can lead to excessive calcification of bones and hardening of blood vessels, kidneys, lungs and heart tissue.

The most common symptoms of excess vitamin D include headache and nausea. However, too much vitamin D can also lead to:

• Loss of appetite
• Dry mouth
• Metallic taste
• Vomiting
• Constipation
• Diarrhea

Excessive vitamin D is usually caused by taking too many supplements. It’s best to get vitamin D from natural sources.

If someone is taking supplements, they should choose their brand carefully because the FDA does not monitor supplements for safety or purity.

Overall diet and eating patterns are most important for disease prevention and good health. It's best to eat a diet that contains a variety of nutrients, rather than focusing on one nutrient, as this is key to staying healthy.