Vitamin D is often referred to as the “sunshine vitamin” because it’s produced naturally by your body when your skin is directly exposed to sunlight.
Your body can also get Vitamin D from foods such as oily fish, red meat and egg yolks. As it can be difficult to get enough Vitamin D from diet alone, NHS UK advises that everyone should consider taking a supplement during Autumn and Winter.
Vitamin D has several important functions. Perhaps the most vital are regulating the absorption of calcium and phosphorus, and facilitating normal immune system function. Getting a sufficient amount of vitamin D is important for normal growth and development of bones and teeth, as well as improved resistance against certain diseases.
If your body doesn’t get enough vitamin D, you’re at risk of developing bone abnormalities such as soft bones (osteomalacia) or fragile bones (osteoporosis).
Benefits Of Vitamin D
Vitamin D has multiple roles in the body. It assists in:
- promoting healthy bones and teeth
- supporting immune, brain, and nervous system health
- regulating insulin levels and supporting diabetes management
- supporting lung function and cardiovascular health
- influencing the expression of genes involved in cancer development
1. Healthy bones
Vitamin D plays a significant role in the regulation of calcium and maintenance of phosphorus levels in the blood. These factors are vital for maintaining healthy bones.
People need vitamin D to allow the intestines to stimulate and absorb calcium and reclaim calcium that the kidneys would otherwise excrete.
Vitamin D deficiency in children can cause rickets, which leads to a severely bowlegged appearance due to the softening of the bones.
Similarly, in adults, vitamin D deficiency manifests as osteomalacia, or softening of the bones. Osteomalacia results in poor bone density and muscular weakness.
A vitamin D deficiency can also present as osteoporosis.
2. Healthy infants
Vitamin D deficiency has links to high blood pressure in children. One 2018 study found a possible connection between low vitamin D levels and stiffness in the arterial walls of children.
The American Academy of Allergy Asthma and Immunology (AAAAI) suggest that evidence points to a connection between low vitamin D exposure and an increased risk of allergic sensitization.
An example of this is children who live closer to the equator and have lower rates of admission to hospital for allergies plus fewer prescriptions of epinephrine autoinjectors. They are also less likely to have a peanut allergy.
The AAAAI also highlight an Australian study of egg intake. Eggs are a common early source of vitamin D. The children who started eating eggs after 6 months were more likely to develop food allergies than children who started between 4–6 months of age.
Furthermore, vitamin D may enhance the anti-inflammatory effects of glucocorticoids. This benefit makes it potentially useful as a supportive therapy for people with steroid resistant asthma.
3. Healthy pregnancy
A 2019 review suggests that pregnant women who are deficient in vitamin D may have a greater risk of developing preeclampsia and giving birth preterm.
Doctors also associate poor vitamin D status with gestational diabetes and bacterial vaginosis in pregnant women.
It is also important to note that in a 2013 study, researchers associated high vitamin D levels during pregnancy with an increased risk of food allergy in the child during the first 2 years of life.
2. Reduced risk of flu
A 2018 review of existing research suggested that some studies had found that vitamin D had a protective effect against the influenza virus.
However, the authors also looked at other studies where vitamin D did not have this effect on flu and flu risk.
Further research is, therefore, necessary to confirm the protective effect of vitamin D on the flu.
Causes of Vitamin D Deficency
Although the body can create vitamin D, a deficiency can occur for many reasons.
Skin type: Darker skin, for example, and sunscreen, reduce the body’s ability to absorb the ultraviolet radiation B (UVB) rays from the sun. Absorbing sunlight is essential for the skin to produce vitamin D.
Sunscreen: A sunscreen with a sun protection factor (SPF) of 30 can reduce the body’s ability to synthesize the vitamin by 95% or more. Covering the skin with clothing can inhibit vitamin D production also.
Geographical location: People who live in northern latitudes or areas of high pollution, work night shifts, or are homebound should aim to consume vitamin D from food sources whenever possible.
Breastfeeding: Infants who exclusively breastfeed need a vitamin D supplement, especially if they have dark skin or have minimal sun exposure. The American Academy of Pediatrics recommend that all breastfed infants receive 400 international units (IU) per day of oral vitamin D.
Although people can take vitamin D supplements, it is best to obtain any vitamins or minerals through natural sources wherever possible.
Symptoms of Vitamin D deficency
- regular sickness or infection
- bone and back pain
- low mood
- impaired wound healing
- hair loss
- muscle pain
If Vitamin D deficiency continues for long periods, it may result in further complications, such as:
- cardiovascular conditions
- autoimmune problems
- neurological diseases
- pregnancy complications
- certain cancers, especially breast, prostate, and colon.
Good Sources of Vitamin D
- Fatty fish
- beef liver
- fortified milk
- fortified cereals and juices
- egg yolks
How much vitamin D you need depends on many factors. These include:
- sun exposure
This is only a partial list of factors that help determine the amount of vitamin D a person needs.
NHS UK recommends an average daily intake of at least 10 micrograms (400 IU) and no more than 100 micrograms (4000IU) for adults and children over 10. Children aged 1-10 should not exceed 50 micrograms (2,000 IU) a day and babies under 1 year old should not have more than 25 micrograms (1,000 IU) a day.
Some studies find that the daily intake needs to be higher if you aren’t being exposed to the sun or have darker skin tones.
Studies in postmenopausal women with vitamin D levels below 20 ng/ml found that ingesting 800–2,000 IU raised blood levels above 20 ng/ml. However, higher doses were needed to reach 30 ng/ml.
People who are overweight or have obesity and postmenopausal women may also need higher amounts of vitamin D.
All things considered, a daily vitamin D intake of 1,000–4,000 IU, or 25–100 micrograms, should be enough to ensure optimal blood levels for most people.
Vitamin D is essential for bone health and many other aspects of health. Deficiency is prevalent and may have health consequences for many people. If you’re thinking about adding more vitamin D to your diet and have any concerns or questions, always consult a healthcare professional.