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Vitamin D is also known as the "sunshine vitamin" because your body produces it from cholesterol when you expose your skin to sunlight.
This vitamin has recently received a lot of attention for its role in immune health, particularly COVID-19. It's also important for bone health and a variety of other bodily functions.
The average adult should consume 1,500–2,000 international units (IU) of vitamin D per day. While certain foods, such as fatty fish and fortified dairy products, do contain this vitamin, getting enough through diet alone is difficult.
As a result, it's no surprise that vitamin D deficiency is one of the most common nutritional deficiencies worldwide.
This article discusses vitamin D and why it is essential to get enough of it.
WHAT IS THE SIGNIFICANCE OF VITAMIN D?
Vitamin D is a fat-soluble vitamin that is essential for proper body function, including bone health and immunity. It may even help prevent cancer and protect against a number of chronic diseases, such as:
- bone loss
- depression
- Diabetes type 2
- heart disease
- multiple sclerosis
Around the world, an estimated 1 billion people have low vitamin D levels in their blood.
According to one study, nearly 42 percent of adults in the United States are vitamin D deficient. This figure rises to nearly 63 percent among Hispanic adults and 82 percent among African Americans.
WHAT ARE THE SIGNS AND SYMPTOMS OF VITAMIN D DEFICIENCY?
Vitamin D deficiency is difficult to detect because symptoms may not appear for months or years. You may not have any symptoms at all at times.
Keeping this in mind, knowing what signs and symptoms to look for is still beneficial.
- Infections or illnesses that occur frequently: One of vitamin D's most important functions is to support immune health, which aids in the defense against viruses and bacteria that cause illness.
Vitamin D interacts directly with the cells that are in charge of fighting infections. If you get sick frequently, especially with colds or the flu, low vitamin D levels may be a factor. A deficiency has been linked to respiratory tract infections such as colds, bronchitis, and pneumonia in several large observational studies.Taking up to 4,000 IU of vitamin D daily may reduce the risk of respiratory tract infections, according to several studies.Vitamin D deficiency has recently been linked to an increased risk of COVID-19, as well as an increased risk of experiencing severe symptoms from the condition. It is important to note, however, that taking vitamin D supplements – at any dose – will not prevent COVID-19.
- Bone and back pain: Inadequate vitamin D levels may cause bone and lower back pain. Vitamin D promotes bone health by improving calcium absorption in the body.
In one study of 98 adults with lower back pain, lower levels of vitamin D were linked to more severe pain. A large research review, however, discovered that this association was inconsistent across other similar studies.A meta-analysis of 81 studies also discovered that people with arthritis, muscle pain, and chronic widespread pain had lower levels of vitamin D than those who did not have these conditions. More research is still required.
- Tiredness and fatigue: Tiredness can be caused by a variety of factors, one of which is a vitamin D deficiency. In contrast to more obvious causes such as stress, depression, and insomnia, vitamin D deficiency is frequently overlooked as a potential cause of fatigue.
One study of 480 older adults found a link between vitamin D deficiency and fatigue symptoms.Furthermore, a study of 39 children found that low vitamin D levels were associated with poor sleep quality, shorter sleep duration, and later bedtimes.One observational study of female nurses discovered a strong relationship between low vitamin D levels and self-reported fatigue. Furthermore, 89 percent of those who took part were deficient in this vitamin.Interestingly, several studies have found that supplementing with this vitamin may reduce the severity of fatigue in people who are deficient. Nonetheless, more research is required.
- Depression: Vitamin D deficiency has been linked to depression, particularly in older adults, though some research findings are contradictory. The effects of vitamin D supplements have been mixed, but some studies have found that they can help relieve depression symptoms.
More research is needed to fully understand the link between vitamin D and depression.
- Wound healing impairment: Slow wound healing after surgery or injury may indicate a deficiency in vitamin D. In fact, a test-tube study found that vitamin D increases the production of compounds necessary for the formation of new skin as part of the wound-healing process.
Vitamin D deficiency hampered certain aspects of healing in people who had dental surgery, according to a review of four studies. The role of vitamin D in reducing inflammation and fighting infections may also be important for proper healing.An older study of 221 people, 112 of whom had diabetes-related foot infections, discovered that those with severe vitamin D deficiency had higher levels of inflammatory markers that can jeopardize healing.In a 12-week study of 60 people with diabetes-related foot ulcers, those who took a vitamin D supplement had significantly better wound healing than the placebo group. However, more research is required.
- Bone loss: Vitamin D is essential for calcium absorption and bone metabolism. This is significant because taking vitamin D and calcium together allows your body to maximize absorption. A decrease in bone mineral density indicates that your bones have lost calcium and other minerals. This puts older people, particularly women, at a higher risk of fractures. Researchers discovered a strong link between low vitamin D levels and low bone mineral density in a large observational study of over 1,100 middle-aged menopausal or postmenopausal women.
However, studies on vitamin D supplementation therapy in independent older adults have produced conflicting results. While some studies show some benefits, such as reduced muscle pain, others have found that it does not prevent fractures caused by bone loss.According to one study, women who were deficient in vitamin D saw no improvement in bone mineral density when they took high dose supplements, even though their blood levels improved.Nonetheless, getting enough vitamin D may be a good way to protect your bone mass and lower your risk of fracture.
- Loss of hair: Many foods and nutrients can have an impact on hair health. While stress is a common cause of hair loss, severe hair loss can be caused by a disease or a nutrient deficiency. Women's hair loss has been linked to low vitamin D levels, though research is limited. Low vitamin D levels, in particular, have been linked to alopecia areata, an autoimmune disease characterized by severe hair loss.
In one study of people with this condition, lower vitamin D levels were linked to more severe hair loss. Another study in 48 people with this condition found that applying a synthetic form of vitamin D topically for 12 weeks increased hair regrowth significantly.According to another study, vitamin D levels may have an inverse relationship with non-scarring hair loss. This means that the higher the vitamin D levels, the less hair loss was discovered in the study, and vice versa.
- Weight gain: One risk factor for vitamin D deficiency is obesity. One adult study discovered a possible link between low vitamin D status and both belly fat and increased weight, though the effects were more pronounced in men.
While vitamin D deficiency has been linked to obesity, more research is needed to determine whether supplementing with this vitamin can help prevent weight gain.
- Muscle pain: Muscle pain is frequently difficult to diagnose. However, evidence suggests that vitamin D deficiency may be a contributing factor. In an earlier study, 71 percent of people with chronic pain were found to have a vitamin deficiency.
The vitamin D receptor is found in pain-sensing nerve cells called nociceptors. This vitamin may also be involved in pain signaling pathways in your body, which may play a role in chronic pain.According to a few studies, high-dose vitamin D supplements may reduce various types of pain in people who are vitamin D deficient. In one study of 120 children with vitamin D deficiency who were experiencing growing pains, a single dose of this vitamin reduced pain scores by an average of 57%.
- Anxiety: Anxiety disorders have been linked to vitamin D deficiency. According to one study, people with anxiety and depression had lower levels of calcidiol, a type of vitamin D.
A separate study in pregnant women discovered that adequate vitamin D levels can help reduce anxiety symptoms, improve sleep quality, and even prevent postpartum depression. More research is still required.
WHAT ARE THE CAUSES OF VITAMIN D DEFICIENCY?
Blood levels of vitamin D below 20 ng/mL are considered deficient, while levels between 21–29 ng/mL are considered insufficient.
While there is no single cause of deficiency, your overall risk may be increased due to underlying conditions or lifestyle factors. The following are some of the most common risk factors for vitamin D deficiency:
- possessing dark skin
- growing older
- being overweight or obese
- not eating a lot of fish or dairy
- living far away from the equator or in areas with little sunlight all year
- staying or working at home
- working on the overnight shift
- afflicted with chronic kidney disease, liver disease, or hyperparathyroidism
- having a disease that impairs nutrient absorption, such as Crohn's disease or celiac disease
- undergoing gastric bypass surgery
- using certain medications, such as statins and steroids, that affect vitamin D metabolism
People who live near the equator and get plenty of sun are less likely to be deficient because their skin produces enough vitamin D.
While people who frequently wear sunscreen outside are at a higher risk of deficiency, using sunscreen is important to reduce skin damage and cancer risk from sun exposure.
If you are at high risk of vitamin D deficiency, speak with a healthcare professional about your vitamin D status.
VITAMIN D DEFICIENCY TESTS
Simple blood tests can help determine whether you are deficient in vitamin D. This vitamin can be found in two forms in your blood:
- 25-hydroxy vitamin D (25-OH D), or calcidiol
- 1,25-dihydroxy vitamin D, or calcitriol
The 25-hydroxy vitamin D test is the most commonly used test for vitamin D deficiency. This is due to the fact that 25-hydroxy, or calcidiol, has higher concentrations and remains in your blood longer, making it easier to detect.
You may also be able to perform an at-home test in which you collect a small drop of blood yourself via a simple finger prick. These tests are simple and convenient, but you may still need the assistance of a healthcare professional to interpret the results.
HOW IS VITAMIN D DEFICIENCY TREATED?
Supplements are typically used to treat vitamin D deficiency. If a healthcare professional discovers that you have a deficiency, they may suggest the following treatments.
- Supplements: Vitamin D deficiency is typically treated with oral supplements. You can get these over the counter, but you should consult a doctor for dosage recommendations.
Magnesium aids in the activation of vitamin D, so you may want to supplement with this mineral as well. A doctor may prescribe prescription vitamin D for severe deficiency, which comes in much higher doses of up to 50,000 IU. Vitamin D injections may also be recommended by your doctor.
- Food sources: Consuming more vitamin D-rich foods may also help. Among the options are:
- fatty fish
- egg yolks
- fortified cereals
- fortified milk and juices
- yogurt
- beef liver
Because sunlight is a natural source of vitamin D, your doctor may also advise you to spend more time outside. However, given the negative effects of excessive ultraviolet exposure, it's critical to take precautions such as limiting your total time in the sun and using sunscreen.
CONCLUSION
Vitamin D deficiency is surprisingly common, but the symptoms are often subtle and nonspecific, making it difficult to distinguish between a deficiency and another health condition.
If you suspect you have a deficiency, consult a healthcare professional about getting a blood test.
Vitamin D deficiency is typically treated with supplements, but the correct dosage may necessitate the advice of a doctor. Getting more sun and eating more vitamin D-rich foods like fatty fish and fortified dairy products can also help.
Addressing a vitamin D deficiency is worthwhile and can have long-term health benefits.