Considered as one of the most important nutrients, vitamin D influences the functioning of several systems in the human body. Every cell in the body has a receptor for vitamin D. Vitamin D is different from other vitamins in that it functions as a hormone.
Key Facts By Numbers
- Key Hormone: Vitamin D is infact a key hormone.
- Sun: Not enough sun exposure in current lifestyle to produce sufficient vitamin D.
- 70-100%: Is the prevalence of vitamin D deficiency in the Indian population.
- 200+: Vitamin D is a cofactor in more than 200 physiological functions.
- <30 ng/ml: Less than 30 ng/ml is considered to be insufficient.
- <20 ng/ml: Less than 20 ng/ml is considered to be deficient.
- 50-60 ng/ml: is considered to be optimal.
- >150 ng/ml: More than 150 ng/ml is considered to be toxic.
- 60000 IU: 60000 IU once per week is well tolerated and easy to follow.
A particularly well-known aspect of vitamin D is that it can be produced from cholesterol when the skin is exposed to sunlight.
The recommended daily intake (RDI) of vitamin D is 400 to 800 IU, with some experts stating that the requirement could be much more. This usually remains unfulfilled by a regular diet. Even foods that contain vitamin D like fortified dairy products or fatty fish have proven to be insufficient.
This could probably be the reason why an estimated 1 billion individuals worldwide are said to be deficient in vitamin D.
What are the guidelines for vitamin D dosage?
- Sufficient: above 30 ng/ml
- Optimal: 50- 60 ng/ml
- Safe upper limit: 100 ng/ml
- Toxic: Above 100 ng/mL
What are some of the common risk factors for vitamin D deficiency?
Some of the common risk factors for vitamin D deficiency are listed below:
- Dark skin tone
- Being in the older age group
- Being obese
- Inadequate amount of fish or dairy products in the diet
- Living away from the tropics
- Overuse of sunscreen
- Being sedentary
People who live in locations where there is adequate exposure to sunlight, such as the tropics are usually not deficient in vitamin D.
What are the signs and symptoms of vitamin D deficiency?
Symptoms of vitamin D are usually subtle, and most people do not recognize the effect it has on their quality of life.
Some of the common symptoms of vitamin D deficiency are listed below:
- Frequent sickness and infections
- Frequent tiredness or fatigue
- Back pain
- Weakened healing process
- Low bone-mineral density
- Hair loss
- Pain in the muscles
Frequent Sickness And Infections
Vitamin D interacts directly with the cells of the immune system aiding in protecting the body against bacterial and viral infections.
Hence, vitamin D deficiency could be a reason why individuals frequently catch infectious conditions like flu or common cold.
Studies have shown that a daily dosage of 4000 IU of vitamin D per day reduces the risk of respiratory tract infections like cold, bronchitis, and pneumonia.
In a study involving subjects with chronic obstructive pulmonary disease (COPD), a lung disorder, those who were severely deficient in vitamin D, benefited from a high dose of the supplement for 12 months.
Other studies have shown that 4000 IU per day dosage of vitamin D supplement reduces the risk of respiratory tract infections.
Frequent Tiredness Or Fatigue
Vitamin D deficiency is one of the causes of frequent tiredness. According to case studies, low blood levels of vitamin D causes fatigue which has an adverse effect on the quality of life. By standard, less than 20 ng/ml of blood of vitamin D is considered a deficiency.
In one particular case a woman who complained of chronic daytime fatigue and headache. A blood test showed a vitamin D level of only 5.9 ng/ml. When she started taking vitamin D supplements, and the blood levels raised to 39 ng/ml, the symptoms disappeared.
However low blood levels are not the only indicators of vitamin D deficiency. In fact, a study reported that young women with vitamin D levels below 20 ng/ml or between 21-29 ng/ml, were more likely to complain of fatigue than those with blood levels over 30 ng/ml.
Furthermore, researchers found that 89% nurses were deficient in vitamin D.
Vitamin D helps in the absorption of calcium by the body thereby playing a role in maintaining healthy bones. Lower back pain and bone pain may indicate low blood vitamin D levels. This is supported by the results of large observational studies
Another controlled study reported that individuals with vitamin D deficiency were almost two times likely to have pain in their lower limbs, ribs or joints compared to those with normal vitamin D levels.
Depression may also be a sign of vitamin D deficiency. Literature reviews have reported an association between vitamin D deficiency and depression, especially in older adults.
Although this is unsupported by more robust controlled trials, 65% of the observational studies showed a relationship between low blood vitamin D levels and depression.
It is must be noted however that experts who analyzed the different studies observed that the dosage of vitamin D used to conduct the controlled studies were low and the time period of the study was also too low to draw a credible conclusion.
Other controlled studies showed improvement in symptoms of depressed individuals who started taking vitamin D supplements.
Weakened Healing Process
Low levels of vitamin D may also result in slow healing of wounds after an injury or surgery. Some studies suggest that the anti-inflammatory and immune system strengthening function of vitamin D could be the reason for this.
A study on subjects who had undergone a dental surgery indicated that vitamin D deficiency led to a lack of certain aspects of healing. An in-vitro study showed that vitamin D enhances the productions of biochemicals which are important for wound-healing and formation of new skin.
Another analysis involving patients with diabetic foot infections showed that those with severe vitamin D deficiency have higher levels of inflammatory markers that can compromise healing.
Other than one study that showed a decrease in size of leg ulcers on patients who were treated with vitamin D supplements there is very little research on the effects of this vitamin on wound healing in people who are deficient.
Low Bone Mineral Density
Older people who are diagnosed with bone loss usually think that the reason could be low calcium levels. However, this may also be due to deficiency of vitamin D since they play a vital role in calcium absorption and bone metabolism.
Older adults and women are the high risk groups with regard to fractures due to low bone mineral density.
Nevertheless, maintaining an optimal level of vitamin D in the blood may be a good approach to protect bone mass and reduce risk of fracture.
Although hair loss is often attributed to stress, severe cases could also indicate a nutrient deficiency. Hair loss in women has been associated with vitamin D levels. It is also associated with certain diseases.
Alopecia areata, an autoimmune disease characterized by severe hair loss from the head and other parts of the body is linked to rickets (soft bones), a vitamin D deficiency in children.
This link has also been reported by a study which showed that individuals with low vitamin D levels and alopecia areata had more severe hair loss. One particular case study highlighted the successful treatment of hair loss in a young boy by topical application of a synthetic form of vitamin D.
Pain In The Muscles
Vitamin D deficiency could be a potential cause of muscle pain in children and adults. A particular study reported that 71% people with chronic muscle pain were vitamin D deficient.
Nociceptors are vitamin D receptors that function as pain receptors. They are found in nerve cells. A study in rats showed that vitamin D deficiency led to pain and sensitivity on stimulation of the nociceptors in the muscles.
In another study 120 children with vitamin D deficiency and growing pains were given a single high dose of vitamin D. The results showed that the pain scores were reduced by 57%.
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Vitamin D deficiency is very common but subtle. It is difficult to detect since the symptoms are nonspecific. However, it can be treated easily by either increasing exposure to the sun, by eating more vitamin D rich foods or by taking supplements.
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