Contents
Introduction
Vitamin deficiency occurs when the body does not get the recommended daily dose of vitamins from any of the natural sources . And the most common types of vitamin deficiency is vitamin D deficiency. It is prevalent in all age groups. The major reason for this deficiency could be the decreased exposure to sunlight. Moreover, our body produces most of the vitamins needed, with the help of the precursors we derive from the food that we eat. In general, vitamins can be either be fat-soluble or water-soluble. Vitamin D is soluble in fat. This vitamin is necessary for the body’s absorption of calcium and the proper functioning of the bones. And the deficiency of this vitamin can cause diseases like rickets and osteromalacia (in children) and osteoporosis (in adults). Thus, vitamin D plays a major role in the proper functioning of the nervous, and immune system, and muscles.
Activation of vitamin D
Vitamin D synthesis begins in the skin. During exposure to sunlight , the epidermis, or topmost layer of skin interacts with the ultraviolet radiation from the sun. As a result of this interaction the Provitamin D3 is converted to previtamin D3. Then, this previtamin D3 is converted to colecalciferol (vitamin D3) . Ergocalciferol, or vitamin D2, is mostly obtained by diet, primarily from plants. Ergosterol and cholecalciferol undergo additional conversion in the liver, where the enzyme 25-hydroxylase changes them into 25-hydroxyvitamins D2 and D3, respectively.
Later on the 25 hydroxyvitamin D2 and D3, are converted to 1,25- dihydroxyvitamin D (vitamin D) by the enzyme 1-alpha-hydroxylase present in the kidney. This is the active form of vitamin D, and it increases the absorption of calcium in the intestine, thereby helping in the reabsorption of calcium by bone, and it also prevents the excessive loss of calcium and phosphate by the kidney through urine.
Causes of vitamin D deficiency
Lack of sunlight exposure
Exposure to sunlight is the major source of vitamin D in our body. At least, a minimum of 20 minutes exposure to sunlight is necessary. Mostly, people refrain from this because exposure to sunlinght causes aging and tanning. In older people and people with dark skin colour only a small amount of vitamin D synthesis occurs through this process. And, people who are mainly staying indoors due to work conditions or hospitalization have limited exposure to sunlight, as a result, they suffer from vitamin D deficiency.
Dietary factors and malabsorption
Other than sunlight exposure, dietary intake of vitamin D is the major source of vitamin D in our body. In children and old people, the dietary intake is lower, because they do not prefer certain foods or because it does not suit them. Thus, resulting in vitamin D deficiency in them. Also vitamin D deficiency occurs in individuals suffering from diseases like Crohn’s disease, cystic fibrosis, and celiac disease that affects the absorption of vitamin D from the food .
Kidney and liver diseases
As the liver and kidney are the places where vitamin D is converted to its active form, any disease condition that affects the proper functioning of these organs can cause a significant decrease in the levels of this vitamin.
Gastric bypass surgery
Some individuals undergo gastric bypass surgery to help with weight loss. Through this procedure, a part of the small intestine is bypassed. The small intestine is the part of the digestive tract where digestion of food gets completed and nutrients are absorbed by the body. As a part of the small intestine is bypassed, the absorption of vitamin D is affected, and as a result, a deficiency condition can arise.
Obesity
Obesity is a condition where there are a lot of fats in the body of an individual. These fats can prevent the utilization of vitamin D by binding to it. This causes the storage of vitamin D in the fat cells of the body, and only low levels are present in the blood.
Medication
Some of the medicines can prevent the absorption of vitamin D in the body. These drugs include
- Cholesterol drug
- Anti-seizure drug
- Anti-depression drug
- Sterols
- Weight-loss medicines
Symptoms of vitamin D deficiency
Some of the common symptoms of vitamin D deficiency include
- Improper growth and bowed legs in children, in case of severe deficiency
- Deformed joints
- Fatigue and tiredness
- Bone and back pain
- Depression and mood swings
- Impaired wound healing
- Bone loss and weakness
- Hair loss
- Muscle pain
- Frequent infections
Recommended dosage of vitamin D
Age group | Recommended dosage |
---|---|
Birth to 12 months | 400 IU |
Children 1-13 years | 600 IU |
Teens 14-18 years | 600 IU |
Adults 19-70 years | 600 IU |
Adults 71 years and older | 800 IU |
Pregnant and breastfeeding women | 600 IU |
Diagnosis
In general, the diagnosis of vitamin D deficiency is made through blood tests. A physician might order a 25-hydroxyvitamin D test if a patient complains of muscle and bone pain. This test is not part of a routine blood test.
Treatment
The treatment for vitamin D deficiency includes dietary changes to include foods rich in vitamin D like fish, milk, and milk products like ghee, paneer, orange, beef liver, cheese, etc. Along with this people are prescribed to take vitamin D supplements. Also, exposure to sunlight is also recommended to to obtain the daily dosage of vitamin D
Toxicity of vitamin D
Toxicity of vitamin D is a condition in which there are high levels of vitamin D in the body. This typically occurs, when someone takes vitamin D supplements. Because, the skin inhibits the overproduction of vitamin D during its natural synthesis. Symptoms of vitamin D toxicity are
- Nausea and vomiting
- Constipation
- Muscle weakness
- Irregular heartbeat occurs incase of very high dosage
- A high dose can lead to kidney failure
- High levels of calcium in blood
Conclusion
Vitamin D is one of the essential vitamins needed for the proper development and maintenance of bones and muscles. Also, vitamin D deficiency is associated with cardiovascular disease, cancer, and depression. The daily dosage can be easily reached with a diet and daily sun exposure.
Reference
1. https://my.clevelandclinic.org/health/diseases/15050-vitamin-d-vitamin-d-deficiency
2. https://www.ncbi.nlm.nih.gov/books/NBK532266/
3. https://medlineplus.gov/vitaminddeficiency.html
4. https://www.webmd.com/diet/vitamin-d-deficiency
5, https://emedicine.medscape.com/article/128762-overview?form=fpf
6. https://www.yalemedicine.org/conditions/vitamin-d-deficiency
7. https://www.ncbi.nlm.nih.gov/pmc/articles/P. MC2912737/
Krishnambal.S