WHY VITAMIN D IS NECESSARY
Apart from maintaining Bone health vitamin-D plays an important role in many other functions in the human body which can range from prevention of obesity, Cardiovascular diseases to the prevention of infections. Thus, Adequate levels of Vitamin-D are essential for the healthy functioning of the human body. In this article, we are going to study the various functions vitamin-D performs to keep our body healthy and functioning effectively
THE VARIOUS FUNCTIONS OF VITAMIN D
- VITAMIN-D AND BONE HEALTH:
- The most important and primary function of Vitamin D is the regulation of serum Calcium levels in the body. It is considered to be the essential factor for the proper absorption of Calcium from the intestine. Vitamin D and Parathyroid Hormone are the two most important regulators of Serum Calcium. Vitamin D also plays an important role in regulating adequate Phosphorous levels in the body. Vitamin D mediates the active absorption of calcium from intestines into the blood (serum).
- Calcium is actively as well as passively absorbed from the intestine. The active transport of calcium is carried out by a protein known as Calbindin, it attaches to the calcium and transports it across the intestines. Vitamin D is essential for the production of this Calbindin and hence it is the most important factor for calcium absorption.
- Whenever either calcium intake is low or vitamin D levels are lower than normal, the absorption of calcium is hampered &the serum calcium levels are reduced. To counter this, the parathyroid hormone is released from the parathyroid gland. This hormone shifts the calcium from our bones into the circulation. This leads to an increase in the serum (Blood) calcium levels and normalizes the effect of low calcium intake and vitamin D levels. Removal of calcium from our bones makes them weak & poorly mineralized. This leads to Rickets in small children and Osteomalacia and Osteoporosis in adults. As a result of this, the risk of fractures increases significantly.
The clinical manifestation of the Low Vitamin-D level is characterized by:
- Muscle pains
- Poor muscle strength
- Bone pains.
- Increase risk of Fractures
In children, Vitamin D deficiency causes Rickets, a disease that leads to soft bones with very poor bone mineralization.
- ROLE OF VITAMIN-D IN CARDIOVASCULAR DISEASE
A definite association between Low levels/deficiency of Vitamin D &cardiovascular disease has been established. A high percentage of persons deficient in vitamin D also had cardiovascular diseases. Low Vitamin D levels have been associated with left ventricular hypertrophy (Thickening of heart chamber) and abnormalities of renin-angiotensin system activation.
It is now proved that patients with vitamin D levels below the recommended 30 ng/ml have a higher blood pressure level. According to the ‘Health Professional Follow-Up Study at Harvard’: Men with Vitamin D deficiency are twice as likely to have a Heart Attack as men who had adequate levels of vitamin D”.
There have been many studies with the aim of establishing whether Low levels/deficiency of Vitamin D can also be considered to be a cause of cardiovascular diseases; but this fact has not been yet established, this needs further investigation.
- ROLE OF VITAMIN D IN OBESITY:
Vitamin D and obesity has been studied in quite some detail. Leptin is a hormone closely related to obesity. It has been labelled as the “obesity hormone” by some and as the “starvation hormone” by others. This hormone indicates satiety to the body and signals it to stop eating once an adequate amount of food has been ingested.
- More amount of Leptin is released in the body of individuals having normal Vitamin D levels than those who are deficient. This means that Vitamin D deficient individuals are at greater risk of obesity (insufficient leptin levels) than those having adequate Vitamin D levels.
- Reduced Vitamin D levels also develop insulin resistance leading to overeating and obesity.
- Reduced Vitamin D levels are associated with increased secretion of the Parathyroid hormone. Parathyroid hormone is known to reduce the rate of fat metabolism, thereby leading to obesity. Increased Parathyroid levels also cause a reduction in the speed of breakdown of the fat cell leading to obesity.
- ROLE OF VITAMIN D IN CANCER:
- A clear association between Vitamin D deficiency/insufficiency and Colon Cancer (Large Intestine) has been established and lower the Vitamin D levels, higher is the risk of developing colon cancer.
- Intake of 2000 IU/day of Vitamin D3, and, whenever possible, very moderate exposure to sunlight, could raise serum vitamin D levels to 52 ng/ml, a level associated with a reduction by 50% in the incidence of Breast Cancer.
- According to some clinical studies, there is a definite reduction in the all-cancer risk in postmenopausal women receiving calcium and vitamin D supplementation. The cancer specifically studied under this trial were Breast, Colon, Lung cancers and Bone Marrow/Lymphoma.
- ROLE OF VITAMIN D IN DIABETES MELLITUS:
- According to some observational studies, vitamin D supplementation in early childhood had reduced the incidence of Type 1 Diabetes Mellitus. However, these results are yet to be confirmed by further clinical studies.
- Inadequate vitamin D levels, insufficient exposure to the ultraviolet rays of the sun and low dietary intake of vitamin D have each been associated with an increased risk for the development of Type 1 diabetes mellitus.
- Low vitamin D levels lead to the development of insulin resistance, which indicates its association with Type 2 diabetes mellitus. Moreover, the risk of developing cardiovascular complications secondary to diabetes is also raised as a result of vitamin D deficiency.
- On the positive side, Vitamin D supplementation in patients having diabetes reduces the risk of having any major complication of the same.
- ROLE OF VITAMIN D IN PSORIASIS:
Psoriasis is an autoimmune disease primarily affecting the skin. Vitamin D supplementation has shown very promising results in the treatment of Psoriasis.
- ROLE OF VITAMIN D IN RESPIRATORY INFECTIONS:
- Vitamin D has been known to provide better immunity against respiratory infections. Children having Rickets(Vitamin D deficiency) were found to be more likely to have a frequent common cold and other respiratory infection.
- In adults with Vitamin D deficiency, the occurrence of the common cold was found to be significantly higher. On the other hand, the incidence of Influenza A was found to be reduced significantly in individuals having adequate Vitamin D levels either naturally or those receiving Vitamin D supplements.
- The role of Vitamin D deficiency in the development of tuberculosis is currently under study and the results of the trials are awaited.
- VITAMIN D & THE GERIATRIC POPULATION:
- As we have already seen above, Vitamin D is essential for normal mineralisation of bones and maintenance of their strength. In old aged individuals, osteoporosis is more common and hence the bones are already softer/weaker than normal (Young individuals). This coupled with many age-related co-existent co-morbidities further increase the risk of fractures. Falls are common in old age and are the most common cause of fractures.
- Vitamin D deficiency has been shown to increase the risk of falls as well as increase the risk fractures as a result of the falls. In the geriatric age group, a fall can have devastating results.
- The most common fracture suffered as a result of falls in the old age is the fracture of the neck of the femur. This fracture is notorious for the fact that the mortality rates of old persons having suffered a fracture neck femur are significantly higher than those who have not.
In this article, we have discussed why sufficient vitamin D is necessary for the well-being of our health. The deficiency/Low level of vitamin D is associated with significant health risk. Thus, it is important for us to make some cautious efforts and try to maintain a sufficient level of Vitamin D in the body. The next article in this series will guide you on how to maintain your Vitamin D levels and how to improve it in case of deficiency….