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The importance of the sunshine vitamin

Published On: November 17, 2017 10:01 AM NPT By: Dr. Kamakshya Shah

Vitamin D deficiency and diabetes mellitus are two common conditions that are widely prevalent across all ages, races, geographical regions, and socioeconomic conditions. With all the medical advances of past century, deficiency of vitamin D3 also known as the ‘sunshine vitamin’ is still epidemic. This is due to less outdoor activities as most people do deskbound jobs in this digital day and age and wearing sun protection that limits their ability to make vitamin D in the skin.

Vitamin D deficiency can limit daily activities by causing fatigue, bone and joint pain, muscle weakness, increased incidence of infections, increased risk of falling, depression, while chronic deficiency can result in heart disease, hypertension, obesity, osteoporosis, cancer and type 2 diabetes. Among nutritional factors, vitamin D is likely to have a crucial role either in glycemic control or in reducing diabetic complications. In those people who have optimum level of vitamin D there is 48% reduced chance of developing type 2 diabetes.  I’m here to brief you about vitamin D and its benefits. 

First of all, what is vitamin D?

Vitamin D is a fat-soluble vitamin and is a steroid with hormone like activity that promotes calcium and phosphorous absorption in the gut. It plays a number of important roles in the body, including maintaining good health of bones, teeth, and joints and as well as assisting various immune system functions. 

What are the sources of vitamin D?

Vitamin D comes in two forms. Vitamin D2 is found naturally in sun exposed mushrooms. Vitamin D3, which is the major source of vitamin D (50-90%), comes from exposure of the skin to natural sunlight. Very few foods like cod liver oil, egg yolk, fatty fish (salmon, sardines, mackerel etc) naturally contain vitamin D3. Thus, the major cause of vitamin D deficiency is inadequate exposure to sunlight. 

Both vitamin D2 and vitamin D3 are used for food fortifications and in vitamin D supplements. But studies have shown that vitamin D3 appears to be more than three times as effective as vitamin D2, so while buying supplements or foods fortified with vitamin D, make sure the vitamin content of the item is D3.  

Who are at risk of vitamin D deficiency?

Children, adolescence, adults and elderly, including pregnant women, obese people, patients having malabsorption syndromes and on a wide variety of medications like anticonvulsants, steroids, HIV/AIDS treatment etc are at high risk for vitamin D deficiency and insufficiency worldwide. In our part of the world, people residing in crowded areas of Kathmandu like Ason and Indrachok are more prone to the deficiency due to limited sun exposure besides those whose jobs demand them to stay bound to a desk all day long. 

Wearing a sunscreen with a sun protection factor (SPF) of 30 reduces vitamin D synthesis in the skin by more than 95%. People with naturally dark skin tone have natural sun protection and require at least three to five times longer exposure to make the same amount of vitamin D as a person with a white skin tone. 

How does vitamin D deficiency increase the risk of diabetes?

Vitamin D improves insulin sensitivity and thus reduces the risk of insulin resistance, which is often a precursor of type 2 diabetes. This vitamin also improves the production of insulin by the pancreas. Moreover, good vitamin D status actually aid weight loss by enabling you to eat less and feel more satisfied by increasing the level of hormone called leptin. It also helps to reduce parathyroid hormone and cortisol (stress hormone) level that in turn reduce the risk of obesity which is a major risk factor of type 2 diabetes.

How can you prevent vitamin D deficiency?

Recommended daily allowance of vitamin D is 600IU per day and for people more than 70 years it is 800IU per day. Blood level of vitamin D should ideally be between 30-100ng/ml.

A major source of vitamin D comes from exposure of the skin to sunlight typically between 10 am to 3 pm in the spring, summer and fall. To prevent its deficiency one should spend 15 to 20 minutes in the sunshine with 40% of skin surface (face, upper limbs and lower limbs) exposed. Vitamin D produced in the skin may last at least twice as long in the blood as compared to ingested vitamin D. Supplementation of vitamin D3 maintains the blood level of vitamin D in the long run, especially during winter when sunlight is scarce.

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