All you wanted to know about Vitamin D

Why is vitamin D important?
The main action of vitamin D is to help calcium and phosphorus — essential for the structure and strength of our bones — in our diet to be absorbed from the gut. Scientists have found that vitamin D may help prevent diseases such as cancer, diabetes and heart ailments.

Vitamin D is a fat-soluble vitamin. The fact that it dissolves in fat is important, because it means the body can store it for future use. Ultraviolet B (UVB) in sunlight rays convert cholesterol in the skin into vitamin D.

What are the symptoms of vitamin D deficiency?
Many people have no symptoms, or only vague ones such as tiredness or general aches. Because symptoms of vitamin D deficiency are often very non-specific, the problem is often missed. The diagnosis is more easily reached in severe deficiencies with some of the classical (typical) symptoms and bone deformities. Symptoms in adults:

• General vague aches and  pains.
• In more severe deficiency, there may be more severe pain and also weakness. This may lead to difficulty in standing up or climbing stairs, or can lead to the person walking with a ‘waddling’ pattern. This is known as osteomalacia.
• Pain in the ribs, hips, pelvis, thighs and feet.

How much vitamin D do I need?
Our daily requirement is being increased depending on newer research. A few years ago, 400 iu was thought to be all we needed, but now for adults around 2000 units is considered good for health.

Which foods contain vitamin D?
Surprisingly few foods contain vitamin D. This is because the human body is built to get vitamin D through the skin (from sunlight).
There are three vitamin D super foods: salmon, mackerel, mushrooms exposed to ultraviolet light. Other food sources of vitamin D include: cod liver oil, tuna canned in water, sardines canned in oil, milk or yogurt — regardless of whether it is whole, non-fat, or reduced fat — fortified with vitamin D, beef or calf liver, egg yolks, cheese.

Who gets vitamin D deficiency?
A significant percentage of us are becoming vitamin-deficient. This is mainly due to our indoor lifestyle, our dresses, the use of burqa in Muslim women, our skin colour.

Particularly vulnerable are growing children, pregnant and breast-feeding women, those in hospital for a long time, or housebound people, people using a lot of sunscreen (sun-protection factor — 15 or above), elderly people (due to thinner skin than younger people) and those with some medical conditions like Crohn’s disease, coeliac disease, liver and kidney disease.

How is deficiency diagnosed?
It may be suspected from your medical history, symptoms or lifestyle. A simple blood test for vitamin-D level can make the diagnosis. Blood tests for calcium and phosphate levels may also show changes linked to a low level of vitamin D.

—Dr Swaraj W, Dr Shaila B and Dr Arpandev Bhattacharyya, Department of Diabetes and Endocrinology, Manipal Hospital, Bangalore