Role of Vitamin D

There are a number of essential elements that are an important part of the human body. Vitamins, calcium,

minerals and carbohydrates are some of these elements. Each element is beneficial in its own way and Vitamin D is no exception. It is a chemical that aids in the transfer of calcium obtained from the digested food, into the blood, which in turn helps in keeping the bones strong. Vitamin D is also beneficial as it reduces inflammation and strengthens the immune system. Calcium and phosphate are very essential for the smooth and proper functioning of the nervous and muscular system, and Vitamin D is helpful in its absorption.

Before moving on to discuss the sources of Vitamin D, there is a need to understand the importance of Vitamin D, in a human body. The deficiency of this Vitamin in the body can pose a major health risk. In children, the deficiency of Vitamin D causes ‘Rickets’. This is a degenerative disease of the bones, causing them to be become deformed. In adults, Vitamin D deficiency leads to ‘Osteomalacia’. Due to this disease, the bones become weak with continuous pain, and frequent bone fractures. Hence, vitamin D is very important for both adults and children.

Vitamin D Sources

Consuming vitamin D enriched foods and supplements

Exposing one self to the sun

I. Vitamin D Enriched Foods

Vitamin D can be obtained by consuming foods enriched with Vitamin D. Under this category, there are fortified foods, animal foods and plant foods.

Animal sources

In the case of animal foods, vitamin D3 is abundant and naturally present in fishes. Fish oil and Fish liver are the natural sources rich in Vitamin D. Other natural sources of vitamin D are beef liver and egg yolk.

Plant sources

A few plants are known to contain Vitamin D and that too in small quantities. They contain ergocalciferol or D2 variety of Vitamin D.

Fortified Foods and Beverages

The best sources of vitamin D, besides exposure to the sun are the fortified foods and beverages. Examples of this source are milk, soy drinks, margarine, cheese and fortified rice. Some countries like the UK and the US, allow the addition of vitamin D3 to milk, morning cereals, margarine and orange juices thus making them fortified products containing prescribed amount of Vitamin D.

The following tables broadly explain how much vitamin D is contained in each food category:

Table1. Natural foods enriched with Vitamin D

Table2. Fortified foods enriched with Vitamin D

* IU: International Units

**DV: Daily value – the Food and Drug Administration have developed reference numbers that aid in determining the quantity of nutrients contained in a food.

II. Sunlight

Sunlight is an important source of Vitamin D and hence sometimes this vitamin is termed as Sunshine vitamin. When the skin is exposed to sunlight, the ultraviolet rays cause the skin to produce vitamin D. The process of vitamin D production involves the conversion of a chemical in the cholesterol of the skin to vitamin D3 or cholecalciferol. This is further converted to calcitrol – an active vitamin D form, first in the liver and in the kidneys later.

Many factors like geographic location, season, cloud cover, smog and pollution, time of the day and sunscreen affect the synthesis of Vitamin D in the skin. If the body is producing excess amount of vitamin D on account of geographical location, then the fatty tissues store the excessive vitamin D. exposure to the sun is recommended twice a week for just ten to fifteen minutes. This would ensure a healthy supply of Vitamin D to the body. If the exposure to sun is limited, adequate food supplements should be added to the diet to ensure adequate Vitamin D absorption.

How Much Vitamin D Is Recommended?

Actually speaking, there is insufficient information to recommend what the ideal intake for Vitamin D should be. However, following is a list that indicates the Adequate Intake (AI). This intake is sufficient in maintaining healthy bones and normal metabolism of calcium and phosphate.

Table3. Daily Adequate Intake of Vitamin D

Conclusion

Although there are a number of fortified products are available to fulfill the dietary demands of Vitamin D, still the natural sources are considered better than their fortified counterparts. Also, it is important to support the vitamin D intake with adequate amount of magnesium and calcium as the three supplements complement each other and are beneficial for the overall good health. As per the table signifying the daily intake adequate for healthy well-being, efforts should be made to provide enough vitamin D to those brackets of the society which are mal-nutritioned and prone to diseases.