If you want to be healthy you should look through the usefulness of the vitamin D and include it into your nutrition.
Like many other vitamins which are preserved in certain foods vitamin D can be obtained not only from the UV rays of the sun but also from various food groups.
Vitamin D itself can’t give you great results because it should be chemically converted into dihydroxyvitamin D. This conversion is done by the kidneys and liver. This form of vitamin D is very beneficial for stimulating the absorption of calcium and phosphorus; creating strong bones. Along with other vitamins and minerals it assists in the mineralization of bones; keeps your immune system healthy; preventing rickets in children and osteomalacia in adults; controls the growth of cells.
A regular dose of vitamin D can be taken from fortified foods or regular food groups that have essential amount of vitamin D.
Here are some foods which are the great source of vitamin D:
Cooked mackerel and salmon
Canned tuna fish and sardines
Milk (whether whole milk, reduced fat milk, nonfat milk, or milk fortified with Vitamin D)
Margarine containing Vitamin D
Cooked beef and liver
Cereals and Vitamin Egg yolk (although eating the whole egg is advisable)
Swiss cheese
Sunlight
In spite of the fact that the main source of vitamin D is the sunlight, there are some factors which can have a negative impact on the synthesis of this vitamin in the skin, such as smog, pollution, cloud cover, time of the day when exposed, season and the use of sunscreen (sunscreen with at least an SPF 8 will inhibit the exposure to UV rays of the sun). To stimulate the synthesis of vitamin D your body should be exposed to the rays of sun not more than 10 minutes. You shouldn’t forget to use sunscreen with SPF 15 to protect your skin from harmful effects of the sun.
In order to maintain healthy bones you should take proper amount of the vitamin D.
 Here is a guide to daily consumption of the vitamin D given in International Units or IU according to the age groups:
children up to 13 years old should take 200 IU;
men and women who are 14 to 18 years old─200IU;
men and women aged 51 to 70 years old─400 IU;
men and women who are over 71 years of age─600 IU;
pregnant women 14 to 50 years old─200 IU;
lactating women 14 to 50 years old─200 IU.
Despite of the huge variety of foods including vitamin D the deficiency can be viewed among people of different age groups. The resons are: the absorption defects (problem with the kidney resulting to failure in conversion), improper diet, lack of sun exposure and increasing requirement of the Vitamin. In most cases people that suffer from the vitamin D deficiency are vegetarians, lactose intolerant or those who have dairy allergies.
Effects of Vitamin D deficiency
People with vitamin D deficiency can be prone to the bone-related diseases such as rickets (the deformation of bones). It has been proved that this disease can be treated by consuming up to 3 teaspoons of cod liver oil per day; osteomalacia (occurs in adults and is characterized by weak bones and muscles); osteoporosis (can be also a result of long term effects of deficiency of vitamin D). If you consume enough amount of vitamin D you will have lesser risks of getting osteoporosis.
However, if you take too much vitamin D it may be also harmful for your health and may cause vomiting, nausea, weight loss and constipation. If you take supplements you should be very carefull and follow all the recommendations on the bottle.
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