Vitamin D is the ‘vitamin of sunshine’. The main function of vitamin D is to maintain the level of calcium and phosphorus in the blood by stimulating the intestines to absorb more calcium and phosphorus from the food we eat. If you do not take enough calcium, the body will borrow it from the bones and over the years that will cause osteoporosis. Recent researches indicate that vitamin D may have other functions and may protect the body from many diseases like cancers, heart disease, high blood pressure, hair loss, diabetes and others.
What are the sources of vitamin D?
The main source of vitamin D is the exposure to the sun (90%) and there are a few types of food that have vitamin D such as fish (sardines, tuna, salmon, mackerel), fish oils, liver, egg yolk and some types of milk and dairy products that are supplemented during production with vitamin D.
Surprisingly, most people living in sunny areas do not get adequate vitamin D, and this is attributed to the use of protective sun lotions, avoidance of direct sun exposure and the nature of clothing that covers most of the body.
Vitamin D also comes in the forms of tablets, capsules, syrup and injections, and adults may need to take 800-2000 IU daily and should see a doctor to determine appropriate doses. Usually we prescribe large doses during the early months of treatment, especially if the vitamin D level is very low, following which we prescribe a smaller dose at weekly, monthly or other intervals.
To get enough vitamin D from the sun, you need at least to expose arms, hands and face to the sun for 10 to 30 minutes two or three times a week, if there is no contraindications such as skin disease or skin cancer. Exposure time depends on the sensitivity of the skin to sunburn and exposure time during the day and you will need to expose the skin directly to sunlight and not behind glass. You may need to increase the duration if you have dark skin (the best time of the day early morning and late afternoon - try to avoid the peak time of the sun).
VITAMIN D DEFICIENCY
What is calcium?
Calcium is an important mineral in the body and has many functions, including building bones and teeth and controlling the functions of the heart, muscles and nerves. Most of the calcium (99%) is present in the bones and the body gets its needs from dairy products (cheese, milk and yoghurt), spinach, broccoli, sardines, almonds or calcium tablets. An adult needs from 1000-1200 mg of calcium per day. We advise to have low fat milk and milk products twice a day (if there is no lactose intolerance) and also to take one calcium tablet daily.
Calcium in the body is controlled by Vitamin D which helps to absorb calcium from the intestine and parathyroid hormone which comes from parathyroid glands (four glands located behind the thyroid gland in the lower neck). These help in withdrawing calcium from the bones in cases of low calcium or vitamin D. Lack of vitamin D and calcium will increase the parathyroid hormone, which overtime will weaken the bones and causes eventually osteopenia or osteoporosis.
What are the symptoms that are caused by lack of vitamin D?
Lack of vitamin D will cause low calcium and phosphorus, which affects the bones and teeth.
In children it may cause rickets, which can delay growth and the appearance of the permanent teeth and also may cause deformities in the bones. In adults lack of vitamin D will go for many years undiagnosed (silent) and eventually will lead to thinning and weakening of the bones (osteopenia and osteoporosis), which could lead to fractures and muscle weakness.
How to diagnose vitamin D deficiency?
Given the prevalence of vitamin deficiency, it is advised to get a blood test to measure it on a regular basis at least annually if you have normal levels.
What are the reasons for vitamin D deficiency?
- The main reason for a lack of vitamin D is the lack of exposure to sunlight (long stays inside homes or offices or the nature of the clothing that covers most of the body or going out after sunset)
- Lack of eating foods that contain vitamin D
- Dark skinned people can suffer from a lack of vitamin D more than others as they need longer periods of sun exposure to form vitamin D
- People over 50 years of age are more likely to lack vitamin D, as the skin becomes less efficient in making it
- Inborn problem in the function of vitamin D or problems in making it in the body as a result of liver diseases, kidney diseases or parathyroid glands hormone deficiency
- Lack of absorption in cases of chronic diarrhoea or cases of malabsorption
- The use of some medications for long periods of time, such as some epilepsy drugs
- Obesity and being overweight
Is it possible to overdose on vitamin D?
No overdose of vitamin D is possible from sun exposure, however taking a large amount of vitamin D through oral or injectable forms may lead to an increase in vitamin D levels and may subsequently increase calcium in the blood and the urine, leading to nausea, loss of appetite, headache, constipation, discomfort, fatigue and kidney stones.
It is advisable to have blood tests at least twice per year to determine the level of calcium and vitamin D if you are on treatment.
People who have Sarcoidosis (lung disease), tuberculosis or hyperparathyroidism accompanied by an increase of calcium or people who suffer from kidney stones should take vitamin D only after consulting their doctor to determine the doses suitable for them.