What is it?
Vitamin D is a vitamin which is found in small amounts in fatty fish like sardines, tuna, mackerel and herring. It is also fortified in food like cereals, juices and milk to increase the amount of vitamin D that can be obtained from food.
But most of of vitamin D we get, about 80-90% is derived from sunlight exposure. Sunlight is the easiest way and fastest way to replace vitamin D. 6 days of casual sunlight without sunblock is sufficient to to make up for 49 days of no sunlight. But amount of sunlight exposure is subjected to one's health condition and age.
Vitamin D is required by our body for the regulation of minerals like calcium and phosphorus which are required for the maintenance of proper bone structure.
There are ongoing research conducted to prove that it is effective for patient with low levels of phosphate ( fanconi syndrome and familial hypophosphatemia), hypoparathyroidism, osteomalacia patients who has brittle bones, psoriasis patients who benefit from topical vitamin D, renal osteodystrophy in kidney failure patients, rickets disease, vitamin D deficiency patients, osteoporosis caused by steroids and in elderly patients, cancer patients who may have vitamin D deficiency, rheumatoid arthritis and multiple sclerosis.
More randomized controlled research studies need to be conducted to prove other proclaimed benefits.
Possible side effects
At normal dosing it is likely safe for most people including children, pregnant and lactating woman. At very high doses of more than 4000 units daily is of course unsafe and cause side effects. Some possible side effects include fatigue, headache, loss of appetite, weakness, nausea, vomiting and dry mouth.
Aluminum in antacids: Vitamin D will increase the aluminium absorption hence it should be taken two hours apart.
Calcipotriene (Dovonex) which is a Vitamin D derivative when taken together with Vitamin D will increase the former effects and side effects.
Diltiazem, Verapamil, Digoxin: Taking vitamin D which regulates serum calcium level may increase th effects of these heart medications.
According to scientific research on Vitamin D dosing :
For preventing osteoporosis and fractures: 400-1000 IU per day has been used for elderly.
For preventing multiple sclerosis (MS): long-term consumption of at least 400 IU per day is required.
For preventing falls in elderly: 800-1000 IU/day has been used in combination with calcium 1000-1200 mg/day.
Most vitamin supplements contain only 400 IU (10 mcg) vitamin D.
The recommended daily allowance (RDA) based on age as follows:
Infants ages 0-12 months: 400 IU is recommended.
1-70 years of age: 600 IU daily
71 years and older, 800 IU daily
Pregnant and lactating women: 600 IU daily.