Vitamin D3 (cholecalciferol)
What role does it play in the organism?
Its most important function is to maintain the calcium balance: it helps calcium absorption and inhibits its excretion, thus ensuring the adequate calcium level in the blood, in other words the presence of the adequate level of calcium at all times essential for bone formation. Lately, vitamin D has been increasingly referred to as hormone D, because it was proven to have a hormone-like effect in nearly each tissue of the body (e.g. it influences the functioning of the thyroid gland, the pancreatic gland and the ovary).
What foodstuffs contain it?
Good dietary sources of vitamin D are milk and diary products, eggs and liver. It is important to note that vitamin D3 is produced also in the skin when exposed to the ultraviolet rays of sunlight.
Who are exposed to vitamin D deficiency and what does this deficiency state cause?
The most frequent reason for the deficiency state is the inadequate dietary intake, the lack of sunshine, but chronic liver and kidney diseases might also be found in the background. Children are considered a group at risk, but it has also been found lately that the vitamin D supply of the adult, mainly of a significant ratio the older generation is not sufficient either. The deficiency disease of vitamin D is rickets in children and osteomalacia in adults. Both diseases can be characterised by bone changes and deformations.
What is the recommended intake for vitamin D3?
The recommended daily intake is 400 IU (=10 micrograms) for both children and adults. Yet, the requirement can be as high as 600-800 IU a day for older people depending on their diet and exposure to the sun.
What are the health risks of excessive vitamin D3 intake?
The intake of 40000 IU/day for children and 100000 IU/day for adults (100-250 times the daily recommended allowance) for months leads to an overdose, manifested in an increased level of calcium in the blood, pathological calcium accumulation and kidney impairment. As seen here, vitamin D overdose is possible only with intakes much higher than the recommendation, except for some special cases.
