Why vitamin D not allowed to consume in higher doses?

Treating infection-prone patients over a 12-month period with high doses of vitamin D reduces their risk of developing respiratory tract infection and consequently their antibiotic requirement. 

Vitamin D is a group of fat-soluble secosteroids responsible for intestinal absorption of calcium and phosphate compounds. For human bodies, vitamin D is a good thing because it can be ingested as cholecalciferol (vitamin D3) or ergocalciferol (vitamin D2) and because the body can also synthesize it (from cholesterol) when sun exposure is adequate. 

Although vitamin D is commonly using by many people, it is not actually an essential vitamin for people on diet and surely in the strict sense. Besides that, it can be synthesized in adequate amounts by most mammals exposed to sunlight (cats and dogs cannot synthesize vitamin D and must receive it in their diet). An organic chemical compound (or related set of compounds) is only scientifically called a vitamin when it cannot be synthesized in sufficient quantities by an organism, and must be obtained people who are running diet. However, as with other compounds commonly called vitamins, vitamin D founded in an aiming to find the dietary substance that was lacking in a disease called rickets and on the childhood form of osteomalacia.  Additionally, the same as the compounds we called vitamins, and vitamin D was developing in addition to foods and drink, such as milk, to prevent from disease due to deficiency.

Measures of serum levels reflect endogenous synthesis from exposure to sunlight as well as intake in diet and it is believed that synthesis may contribute generally to the maintenance of adequate serum concentrations. The result indicates that the synthesis of vitamin D from sun exposure works in a feedback loop that prevents from the toxic, because of there are possibilities to made cancer risk from sunlight, have no issued by the Institute of Medicine, USA, for the amount of sun required to get vitamin D for the body. Accordingly, the Dietary Reference consumed for vitamin D that no synthesis occurs and that all of a person's vitamin D who running diet, although that will rarely occur in practice.

"Our research can have important implications for patients with recurrent infections or a compromised immune body, such as a lack of antibodies, and can also help to prevent the emerging resistance to antibiotics that come from consuming the vitamin in high dose," says Peter Bergman, researcher at Karolinska Institute. "In another side, nothing to support the idea that vitamin D would help otherwise healthy for normal people, and it caused infection the respiratory in a while.”

Vitamin D is synthesised in the skin through exposure to sunlight and obtained through some foods. In Europe, especially Sweden there are some cases variation in vitamin D in the blood, come through while making darker half of the year. The result study shown that low levels of vitamin D could increasing the risk of infection, and it has been known that the vitamin can also activate the immune in human body defence.

For the present study now published in BMJ Open the researchers examined whether treatment with vitamin D can prevent and relieve respiratory tract infections in particularly for infected patients. All the 140 participants from the Immunodeficiency Unit had symptoms of disease in their respiratory tracts for at least 42 days prior to the study. There are two groups for patient which chosen randomly, one of groups consuming vitamin D in relatively high doses, the other opposite that. They were also asked to keep a diary recording their state of health every day during the year-long study period.

The results show that symptoms of respiratory tract infection declined by almost a quarter and the use of antibiotics in half amount. Vitamin D treatment was tolerated well by all patients and gave no serious side-effects.

The effect of vitamin D in infecting respiratory still controversial, and recently major study from New Zealand published in the scientific journal found that it did not decrease the incidence or severity of viral respiratory infections. However, the present study is significantly different from the study in a simple respect, which could explain their different results. The scientific journal study examined a group of healthy people with initially normal levels of vitamin D in the blood, when it used on unstable dose (such large doses for sometimes), which is thought to be less effective that daily doses.

"However, the most important difference is probably due to the fact that our participants had much lower initial levels of vitamin D than those in the New Zealand." According from research by Dr. Anna-Carin Norlin and Dr Bergman. "The research show, there are same result from previous research that vitamin D supplements are only effective in patients who fall well below the level which recommended, and that it would be wise to check the vitamin D levels of patients with before human get infected." According by the researchers.

In healthy adults, sustained intake of more than 1250 micrograms/day (50,000 IU) could increase the risk of toxicity after several months, and those with certain medical conditions such as primary hyperparathyroidism are far more sensitive to vitamin D and develop hypercalcemia in response to any increase in vitamin D for human body nutrition, while some body part such as maternal hypercalcemia during pregnancy may increase fetal sensitivity to effects of vitamin D and lead to a syndrome like degradation in mentality and facial deformities.  For Pregnant or breastfeeding women should consult a medical treatment to doctor before consuming vitamin D as a supplement. For baby (birth to 12 months), the best consuming level (maximum amount that can be tolerated without harm) is set at 25 micrograms/day (1000 IU). One thousand micrograms (40,000 IU) per day in infants has produced toxicity within one month.