Vitamins. Have side effects doses?

Vitamins are defined as "natural constituents of food ... essential to life and welfare of animals and man. It must be inferred that its ingestion in amounts equivalent to those found in a normal mixed diet should be more beneficial than harmful. Therefore, an intake level at which play their role as vitamins, adverse reactions are unknown except in some rare clinical disorders.

Over the past twenty or thirty years, known records as to the safety and benefits of vitamin use have led to the administration of high doses, often with dramatic therapeutic benefits. In some cases, the intakes have reached very high levels. Consequently, cases of adverse reactions to vitamins occasionally appear in the press, with supporting evidence ranging from the anecdotal and scientific.

This information, in turn, are frequently propagated by authors in good faith without any details of the case and without any scientific basis, which further increases the credibility. At the same time, international big wave of consumerism has generated greater interest in the safety of all natural and manufactured products, among which include the ingredients of foods and medicines.

The difficulty of vitamin safety studies
The description of a vitamin safety covering all possible circumstances is very difficult if not impossible.

First, there are natural differences from one to another individual. A variation of activity curve fit "normal" is a characteristic of all living creatures. Besides, we do not take into account the additional variations imposed by the idiosyncrasy, hypersensitivity, for example, food allergies, gluten enteropathy and so on., Or diseases, such as the liver or kidney. Therefore, not surprisingly, is big enough dissemination of information about vitamin levels that have been reported as leading to adverse reactions.

Second, the period of ingestion and the rate of intake of vitamins differ. At one end of the spectrum is the daily consumption of foods fortified with vitamins for the majority of the population, at the opposite end, the prescription of high dose therapy for a limited period for a specific disease, which are monitored and controlled carefully and directly by the Health Professional: between these two extremes we find ourselves with a wide range of different forms of self-medication.

This monograph is oriented in the sense of trying to find a definition for safety standards for fortified foods and supplementation self-administered. Only indirectly relates to prescription cases under supervision, since the Health Professional, as a connoisseur of the specific disease and possible adverse reactions, he knows exactly how to judge the response of each individual patient. Therefore, the focus of this work is aimed at defining, based on experimental research and epidemiological levels, what factors can cause adverse reactions in order to suggest a safe level for daily intake prolonged. This evaluation is not considered the rationalization of high doses in terms of security vitamin. Therefore, the expression of a high safe dose should not be considered as a reference to its therapeutic value.

Reference range for a studio. RDA
Another problem is posed, the researcher of safe levels of intake of a vitamin is the baseline from which shall be set in different dosages. Traditionally, the main reference point is the recommended daily intake for the average adult. Unfortunately, even these figures are not fully recognized internationally. The recommended level of dietary intake of each vitamin has been investigated by groups of experts in many countries. There may be differences between the level four times higher and the lowest recommended, although many of these levels fall within a much narrower band.

One of the best documented and most widely accepted of all these national research is conducted in the United States by the National Research Council, the Food and Nutrition Board (Food and Nutrition), published as tolerances Recommended Dietary Allowance (RDA: Recommended Dietary Allowances), in its latest edition DE 19802. Given the absence of an internationally recognized standard, we will use these figures as a starting point of reference.

What research shows
Given this background, what are the facts about safety? Are well-founded fears about toxicity? Are vitamins as safe as we have been thinking?

Some years ago two prestigious scientific panels examined the issue. The first was a commission "ad hoc" established by the Food and Drug Administration (FDA: Food and Drug Administration) to conduct a study on vitamin and mineral products contained in medicines for human use without a prescription. This committee reviewed the available scientific evidence and expert testimony sought from both industrial and community científicas3 academics. The second study, prepared for the FDA, was conducted by the Office of Scientific Research of Life (Life Sciences Research Office) of the North American Federation of Experimental Biology (Federation of American Societies for Experimental Biology). This research was very focused particularly on the factilidad identification of adverse effects to health, both in vitamins and in minerals, especially in relation to "individuals who use dietary supplements without medical supervision, the test subjects experimental treatment with large doses of nutrients and certain medical conditions and subgroups of the general population who consume diets with an unusual or restricted composition of nutrients. "
Since these reports are of many years, you should consider whether their conclusions about the safety of vitamins in the broadest sense can be kept to a critical analysis and this is what it comes to bringing out this document. Based on the analysis of both the original documents as more general reviews recientes3-13, can make the following general conclusions:

There is no internationally accepted standard satisfactory in terms of the recommended intake of vitamins. Given the absence of an international standard, RDA applied in the United States have been adopted as a basis. These levels are safe by definition.

Research findings about the risks of high doses
The levels of vitamins that normally eats most of the general population in diets and the multi-vitamin supplements, whether on prescription or purchased over the counter, not normally exceed the RDA for an extended period and, therefore, are safe. A small proportion of the population consume vitamins at high levels. In some cases, they do so under the direction of your Healthcare Professional who knows why they do. The risk of adverse reaction appears to be greatest when excessively high doses are taken without professional assistance.

There is a substantial safety margin for most of the vitamins, since very few side effects attributable to the administered dose vitamin levels even substantially above the RDA.

This margin is particularly true for water-soluble vitamins except vitamin B6. When taken orally, the excess can not be used or is not absorbed or is rapidly excreted in the urine.

It takes forever and in any case special precautions during the prolonged treatment of parenteral nutrition.

With the exception of any adverse reactions after excessive ingestion of long duration and vitamins A, D and B6, side effects of vitamins, when present, are rapidly reversed by removing the supplementation, and leave minimal impact or usually nothing lasting.

Values of the RDA for men 23 to 50 years of age and their relationship "High Security" / RDA

RDA                                Vitamin                            Security Level
1.4 mg                         Thiamin (B1)                          over 100          
1.6 mg                         Riboflavin (B2)                       over 100
18 mg                          Niacin (B3)                         NE about 100
4-7 mg                  Pantoténico1 acid (B5)                over 100
2.2 mg                       Pyridoxine (B6)                            100
400 ug                       Folic acid (B9)                           over 50
3 ug                             Vitamin B12                             over 100
60 mg                           Vitamin C                              about 100
100-200 ug                  Biotin (B7)                              over 100
5 ug (200 IU)                Vitamin D                                about 10
10 mg-TE (15 IU)         Vitamin E                                over 100
70-140 ug                    Vitamin K                                 over 50
1000 ug RE2                Vitamin A                               around 10 *

about 3 **

NE = Niacin equivalent in

RE = Retinol Equivalence in

TE = Tocopherol

1 = estimate of a safe and adequate level instead of RDA, due to limited available evidence.

2 = is the equivalent of 3333 IU of retinol or 5000 IU vitamin A diet.

* = Relationship between the levels are still considered safe in the vast majority of adults and RDS Standard.

** = Women of childbearing age.

Source: Lamberts medicines.

*Automatic Translation