Toxicity, vitamin

Reported cases of vitamin toxicity owing to overdose are usually associated with increased over-the-counter availabiHty of supplemental vitamins and indiscriminate supplementation. The misconception that if a Httle is good a lot is better has compounded toxicological problems with the vitamins. Eat-soluble vitamins tend to accumulate in the body with relatively inactive mechanism for excretion and cause greater toxicological difficulties than do water-soluble vitamins. 

The k value depends on all sorts of things temperature, presence of trace elements, vitamins, toxic substances, light intensity, etc. 

Hypervitaminosis E. This is a relatively safe vitamin. Toxicities have been reported involving chronic administration of 300-1200 mg per day. The symptoms can be very serious and include thrombophlebitis, pulmonary embolism, hypertension, breast development in men and children, severe fatigue, and nonmalignant breast tumors. Nevertheless, the UL to RDA ratio is about 66 to 1 for adults, making it a very safe vitamin. 

Hypervitaminosis Riboflavin. The combination of regulated active transport and conversion to the coenzyme forms prevents hypervitaminosis problems with this vitamin. Toxicities from the water-soluble riboflavin phosphate have not been reported. There are... 

Some vitamins (A, D, E, and K) have very nonpolar molecular structures and therefore dissolve only in nonpolar solvents. In the body, the nonpolar solvents are the lipids we have classified as fats, so these vitamins are called fat-soluble. The fat-soluble vitamins have diverse functions in the body, and they act somewhat like hormones (Table 12.3). Care must be taken to avoid overdoses of the fat-soluble vitamins. Toxic effects are known to occur, especially with vitamin A, when excess amounts of these vitanfins accumulate in body tissue. Excesses of water-soluble vitamins are excreted readily through the kidneys and are not normally a problem. 

While this information appears to indicate minimal chances for vitamin toxicity to occur unless large amounts of vitamin... 

Generally, excesses In water-soluble vitamins are rapidly excreted. Until recently little concern was directed to water-soluble vitamin toxicity however, as this publication will show, there Is substantial reason for concern and research. Even now research Is beginning to associate some side effects with excess Intakes of the water-soluble vitamins. 

Think Aix>ut It Elimination of vitamin C causes the urine to be more acidic, which can inhibit the growth of some bacteria responsible for urinary tract infections. Taking laiger doses than the official recommended daily amount of 60 mg is recommended by many physicians to lower the incidence of such infections. Fat-soluble vitamins cannot be eliminated in this way, and taking too much can lead to vitamin toxicity. 

Vitamin overdoses (hypervitaminoses)— The best known vitamin toxicities are those which result from vitamin A and vitamin D, because (1) these vitamins are fat soluble, (2) small amounts of them have strong effects, and (3) they tend to accumulate in the liver. Toxic effects do not occur so readily with vitamins E and K, which are also fat-soluble, unless high potency supplements are taken. 

Additional information on vitamin toxicities is provided in the general article on vitamins and in the separate articles dealing with the individual vitamins. 

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