International Journal for Vitamin and Nutrition Research. Supplement

With a normal and varied food intake, the vitamin supply is often sufficient to avoid vitamin deficiency. Since synthetic vitamins have become available, it has become possible to take with one dose the amount of vitamins normally taken up from food in one year. In these pharmacological doses vitamins must therefore be considered as drugs. And in pharmacological doses, their actions are often different and not directly linked to their physiological activity. Two types of pathologic state are unquestionably the concern of vitaminotherapy: More or less specific and intense vitamin deficiencies: Rickets, scurvy, beri beri, pellagra, vitamin deficiency related to alcohol consumption, polyneuritis, encephalopathy, malabsorption, mucoviscidosis, etc...

Concepts of vitamin B6 megatherapy are classified in three categories: 1. megatherapy with well-known mechanism of action; 2. megatherapy with hypothetical or unknown, but nevertheless plausible mechanism of action; 3. megatherapy on the basis of pure speculation. Examples of all three categories are shown. The dosages applied extend from 100 mg up to several grams; the duration of treatment varies from weeks to several years. After long-term intake of high doses toxic effects can occur in the form of peripheral sensory neuropathy, in two reported cases combined with a subepidermal vesicular dermatosis...

On the basis of the reviewed information it is considered that the vitamins can be divided into two broad categories. a) Those with a safety level at least 50-100 times the RDA and no clear indication of serious adverse reactions above the level. This level should be adequate to match any required pharmacological dose, and these vitamins should be regarded as safe for elevated dose use, not necessarily controlled by doctors. b) Those with a safety ratio of about 10 times, often influenced by the health status of the individual or those with serious irreversible adverse reactions...

N-Nitroso compounds are known to form endogenously in the human stomach from the precursors nitrite as well as secondary and tertiary amines. Ascorbic acid has been found to be an effective blocking agent for this process of formation of carcinogenic substances, both in vitro and in vivo. The mechanism by which ascorbic acid reacts is chemical in nature and results in the formation of NO and dehydroascorbic acid. Since NO can be recycled in the presence of O2 to form [NO]x, which is capable of additional nitrosation, greater than stoichrometric amounts of ascorbate are required for effective inhibition in vivo...

Iron requirements remain the same despite the current lower energy requirement. This means that more iron must be absorbed per unit energy. A higher bioavailability of the dietary iron can be achieved by increasing the content of food components enhancing iron absorption (ascorbic acid, meat/fish) or by decreasing the content of inhibitors (e.g., phytates, tannins). The latter is not feasible considering the recent and reasonable trend toward increasing the intake of dietary fibre. The key role of ascorbic acid for the absorption of dietary nonheme iron is generally accepted...

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